WT/DS381/RW  
 
14 April 2015  
(15-1969)  Page: 1/143  
  Original: English  
 
 UNITED STATES – MEASURES CONCERNING THE IMPORTATION, 
MARKETING AND SALE OF TUNA AND TUNA PRODUCTS 
RECOURSE TO ARTICLE 21.5 OF THE DSU BY MEXICO 
REPORT OF THE PANEL 
 
 WT/DS381/RW 
 
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  TABLE OF CONTENTS 
 
1  INTRODUC TION .................................................................................................. 9  
1.1  General .............................................................................................................. 9  
1.2  Request for enhanced  third-party rights .................................................................. 9  
1.3  Background of the dispute .................................................................................... 10 
2  PARTIES' REQUESTS FOR FI NDINGS AND RECOMMENDATIONS ........................ 11  
3  OVERVIEW OF THE MEASURE AT ISSUE ............................................................ 11  
3.1  The Dolphin Protection Consumer Info rmation Act and its Original Implementing 
Regulati ons ........................................................................................................ 12 
3.2  The 2013 Final Rule ............................................................................................. 18 
4  ARGUMENTS OF THE PARTIES ........................................................................... 21  
5  ARGUMENTS OF THE THIRD PARTIES ................................................................ 21  
6  INTERIM REVIEW ............................................................................................. 22  
6.1  Genera l issues .................................................................................................... 22 
6.2  Specific issues .................................................................................................... 22 
6.2.1  Evidence concerning observable and unobservable harms caused by different 
fishing methods .................................................................................................. 22 
6.2.2  Description of the Appellate Body's finding on observed and unobserved harms 
caused by setting on dolphins as compared with other tuna fishing methods ................ 22 
6.2.3  Mexico's evolving argument on the different observer requirements under 
Article 2.1 of the TBT Agreement ........................................................................... 23 
6.2.4  Evidence conc erning log-books ............................................................................. 23 
6.2.5  Tracking and ve rification systems .......................................................................... 23 
6.2.6  The Panel's description of Mexico's argument on less favourable treatment ................. 24 
6.2.7  Regulated vs. unregulated setting on dolphins ......................................................... 25 
7  FINDIN GS ......................................................................................................... 26  
7.1  Claims ............................................................................................................... 26 
7.2  Order of analysis ................................................................................................. 26 
7.3  Parameters of the Panel's mandate: the measure at issue and the scope of 
these Article 21. 5 proceedings .............................................................................. 27 
7.4  Burden and standard of proof applicable in th ese proceedings ................................... 35 
7.4.1  Burden of proof .................................................................................................. 35 
7.4.2  Standard of proof ................................................................................................ 38 
7.5  Article 2.1 of the TBT Agreement ........................................................................... 40 
7.5.1  Legal test under Article 2.1 of the TBT Agreement ................................................... 40 
7.5.2  Application of Articl e 2.1 of the TBT Agreement ....................................................... 47 
7.5.2.1  Mexi co's cl aim .................................................................................................... 47 
7.5.2.2  The eligibility criteria ........................................................................................... 49 
7.5.2.3  Mexico's remaining claims of less favourable treatment: the different 
certification and tracking and verification requirements ............................................ 56 
7.5.2.4  The different cert ification requirements .................................................................. 58 WT/DS381/RW 
 
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  7.5.2.5  The different tracking and verification requirements ................................................. 84 
7.6  Claims under the GATT 1994 .............................................................................. 106  
7.6.1  Article I:1 of  the GATT 1994 ............................................................................... 106  
7.6.1.1  Legal test ........................................................................................................ 10 6 
7.6.1.2  Application ....................................................................................................... 10 8 
7.6.2  Article III:4 of the GATT 1994 ............................................................................. 117  
7.6.2.1  Legal test ........................................................................................................ 11 7 
7.6.2.2  Application ....................................................................................................... 11 9 
7.7  The United States' defence under Article XX of the GATT 1994 ................................. 122  
7.7.1  Article XX(g) .................................................................................................... 122  
7.7.1.1  Legal test un der Article XX(g) ............................................................................. 122  
7.7.1.2  Application ....................................................................................................... 12 4 
7.7.2  Article XX(b) .................................................................................................... 128  
7.7.3  The chapeau of Article XX .................................................................................. 129  
7.7.3.1  Legal test under th e chapeau of Article XX ............................................................ 129  
7.7.3.2  Relationship between the chapeau of Article XX of the GATT 1994 and 
Article 2.1 of the TBT Agreement ......................................................................... 130  
7.7.3.3  Application ....................................................................................................... 13 2 
8  CONCLUSIONS AND RECOMMENDAT IONS ....................................................... 141  
 WT/DS381/RW 
 
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  LIST OF ANNEXES 
 
ANNEX A 
WORKING PROCEDURES OF THE PANEL 
Contents Page 
Annex A Working Procedures of the Panel A-1 
ANNEX B 
ARGUMENTS OF THE PARTIES 
MEXICO 
Contents Page 
Annex B-1 Executive summary of the first written submission of Mexico  B-2 
Annex B-2 Executive summary of the second written submission of Mexico B-14 
Annex B-3 Executive summary of the opening oral  statement of Mexico at the meeting of the 
panel  B-21 
 
 
UNITED STATES 
Contents Page 
Annex B-4 Executive summary of the first written submission of the United States B-26 
Annex B-5 Executive summary of the second written submission of the United States B-34 
Annex B-6 Executive summary of the opening oral statement of the United States at the 
meeting of the panel B-42 
ANNEX C 
ARGUMENTS OF THE THIRD PARTIES 
Contents Page 
Annex C-1 Executive summary of the third-party submission of Australia C-2 
Annex C-2 Executive summary of the oral statement of Australia at the meeting of the panel, 
and responses to Panel questions C-6 
Annex C-3 Executive summary of the th ird-party subm ission of Canada C-8 
Annex C-4 Executive summary of the oral statement of Canada at the meeting of the panel C-11 
Annex C-5 Integrated executive summary of the arguments of the European Union C-13 
Annex C-6 Executive summary of the thir d-party submission of Japan C-18 
Annex C-7 Executive summary of the oral statem ent of the Republic of Korea at the meeting 
of the panel C-22 
Annex C-8 Integrated executive summary of  the arguments of New Zealand C-24 
Annex C-9 Executive summary of the thir d-party submis sion of Norway C-28 
Annex C-10 Executive summary of the oral statement of Norway at the meeting of the panel C-31 
 
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  CASES CITED IN THIS REPORT 
Short Title Full Case Title and Citation 
Argentina – Textiles and 
Apparel Appellate Body Report, Argentina – Measures Affect ing Imports of Footwear, 
Textiles, Apparel and Other Items , WT/DS56/AB/R and Corr.1, adopted 
22 April 1998, DSR 1998:III, p. 1003 
Brazil – Retreaded Tyres Appellate Body Report, Brazil – Measures Affecting Imports of Retreaded 
Tyres , WT/DS332/AB/R, adopted 17 December 2007, DSR 2007:IV, p. 1527 
Canada – Aircraft 
(Article 21.5 – Brazil) Appellate Body Report, Canada – Measures Affecting the Export of Civilian 
Aircraft – Recourse by Brazil to Article 21.5 of the DSU , WT/DS70/AB/RW, 
adopted 4 August 2000, DSR 2000:IX, p. 4299 
Canada – Autos Appellate Body Report, Canada – Certain Measures Affecting the Automotive 
Industry , WT/DS139/AB/R, WT/DS142/AB/R, adopted 19 June 2000, 
DSR 2000:VI, p. 2985 
Canada – Autos Panel Report, Canada – Certain Measures Affe cting the Automotive Industry , 
WT/DS139/R, WT/DS142/R, adopted 19 June 2000, as modified by Appellate Body Report WT/DS139/AB/R, WT/DS142/AB/R, DSR 2000:VII, p. 3043 
Canada – Wheat Exports and 
Grain Imports Appellate Body Report, Canada – Measures Relating to Exports of Wheat and 
Treatment of Imported Grain , WT/DS276/AB/R, adopted 27 September 
2004, DSR 2004:VI, p. 2739 
Chile – Price Band System Appellate Body Report, Chile – Price Band System and Safeguard Measures 
Relating to Certain Agricultural Products , WT/DS207/AB/R, adopted 
23 October 2002, DSR 2002: VIII, p. 3045 (Corr.1, DSR 2006:XII, p. 5473) 
China – Rare Earths Appellate Body Reports, China – Measures Related to the Exportation of Rare 
Earths, Tungsten, and Molybdenum , WT/DS431/AB/R / WT/DS432/AB/R / 
WT/DS433/AB/R, adopted 29 August 2014 
China – Rare Earths Panel Reports, China – Measures Related to the Exportation of Rare Earths, 
Tungsten, and Molybdenum , WT/DS431/R / WT/DS432/R / WT/DS433/R / and 
Add.1, adopted 29 August 2014, upheld by Appellate Body Reports WT/DS431/AB/R / WT/DS432/AB/R / WT/DS433/AB/R 
China – Raw Materials Appellate Body Reports, China – Measures Related to the Exportation of 
Various Raw Materials , WT/DS394/AB/R / WT/DS395/AB/R / 
WT/DS398/AB/R, adopted 22 February 2012, DSR 2012:VII, p. 3295 
Colombia – Ports of Entry Panel Report, Colombia – Indicative Prices and Restrictions on Ports of Entry , 
WT/DS366/R and Corr.1, adopted 20 May 2009, DSR 2009:VI, p. 2535 
EC – Asbestos Appellate Body Report, European Communities – Measures Affecting 
Asbestos and Asbestos -Containing Products , WT/DS135/AB/R, adopted 
5 April 2001, DSR 2001:VII, p. 3243 
EC – Bananas III (Ecuador) Panel Report, European Communities – Regime for the Importation, Sale and 
Distribution of Bananas, Complaint by Ecuador , WT/DS27/R/ECU, adopted 
25 September 1997, as modified by Appellate Body Report WT/DS27/AB/R, DSR 1997:III, p. 1085 
EC – Bananas III (Guatemala 
and Honduras) Panel Report, European Communities – Regime for the Importation, Sale and 
Distribution of Bananas, Comp laint by Guatemala and Honduras , 
WT/DS27/R/GTM, WT/DS27/R/HND, adopted 25 September 1997, as 
modified by Appellate Body Report WT/DS27/AB/R, DSR 1997:II, p. 695 
EC – Bananas III (Mexico) Panel Report, European Communities – Regime for the Importation, Sale and 
Distribution of Bananas, Complaint by Mexico , WT/DS27/R/MEX, adopted 
25 September 1997, as modified by Appellate Body Report WT/DS27/AB/R, 
DSR 1997:II, p. 803 
EC – Bananas III (US) Panel Report, European Communities – Regime for the Importation, Sale and 
Distribution of Bananas, Complaint by the United States , WT/DS27/R/USA, 
adopted 25 September 1997, as modified by Appellate Body Report 
WT/DS27/AB/R, DSR 1997:II, p. 943 
EC – Bed Linen 
(Article 21.5 – India) Appellate Body Report, European Communities – An ti-Dumping Duties on 
Imports of Cotton-Type Bed Linen from India – Recourse to Article 21.5 of 
the DSU  by India , WT/DS141/AB/RW, adopted 24 April 2003, DSR 2003:III, 
p. 965  WT/DS381/RW 
 
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  Short Title Full Case Title and Citation 
EC – Export Subsidies on Sugar Appellate Body Report, European Communities – Export Subsidies on Sugar , 
WT/DS265/AB/R, WT/DS266/AB/R, WT/D S283/AB/R, adopted 19 May 2005, 
DSR 2005:XIII, p. 6365 
EC – Hormones Appellate Body Report, EC Measures Concerning Meat and Meat Products 
(Hormones) , WT/DS26/AB/R, WT/DS48/AB/R, adopted 13 February 1998, 
DSR 1998:I, p. 135 
EC – Seal Products Appellate Body Reports, European Communities – Measures Prohibiting the 
Importation and Marketing of Seal Products , WT/DS400/AB/R / 
WT/DS401/AB/R, adopted 18 June 2014 
EC – Tariff Preferences 
 
 
 Panel Report, European Communities – Conditio ns for the Granting of Tariff 
Preferences to Developing Countries , WT/DS246/R, adopted 20 April 2004, 
as modified by Appellate Body Report WT/DS246/AB/R, DSR 2004:III, 
p. 1009 
India – Patents (US) Appellate Body Report, India – Patent Protection  for Pharmaceutical and 
Agricultural Chemical Products , WT/DS50/AB/R, adopted 16 January 1998, 
DSR 1998:I, p. 9 
Indonesia – Autos Panel Report, Indonesia – Certain Measures Affecting the Automobile 
Industry , WT/DS54/R, WT/DS55/R, WT/DS 59/R, WT/DS64/R and Corr.1 and 
Corr.2, adopted 23 July 1998, and Corr.3 and Corr.4, DSR 1998:VI, p. 2201 
Japan – Alcoholic Beverages II Appellate Body Report, Japan – Taxes on Alcoholic Beverages , 
WT/DS8/AB/R, WT/DS10/AB/R, WT/DS11/AB/R, adopted 1 November 1996, 
DSR 1996:I, p. 97 
Korea – Various Measures on 
Beef Appellate Body Report, Korea – Measures Affecting Imports of Fresh, Chilled 
and Frozen Beef , WT/DS161/AB/R, WT/DS169/ AB/R, adopted 10 January 
2001, DSR 2001:I, p. 5 
Philippines – Distilled Spirits Appellate Body Reports, Philippines – Taxes on Distilled Spirits , 
WT/DS396/AB/R / WT/DS403/AB/R, adopted 20 January 2012, DSR 
2012:VIII, p. 4163 
Thailand – Cigarettes 
(Philippines) Appellate Body Report, Thailand – Customs and Fiscal  Measures on Cigarettes 
from the Philippines , WT/DS371/AB/R, adopted 15 July 2011, DSR 2011:IV, 
p. 2203 
US – Clove Cigarettes Appellate Body Report, United States – Measures Affecting the Production 
and Sale of Clove Cigarettes , WT/DS406/AB/R, adopted 24 April 2012, DSR 
2012: XI, p. 5751 
US – COOL Appellate Body Reports, United States – Certain Country of Origin Labelling 
(COOL) Requirements , WT/DS384/AB/R / WT/DS386/AB/R, adopted 
23 July 2012, DSR 2012:V, p. 2449 
US – COOL 
(Article 21.5 – Canada and 
Mexico)  Panel Reports, United States – Certain Country of Origin Labelling (COOL) 
Requirements – Recourse to Article 21.5 of the DSU by Canada and Mexico , 
WT/DS384/RW / WT/DS386/RW / and Add.1, circulated to WTO Members 
20 October 2014 [appeal in progress] 
US – Countervailing Measures 
on Certain EC Products Panel Report, United States – Countervailing Measures Concerning Certain 
Products from the Europe an Communities, WT/DS212/R, adopted 8 January 
2003, as modified by Appellate Body Report WT/DS212/AB/R, DSR 2003:I, p. 73 
US – FSC 
(Article 21.5 – EC) Appellate Body Report, United States – Tax Treatment for "Foreign Sales 
Corporations" – Recourse to Article 21.5 of the DSU by the European 
Communities , WT/DS108/AB/RW, adopted 29 January 2002, DSR 2002:I, 
p. 55 
US – Gambling Appellate Body Report, United States – Measures Affecting the Cross-Border 
Supply of Gambling and Betting Services , WT/DS285/AB/R, adopted 
20 April 2005, DSR 2005:XII, p. 5663 (Corr.1, DSR 2006:XII, p. 5475) 
US – Gasoline Appellate Body Report, United States – Standards for Reformulated and 
Conventional Gasoline , WT/DS2/AB/R, adopted 20 May 1996, DSR 1996:I, 
p. 3 
US – Hot-Rolled Steel Panel Report, United States – Anti-Dumping Measures on Certain Hot-Rolled 
Steel Products from Japan , WT/DS184/R, adopted 23 August 2001 modified 
by Appellate Body Report WT/DS184/AB/R, DSR 2001:X, p. 4769 
US – Tuna II (Mexico) Appellate Body Report, United States – Measures Concerning the 
Importation, Marketing and Sale  of Tuna and Tuna Products , 
WT/DS381/AB/R, adopted 13 June 2012, DSR 2012:IV, p. 1837 WT/DS381/RW 
 
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  Short Title Full Case Title and Citation 
US – Tuna II (Mexico) Panel Report, United States – Measures Concerning the Importation, 
Marketing and Sale of Tuna and Tuna Products , WT/DS381/R, adopted 
13 June 2012, as modified by Appellate Body Report WT/DS381/AB/R, DSR 2012:IV, p. 2013 
US – Shrimp Appellate Body Report, United States – Import Proh ibition of Certain Shrimp 
and Shrimp Products , WT/DS58/AB/R, adopted 6 November 1998, 
DSR 1998:VII, p. 2755 
US – Shrimp 
(Article 21.5 – Malaysia) Appellate Body Report, United States – Import Proh ibition of Certain Shrimp 
and Shrimp Products – Recourse to Article 21.5 of the DSU by Malaysia , 
WT/DS58/AB/RW, adopted 21 November 2001, DSR 2001:XIII, p. 6481 
US – Softwood Lumber IV Appellate Body Report, United States – Final Countervailing Duty 
Determination with Respect to Ce rtain Softwood Lumber from Canada , 
WT/DS257/AB/R, adopted 17 February 2004, DSR 2004:II, p. 571 
US – Softwood Lumber IV 
(Article 21.5 – Canada) Appellate Body Report, United States – Final Countervailing Duty 
Determination with Respect to Cert ain Softwood Lumber from Canada – 
Recourse by Canada to Article 21.5 of the DSU , WT/DS257/AB/RW, adopted 
20 December 2005, DSR 2005:XXIII, p. 11357 
US – Upland Cotton Appellate Body Report, United States – Subsidies on Upland Cotton , 
WT/DS267/AB/R, adopted 21 March 2005, DSR 2005:I, p. 3 
US – Upland Cotton 
(Article 21.5 – Brazil)  Appellate Body Report, United States – Subsidies on Upland Cotton – 
Recourse to Article 21.5 of the DSU by Brazil , WT/DS267/AB/RW, adopted 
20 June 2008, DSR 2008:III, p. 809 
US – Wool Shirts and Blouses Appellate Body Report, United States – Measure A ffecting Imports of Woven 
Wool Shirts and Blouses from India , WT/DS33/AB/R, adopted 23 May 1997, 
and Corr.1, DSR 1997:I, p. 323 
US – Zeroing (EC)  Appellate Body Report, United States – Laws, Regulations and Methodology 
for Calculating Dumping Margins ("Zeroing") , WT/DS294/AB/R, adopted 
9 May 2006, and Corr.1, DSR 2006:II, p. 417 
US – Zeroing (EC)  
(Article 21.5 – EC) Appellate Body Report, United States – Laws, Regulations and Methodology 
for Calculating Dumping Margins ("Zeroing") – Recourse to Article 21.5 of 
the DSU by the European Communities , WT/DS294/AB/RW and Corr.1, 
adopted 11 June 2009, DSR 2009:VII, p. 2911 
 
 WT/DS381/RW 
 
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  ABBREVIATIONS USED IN THIS REPORT 
Abbreviation Description 
AIDCP Agreement on International Dolphin Conservation Program 
DPCIA Dolphin Protection Consumer Information Act of 1990 
DSB Dispute Settlement Body 
DSU Understanding on Rules and Procedures Governing the Settlement of Disputes 
EPO Eastern Pacific Ocean 
ETP Eastern Tropical Pacific Ocean 
FAD Fish Aggregating Device 
IATTC Inter-American Tropical Tuna Commission 
ICCAT International Commission for the Conservation of Atlantic Tunas 
IOTC Indian Ocean Tuna Commission 
IDCP International Dolphin Conversation Program 
GATT 1994 General Agreement on Tariffs and Trade 1994 
MMPA Marine Mammal Protection Act 
NOAA National Oceanic Atmospheric Administration 
NMFS National Marine Fisheries Service 
RFMOs Regional Fishery Mana gement Organizations 
RPT Reasonable Period of Time 
TBT Agreement Agreement on Technical Barriers to Trade 
TTF Tuna tracking form 
TTVP Tuna Tracking and Verification Program 
USC United States Code 
Vienna Convention Vienna Convention on the Law of Treaties, Done at Vienna, 23 May 1969, 1155 
UNTS 331; 8 International Legal Materials 679 
WTO World Trade Organization 
 WT/DS381/RW 
 
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  1  INTRODUCTION 
1.1  General 1.1.  On 14 November 2013, Mexico requested the establishment of a panel pursuant to 
Article 21.5 of the Understanding on Rules and Procedures Governing the Settlement of Disputes  
(DSU) concerning the United States' alleged failure to implement the recommendations and rulings 
of the Dispute Settlement Body (DSB) in the dispute United States – Measures Concerning the 
Importation, Marketing and Sale of Tuna and Tuna Products .
1 At its meeting on 22 January 2014, 
the DSB referred, if possible, to the original Pane l in accordance with Article 21.5 of the DSU to 
examine the matter referred to the DSB by Mexico in document WT/DS381/20.2  
1.2.  The Panel's terms of reference are the following: 
To examine, in the light of the relevant pr ovisions of the covered agreements cited by 
the parties to the dispute, the matter referred to the DSB by Mexico in document 
WT/DS381/20 and to make such findings as will assist the DSB in making the recommendations or in giving the rulings provided for in those agreements. 
1.3.  On 27 January 2014, the Panel was composed as follows: 
Chairperson: Mr Mario Matus 
 
 Members:  Ms Elizabeth Chelliah 
    M r  F r a n z  P e r r e z   1.4.  Australia, Canada, China, European Unio n, Guatemala, Japan, the Republic of Korea, 
New Zealand, Norway, and Thailand reserved their third-party rights. 
1.5.  The Panel met with the parties from 19 to  21 August 2014. A session with the third parties 
took place on 20 August 2014.  
1.6.  On 27 October 2014, the Panel issued the descr iptive part of its Report to the parties. The 
parties provided comments to the descriptive part of the Panel Report on 10 November 2014. The Panel issued its Interim Report to the parties on 28 November 2014. On 12 December 2014, the 
parties separately requested the revision of specific aspects of the Interim Report; on 
19 December 2014, the parties made comments on other party's request. The Panel issued its Final Report to the parties on 30 January 2015. 
1.2  Request for enhanced third-party rights 
1.7.  On 5 August 2014, in its third-party submission
3, the European Union requested the following 
rights for itself and the other third parties in these proceedings:  
[T]o be present throughout the hearing; to comment, at the invitation of the Panel, on 
matters arising during the hearing; to receive copies of any questions to the Parties, 
their responses and comments; and to be present at any subsequent meeting of the compliance Panel with the Parties. The European Union reiterated its request in its oral 
statement at the third-party session of the substantive meeting of the Panel with the 
parties.
4 
1.8.  After considering the European Union's request and consulting the parties, who both objected 
to the request, the Panel informed the European Union orally at the third-party session that it had 
decided to decline its request. The Panel concluded that, in the absence of the parties' agreement 
to this request, it need not deviate from the third-party rights established in paragraphs 2 and 3 of 
                                               
1 WT/DS381/20. 
2 WT/DSB/M/341. 
3 European Union's third-part y submission, paras. 3-9. 
4 European Union's oral  statement, para. 1. WT/DS381/RW 
 
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  Article 10 of the DSU, paragraph 6 of Appendix 3 to the DSU, and panel practice regarding third-
party rights.  
1.3  Background of the dispute 1.9.  This dispute concerns the implementation by the United States of the DSB recommendations 
and rulings in United States – Measures Concerning the Importation, Marketing and Sale of Tuna 
and Tuna Products . 
1.10.  On 13 June 2012, the DSB adopted the Appellate Body Report on United States – Measures 
Concerning the Importation, Marketing and Sale of Tuna and Tuna Products (WT/DS381/AB/R) and 
the Panel Report (WT/DS381/R), as modified by the Appellate Body Report.
5 
1.11.  The DSB ruled inter alia  that the US "dolphin-safe" labelling provisions were inconsistent 
with Article 2.1 of the TBT Agreement and recomm ended that the United States bring its measure 
into conformity with its obligations under that Agreement.6 The dolphin-safe labelling provisions 
comprised the US Code, Title 16, Section 1385 (the "Dolphin Protection Consumer Information Act"); the implementing regulations at US Code of Federal Regulations, Title 50, Section 216.91 
and Section 216.92; and a ruling by a US federal appeals court in Earth Island Institute v. 
Hogarth , 494 F.3d 757 (9th Cir. 2007) (the Hogarth ruling).
7 
1.12.  On 2 August 2012, Mexico and the United St ates informed the DSB that additional time was 
required to discuss a mutually agreed reasonable period of time (RPT) for the United States to 
implement the recommendations and rulings of the DSB.8 On 17 September 2012, Mexico and the 
United States informed the DSB that they had agreed that the RPT was 13 months from 13 June 2012, the date of adoption of the DSB's recommendations and rulings. The RPT expired on 
13 July 2013.
9 
1.13.  On 9 July 2013, the United States published in its Federal Register a legal instrument 
entitled "Enhanced Document Requirements to Support Use of the Dolphin Safe Label on Tuna 
Products", which the United States refers to as the "2013 Final Rule". According to the 
United States, the 2013 Final Rule constitutes the measure taken to comply with the DSB recommendations and rulings pursuant to Article 21.5 of the DSU. Furthermore, the United States 
refers to all three measures – the statute, the implementing regulations (as amended by the 2013 
Final Rule), and the Hogarth decision, collectively – as the "amended dolphin safe labeling 
measure" or the "amended measure".
10 
1.14.  Mexico considers that the United States has not brought its dolphin-safe labelling provisions 
into compliance with the DSB's recommendations and rulings. Furthermore, Mexico argues that the 
amended tuna measure is not consistent with the United States' obligations under the covered agreements.
11 
1.15.  On 2 August 2013, Mexico and the United States informed the DSB of Agreed Procedures 
under Article 21 and 22 of the DSU. Pursuant to paragraph 2 of the said Procedures, Mexico was not required to hold consultations with the United States prior to requesting the establishment of 
an Article 21.5 panel.
12 
                                               
5 Minutes of DSB Meeting held on 13 June 2012, WT/DSB/M/317, para. 37. 
6 Appellate Body Report, US – Tuna II (Mexico) , paras. 407(b) and 408. 
7 Appellate Body Report, US – Tuna II (Mexico) , para. 172. 
8 Communication from Mexico and the United States concerning Article 21.3(c) of the DSU, 
WT/DS381/16. 
9 Agreement under Article 21.3(b) of the DSU, WT/DS381/17. 
10 United States' first written submission, para. 10. 
11 Mexico's request for establishment of a panel, WT/DS381/20, p. 2. 
12 WT/DS381/19. WT/DS381/RW 
 
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  2  PARTIES' REQUESTS FOR FI NDINGS AND RECOMMENDATIONS 
2.1.  Mexico considers that in this dispute, the "measure taken to comply with the 
recommendations and rulings" of the DSB, to which Mexico refers collectively as the "Amended Tuna Measure", comprises:
13 
a. Section 1385 ("Dolphin Protection Consumer Information Act"), as contained in 
Subchapter II ("Conservation and Protection of Marine Mammals") of Chapter 31 ("Marine Mammal Protection"), in Title 16 of the US Code;  
b. US Code of Federal Regulations, Title 50, Part 216, Subpart H ("Dolphin Safe Tuna 
Labeling"), as amended by the 2013 Final Rule;  
c. The court ruling in Earth Island Institute v. Hogarth , 494 F.3d 757 (9th Cir. 2007); and 
d. Any implementing guidance, directives, policy announcements or any other document 
issued in relation to instruments a. through c. above, including any modifications or 
amendments in relation to those instruments. 
2.2.  Mexico has identified a number of claims in its panel request and requests the Panel to find 
that:
14 
a. The amended tuna measure is inconsistent with Article 2.1 of the TBT Agreement 
because it continues to accord Mexican tuna products treatment less favourable than 
that accorded to like tuna products of the United States and to like tuna products 
originating in any other country; 
b. The amended tuna measure is inconsistent with Article I:1 of the GATT 1994 because it 
continues to confer on tuna products originating in other countries an advantage which is 
not accorded immediately and unconditionally to like tuna products originating in 
Mexico; 
c. The amended tuna measure is inconsistent with Article III:4 of the GATT 1994 because it 
continues to accord Mexican tuna products treatment less favourable than that accorded 
to like tuna products of United States' origin in respect of all laws, regulations and requirements affecting their internal sale, offering for sale, purchase, transportation, 
distribution or use; 
d. The amended tuna measure nullifies or impairs benefits that accrue to Mexico under the 
GATT 1994 within the meaning of GATT Article XXIII:1(b). 
2.3.  Mexico requests the Panel to find that the United States had failed to comply with the 
recommendations and rulings adopted by the DSB on the basis that the amended tuna measure 
remains inconsistent with Article 2.1 of the TBT Agreement, and Articles I:1 and III:4 of the GATT 1994.
15 
2.4.  The United States requests that the Panel reject Mexico's claims in their entirety. 
3  OVERVIEW OF THE MEASURE AT ISSUE 3.1.  In the original proceedings, Mexico challenged three measures: 1) the Dolphin Protection 
Consumer Information Act (DPCIA); 2) the statute' s implementing regulations; and 3) the Ninth 
Circuit Court of Appeals decision in Earth Island Institute v. Hogarth ("Hogarth ").
16 The original 
panel and the Appellate Body found that these measures provide for the conditions under which 
                                               
13 See WT/DS381/20, and Mexico's fi rst written submission, para. 11. 
14 See WT/DS381/20. 
15 Mexico's first written submission, para. 331. 
16 Panel Report, US – Tuna II (Mexico) , para. 2.1; Appellate Body Report, US – Tuna II (Mexico),  
para. 172. WT/DS381/RW 
 
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  tuna products may receive a "dolphin-safe" label, and referred to them collectively as the 
"measure at issue" or the "US dolphin-safe labelling provisions."17  
3.2.  Taken together, the DPCIA, the implementing  regulations, and the Hogarth ruling set out the 
requirements for when tuna products sold in the United States may be labelled as "dolphin-safe". 
More specifically, they condition eligibility for a "dolphin-safe" label upon certain documentary 
evidence that varies depending on the area where the tuna contained in the tuna product is harvested and the type of vessel and fishing method by which it is harvested. In particular, tuna 
caught by "setting on" dolphins is currently not eligible for a "dolphin-safe" label in the 
United States, regardless of whether this fishing method is used inside or outside the Eastern Tropical Pacific Ocean (the "ETP"). The DPCIA and the implementing regulations also prohibit any reference to dolphins, porpoises, or marine mammals on the label of a tuna product if the tuna 
contained in the product does not comply with the labelling conditions spelled out in the DPCIA. 
However, they do not make the use of a "dolphin-safe" label obligatory for the importation or sale of tuna products in the United States.
18 
3.3.  The relevant provisions of the original measure are described below.19 The 2013 Final Rule, 
which the United States claims to be the measure taken to comply, is also described in the following paragraphs.  
3.1  The Dolphin Protection Consumer Info rmation Act and its Original Implementing 
Regulations 
3.4.  The DPCIA is codified in Title 16, Section 1385 of the United States Code (USC). Regulations 
promulgated in accordance with the DPCIA are co dified in Title 50, Section 216 of the Code of 
Federal Regulations. The core of the US "dolphin-safe" labelling scheme is contained in 
subsection 1385(d)(1)-(3) of the DPCIA.  Paragraph (d) of Section 1385 of the DPCIA provisions regulates the use of the term "dolphin-safe" when it appears on tuna products.
20 
Fishing method 
 3.5.  Under the DPCIA, tuna caught by large scale driftnet fishing on the high seas, and tuna 
products containing tuna harvested anywhere in the world by setting on dolphins are not eligible to 
be labelled dolphin-safe.
21 
Certification by captain and observer 
 
3.6.  Subparagraph (h)(1) of the DPCIA establishes the following: 
(h) Certification by captain and observer (1) Unless otherwise required by paragraph (2), the certification by the captain 
under subsection (d)(2)(B)(i) of this section and the certification provided by the 
observer as specified in subsection (d)(2)(B)(ii) of this section shall be that no dolphins were killed or seriously injured during the sets in which the tuna were 
caught. 
(2) The certification by the captain under subsection (d)(2)(B)(i) of this section and 
the certification provided by the observer as  specified under subsection (d)(2)(B)(ii) of 
this section shall be that no tuna were caught on the trip in which such tuna were 
harvested using a purse seine net intentionally deployed on or to encircle dolphins, 
and that no dolphins were killed or seriously injured during the sets in which the tuna were caught, if the tuna were caught on a trip commencing— 
                                               
17 Appellate Body Report, US – Tuna II (Mexico) , para. 172 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.24). 
18 Appellate Body Report, US – Tuna II (Mexico) , para. 172. 
19 The description of the unchanged aspects of the measure is taken from the panel's report in the 
original proceedings. 
20 Panel Report, US – Tuna II (Mexico) , para. 2.3. 
21 Panel Report, US – Tuna II (Mexico) , para. 2.3. WT/DS381/RW 
 
- 13 - 
 
  (A) before the effective date of the initial finding by the Secretary under 
subsection (g)(1) of this section; 
(B) after the effective date of such initial finding and before the effective date of the 
finding of the Secretary under subsection (g)(2) of this section, where the initial 
finding is that the intentional deployment on or encirclement of dolphins is having a 
significant adverse impact on any depleted dolphin stock; or 
(C) after the effective date of the finding under subsection (g)(2) of this section, 
where such finding is that the intentional deployment on or encirclement of dolphins is 
having a significant adverse impact on any such depleted stock.22 
3.7.  The DPCIA provisions refer to four criteria to establish five basic categories of circumstances 
in which tuna may be caught. These criteria are: location ( inside  or outside the ETP); fishing gear 
(with or without the use of purse seine nets); type of interaction between tuna and dolphin schools 
(there is or there is no regular or significant association between tuna and dolphin schools) and 
the level of dolphin mortalities or injuries ( there is or there is no regular and significant mortality 
or serious injury). The five categories that result from the combined application of these criteria 
are described in subparagraphs (A) to (D) of subsection 1385(d)(1) of the DPCIA.23 
3.8.  These subparagraphs refer to tuna caught: 
A) On the high seas by a vessel engaged in driftnet fishing; 
B) Outside the ETP by a vessel using purse seine nets: (i) in a fishery in which the US Secretary of Commerce has determined that there 
is a regular and significant tuna-dolphin association similar to the association between 
dolphins and tuna in the ETP;  
(ii) in any other fishery (other than a fishery described in subparagraph (D)).  
C) In the ETP by a vessel using purse seine nets; and 
D) In a fishery other than the ones described in the previous categories that is 
identified by the US Secretary of Commerce as having a regular and significant mortality or serious injury of dolphins.
24 
3.9.  Tuna products containing tuna caught und er the scenario described in subparagraph (A) of 
subsection 1385(d)(1), i.e. tuna caught on the hi gh seas using driftnet fishing, may under no 
circumstances be labelled as "dolphin-safe" or display any analogous claim. Subsections 1385(d)(1)(2) and (h) of  the DPCIA establish specific conditions for the use of the 
term "dolphin-safe" or any analogous claims on tu na products for each of the categories described 
in subparagraphs (B) through (D) of subsection 1385(d)(1). The documentary evidence required under the DPCIA for the categories (B) through (D) is described below.
25 
3.10.  With respect to tuna products containing tuna caught outside the ETP by a vessel using 
purse seine nets in a fishery in which the US Secr etary of Commerce has determined that a regular 
and significant dolphin-tuna association exists (subparagraph (B)(i)), the use of the term "dolphin-
safe" or any analogous term is conditional upon a written statement executed by the captain of the 
vessel and an observer participating in a national or international program acceptable to the Secretary of Commerce, certifying that no purse se ine net was intentionally deployed on or used to 
encircle dolphins during the particular voyage on which the tuna were caught and no dolphins were 
killed or seriously injured in the sets in which the tuna were caught.
26 
                                               
22 Panel Report, US – Tuna II (Mexico) , para. 2.4. 
23 Panel Report, US – Tuna II (Mexico) , para. 2.7. 
24 Panel Report, US – Tuna II (Mexico) , para. 2.8. 
25 Panel Report, US – Tuna II (Mexico) , para. 2.9. 
26 Panel Report, US – Tuna II (Mexico) , para. 2.10. WT/DS381/RW 
 
- 14 - 
 
  3.11.  For tuna caught outside the ETP by a vessel using purse seine nets in any fishery, other 
than a fishery described in subparagraph (D) of subsection 1385(d)(1) of the DPCIA provisions,  
(subparagraph (B)(ii)), a written statement executed by the captain of the vessel is required, certifying that no purse seine net was intentionally deployed on or used to encircle dolphins during 
the particular voyage on which the tuna was harvested.
27 
3.12.  For tuna harvested in the ETP  by a large purse seine28 vessel (subparagraph (C)), the 
conditions are: 
 a written statement executed by the captain  certifying that no dolphins were killed or 
seriously injured during the sets in which the tuna were caught; and, unless there is a 
previous determination by the Secretary of  Commerce that the fishing technique of 
setting on dolphins is not having a significant adverse impact on any depleted dolphin 
stock in the ETP, also certifying that no purse seine net was intentionally deployed on or 
used to encircle dolphins ; 
 a written statement executed by either the Secretary of Commerce or the Secretary's 
designee, or a representative of the Inter-American Tropical Tuna Commission (IATTC), 
or an authorized representative of a participating nation whose national program meets the requirements of the IDCP stating that th ere was an observer approved by the IDCP 
on board the vessel during the entire trip and that such observer provided the same 
certifications as the vessel captain;  
 the written endorsement by each exporter, importer, and processor of the tuna; and  
 the above mentioned written statements an d endorsements comply with regulations 
promulgated by the Secretary which provide for the verification of tuna products as 
dolphin-safe. 
Small purse seine vessels in the ETP are not subjected to these requirements. Therefore, 
considering only the DPCIA and not the other aspects of the US measure, tuna caught in the ETP 
by this type of vessel may be labelled "dolphin-safe" without the need to submit any documentary evidence.
29 
 
3.13.  For tuna caught in a fishery other  than those described in subsection 1385(d)(1)(A)-(C) 
(that is, tuna caught without purse seine nets or large driftnets in the high seas) that is identified by the US Secretary of Commerce as having a regular and significant mortality  or serious injury  of 
dolphins (subparagraph (D)), the use of the term "dolphin-safe" or any analogous terms is subject 
to a written statement executed by the captain  of the vessel and an observer participating in a 
national or international program acceptable to the Secretary of Commerce that no dolphins were 
killed or seriously injured in the sets or other gear deployments in which the tuna were caught, 
provided that the Secretary of Commerce determines that such an observer statement is necessary.
30 
3.14.  For tuna caught without purse seine nets in fisheries where there has not been a finding of 
regular and significant mortality  or serious injury  of dolphins, the DPCIA provisions do not require 
any written statement or certification. 
3.15.  As described above, subparagraph (h)(1) of the DPCIA provisions establishes that, unless 
otherwise required by paragraph (2), tuna harves ted in the ETP by a vessel using purse seine nets 
may be labelled "dolphin-safe" if the captain of the vessel and an approved observer certify that no dolphins were killed or seriously injured  during the sets in which the tuna were caught.
31 
                                               
27 Panel Report, US – Tuna II (Mexico) , para. 2.11. 
28 Consistent with the AIDCP, US law, and the reports in the original proceeding, the Panel uses the 
term "large purse seine vessel" to re fer to purse seine vessels in the ETP with a carrying capacity greater than 
363 metric tons and the term "small purse seine vessel" to refer to purse seine vessels in the ETP with a 
carrying capacity of 363 metric tons or less.  
29 Panel Report, US – Tuna II (Mexico) , para. 2.12. 
30 Panel Report, US – Tuna II (Mexico) , para. 2.13. 
31 Panel Report, US – Tuna II (Mexico) , para. 2.15. WT/DS381/RW 
 
- 15 - 
 
  3.16.  However, subparagraph (h)(2) establishes that tuna harvested in the ETP by a large vessel 
using purse seine nets may be labelled "dolphin-saf e" if the captain of the vessel and an approved 
observer certify that (i) no purse-seine net were intentionally deployed on or used to encircle dolphins during the trip in which the tuna was caught, and (ii) no dolphins were killed or seriously 
injured during the sets in which the tuna were caught. Subparagraph (h)(2) of the DPCIA 
provisions conditions the applicability of subparagraph (h)(1) to the existence of a finding by the US Secretary of Commerce that the intentional deployment on or encirclement of dolphins with 
purse seine nets is not having a significant adverse impact on any depleted dolphin stock in the 
ETP. Subparagraph (g) requires the Secretary of Commerce to conduct this task in two stages resulting in an initial and a final finding on the impact of setting on dolphins in the ETP.
32 
3.17.  In the event of a negative finding, a certif ication that "no dolphins were killed or seriously 
injured during the sets in which the tuna were caught" is sufficient in order to make the tuna 
products eligible for a "dolphin-safe" label. In the event of a positive finding, an additional certification that "no tuna were caught on the trip  in which such tuna were harvested using a purse 
seine net intentionally deployed on or to encircle dolphins" is required.
33 
3.18.  The US Secretary of Commerce made a final finding that "the intentional deployment on or 
encirclement of dolphins with purse seine nets [was] not having a significant adverse effect on any 
depleted dolphin stock in the ETP."34 However, this finding was overturned through US court 
rulings, on the basis that the Secretary failed to conduct statutorily mandated studies and that the best available scientific evidence did not support the Secretary's finding.
35 
3.19.  Hence, given that the Secretary's ruling has b een overturned with the result that there is no 
finding that intentional deployment on or encirclement of dolphins with purse seine nets is not 
having a significant adverse impact on any depleted dolphin stock in the ETP, tuna harvested in the ETP by a large purse seine vessel may be labelled dolphin-safe only if the captain certifies that 
no dolphins were killed or seriously injured during the sets in which the tuna were caught and that 
no purse seine net was intentionally deployed on or used to encircle dolphins  during the same 
fishing trip. This certification must be accompanied by a written statement executed by the 
Secretary of Commerce (or designee), a representative of the Inter-American Tropical Tuna 
Commission or an authorized representative of a participating nation whose national program meets the requirements of the IDCP that an ob server approved by the IDCP was on board the 
vessel during the entire trip and that such observer provided the same certifications as the 
captain, and the endorsement by the exporter s, importers and processors required in 
subparagraphs (d)(2)(B)-(C) of Section 1385 of the DPCIA provisions.
36 
3.20.  As explained above, subparagraphs (d)(1)(B) and (D) of the DPCIA provisions establish 
different categories of tuna harvested outside  the ETP large purse seine fishery.  These categories 
are:37 
 Tuna caught using purse seine nets in a fishery in which the US Secretary of Commerce 
has determined that a regular and significant tuna-dolphin association  exists similar to 
the association in the ETP (§1385 (d)(1)(B)(i)); 
 Tuna caught using purse seine nets in a fishery in which the US Secretary of Commerce 
has not determined that a  regular and significant association  between tuna and dolphins 
exists (§1385 (d)(1)(B)(ii)); and 
 Tuna caught in a fishery other  than the ones described in subparagraphs (d)(1)(A)-(C) 
that is identified by the US Secretary of Commerce as having a regular and significant 
mortality  or serious injury  of dolphins (§1385 (d)(1)(C)). 
                                               
32 Panel Report, US – Tuna II (Mexico) , para. 2.16. 
33 Appellate Body Report, US – Tuna II (Mexico) , para. 175. 
34 Panel Report, US – Tuna II (Mexico) , para. 2.18. 
35 Panel Report, US – Tuna II (Mexico) , para. 2.19; See also Earth Island Institute v. Evans , affirmed by 
Earth Island Institute v. Hogarth . 
36 Panel Report, US – Tuna II (Mexico) , para. 2.20. 
37 Panel Report, US – Tuna II (Mexico) , para. 2.21. WT/DS381/RW 
 
- 16 - 
 
  3.21.  As also mentioned above, the DPCIA provisions establish a specific set of conditions that 
must be fulfilled by each of these categories of tu na in order to use the term "dolphin-safe" or to 
make similar claims.  In two of these instances (i.e. tuna caught in a fishery in which the US Secretary of Commerce has determined  that a regular and significant tuna-dolphin association 
exists, and in the case of tuna caught in a fishery other than the ones described in 
subparagraphs (d)(1)(A)-(C) that is identified  by the US Secretary of Commerce as having a 
regular and significant mortality or serious injury of dolphins), the applicability of the relevant 
requirements is conditioned on the existence of a determination by the Secretary of Commerce 
that in the fishery in question there is regular and significant tuna-dolphin association similar to the association in the ETP, or regular and significant mortality or serious injury of dolphins.
38 
3.22.  The United States indicated that no fishery outside the ETP has been determined to have a 
regular and significant association between tuna and dolphins similar to the association in the ETP. 
Moreover, the United States has also explained that it has not made a determination that any non-purse seine tuna fishery has regular and significant dolphin mortality.
39 
3.23.  Therefore, although it remains a possibili ty under the DPCIA provisions, that the Secretary 
of Commerce may determine that there is regular and significant dolphin-tuna association, or regular and significant mortality or serious injury of dolphins in fisheries outside the ETP, such 
determinations have not been made to date. Hence the "dolphin-safe" requirements for tuna 
caught under the circumstances described in  subparagraphs (d)(1)(B)(i) and (d)(1)(D) of 
Section 1385 are not currently applied with respect to any fishery.
40 
3.24.  Consequently, the scenarios described in subparagraphs (d)(1) of Section 1385 that are 
currently applicable are those described in: 
a. subparagraph (d)(1)(A), which refers to tuna caught on the high seas by driftnet fishing; 
b. subparagraph (d)(1)(C), which refers to tuna caught in the ETP by a large vessel using 
purse seine nets; and 
c. subparagraph (d)(1)(B)(ii), which refers to tuna caught by a purse seine vessel outside 
the ETP in a fishery that has not been the su bject of a determination by the Secretary of 
Commerce  of regular and significant dolphin-tuna association. The "dolphin-safe" 
certification required for this type of tuna must be provided by the captain  of the vessel 
and, according to subparagraph (d)(1)(B)(ii), must state only that no purse seine net 
was intentionally deployed on or used to encircle dolphins  during the particular voyage 
on which the tuna was harvested.41 
3.25.  As subparagraph (d)(1)(D) of Section 1385 is not currently applicable, the DPCIA provisions 
do not require any written statement or certification for tuna caught without purse seine nets in 
any fishery. 
Tracking and Verification Program (TTVP) 
 
3.26.  The United States National Marine Fisheries Service (NMFS) has established the Tuna 
Tracking and Verification Program (TTVP) for tracking and verifying the "dolphin-safe" or "non-dolphin-safe" condition of tuna. The provisions establishing this program are mainly contained in Title 50, Sections 216.24 and 216.91-216.93 of the US Code of Federal Regulations. 
Through the use of the TTVP, the United States government collects information from domestic 
tuna processors, US tuna vessels, and importers of tuna products, to verify whether tuna products 
labelled dolphin-safe meet the statutory conditions.
42 
                                               
38 Panel Report,  US – Tuna II (Mexico) , para. 2.22. 
39 Panel Report, US – Tuna II (Mexico) , para. 2.23. 
40 Panel Report, US – Tuna II (Mexico) , para. 2.24. 
41 Panel Report, US – Tuna II (Mexico) , para. 2.25. 
42 Panel Report, US – Tuna II (Mexico) , para. 2.31. WT/DS381/RW 
 
- 17 - 
 
  Form 370 
 3.27.  Every import of tuna and tuna products to the United States, regardless of whether the "dolphin-safe" label is intended to be used, must be accompanied by a Fisheries Certificate of 
Origin (National Oceanic and Atmospheric Administration (NOAA) Form 370). One copy of this form 
must be submitted to Customs and Border Protection at the time of importation, and a second one to the TTVP.
43 
Tuna Tracking Form (TTF)  
 3.28.  For tuna caught by US vessels, section 216.93 establishes a "tracking and verification program" for large US purse seine vessels fishing in the ETP, which is designed to be consistent 
with the AIDCP.  The regulation requires that the observer on the vessel record every set made 
during a fishing voyage on a Tuna Tracking Form (TTF) bearing a unique identification number. One TTF is used to record dolphin- safe sets (i.e. where no dolphins were killed or seriously injured) 
and a second TTF is used to record non-dolphin-safe sets (i.e. where there was a dolphin mortality 
or serious injury). The information entered on the TTFs for each set includes the date, well 
number, weights by species composition, estimated to ns loaded, and additional notes, if any.  The 
observer and the vessel engineer initial the entry following each set, and the vessel captain and 
the observer review and sign both TTFs at the end of the fishing trip certifying that the information 
on the forms is accurate.  The requirement for TTFs does not apply to US vessels operating outside the ETP, nor to US vessels operating in the ETP that are not large purse seine vessels.  The TTF 
forms must be certified by the independent observ ers required on large purse seine vessels in the 
ETP.
44 TTF(s) are a component of the Agreement on the International Dolphin Conservation 
Program (AIDCP). During any fishing trip in the ETP, large purse seine vessels are required to 
record on TTF(s) every purse seine set made and any dolphin mortalities or serious injuries. As 
required by the AIDCP, section 216.93(a) requires that separate TTFs be used to record tuna harvested in dolphin-safe and non-dolphin-safe sets. Subsection (c)(1)(i) provides that a set is 
"non-dolphin-safe" if a dolphin died or was seriously injured during the set.
45 
3.29.  For tuna products containing tuna caught in the ETP by non-US vessels, there are separate 
regulations. Section 216.92(b)(1) applies to import ed tuna products made  with yellowfin tuna 
harvested in the ETP, and requires the tuna to be caught by a vessel belonging to a nation that 
has obtained an affirmative finding under § 216.24(f)(8), which is a determination by the US 
government that a nation is in compliance with the AIDCP. For other tuna products not containing yellowfin tuna, Section 216.92(b)(2)(i) requires that the tuna have been caught by a vessel 
belonging to a nation that is a party to the AIDCP and is adhering to its requirements. Thus, the 
same requirements for compliance with the AIDCP apply to imported tuna products containing both yellowfin and non-yellowfin tuna. The AIDCP requires member nations to implement the same 
TTF system for fishing by large purse seine vessels in the ETP as is implemented for US vessels 
under section 216.93.
46 The Form 370 required for imported tuna products containing tuna caught 
in the ETP must list the numbers for the associated TTF(s).47 
3.30.  The TTF requirement applies only to tuna caught by large purse seine vessels in the ETP.  
Physical segregation  
 3.31.  Under the original measure, there were no requirements for segregating dolphin-safe from 
non-dolphin-safe tuna for any tuna other than that caught by large purse seine vessels in the ETP. 
For tuna caught by large purse seine vessels in the ETP only, tuna caught in sets designated as dolphin-safe by the vessel observer must be stored separately from tuna caught in non-dolphin-
safe sets from the time of capture through unloading at port. Specifically, if tuna was caught in a 
set during which a dolphin was killed or seriously injured, that tuna must be stored in a "well" on the vessel separate from dolphin-safe tuna. If any dolphin-safe tuna is mixed in the same well with 
the non-dolphin-safe tuna, all of the tuna in that well must be treated as non-dolphin-safe. 
Furthermore, tuna offloaded to trucks, storage fa cilities, or carrier vessels must be loaded or 
                                               
43 Panel Report, US – Tuna II (Mexico) , para. 2.32. 
44 Mexico's first written submission, paras. 82-83. 
45 See United States' first written submission, footnote 63. 
46 Mexico's first written submission, paras. 85-88. 
47 United States' first written submission, para. 42. WT/DS381/RW 
 
- 18 - 
 
  stored in such a way as to maintain the identification of the dolphin-safe or non-dolphin-safe tuna 
as it left the vessel.48 The TTF documentation required for tuna caught by large purse seine vessels 
in the ETP is used for this purpose.49 
3.2  The 2013 Final Rule 
3.32.  On 9 July 2013, the United States published in its Federal Register a Final Rule entitled 
"Enhanced Document Requirements to Support Use of the Dolphin Safe Label on Tuna Products" 
(2013 Final Rule). The 2013 Final Rule made chan ges to the previous regulations at Sections 
216.91 and 216.93.50 However, neither the DPCIA, nor the Hogarth  ruling, has been amended 
since the original panel circulated its report.51 
3.33.  The amended dolphin-safe labelling measure places three types of conditions on use of the 
dolphin-safe label for tuna products: 1) conditions relating to fishing methods, 2) conditions 
relating to certifications, and 3) conditions relating to record-keeping (tracking and verification).52 
3.34.  The relevant changes to the original implementing regulations are explained below. 
Fishing method 
 
3.35.  Under the amended measure, as under the original measure, tuna harvested using large-scale driftnets on the high seas is not eligible for the dolphin-safe label.
53  
3.36.  Under the amended measure, as under the or iginal measure, tuna products containing tuna 
harvested anywhere in the world by setting on dolphins are not eligible to be labelled dolphin-safe. This prohibition is implemented through 50 C.F.R. section 216.91(a)(1), which applies to large purse seine vessels in the ETP, and section 216.91(a)(2), which applies to purse seine vessels 
outside the ETP. Both provisions stipulate that tuna caught by a covered vessel is not eligible for 
the dolphin-safe label unless it is accompanied by a captain's certification that no purse seine nets were intentionally deployed on or used to encircle dolphins during the particular trip on which the 
tuna was harvested and that no dolphins were killed or seriously injured during the sets in which 
the tuna were caught"
54 
3.37.  Tuna products harvested by fishing methods other than large-scale high seas driftnet fishing 
or setting on dolphins are eligible to be labelled dolphin-safe only if no dolphins were killed or 
seriously injured in the gear deployments in which the tuna were caught. To ensure this condition is met, tuna products labelled dolphin-safe are subject to the certification and record-keeping conditions discussed below.
55 
Certifications  
 
Captain certification 
 
3.38.  Under the amended measure, the use of the dolphin-safe label on any tuna product is conditioned on the product being accompanied by certain certifications by the captain of the 
harvesting vessel and, in some circumstances, an observer from an approved national or 
international observer program.
56 
3.39.  The certification requirements under the original DPCIA statute for all tuna harvested in the 
ETP by a large purse seine vessel remain unchanged. For US-flagged vessels, 
sections 216.92(a)(1) and 216.93(a) implement this condition by requiring that captain-certified 
TTFs, which show whether a dolphin was killed or seriously injured in the set in which the tuna 
                                               
48 Mexico's first written submission, paras. 60-61. 
49 Mexico's first written submission, paras. 90-92. 
50 Mexico's first written submission, para. 10. 
51 United States' first written submission, para. 11. 
52 United States' first written submission, para. 20. 
53 United States' first written submission, para. 22. 
54 United States' first written submission, para. 30. 
55 United States' first written submission, para. 32. 
56 United States' first written submission, para. 33. WT/DS381/RW 
 
- 19 - 
 
  were caught, accompany all tuna caught by large purse seine vessels in the ETP. For foreign-
flagged vessels, section 216.24(f)(2) requires that all tuna imports be accompanied by a NOAA Form 370, which indicates dolphin-safe status and contains the certifications described in section 216.91(a) as necessary.
57 The certification must include validation that the dolphin-safe 
status was certified by an independent observer meeting the requirements of the AIDCP.58 
3.40.  In addition to the certification that no dolphins were killed or seriously injured, tuna 
products containing tuna harvested by a purse seine vessel may be labelled dolphin-safe only if 
accompanied by a certification by the vessel captain that no purse seine net was intentionally 
deployed on or used to encircle dolphins during the trip on which the tuna were caught. Under the amended measure, this condition applies to tuna  products containing tuna harvested by large 
purse seine vessels in the ETP, and by purse seine vessels outside the ETP.
59 
3.41.  Under the amended measure, a captain's certification that no dolphins were killed or 
seriously injured in the sets or other gear deployments in which the tuna was caught is also needed for tuna products containing tuna harvested in any other fishery to be labelled dolphin-
safe. Section 216.91(a)(2) implements this condition for tuna caught by a purse seine vessel 
outside the ETP on trips beginning on or after 13 July 2013. Section 216.91(a)(4) establishes the same condition for tuna harvested in all other fisheries (i.e . all fisheries other than the large purse-
seine fishery in the ETP and purse seine fisheries outside the ETP). (The original tuna measure did 
not require any certification for tuna products containing tuna caught (i) not using purse seine nets or (ii) by small purse seine vessels in the ETP.)
60 
Observer on-board and observer certification  
 
3.42.  Tuna products containing tuna caught by large purse seine vessels in the ETP may be 
labelled dolphin-safe only if accompanied by valid documentation signed by a representative of the 
appropriate IDCP–member nation certifying that: (i) there was an IDCP-approved observer on 
board the vessel during the entire trip; and (ii) no purse seine net was intentionally deployed on or to encircle dolphins during the fishing trip and no dolphins were killed or seriously injured in the 
sets in which the tuna were caught. In addition, the documentation must list the numbers for the 
associated Tuna Tracking Forms which contain the required captain and observer certifications.
61 
3.43.  For tuna caught by large US purse seine vessels in the ETP, sections 216.91(a)(1) and 
216.93(a) implement this condition by requiring th at the IDCP observer on board certify the TTF 
accompanying the tuna caught by that vessel.62 A  T T F  t h a t  i s  u s e d  t o  r e c o r d  d o l p h i n - s a f e  s e t s  
attests that no dolphins were killed or seriously injured in the set in which the tuna was caught.63 
3.44.  For tuna caught by large non-US purse seine vessels in the ETP, sections 216.92(b) and 
216.24(f)(4) implement this provision by requir ing that the NOAA Form 370 accompanying the 
tuna products contain the necessary observer certifications. For tuna products to be labelled dolphin-safe, the accompanying Form 370 must be signed by a representative of an IDCP-member 
nation, and the representative must certify that  (i) there was an IDCP observer on the vessel 
during the entire trip, (ii) no purse seine net was intentionally deployed on or to encircle dolphins, and (iii) no dolphins were killed or seriously injured in the sets in which the tuna were caught. The Form 370 must also list the numbers for the associated TTF(s), which contains the required 
captain and observer's certifications.
64   
3.45.  For tuna caught other than by large purse seine vessels in the ETP, the amended measure 
does not require an observer certification requirement unless the NMFS Assistant Administrator 
                                               
57 United States' first written submission, para. 35. 
58 16 USC § 1385(d)(2)(B) (Exhibit MEX-8). 
59 United States' first written submission, para. 37. 
60 United States' first written submission, para. 36. 
61 United States' first written submission, para. 40. 
62 See 50 C.F.R. §§ 216.92(a)(1) (Exh. US-2). For US vessels, NOAA's TTVP is the representative of the 
IDCP-member nation (i.e. the United States) and US  certification is made by reviewing TTFs.   
63 United States' first written submission, para. 41; (Under Section 216.93(a), one TTF is used to record 
dolphin-safe sets and a second TTF is us ed to record non-dolphin-safe sets). 
64 United States' first written submission, para. 42. WT/DS381/RW 
 
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  has made certain findings. More specifically, under  the amended measure, observer certification is 
required under the following circumstances:65  
(i) In a non-ETP purse seine fishery in which the Assistant Administrator has 
determined that a regular and significant association occurs between dolphins 
and tuna (similar to the association between dolphins and tuna in the ETP) 
(50 C.F.R. §§ 216.91(a)(2)(i)); 
(ii) In a non-ETP purse seine fishery where the Assistant Administrator has 
determined that observers participating in a national or international observer 
program are qualified and authorized to certify that no purse seine net was intentionally deployed on or used to encircle dolphins during the fishing trip in which the tuna were caught, and that no dolphins were killed or seriously 
injured in the sets in which the tuna were caught" (50 C.F.R. §§ 216.91 
(a)(2)(iii)(B)); 
(iii) In any other fishery where the Assistant Administrator has determined that 
observers participating in a national or international observer program are 
qualified and authorized to certify that no dolphins were killed or seriously injured in the sets or other gear deployments in which the tuna were caught" 
(50 C.F.R. §§ 216.91(a)(4)(ii)); and 
(iv) In any other fishery that is identified by the Assistant Administrator as having 
a regular and significant mortality or serious injury of dolphins" (50 C.F.R. §§ 216.91(a)(4)(iii)). 
3.46.  Under the current measure, for tuna caught outside the ETP, the amended tuna measure 
does not impose any observer certification requirements, other than with respect to seven US domestic fisheries for which the Assistant Administrator has determined that US observers are 
qualified and authorized to certify that no that no dolphins were killed or seriously injured in the 
sets or other gear deployments in which the tuna were caught. The certification is required only when the observer is on board the vessel for other reasons, and tuna caught when there is not an 
observer on board may still be labelled dolphin-safe with a captain's statement.
66 
Tracking and Verification 
  Documentation requirements 
 
  Tuna Tracking Form (TTF)  
3.47.  As in the original measure, under the am ended measure tuna harvested in the ETP by large 
purse seine vessels may be labelled dolphin-safe only if the documentation requirements of sections 216.92 and 216.93 are met. For tuna caught by US-flagged vessels, the dolphin-safe label 
may be used if the tuna is accompanied by a TTF certified by the vessel captain and the 
IDCP-approved observer and delivered to a US tuna  processor that is in compliance with the tuna 
tracking and verification requirements of section 216.93.
67  
3.48.  The same tracking and verification requirem ents, e.g. that the tuna in question should be 
accompanied by a TTF certified by the vessel ca ptain and the IDCP-approved observer, apply to 
imported tuna products harvested in the ETP by large purse seine vessels. Such tuna products may be labelled dolphin-safe only if the tuna was harvested by a vessel flagged to an AIDCP party 
(or a country that is provisionally applying the AIDCP) that is adhering to all the requirements of 
the IDCP Tuna Tracking and Verification Plan. Th is requirement is implemented by the Form 370, 
which requires that tuna harvested in the ETP by large purse seine vessels be accompanied by 
documentation from the appropriate IDCP-member country certifying that there was an IDCP 
observer on the vessel at all times and listing the numbers for the associated TTF(s).
68 
                                               
65 United States' first written submission, para. 43. 
66 United States' second written submission, para. 128. 
67 United States' first written submission, para. 45. 
68 United States' first written submission, para. 46. WT/DS381/RW 
 
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  Form 370 
 3.49.  Every imported tuna product, regardless of where the tuna was caught and whether the dolphin-safe label is used, must be accompanied by a NOAA Form 370, which designates the gear 
type with which the tuna was caught and, if the product is to be labelled dolphin-safe, contains the 
necessary certifications. At the time of importation, one copy of this form is required to be submitted to Customs and Border Protection and another is required to be submitted, within 
10 days of the importation, to the Tuna Tracking and Verification Program (TTVP).
69 
Physical segregation  
 3.50.  The amended measure requires that, to be contained in tuna product labelled dolphin-safe, 
tuna must be segregated from non-dolphin-safe tuna from the time it was caught through 
unloading and processing. Section 216.93(c)(1) implements this requirement for tuna caught by large purse seine vessels in the ETP, requiring that dolphin-safe tuna be loaded into designated 
wells and offloaded to trucks, storage facilities, or carrier vessels in such a way as to safeguard the 
distinction between dolphin-safe and non-dolphin-safe tuna. Independent observers monitor the loading and unloading of wells, and individual lots  of tuna are assigned TTF tracking numbers that 
can be traced through each step of production of the tuna products.
70 
3.51.  Sections 216.93(c)(2) and (3) apply the same requirement to tuna caught by purse seine 
vessels outside the ETP and to tuna caught in othe r fisheries. Any mixing in the affected wells or 
storage areas should result in the tuna being designated non-dolphin-safe.71 
Tracking cannery operations and processor operations other than cannery operations, 
subject to US jurisdiction 
 
3.52.  Whenever a US cannery receives a shipment of domestic or imported tuna for processing, a 
NMFS representative may be present to monitor delivery and verify the dolphin-safe designations. Further, US tuna processors are required to submit monthly reports to the TTVP for all tuna 
received at their processing facilities. These re ports indicate, for all tuna received, whether the 
tuna is eligible to be labelled dolphin-safe under section 216.91, species, condition of the tuna products, weight, ocean area of capture, catche r vessel, gear type, trip dates, carrier name, 
unloading dates, location of unloading and, if the tuna products are labelled dolphin-safe, the 
required certifications for each shipment of tuna. All US exporters, trans-shippers, importers, 
processors, and distributors of tuna or tuna products must maintain records related to the tuna for at least two years, including Form 370s and associ ated certifications, and all additional required 
reports.
72 
4  ARGUMENTS OF THE PARTIES 4.1.  The arguments of the parties are reflecte d in their executive summaries, provided to the 
Panel in accordance with paragraph 17 of the Working Procedures adopted by the Panel (see 
Annexes B-1, B-2, B-3, B-4, B-5 and B-6). 
5  ARGUMENTS OF THE THIRD PARTIES 5.1.  The arguments of Australia, Canada, the Eu ropean Union, Japan, the Republic of Korea, 
New Zealand, and Norway are reflected in their respective executive summaries, provided in 
accordance with paragraph 18 of the Working Proc edures adopted by the Panel (see Annexes C-1, 
C-2, C-3, C-4, C-5, C-6, C-7, C-8, C-9 and C- 10). The Republic of Korea did not submit written 
arguments to the Panel. Japan did not make an oral statement. China, Guatemala and Thailand did 
not submit written or oral arguments to the Panel. 
                                               
69 United States' first written submission, para. 49. 
70 Mexico's first written submission, para. 92. 
71 United States' first written submission, para. 50. 
72 United States' first written submission, para. 52. WT/DS381/RW 
 
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  6  INTERIM REVIEW 
6.1  General issues 6.1.  All paragraph references in this section are to the paragraph numbers in the final report. This 
section of the Report constitutes an integral part of the Panel's findings. 
6.2.  In response to the parties' requests, the Pa nel made typographical and stylistic corrections in 
the following paragraphs: 7.11, 7.16, 7.34, 7.35, 7.62, 7.71, 7.80, 7.98, 7.120, 7.124, 7.126, 7.136, 7.143, 7.147, 7.160, 7.161, 7.167, 7.172, 7.177, 7.187, 7.185, 7.192, 7.198, 7.199, 
7.206, 7.208, 7.231, 7.233, 7.248, 7.249, 7.251, 7.252, 7.253, 7.256, 7.262, 7.283, 7.294, 
7.297, 7.298, 7.300, 7.302, 7.303, 7.304, 7.306, 7.310, 7.312, 7.346, 7.349, 7.352, 7.355, 7.365, 7.363, 7.367, 7.368, 7.370, 7.377, 7.378, 7.401, 7.433, 7.439, 7.444, 7.450, 7.453, 7.454, 7.458, 7.466, 7.477, 7.483, 7.486, 7.508, 7.517, 7.519. 7.528, 7.533, 7.539, 7.554, 
7.577, 7.579, 7.585, 7.587, 7.591, 7.593, and 7.599. 
6.3.  In response to comments from both parties, the Panel has made minor revisions to the 
descriptive part of its Report at paragraphs 1.1, 1.10, 3.1, 3.13, 3.14, 3.28, 3.29, 3.30, 3.31, 
3.32, 3.36, 3.40, and 3.47.  
6.4.  In light of the requests made by the partie s during the interim review stage, and in order to 
reflect the parties' arguments and exhibits more precisely, the Panel made adjustments to the 
following paragraphs: 7.104, 7.111, 7.112, 7.116, 7.154, 7.156, 7.193, 7.291, 7.309, 7.324, 
7.328, 7.339, 7.349, 7.360, 7.374, 7.467, 7.589, and 7.592. 
6.5.  Both parties requested that the Panel clarif y and, in some cases, revise its reasoning and 
findings in a number of paragraphs. In response to these requests, the Panel has adjusted its 
Report at paragraphs: 7.66, 7.105, 7.148, 7.150, 7.366, and 7.601.  
6.2  Specific issues 6.2.1  Evidence concerning observable an d unobservable harms caused by different 
fishing methods 
6.6.  Both parties requested the Panel to explain in more detail its views of certain evidence 
pertaining to the different eligibility criteria. The Panel did not consider it necessary to review 
evidence submitted by the parties in the original dispute. The Panel did, however, review the new 
evidence, and found that it simply confirmed the findings made in the original proceedings on this issue. For this reason, the Panel did not discuss this new evidence in great detail in its interim report. Nevertheless, in light of the parties' requests, we have decided to describe the new 
evidence in some more detail, and to provide more detailed explanations of the Panel's 
understanding and views of the various document s. The Panel notes that this new evidence 
confirms the factual findings made by the original panel and upheld by the Appellate Body. 
Accordingly, we have revised the report at paragraphs 7.111, 7.112, 7.116, 7.122, 7.123, and 
7.129 to 7.135.  
6.2.2  Description of the Appellate Body's  finding on observed and unobserved harms 
caused by setting on dolphins as comp ared with other tuna fishing methods 
6.7.  The United States requested that the Panel review its description of the Appellate Body's 
findings in paragraphs 7.120, 7.122, 7.579, and 7.585 of its Report. Mexico did not agree with the United States' request, and asked the Panel to reject it.  
6.8.  The paragraph as originally drafted accurately  reflects our understanding of the original panel 
and Appellate Body reports. The Appellate Body expressly confirmed that "setting on dolphins causes observed and unobserved adverse effects on dolphins".
73 Neither party denies that setting 
on dolphins causes observed and unobserved harm to dolphins. However, the original panel and 
the Appellate Body were also clear in holding that "the risks to dolphins from other fishing techniques are [not] insignificant, and [may] under some circumstances rise to the same level as 
                                               
73 Appellate Body Report, US – Tuna II (Mexico) , para. 287. WT/DS381/RW 
 
- 23 - 
 
  the risks from setting on dolphins".74 In our view, what makes setting on dolphins particularly 
harmful is the fact that it causes certain unobserved effects  beyond  mortality and injury "as a 
result of the chase itself".75 These harms would continue to exist "even if measures are taken in 
order to avoid the taking and killing of dolphins on the nets".76 It is precisely because these 
unobserved harms cannot be mitigated by measures to avoid killing and injuring dolphins that the 
original panel and the Appellate Body found that the United States is entitled to treat setting on dolphins differently from  other fishing methods. 
6.9.  To ensure clarity, we have revised our drafting of paragraphs 7.120, 7.122, 7.123, 7.579 and 
7.585. 
6.2.3  Mexico's evolving argument on the different observer requirements under 
Article 2.1 of the TBT Agreement 
6.10.  The United States requested the Panel to revise its description of Mexico's argument in 
paragraphs 7.154 and 7.161 of the Report. Mexico re quested the Panel to reject this request, and 
stated that the United States' proposed redraft would "mischaracterize Mexico's arguments".
77 
6.11.  In our view, the original text accurately  summarizes Mexico's argument. Mexico explicitly 
argued that the different certification requirem ents "impose two distinct … standards for the 
accuracy of information regarding the dolphin-safe status tuna: one standard for tuna caught 
inside the ETP, and a separate and much lower standard for tuna outside the ETP".78 In the Panel's 
view, this sentence clearly means that, in Mexico's view, the amended tuna measure imposes a lighter (or, in Mexico's words, a "much lower") burden on tuna caught outside of the ETP large 
purse seine fishery on tuna caught within that fish ery. For the sake of clarity, the Panel has added 
a footnote in paragraph 7.154 explicitly linking the Panel's summary to Mexico's submission.  
6.12.  In addition, the Panel notes that its description of Mexico's argument takes into account the 
way in which Mexico's arguments developed over the course of these proceedings, and in 
particular its (Mexico's) development of arguments concerning the different cost burdens imposed 
by the amended tuna measure. As both parties will  recall, one of the main issues discussed by the 
Panel and the parties at the meeting concerned the various costs imposed by the amended tuna 
measure. A number of the Panel's written questions to the parties also concerned the different cost 
burdens imposed by the measure at issue, and both  parties responded to these questions. As the 
Panel explains in paragraph 7.162 the amended tuna measure appears to impose different cost burdens on different countries, and this is an  important element of the differential burdens 
imposed by the measure. In light of these consid erations, we believe that our understanding and 
representation of Mexico's argument is accurate and should stand.  
6.2.4  Evidence concerning log-books 
6.13.  The United States requested the Panel to review certain factual findings in paragraphs 7.219 
and 7.601. In particular, the United States reques ted that the Panel explicitly note that some 
logbooks do require or allow captains to record mammal bycatch. The Panel reviewed this 
evidence, and has revised its Report at paragraphs 7.219-7.226. 
6.2.5  Tracking and verification systems 6.14.  The United States requested the Panel to revise its findings in a number of 
paragraphs concerning the tracking and verification system that applies to tuna caught other than 
in the ETP large purse seine fishery. Specifically, the United States requested that the Panel find: 
(a) that can codes enable tracking back not only to the vessel by which the tuna in the can was caught, but also to the captain's statement associated with the tuna contained in the can; (b) that 
captains' certifications are associated with batches of tuna at their "first point of unloading"; and 
(c) that in some cases tuna products made from tuna caught other than in the ETP large purse 
                                               
74 Appellate Body Report, US – Tuna II (Mexico) , para. 289. 
75 Panel Report, US – Tuna II (Mexico) , para. 7.504. 
76 Panel Report, US – Tuna II (Mexico) , para. 7.504. 
77 Mexico's Comments on the United States' Comments on the Inte rim Report, para. 25. 
78 Mexico's second written submission, para. 193. WT/DS381/RW 
 
- 24 - 
 
  seine fishery can be tracked back to the well in which it was stored during the fishing trip on which 
it was caught. 
6.15.  With respect to the part (a) of the United States' request, the Panel declines to make the 
additional finding requested by the United States, i.e. that can codes enable tuna to be tracked 
back to the captain's statement associated with th e tuna contained in the can. In the first place, 
the additional finding would not be consistent with the United States' own argumentation. [[BCI
79 80]]. Accordingly, a general finding that can codes enable trace-back to captains' 
certifications would be inappropriate. 
6.16.  Additionally, we do not agree that the evidence supports the United States' allegation on 
this point. [[BCI]] .  
6.17.  Although we decline to make the addition al finding requested by the United States, the 
Panel considers it appropriate to more clearly describe the United States' argument on this point. 
Accordingly, we have revised paragraphs 7.310 and 7.355. 
6.18.  With respect to part (b) of the United States' request, the Panel declines to make the 
change requested, that is, to find that captains' certifications appear to be assigned at the "first 
point of unloading". The Panel's finding [[BCI81 82]] Nevertheless, in order to ensure clarity, we 
have replaced the word "production" with the word "loining", so that the text of paragraph 7.370 
more closely reflects the evidence presented by the United States. 
6.19.  In respect of part (c) of the United States' request, the Panel declines to make the 
additional finding requested by the United States. We have revised paragraphs 7.356-7.359 to explain more clearly why we do not agree with the United States' interpretation of the evidence.  
6.20.  Moreover, Mexico requested the Panel to make an additional finding concerning the tracking 
and verification system for tuna caught other than in the ETP large purse seine fishery. Specifically, Mexico requests the Panel make clear that the United States "is not able to track the 
movement and dolphin safe status of tuna from the time of catch up to the point of delivery to a 
non-US cannery and subsequent shipment to the United States".
83 The United States disagrees 
with the changes suggested by Mexico. 
6.21.  The Panel has decided to revise paragraphs 7.365-7.368 by adding the word "directly" to 
Mexico's suggested text, the Panel has addressed the United States' contention that Mexico's proposed drafting was inaccurate because US importers themselves are supposed to have the documentation necessary to trace tuna back to the point of catch. We note that in its comments on 
this request the United States stated that it did not contest three of Mexico's four requested 
revisions. 
6.2.6  The Panel's description of Mexico's  argument on less fa vourable treatment  
6.22.  Mexico requested the Panel to revise its description of Mexico's argument in 
paragraphs 7.104 and 7.105. The United States does not support this request, and asks the Panel to reject it. According to the United States, the original paragraph properly characterizes Mexico's 
argument.  
6.23.  The Panel has decided to revise these paragraphs. In the Panel's view, Mexico's 
argumentation has consistently distinguished between the way in which the different eligibility 
criteria  on the one hand and the different certification and tracking and verification requirements  
on the other hand have a detrimental impact on the competitive opportunities of Mexican tuna and 
tuna products. In particular, beginning in its second written submission, Mexico has maintained that whereas the eligibility criteria have a direct negative impact on Mexican tuna and tuna 
products by disqualifying tuna caught by setting on dolphins from ever accessing the label, the 
other two regulatory distinctions (the different certification and tracking and verification 
                                               
79 United States' response to Panel question No. 44, para. 242. [[BCI]]. 
80 United States' response to Pa nel question No. 44, para. 242. 
81 United States' response to Pa nel question No. 44, para. 241. 
82 Cannery Slides on Tuna Trace Systems (Exhibit US-189) (BCI). 
83 Mexico's Comments on th e Interim Report, para. 14. WT/DS381/RW 
 
- 25 - 
 
  requirements) have a detrimental impact on Mexican tuna and tuna products indirectly, as it were, 
because they provide "an illegitimate competitive advantage"84 to tuna caught other than in the 
ETP large purse seine fishery. This illegitimate advantage de facto  modifies the conditions of 
competition to the detriment of Mexican tuna and tuna products. 
6.24.  Mexico articulated this distinction most cl early in response to a question from the Panel. 
Mexico explained that the amended tuna measure has a detrimental impact on Mexican tuna and tuna products because:
85 
a. "Mexico's primary fishing method is permanently disqualified from being used to catch 
dolphin-safe tuna, while the fishing methods used by the United States and other countries are qualified to be used to catch dolphin-safe tuna; 
b. Mexican-origin tuna and tuna products are subject to comprehensive and strict record 
keeping and verification requirements that prevent non-dolphin-safe tuna from being 
labelled as dolphin-safe. In contrast, tuna and tuna products from the United States and other countries are not subject to such comprehensive and strict requirements. As a 
consequence, tuna and tuna products from the United States and other countries can be 
mislabelled as dolphin-safe when, in fact, such tuna and tuna products are not dolphin-safe; and 
c. In the case of Mexican tuna, the initial designation of dolphin-safe status is subject to 
mandatory independent observer requirements at the point when the tuna is harvested from the ocean, which prevents non-dolphin-safe tuna from being mislabelled as dolphin-safe. In the case of tuna from the United States and other countries, the initial 
designation of dolphin-safe status is not made by independent observers at the point 
when the tuna is harvested from the ocean, thereby allowing the tuna to be mislabelled as dolphin-safe". 
6.25.  The passage cited above clearly distingu ishes between two types of alleged detrimental 
impact: the first, caused by the eligibility cr iteria, directly disadvantage Mexican tuna by 
disqualifying tuna caught using Mexico's primary tuna fishing method from accessing the dolphin-
safe label; and the second, caused by the differe nt certification and tracking and verification 
requirements, which disadvantage Mexican tuna products by granting an advantage to tuna caught outside the ETP large purse seine fishery and theref ore modifies the conditions of competition to 
the detriment of Mexican tuna and tuna products. 
6.26.  In the Panel's view, by distinguishing between the detrimental impact caused by the 
eligibility criteria on the one hand and the different certification and tracking and verification requirements on the other hand, Mexico clearly premised its argument on the notion that the 
different regulatory distinctions caused detrimental treatment in different ways and for different 
reasons.  
6.27.  As such, the Panel believes that the text in paragraphs 7.104 and 7.105 and the 
interpretation of Mexico's argument contained therein is accurate and should stand. Nevertheless, 
the Panel has made some drafting revisions for a dded clarity, and has also completed the citation 
requested by Mexico. 
6.2.7  Regulated vs. unregulated setting on dolphins 
6.28.  Mexico requested the Panel to modify the drafting of paragraph 7.577. Specifically, Mexico 
seeks the inclusion of language suggesting that setting on dolphins is "particularly harmful" to dolphins "when unregulated". 
6.29.  The Panel declines to make the changes requested by Mexico. As we have explained in 
various parts of this Report, our understanding is that setting on dolphins is "particularly harmful" to dolphins because, as a method of harvesting tuna, it requires, for its efficacy, that dolphins be 
                                               
84 Mexico's second written submission, para. 147. 
85 Mexico's response to Panel ques tion No. 9, para. 36. The same point was made in Mexico's second 
written submission, paras. 147, 163; Mexico's respon se to Panel question No. 7, paras. 19 and 21. WT/DS381/RW 
 
- 26 - 
 
  "set on" – that is, chased and encircled, in each  and every fishing set. As we have discussed in 
detail elsewhere, setting on dolphins gives rise to observable and unobservable harms. Although the observable harms, including mortality and serious injury, may be containable through regulation, the original panel made clear that th e unobservable effects caused by the chase itself 
would "exist even if measures are taken to avoid the taking and killing of dolphins in the nets".
86 
While unregulated setting on dolphins may very we ll be more dangerous than regulated setting on 
dolphins – and that is a point on which we need not decide – the relative safety of regulated or 
unregulated setting on does not, as we understan d it, change fact that setting on dolphins is 
particularly harmful to dolphins because it causes unobserved effects beyond observable mortality and serious injury, and which cannot be removed through regulations that reduce mortality and serious injury.  
7  FINDINGS 
7.1  Claims 7.1.  Mexico claims that the amended tuna measure is inconsistent with the following provisions of 
the covered agreements: 
a. Article 2.1 of the TBT Agreement, becaus e the amended tuna measure continues to 
accord Mexican tuna products treatment less favourable than that accorded to like tuna 
products of the United States and to like tuna products originating in any other country; 
b. Article I:1 of the GATT 1994, because the amended tuna measure continues to confer on 
tuna products originating in other countries an advantage which is not accorded immediately and unconditionally to like tuna products originating in Mexico; 
c. Article III:4 of the GATT 1994, because the am ended tuna measure continues to accord 
Mexican tuna products treatment less favourable than that accorded to like tuna products of United States' origin in respect of all laws, regulations and requirements 
affecting their internal sale, offering for sale, purchase, transportation, distribution or 
use. 
7.2.  In its request for the establishment of a panel under Article 21.5 of the DSU, Mexico also 
claimed that the amended tuna measure was incons istent with Article XX III:1(b) of the GATT 1994 
because it "nullifies or impairs benefits that accrue to Mexico under the GATT 1994". However, this claim was not pursued by Mexico in any of its submissions to the Panel, and accordingly the Panel does not address it in this Report. 
7.2  Order of analysis 
7.3.  The parties have not requested that the Panel follow any particular order of analysis. Their 
written submissions address Mexico's claims und er the TBT Agreement first and the GATT 1994 
second.  
7.4.  It is well established that where: 
[A] provision of an agreement included in  Annex 1A of the WTO Agreement … and a 
provision of the GATT 1994 that have identical coverage both apply, … the provision 
that deals specifically, and in detail with a question should be examined first.
87 
7.5.  In the original proceedings in this matter, the panel found that:88  
[T]he TBT Agreement "deals in detail, and specifically" with the matters that it 
addresses. Therefore, where claims under GATT 1994 are presented in parallel with 
claims under the TBT Agreement, claims  under the TBT Agreement should be 
considered first. 
                                               
86 Panel Report, US – Tuna II (Mexico) , para. 7.504. 
87 Appellate Body Report, US – Softwood Lumber IV , para. 134. 
88 Panel Report, US – Tuna II (Mexico) , para. 7.43. WT/DS381/RW 
 
- 27 - 
 
  7.6.  Upon review, the Appellate Body similarly considered the parties' arguments concerning 
Article 2.1 of the TBT Agreement first.  
7.7.  In our view, there is no reason to depart fr om the approach of the original panel in respect of 
the proper order of analysis. Accordingly, the Panel will first analyse Mexico's claim under 
Article 2.1 of the TBT Agreement, and will then pr oceed to consider its claims under Article I:1 and 
Article III:4 of the GATT 1994. 
7.8.  Before considering Mexico's claims under the TBT Agreement and the GATT 1994, the Panel 
will address two preliminary issues: first, the me asure at issue and the scope of these Article 21.5 
proceedings; and second, the burden and stan dard of proof applicable in this case. 
7.3  Parameters of the Panel's mandate: th e measure at issue and the scope of these 
Article 21.5 proceedings 
7.9.  The Panel recalls that the Appellate Body's conclusion on the WTO-inconsistency of the tuna 
measure was framed broadly. Indeed, the Appella te Body's ultimate recommendation to the DSB 
was phrased in terms of the United States' "measure" – that is, the entire  tuna measure, rather 
than one particular aspect or element of it. At  paragraph 299 of its report, the Appellate Body 
explicitly concluded that:89  
[T]he US dolphin-safe labelling provisions  provide "less favourable treatment" to 
Mexican tuna products than that accorded to tuna products of the United States and 
tuna products originating in other countries and are therefore inconsistent with Article 2.1 of the TBT Agreement .  
7.10.  At the end of its report the Appellate  Body recommended that the DSB request the 
United States to "bring its measure " into conformity with WTO law.
90  
7.11.  As the Appellate Body had previously indi cated that it would use the terms "measure at 
issue", "US measure", and "the US 'dolphin-safe' labelling provisions" to refer to "the legal 
instruments challenged by Mexico collectively"91, it is clear that the Appellate Body's conclusions 
and recommendations were meant to apply to the tuna measure as a whole, including all its 
components. Consider, for instance, the manner in which the Appellate Body defined the measure 
at issue in the original proceedings:92 
This dispute arises out of a challenge brought by Mexico against certain legal 
instruments of the United States establishing the conditions for the use of a "dolphin-safe" label on tuna products.  In particular, Mexico identified the following legal 
instruments as the object of its challenge:  the United States Code , Title 16, Section 
1385 (the "Dolphin Protection Consumer Information Act" or "DPCIA"); the United States Code of Federal Regulations , Title 50, Section 216.91 and 
Section 216.92 (the "implementing regulations"); and a ruling by a US federal appeals 
court in Earth Island Institute v. Hogarth  (the "Hogarth ruling"). Taken together, the 
DPCIA, the implementing regulations, and th e Hogarth ruling set out the requirements 
for when tuna products sold in the United St ates may be labelled as "dolphin-safe".   
7.12.  In our view, it is clear that in referring to the "'dolphin-safe' labelling provisions", the 
Appellate Body's conclusions and recommendations were meant to apply to the tuna measure as a 
whole . 
7.13.  We note also that in its findings the Appellate Body made clear that there were various ways 
for the United States to bring its measure into conformity with the even-handedness requirement 
of Article 2.1 of the TBT Agreement: 
                                               
89 Appellate Body Report, US – Tuna II (Mexico) , para. 299 (emphasis added). 
90 Appellate Body Report, US – Tuna II (Mexico) , para. 408 (emphasis added). 
91 Appellate Body Report, US – Tuna II (Mexico) , para. 172. 
92 Appellate Body Report, US – Tuna II (Mexico) , para. 172. WT/DS381/RW 
 
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  The Panel further noted that the provisions of the DPCIA themselves envisage the 
possibility that a fishery outside the ETP would be identified as one having a "regular and significant mortality, or serious injury of dolphins", which would then lead to the application in such fishery of a requirement to certify that no dolphin has been killed 
or seriously injured on the trip on which the tuna was caught.
93 
We see no error in the Panel's assessment. In addition, we note that nowhere in its 
reasoning did the Panel state that imposing a requirement that an independent 
observer certify that no dolphins were killed or seriously injured in the course of the 
fishing operations in which the tuna was caught would be the only way for the 
United States to calibrate its "dolphin-safe" labelling provisions to the risks that the Panel found were posed by fishing techniques other than setting on dolphins.
94  We 
note, in this regard, that the measure at issue itself contemplates the possibility that 
only the captain provide such a certification under certain circumstances.95 
In the light of the above, we conclude th at the United States has not demonstrated 
that the difference in labelling conditions fo r tuna products containing tuna caught by 
setting on dolphins in the ETP, on the one hand, and for tuna products containing tuna caught by other fishing methods outside the ETP, on the other hand, is "calibrated" to 
the risks to dolphins arising from different  fishing methods in different areas of the 
ocean. It follows from this that the United States has not demonstrated that the detrimental impact of the US measure on Mexican tuna products stems exclusively from a legitimate regulatory distinction.  We note, in particular, that the US measure 
fully addresses the adverse effects on dolphins resulting from setting on dolphins in 
the ETP, whereas it does "not address mortality (observed or unobserved) arising from fishing methods other than setting on dolphins outside the ETP".
96 In these 
circumstances, we are not persuaded that the United States has demonstrated that 
the measure is even-handed in the relevant respects, even accepting that the fishing technique of setting on dolphins is particularly harmful to dolphins.
97  
7.14.  In the current proceedings, with a view  to complying with the DSB recommendations, the 
United States has modified its implementing regulation, along the line described in paragraphs 3.32-3.52 above. The United States takes the view that this regulatory change is sufficient to bring its measure into conformity wi th the rulings and recommendations of the DSB. 
7.15.  Mexico has initiated this dispute under Arti cle 21.5 of the DSU, arguing that the modification 
has not brought the US measure into conformity with its WTO obligations.  
7.16.  The task of a panel established under Article 21.5 is to "decide[]" disputes "as to the 
existence or consistency with a covered agreement of measures taken to comply with … 
recommendations and rulings" of the DSB. In th e current proceedings, the parties disagree as to 
the identity of the measure taken to comply wh ich according to the United States defines the 
scope of review of this implementation panel. 
7.17.  Mexico takes a broad view, and argues that the measure taken to comply is coextensive 
with what both parties call the "amended tuna measure". We have described the "amended tuna 
m e a s u r e "  i n  s o m e  d e t a i l  a b o v e ;  f o r  p r e s e n t  p u r p o s e s  w e  s i m p l y  r e c a l l  t h a t  i t  c o n s i s t s  o f  ( a )  
Section 1385 of Title 16 of the United States Code (the legislation), (b) Title 50, Part 216, 
                                               
93 (footnote original) Panel Report, US – Tuna II , para. 7.543. 
94 (footnote original) We note, however, that such a requirement may be appropriate in circumstances 
in which dolphins face higher risks of mortality or serious injury. 
95 (footnote original) See DPCIA, subsection 1385(d)(1)(D): 
(D) by a vessel in a fishery other than one described in subparagraph (A), (B), or (C) that is identified by the Secretary as having a regular and significant mortality or serious injury of 
dolphins, unless such product is  accompanied by a written statem ent executed by the captain of 
the vessel and an observer participating in a nati onal or international program acceptable to the 
Secretary that no dolphins  were killed or seriously injured in  the sets or other gear deployments 
in which the tuna were caught, provided that the Secretary dete rmines that such an observer 
statement is necessary . (emphasis added). 
96 (footnote original) Panel Report, US – Tuna II (Mexico) , para. 7.544. We note that the measure at 
issue does address driftnet fishing in the high seas. 
97 Appellate Body Report, US – Tuna II (Mexico) , paras. 295-297. WT/DS381/RW 
 
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  Subpart H of the United States Code of Federa l Regulations as amended by the 2013 Final Rule 
(the regulations as amended or regulations), and c) the court ruling in  Earth Island Institute v 
Hogarth  (the Hogarth  ruling).98 The United States urges the Panel to take a narrower view. In its 
opinion, while the three instruments identified by Mexico together constitute the "amended tuna 
measure", it is only the 2013 Final Rule, which was adopted in response to the original proceedings 
with the goal of "com[ing] into compliance with the DSB recommendations and rulings", that is the measure taken to comply and for the United States this Panel should limit the scope of its review 
to the measure it took to comply.
99 
7.18.  The Appellate Body has explained that "[p]roceedings under Article 21.5 do not concern just 
any measure of a Member of the WTO; rather, Article 21.5 proceedings are limited to those 
'measures  taken to comply  with the recommendations and rulings of the DSB'".100 Accordingly, a 
panel established under Article 21.5 is not free to consider any measure adopted and maintained 
by a WTO Member. Rather, its jurisdiction is limited to assessing measures taken by a Member to "implement" rulings and recommendations  made by the DSB in relation to another , pre-existing 
measure previously found by the DSB to be WTO-inconsistent – which other measure, while 
necessarily relevant to the inquiry under Article 21.5, is conceptually distinct.
101  
7.19.  We begin our analysis by recalling that what is the "measure taken to comply" in a given 
case is not determined exclusively by the implementing Member. A Member's designation of a 
measure as one taken "to comply", or not, is relevant to this inquiry, but it cannot be conclusive. Conversely, nor is it up to the complaining Member alone to determine what constitutes the measure taken to comply. It is rather for the Panel itself to determine the ambit of its 
jurisdiction.
102 This determination, like all determinations made by a panel, must be conducted on 
the basis of an objective examination of all relevant facts.103 
7.20.  In our opinion, the United States is correc t in asserting that the 2013 Final Rule is, strictly 
speaking, its "measure taken to comply". The 2013 Final Rule is, to use the Appellate Body's 
words, precisely that legal instrument adopted by the United States " in the direction of, or for the 
purpose of achieving, compliance" with the DSB's rulings and recommendations in the original 
proceedings.104 As we have already discussed, at the end of the original proceedings the Appellate 
Body found that the "tuna measure", defined as consisting of the legislation, regulations, and Hogarth ruling, was "inconsistent with Article 2.1 of the TBT Agreement ".
105 The 2013 Final Rule, 
which amends aspects of the original regulations, is the measure "taken" by the United States to 
remedy this WTO-inconsistency. It is precisely th rough the introduction of certain changes to the 
regulations embodied in the 2013 Final Rule that th e United States seeks to correct the illegality 
that the original panel and the Appellate Body identified in the original tuna measure as a whole . 
As a regulatory amendment, the 2013 Final Rule is  integrated into the original tuna measure for 
the precise purpose of remedying that measure, which the DSB found to be inconsistent with WTO law.  
7.21.  As a sovereign nation, the United States is of course free to come into compliance with a 
DSB ruling in any way it chooses. Panels have repeatedly recognized that in "the first instance the modalities of the implementation of [a] recommendation are for the [respondent] to determine".
106 
Indeed, Article 21.3 of the DSU recognizes that a Member may come into compliance on the basis 
of and in accordance with its own "intentions in  respect of implementation of the rulings and 
recommendations of the DSB". A panel's role in an Article 21.5 proceeding is thus not to determine 
                                               
98 Mexico's first written submission, para. 11. 
99 United States' first written submission, para. 13; see also United States' second written submission, 
para. 4. At the Panel's meeting with the parties, the United States confirmed that in its view the measure taken comply is the 2013 Rule and not the amended tuna measure as a whole. 
100 Appellate Body Report, Canada – Aircraft (A rticle 21.5 – Brazil) , para. 36 (emphasis original). 
101 Appellate Body Report, Canada – Aircraft (A rticle 21.5 – Brazil) , para. 36. 
102 Appellate Body Report, US – Softwood Lumber IV (Article 21.5 – Canada) , para. 73. 
103 Appellate Body Report,  US – Zeroing (EC) (Article 21.5 – EC) , para. 205. 
104 Appellate Body Report, US – Softwood Lumber IV (Article 21.5 – Canada) , para. 66 (emphasis 
original). 
105 Appellate Body Report, US – Tuna II (Mexico) , para. 299. 
106 Panel Report, US – Hot Rolled Steel , para. 8.11. See also, e.g. Panel Report, US – Steel Plate , 
para. 8.8 ("the choice of means of  implementation is decided, in the first instance, by the Member 
concerned"); Panel Report, US – Countervailing Measures on Certain EC Products , para. 6.43 ("[T]he Members 
have discretion in how to bring a measure found to  be WTO-inconsistent into conformity with WTO 
obligations"). WT/DS381/RW 
 
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  whether the way chosen by a Member to come into compliance is in any sense the "best" way, but 
rather to make an "objective assessment"107 of whether the course of action actually taken by the 
responding Member is sufficient to bring its measure into conformity with the WTO Agreement.  
7.22.  Having said that, we do not think that a Member's choice of how to come into compliance 
with DSB rulings and recommendations necessarily limits or circumscribes the jurisdiction of a 
panel composed under Article 21.5 of the DSU for the purpose of assessing whether compliance has been achieved. In our view, the overriding qu estion for such a panel is always whether the 
measure found by the DSB to be incompatible with one or more obligations under the 
WTO Agreement has been brought into compliance so that it is no longer WTO-inconsistent. Thus where, for example, a Member modifies one aspect or element of a measure previously found by the DSB to be WTO-inconsistent in its entirety, a panel acting under Article 21.5 is not limited to 
only assessing the WTO-consistency of the modified aspect or element. Rather, this Panel's task 
remains that of assessing whether or not a Member has brought its entire measure – that is, the measure found by the DSB to be WTO-inconsistent - into conformity with WTO law, including 
through or by way of the modification made to th e particular aspect or element. In the present 
proceedings, the Panel's task is not only to determine whether the 2013 Final Rule is in itself WTO-consistent, but rather, and more fundamentally, to assess whether, through or by way of the 
2013 Final Rule, the United States has succeeded in bringing the tuna measure as a whole, as the 
measure found by the Appellate Body in the original proceedings to be WTO-inconsistent, into conformity with the WTO Agreement.  
7.23.  It follows that our finding that the "measure taken to comply" is the 2013 Final Rule in no 
way precludes the Panel from considering the broade r question of whether the modifications to the 
original measure, including the new 2013 Final Rule, is now WTO-compliant. Such a task necessarily requires the Panel to consider not only the contents of the 2013 Final Rule itself, but 
also to examine how the 2013 Final Rule interacts (or does not interact) with the other elements 
that make up the amended tuna measure.  
7.24.  Accordingly, we conclude that our role in these proceedings is not limited to assessing the 
WTO-consistency of the 2013 Final Rule. Rather, we need to determine whether the amended tuna 
measure, including the 2013 Final Rule, brings the United States into compliance with the WTO Agreement.
108  
7.25.  A further, though related, issue that we must address before proceeding to the merits of 
Mexico's case concerns the scope of Article 21.5 proceedings – or, to put it another way, the type 
of claims that may be raised against the 2013 Final Rule and the amended tuna measure more broadly. According to the United States, "Article  21.5 reports issued by the Appellate Body and 
panels have consistently drawn a distinction between claims made against new elements of a 
measure taken to comply and those elements that are unchanged  from the original measure. 
These reports have repeatedly found that the te rms of reference of a compliance panel do not 
include re-examining the WTO consistency of an unchanged  aspect that was not found to be WTO-
inconsistent in that dispute".
109 The United States recalls that, as a general rule, Article 21.5 
proceedings must not give complainants an "unfair second chance with respect to any claims on which they did not prevail in the original proceedings", as such a chance would be inconsistent 
                                               
107 Article 11 of the DSU. 
108 The Panel notes that this approach is analogous to the approach taken by the panel (and not 
reversed by the Appellate Body) in US – Softwood Lumber IV (Article 21.5 – Canada) . In that case, the panel 
made clear that proceedings under Article 21.5 of the DSU are not limited in scope only to measures explicitly 
taken to implement DSB rulings and recommendations. Instead, a panel's jurisdiction under Article 21.5 extends to cover measures or inst ruments that are "closely connected" and "inextricably linked" to the 
measure taken in response to an adverse DSB ruling: Panel Report, US – Softwood Lumber IV (Article 21.5 – 
Canada) , paras. 4.38-4.48. In our opinion, the same reas oning applies with equal force here. The 2013 Final 
Rule can be said to be "closely connected" or "inextrica bly linked" to the tuna measure as a whole because, as 
explained above, the 2013 Final Rule was adopted by the Un ited States precisely to bring the tuna measure as 
a whole into compliance with the DSB's ruling that it (that is, the tuna measure as a whole) was inconsistent with the United States' obligations under the WTO Agre ement. Accordingly, the 2013 Final Rule does not stand 
alone, but assumes legal significance on ly as part of the amended tuna meas ure, which, as we have explained, 
is the measure whose WTO-consistency we are tasked to address in these proceedings. 
109 United States' first written submission, para. 170. WT/DS381/RW 
 
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  with both the need for "prompt settlement of disputes"110 and, perhaps more importantly, the 
respondent's due process rights.111 Additionally, the United States cautions that allowing Mexico to 
challenge unchanged aspects of the amended tuna  measure would threaten the finality of DSB 
rulings and recommendations and undermine the unc onditional acceptance of adopted Appellate 
Body reports required of Members by Article 17.14 of the DSU.112    
7.26.  Applying these principles to the facts of this case, the United States advances the following 
argument in its first written submission:113 
Mexico's entire Article 2.1 claim is premised  on the theory that at least one of the 
following elements is not even-handed:  1)  the distinction between the eligibility for 
the dolphin safe label for tuna product containing tuna caught by setting on dolphins in an AIDCP-consistent manner and tuna caught by other fishing methods;  2) the 
distinction between the differing record-k eeping and verification requirements 
required for tuna caught inside and outside the ETP; and 3) the distinction between the differing observer requirements for tuna vessels operating inside and outside the 
ETP. According to Mexico, if any one of these three elements is not even-handed, the 
detrimental impact already found to exist in the original proceeding would reflect discrimination, and Mexico's Article 2.1 claim would succeed.  
Yet these three elements are unchanged from the original measure and the Appellate 
Body did not consider that any of them pr oved the original measure discriminatory. 
The only regulatory distinction the Appellate Body found not to be even-handed was the requirement that tuna product containing tuna caught in the ETP is ineligible for 
the label where a dolphin had been killed or seriously injured but tuna product 
containing tuna caught outside the ETP could be so labelled where a dolphin had been killed or seriously injured. And it is this distinction that the 2013 Final Rule addresses. 
7.27.  In essence, the United States' argument is that the three elements or aspects of the 
amended tuna measure on which Mexico bases its claims – the eligibility requirements for the dolphin-safe label or the so-called qualification/disqualification distinction
114, the different tracking 
and verification requirements115, and the different observer or certification requirements116 – are 
all unchanged from the original measure, and that , because none of these elements was found to 
be WTO-inconsistent by the Appellate Body in the original proceedings, Mexico cannot raise claims relating to these elements in the present proceedings.  
7.28.  In support of its argument on the scope of the Appellate Body's rulings and 
recommendations, the United States cites to paragraphs 289-292 and 298 of the Appellate Body report. At paragraph 298, the Appellate Body said:  
[I]n our view, the United States has not justified as non-discriminatory under 
Article 2.1 the different requirements that it applies to tuna caught by setting on dolphins inside the ETP and tuna caught by other fishing methods outside the ETP for 
access to the US "dolphin-safe" label. 
7.29.  Earlier, at paragraph 284, the Appellate Body found that:  
The aspect of the measure that causes detrimental impact on Mexican tuna products 
is thus the difference in labelling conditions for tuna products containing tuna caught 
by setting on dolphins in the ETP, on the one hand, and for tuna products containing 
tuna caught by other fishing methods outside the ETP, on the other hand. 
                                               
110 United States' first written submission, paras. 170 and 208 (arguing that if Members were allowed to 
challenge unchanged aspects of a measure in Article 21. 5 proceedings, they would effectively be "allowed to 
raise, and re-raise arguments time  and time again – without limit"). 
111 United States' first written submission, paras. 171 and 207. 
112 United States' first written submission, para. 208. 
113 United States' first written submission, paras. 204 and 205. 
114 United States' response to Pa nel question No. 4, para. 14. 
115 United States' response to Pa nel question No. 4, para. 15. 
116 United States' response to Pa nel question No. 4, para. 16. WT/DS381/RW 
 
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  7.30.  According to the United States, these stat ements show that the Appellate Body only found 
fault with the different certification requirement imposed on tuna caught by setting on dolphins on the one hand and tuna caught by other fishing me thods outside the ETP on the other. It "thus did 
not consider that any of the other numerous regulatory distinctions contained in the original 
measure" – specifically, concerning tracking, ve rification, and observers – "proved the measure 
discriminatory".
117  
7.31.  Mexico rejects the United States' argument on the Panel's jurisdiction on a number of 
related grounds. First, it contends that the Appellate Body's findings – and thus the DSB's rulings 
and recommendations – were "general", and applied to the "US 'dolphin-safe' labelling provisions" considered in their "totality".
118 Second, Mexico maintains that the amended tuna measure is "in 
principle, a new and different measure" from th e one before the original panel and Appellate 
Body119, and accordingly "the Panel should focus on [the measure] as a whole and not [on] 
elements comprising that measure".120 Finally, Mexico argues that the United States is incorrect to 
characterize aspects of the amended tuna measure as "unchanged". According to Mexico, 
important changes have in fact been made to the provisions of the measure concerning tracking 
and verification and observer coverage.121  
7.32.  In our opinion, the United States' fundamental premise – that "[t]he only regulatory 
distinction the Appellate Body found not to be  even-handed was the requirement that tuna 
products containing tuna caught in the ETP is ineligible for the label where a dolphin had been killed or seriously injured but tuna product containing tuna caught outside the ETP could be so labelled where a dolphin had been killed or seriously injured"
122, and that the Appellate Body did 
not find any other aspect of the measure to be WTO-inconsistent – is incorrect. Neither the original 
panel report nor the Appellate Body report is limited in the way the United States suggests.  
7.33.  Rather, the Appellate Body found that the original tuna measure as a whole was not even-
handed, because while the regulatory scheme full y addressed the harms caused by setting on 
dolphins, it did not adequately address harms caus ed by other tuna fishing methods. The Appellate 
Body did not say that any one particular element of the regulatory scheme imposed other than on 
purse seine vessels in the ETP was solely responsibl e for this lack of even-handedness. Rather, the 
entire regulatory scheme was insufficient to address what the original panel and Appellate Body found to be the very real risks posed to dolphi ns by methods of fishing other than setting on 
dolphins. It was this overall lack of "even-handedness" that the Appellate Body found to be 
inconsistent with Article 2.1 of the TBT Agreement,  and, as we read the Appellate Body's reasons, 
this lack of "even-handedness" was ultimately fo und to be characteristic of the entire system 
established by the original tuna measure. It was,  in other words, the tuna measure as a whole, 
with its varying regulatory requirements, that was found to be inconsistent with Article 2.1 of the 
TBT Agreement. 
7.34.  We have already explained that the Appella te Body's recommendation to the DSB is phrased 
in terms of the United States' "measure" – that is, the entire tuna measure, rather than one 
particular aspect or element of it. As noted ab ove, at paragraph 299 of its report, the Appellate 
Body explicitly concluded that "the US ' dolphin-safe' labelling provisions  provide 'less favourable 
treatment' to Mexican tuna products than that accorded to tuna products of the United States and 
tuna products originating in other countries and are therefore inconsistent with Article 2.1 of the 
TBT Agreement";
123 and at the end of its report the A ppellate Body recommended that the DSB 
request the United States to "bring its measure " into conformity with WTO law.124  
7.35.  We do not agree that the passages of the Appellate Body's report cited by the United States 
support its contention. To the contrary, by referring in the plural to "the difference in labelling conditions" (para. 284) and "different requirements" (para. 298), we understand the Appellate 
Body to have been referring generally to the different requirements that the tuna measure 
                                               
117 United States' first written submission, para. 213. 
118 Mexico's second written submission, paras. 89 and 91. 
119 Mexico's second written submission, para. 89. 
120 Mexico's second written submission, para. 93. 
121 Mexico's second written submission, para. 95. 
122 United States' first written submission, para. 205 (emphasis added). 
123 Appellate Body Report, US – Tuna II (Mexico) , para. 299 (emphasis added). 
124 Appellate Body Report, US – Tuna II (Mexico) , para. 408 (emphasis added). WT/DS381/RW 
 
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  imposed on, on the one hand, tuna caught by large purse seine vessels inside the ETP and, on the 
other hand, tuna caught other than in the ETP large purse seine fishery.  
7.36.  We observe that the Appellate Body was careful to use the plural throughout its reasoning, 
including in its legal findings and overall conclusions. Thus, under the heading "Conclusion on 
Article 2.1 of the TBT Agreement", the Appellate Body said: 
[I]n our view, the United States has not justified as non-discriminatory under 
Article 2.1 the different requirements that it applies to tuna caught by setting on 
dolphins inside the ETP and tuna caught by other fishing methods outside the ETP for 
access to the US "dolphin-safe" label. The United States has thus not demonstrated that the detrimental impact of the US measure on Mexican tuna products stems exclusively from a legitimate  regulatory distinction.  
7.37.  Here again the Appellate Body used the term "requirements" in the plural. To us, this clearly 
indicates that the Appellate Body was not solely concerned with the different certification required in the ETP and outside of it. If that had been th e case, the Appellate Body could, and indeed would 
have referred to the different "requirement" in the singular. The use of the plural indicates that the 
Appellate Body's findings were not limited to the difference in the certification requirement, but encompassed other differences embedded in the original tuna measure, including with respect to 
tracking, verification, and observers.
125  
7.38.  It is true that the Appellate Body's reasoning focused primarily on the disqualification of 
tuna caught by setting on dolphins from accessing the dolphin-safe label. This may very well have been a consequence of the way the case was argued by the parties. At any rate, as Japan said in 
its third-party submission, the United States' attempt to limit this Panel's jurisdiction confuses "the 
Appellate Body's conclusion with the particular reasons that provided the basis for that conclusion".
126 Those reasons are of course central to our analysis in these proceedings, but they 
do not restrict our ability to entertain claims relating to other aspects of the tuna measure, which, 
by virtue of the Appellate Body's broad conclusions, is properly before us. As Japan put it in its third-party submission, "to the extent the amended measure continues to accord less favourable 
treatment to Mexican tuna products" – whether for the reasons identified by the Appellate Body or 
for any other reason – "the United States woul d have failed to comply fully with the DSB's 
recommendations and rulings".
127 
7.39.  In our opinion, Mexico is correct that although the conditions that the amended tuna 
measure imposes on tuna caught by large purse seine vessels in the ETP are formally unchanged, 
the 2013 Final Rule may have altered the legal import and significance  of those conditions, 
meaning that we cannot simply assume that the relevant aspects of the measure are truly – that 
is, in a legally meaningful sense – unchanged. Indeed, previous panel and Appellate Body reports 
have suggested that in cases such as this, where a measure found to be inconsistent in original proceedings is revised rather than repealed or co mpletely recreated, such revision "transforms" 
the original measure, so that the amended measure "in its totality"
128 is properly considered as a 
                                               
125 We note that in its reasoning the Appellate Body referred to "tuna caught by  setting on dolphins" in 
the ETP. However, we note also that tuna caught by se tting on dolphins is always and under all circumstances 
ineligible  to receive the dolphin-safe label. Such tuna cannot be said to be subject to any "labelling conditions" 
or "requirements" as there are no conditions or requirem ents under which such tuna would ever be eligible to 
receive the United States dolphin-safe label. Accordingly, in referring to "tuna caught by setting on dolphins",  
we understand the Appellate Body to be referring to th e whole regulatory regime by which tuna caught by 
setting on dolphins is identified and excluded from acce ssing the label. This regime necessarily includes not 
only the substantive certification requirement, but also the various documentation obligations that support it. It is only through those obligations – tracking, verificati on, and observers – that tuna importers can show that 
they have satisfied the substantive standard (i.e. that no nets were intentionally set on dolphins and that no dolphins were killed or seriously in jured). The differences in the labelling requirements therefore include both 
the substantive certification standard and the mechanisms by which compliance with that standard is monitored and demonstrated. This reading of the Appell ate Body's reasoning is consistent with its overall 
finding, which, as we have  mentioned, found the original tuna "measu re" as a whole to be inconsistent with 
Article 2.1 of the TBT Agreement. 
126 Japan's third-party submission, para. 20. 
127 Japan's third-party submission, para. 19. 
128 Appellate Body Report, US – Shrimp (Article 21.5 – Malaysia ), para. 87. WT/DS381/RW 
 
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  "new and different measure".129 Accordingly, even though the tracking, verification, and 
certification (observer) requirements that apply to ETP-caught tuna may be formally unchanged, the introduction of the 2013 Final Rule has created a new set of legal relations between the various parts of the amended tuna measure, so that even formally unchanged elements may, in 
the context of the amended measure, establish a ne w set of legal circumstances such that it would 
be incorrect to regard them as "unc hanged" from a legal perspective.  
7.40.  We also reject the United States' contention that Mexico's arguments relating to the 
different tracking and verification and observer requirements "are clearly separable from the 
US measure taken to comply". The US measure taken to comply (i.e. the 2013 Final Rule) relates directly to the substantive declarations or certifications that must be made before a catch of tuna can be labelled as being dolphin-safe. However, tracking and verification and observer 
requirements go directly to the issue of the reliability of such certifications. Insofar as the goal of 
the tuna measure remains, inter alia , the provision of accurate information to consumers, the 
tracking and verification mechanisms are central aspects of the tuna measure, working together 
with the substantive certification requirements so as to provide accurate information to consumers 
about the dolphin-safe status of a particular tuna catch. Moreover, we note that the 2013 Rule itself addresses situations in which independent observer certification may be required. In other 
words, it deals directly with one aspect of the measure that the United States claims is 
"separable".
130 In such circumstances, we cannot agree that the tracking and verification 
requirements are "separable" from the certific ation rules contained in the 2013 Final Rule. 
7.41.  To sum up, we do not agree with the United States that the 2013 Final Rule is separable 
from the rest of the tuna measure simply because it does not change any pre-existing 
requirements but instead adds new requirements. In our view, the 2013 Final Rule is not a stand-
alone measure but an integral component of the amended tuna measure. To the extent that it 
interacts with, and indeed forms an integral part of, that measure, the fact that it adds new 
requirements rather than changing pre-existing re quirements is immaterial, and certainly does not 
have the effect of removing the rest of the t una measure, which was the object of the DSB's 
rulings and recommendations, from our jurisdiction.131 
7.42.  In finding that we have jurisdiction to consider all of Mexico's claims, we are not suggesting 
that we have authority to re-examine all of the factual and legal circumstances of the case de novo . We are in full agreement with the European Union that where the original panel or the 
Appellate Body has made a finding on the basis of  certain facts and evidence, and where there is 
no change in the facts and/or evidence on the basis of which that finding was made, we should not re-assess the issue from the beginning, but rather refer to and rely upon the finding previously 
made.
132 This is not the same as saying, as the United States does, that such points are outside of 
our jurisdiction. Rather, our view is that such issues do fall within our jurisdiction, but that we should respect relevant findings made by the panel and the Appellate Body in the original 
proceedings, whether factual or legal, in the intere sts of maintaining the security and predictability 
of the multilateral trading system.  
7.43.  In light of the above, we conclude that the legal question before us in these proceedings is 
whether the amended tuna measure, including the 2013 Final Rule, brings the United States into 
compliance with WTO law. We find that we have jurisdiction to consider all of Mexico's claims, 
including as they relate to the eligibility criteria and the certification and tracking and verification requirements.  
                                               
129 Appellate Body Report, US – Zeroing (Article 21.5 – EC ), para. 432; Appellate Body Report, Canada – 
Aircraft (Article 21.5 – Brazil ), para. 36. 
130 See e.g. United States' response to Panel question No. 4, para. 16. 
131 Indeed, as we suggested above, in situations like the one at issue here, the line between adding new 
requirements to a regulatory scheme and changing pre- existing aspects of that scheme is very fine and 
perhaps illusory, since where an instrument adds new re quirements it will necessarily have the effect of 
changing pre-existing requirements insofar as the latter interact with the former. 
132 European Union's third-pa rty submission, para. 21. WT/DS381/RW 
 
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  7.4  Burden and standard of proof applicable in these proceedings 
7.4.1  Burden of proof 7.44.   As a starting point, we recall the fundamental principle that:
133  
[T]he burden of proof rests upon the party, whether complaining or defending, who 
asserts the affirmative of a particular claim or defence. If that party adduces evidence 
sufficient to raise a presumption that what is claimed is true, the burden then shifts to the other party, who will fail unless it adduces sufficient evidence to rebut the 
presumption. 
7.45.   In disputes concerning the GATT 1994 in which Article XX is invoked, it is for the 
complaining party to show a breach of one or more provisions of that Agreement. If the complainant does so successfully, the burden then  shifts to the respondent either to rebut the 
showing of violation or else to prove that the violation found is nevertheless justified under one of 
the general or security exceptions provided for in Articles XX and XXI.  
7.46.  However, the proper allocation of th e burden of proof under Article 2.1 of the 
TBT Agreement appears to be somewhat less clear. Ensuring that we apply the proper burden of 
proof is especially important in these proceedings because, as both parties recognize, the relevant 
factual evidence is highly contested and, with respect to some of the issues in dispute, minimal.  
In particular, there appears to be limited scientific evidence concerning the scope and nature of 
dolphin mortalities in some non-ETP fisheries
134, which may have important consequences for the 
Panel's analysis.  
7.47.  We begin by recalling that, under Article 2.1,  a technical regulation will be found to afford 
"less favourable treatment" to imported products where (a) it modifies the conditions of 
competition in the relevant market to the detriment of the imported products; and (b), such detrimental modification of the conditions of competition does not stem exclusively from a 
legitimate regulatory distinction. We discuss the legal test under Article 2.1 in more detail 
below.
135 For now, what we must consider is which party bears the burden of showing which  of 
these two elements.  
7.48.  The Appellate Body has explicitly addresse d the allocation of the burden of proof under 
Article 2.1 of the TBT Agreement. First, in the or iginal proceedings in this matter, the Appellate 
Body said that: 
In the context of Article 2.1 of the TBT Agreement , the complainant must prove its 
claim by showing that the treatment accorded to imported products is "less 
favourable" than that accorded to like domestic products or like products originating in any other country. If it has succeeded in doing so, for example, by adducing evidence 
and arguments sufficient to show that the measure is not even-handed, this would 
suggest that the measure is inconsistent with Article 2.1. If, however, the respondent shows that the detrimental impact on imported products stems exclusively from a 
legitimate regulatory distinction, it follows that the challenged measure is not 
inconsistent with Article 2.1.
136 
7.49.  In US – COOL , the Appellate Body again set out the burden of proof under Article 2.1. It 
explained that:  
[A]s with all affirmative claims, it is for the complaining party to show that the 
treatment accorded to imported products is less favourable than that accorded to like domestic products. Where the complaining party has met the burden of making its 
prima facie  case, it is then for the responding party to rebut that showing. If, for 
example, the complainant adduces evidence  and arguments showing that the measure 
                                               
133 Appellate Body Report, US – Wool Shirts and Blouses , p. 14, DSR 1997:1, p. 323 at 335. 
134 R. Charles Anderson, Cetaceans and Tuna Fisheries in the Central and Western Indian Ocean (ITNLF 
Technical Report No. 2, 2014) (Exhibit MEX-161), p. 39. 
135 See section 7.5.1 below. 
136 Appellate Body Report, US – Tuna II (Mexico) , para. 216. WT/DS381/RW 
 
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  is designed and/or applied in a manner that constitutes a means of arbitrary or 
unjustifiable discrimination of the group of imported products and thus is not even-handed, this would suggest that the measure is inconsistent with Article 2.1. If, however, the respondent shows that the detrimental impact on imported products 
stems exclusively from a legitimate regulatory distinction, it follows that the 
challenged measure is not inconsistent with Article 2.1.
137  
7.50.  We understand these passages as indicating that a complainant bears the burden of 
showing that a challenged measure modifies the conditions of competition in the relevant market 
(i.e. the relevant market in the responding Member) to the detriment of products from the complaining Member.
138 As noted above, this criterion must always  be satisfied before a violation 
of Article 2.1 can be found, regardless of whether that violation is claimed to be de facto  or de 
jure. What is less clear to us is whether the complainant or the respondent bears the burden of 
showing, in the first instance, that the detrimental impact established by the complainant stems (or does not stem) exclusively from a legitimate regulatory distinction because it is (or is not) 
even-handed.
139  
7.51.  Our uncertainty arises for the following re ason. In the passages quoted above, the Appellate 
Body indicated that a complainant is expected to show prima facie  that the challenged measure "is 
designed and/or applied in a manner that cons titutes a means of arbitrary or unjustifiable 
discrimination of the group of imported products an d thus is not even-handed", but that once this 
showing is made the burden shifts to the responde nt to show that the detrimental impact in fact 
stems exclusively from a legitimate regulatory di stinction. However, the Appellate Body has also 
explained that when analysing whether detrimenta l treatment stems exclusively from a legitimate 
regulatory distinction, a panel must carefully consider whether that treatment "reflects discrimination", which is "[u]ltimately [a question of] whether the measure is even-handed".
140 In 
particular, while it seems clear that the compla inant must show the existence of detrimental 
treatment, it is not entirely clear to us whether the complainant also must show that such 
treatment does not stem exclusively from a legitimate  regulatory distinction, or if, rather, it is the 
respondent  that must show prima facie  that the detrimental treatment does stem exclusively from 
a legitimate regulatory distinction. In other words, does the complainant bear the burden of showing in the first instance that steps (a) and (b) of the test under Article 2.1 of the TBT Agreement are met, or does the complainant only  need to meet step (a), after which point the 
burden shifts to the respondent to meet step (b)?  
7.52.  In its efforts to ascertain the proper allocation of the burden of proof under Article 2.1 of the 
TBT Agreement, the Panel asked the parties and third-parties to comment on the passages from 
the Appellate Body reports quoted above.
141 Both the United States and Mexico agreed that "the 
complainant bears the initial burden of establishing a prima facie  case in respect of all elements of 
its claim under Article 2.1", and that this meant that "the complainant is required to establish a 
prima facie  case that: (i) the measure at issue modifies the conditions of competition in the 
relevant market to the detriment of imported products vis-à-vis  like domestic products and like 
products originating in any other Member; and (ii) that such detrimental impact reflects discrimination against the imported products and, thus, does not stem exclusively from a 
legitimate regulatory distinction".
142 
                                               
137 Appellate Body Reports, US – COOL , para. 272. 
138 Appellate Body Report, US – Tuna II  (Mexico) , para. 215. 
139 In this connection, and as we discuss in more detail in our discussion of the legal test under 
Article 2.1 of the TBT Agreement, we note that, at least in cases where detrimental treatment is de facto , the 
Panel must proceed to examine whether this treatm ent stems exclusively from a legitimate regulatory 
distinction rather than reflecting discri mination: see e.g. A ppellate Body Report, US – Cloves Cigarettes , 
para. 182. 
140 Appellate Body Reports, US – COOL , para. 328. 
141 Panel question No. 58. In this question, the Panel quoted the passages from US – Tuna II (Mexico)  
and US – COOL  cited above, and asked the parties to explain "t he implications of [the se statements] for the 
allocation of the burden of proof und er Article 2.1 of the TBT Agreement". 
142 Mexico's response to Panel question No. 58, para. 157. See also United States' response to Panel 
question No. 58, paras. 284 and 285. See also Mexico's comments on the United States' response to Panel 
question No. 58, para. 192 ("Mexico and the United States appear to be in agreement that Mexico bears the 
initial burden of establishing a prima facie  case in respect of all elements of its claim under Article 2.1 of the 
TBT Agreement. There is no disagreement that Mexico mu st adduce evidence and arguments sufficient to raise 
a presumption that, first, the Amended Tuna Measure modifi es the conditions of competition in the U.S. market WT/DS381/RW 
 
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  7.53.  Interestingly, a number of third-parties di sagreed with the parties, and suggested that the 
burden of proof should be allocated under Articl e 2.1 of the TBT Agreement in a way that mirrors 
the allocation under Article III:4 and Article XX of the GATT 1994.143  
7.54.  Canada considered that the passages cited above "do not provide a clear indication of where 
the initial burden of proof lies".144 After reviewing the way in which the burden of proof is allocated 
under Article III:4 and Article XX of the GATT 1994 and recalling the close connection drawn by the Appellate Body between those Articles an d Article 2.1 of the TBT Agreement, Canada 
submitted that "[t]here is no logical or conceptual reason why this balance should not also be 
reflected in the allocation of the burden of proof in  Article 2.1. Further, there is nothing in the text 
or context of Article 2.1 that militates against this interpretive approach".
145 It therefore concluded 
that in the context of:  
[A] claim of less favourable treatment under Article 2.1 of the TBT Agreement, it is 
reasonable to expect that the complaining party should bear the burden of establishing a prima facie  case that the technical regulation modifies the conditions of 
competition in the relevant market to the detriment of imported like products. Where 
the complaining party has met the burden of making its prima facie  case, it would 
then be for the responding party to rebut that prima facie  case by demonstrating that 
the detrimental impact is justified because it stems exclusively from a legitimate 
regulatory distinction.
146 
7.55.  Similarly, in its response the European Un ion observed that "in interpreting and applying 
Article 2.1 of the TBT Agreement in the case of a claim of a de facto  breach of the national 
treatment obligation, it should be born in mind that the balance struck in that provision is not 
different from the balance struck in Article III:4 and Article XX of the GATT" and thus concluded that "in some respects the burden of proof will fa ll on the defending Member, just as it does under 
the GATT".
147  
7.56.  Norway, after recalling that "the legal stan dard in Article 2.1 embodies the same balance as 
that in the two GATT Articles"148 – that is, Article III:4 and Article XX – concluded that "the same 
burden of proof, and the same order of the shifting of the burden of proof, applies to Article 2.1 of 
the TBT Agreement" as under Article III:4 and Article XX of the GATT 1994.149 
7.57.  Finally, New Zealand also believed that whil e the "Complaining Party must adduce sufficient 
evidence to raise the presumption that the measure adversely impacts the conditions in which 
imported products compete with like domestic products in the regulating Member's market"150, 
                                                                                                                                               
to the detriment of imported tuna products from Mexico vis-à-vis  like tuna products of U.S. origin or like tuna 
products originating in any other country, and, seco nd, this detrimental impact reflects arbitrary or 
unjustifiable discrimination because, fo r example, the measure at issue is designed or applied in a manner that 
lacks even-handedness. Further,  the parties seem to agree that the burden then shifts to the United States to 
adduce sufficient evidence and arguments to rebut the prima facie  case established by Me xico"); United States' 
comments on Mexico's response to Panel question No. 58, para. 122 ("Mexico correctly agrees with the 
United States that the complainant bears the initial burden of establishing a prima facie  case in respect of all 
elements of its claim under Article 2.1 of the TBT Agreement") (internal citations omitted). 
143 Although some third-parties did agree with the parties: see e.g. Austra lia's response to Panel 
question No. 58; Japan's response to Panel question No . 58, para. 4 (recognizing, however, that "that there 
are competing considerations that suggest different  allocations of the burden of proof": para. 3). 
144 Canada's response to Panel question No. 58, para. 1. 
145 Canada's response to Panel question No. 58, para. 4. 
146 Canada's response to Panel question No. 58, pa ra. 6. Canada continued: "Where the responding 
party succeeds in demonstrating, on a prima facie  basis, that the detrimental im pact is justified because it 
stems exclusively from a LRD, the burden would shift back to the complaining party to demonstrate that the regulatory distinction is not even-handed, for example be cause it is designed and/or  applied in a manner that 
constitutes a means of arbitrary or  unjustifiable discrimination".   
147 European Union's integrated executive summary, para. 35. 
148 Norway's response to Panel question No. 58, para. 7. 
149 Norway's response to Panel question No. 58, pa ra. 8. See also para. 10 ("Norway understands the 
Appellate Body's statements quoted in the Panel's question, as explaining that the allocation of the burden of 
proof under 2.1 should be allocated in much the same way as under Article III:4 and Article XX of the 
GATT 1994"). 
150 New Zealand's response to Pa nel question No. 58, para. 3. WT/DS381/RW 
 
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  nevertheless once this showing is made "the Responding Party bears the burden of demonstrating 
whether any detrimental impact stems exclusivel y from a legitimate regulatory distinction".151 
7.58.  We are mindful that there may be systemic reasons for favouring an approach to the burden 
of proof that would require a complainant to show prima facie  that a measure modifies the 
conditions of competition in the relevant market to the detriment of its (i.e. the complainant's) like 
products, but would place the burden of showing that such detrimental impact stems exclusively 
from a legitimate regulatory distinction on the responding Member. For instance, there may be 
concern that requiring a complainant to prove, in the first instance, both that a measure has a 
detrimental impact on its like products and that such impact does not stem exclusively from a 
legitimate regulatory distinction could have the undesirable effect of discouraging claims under Article 2.1 of the TBT Agreement. This would be so because complainants may decide not to bring 
a claim under Article 2.1 of the TBT Agreement if they are of the view that they could obtain 
essentially the same outcome (i.e. a finding of less favourable treatment) under the GATT 1994 without having to prove as many facts.  
7.59.  Notwithstanding these considerations, give n that in the present proceedings both parties 
agree that it is Mexico that bears the burden of showing prima facie  both that the amended tuna 
measure modifies the conditions of competition in the United States' market to the detriment of 
Mexican tuna and tuna products and that such detrimental treatment reflects discrimination 
because it does not stem exclusively from a legitimate regulatory distinction and is not 
even-handed, we have decided to adopt this approach in the remainder of our report. The Panel is aware that it is not bound by the legal interpreta tions offered by the parties or the third-parties;
152 
however, in the context of the present proceedings,  where Mexico itself has asserted that it bears 
the heavier burden of showing prima facie  that both the first and second steps of the "less 
favourable treatment" test in Article 2.1 of th e TBT Agreement are met, we think it prudent to 
follow this approach. Nevertheless, if at any point in our analysis we consider that allocating the 
burden of proof differently would or could lead to a different outcome or result, we will indicate this in our reasons, in order to ensure that the Appellate Body has sufficient findings of fact should 
this matter be appealed. 
7.4.2  Standard of proof 7.60.  It is useful at this point to say a few words about the standard of proof, since at various 
points in its submissions the United States accuses Mexico of not furnishing evidence to support its 
arguments about the possible operation of the amended tuna measure.
153 In particular, the 
United States suggests that Mexico's arguments about the possibility that non-dolphin-safe tuna could fraudulently access the US dolphin-safe label under the amended tuna measure are based on 
"bare allegation".
154 The Panel will deal with the evidence presented by both parties below in the 
context of assessing the merits of Mexico's claims and in light of the allocation of the burden of 
proof discussed above. For now, the Panel notes a few general points. 
7.61.  The Appellate Body has explained that, as a general principle, "precisely how much and 
precisely what kind of evidence will be required to establish [a prima facie  case] will necessarily 
vary from measure to measure, and provision to provision, and case to case".155 It has also made 
clear on numerous occasions that panels have a significant degree of discretion in weighing and 
analysing evidence, and this discretion includes th e prerogative both to "decide which evidence it 
chooses to utilize in making its findings"156 and "how much weight to attach to the various items of 
evidence placed before it by the parties".157 Ultimately, it is the Panel that has authority to decide 
whether the evidence presented is sufficient to make out Mexico's claims (as well as any 
explanations or defences advanced by the United States).  
                                               
151 New Zealand's response to Pa nel question No. 58, para. 4. 
152 Appellate Body Report, EC – Tariff Preferences , para. 105 ("Consistent with the principle of jura novit 
curia, is not the responsibility of [the parties] to provide us with the legal interpretation to be given to a 
particular provision"). 
153 United States' first written submission, paras. 247 and 312-313; United States' second written 
submission, paras. 25, 37, 77, 99, 101, 102 and 196, 
154 United States' first written submission, para. 247. 
155 Appellate Body Report, US – Wool Shirts and Blouses , p. 14, DSR 1997:1, p. 323 at 335. 
156 Appellate Body Report, EC – Hormones , para. 135. 
157 Appellate Body Report, Chile – Price Band System (Article 21.5 – Argentina) , para. 229. WT/DS381/RW 
 
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  7.62.  Additionally, the Appellate Body has clarifie d that under Article 2.1 of the TBT Agreement, a 
panel's task is to "carefully scrutinize the particular circumstances of the case, that is, the design, architecture, revealing structure, operation, and application of the technical regulation".
158 This 
direction has implications for the type of evidence that a panel analysing a claim under Article 2.1 
may require to make its findings. It suggests that, especially where a claim is made against a 
technical regulation as such, rather than as applied, it will be vital for the panel to closely examine the objective features and characteristics of the measure. It also suggests that evidence regarding 
the actual operation of the measure, while important
159, may not be dispositive in cases where a 
measure's design, structure, and architecture are themselves claimed to be discriminatory.  
7.63.  In this context, we recall the Appellate Bo dy's guidance that in cases concerning measures 
challenged as such, it may not be necessary for the complainant to prove that the application of a 
measure in fact "result[s] in a breach … for each and every  import transaction".160 Concomitantly, 
where a complainant is able to adduce clear and convincing evidence that the design, architecture, and revealing structure of a measure are themselves discriminatory, it may not be sufficient for a 
respondent simply to show that, in practice, the application of the measure has not in all instances 
resulted in actual discriminatory treatment being accorded imported products. 
7.64.  We note that this approach to the standard  of proof was recently followed by the Appellate 
Body in its report on EC – Seal Products . In that case, the Appellate Body accepted the 
complainants' argument that the so-called IC exception in the European Communities seal measure was inconsistent with the chapeau of Article XX of the GATT 1994 because "seal products derived from what should in fact be properly characterized as "commercial" hunts could potentially  
enter the EU market under the IC exception".
161 The Appellate Body did not examine whether 
there had been actual instances of incorrect entry; rather, it focused its analysis on the design and 
structure of the measure. Ultimately, it found a violation on the basis of evidence concerning the 
possible  WTO-inconstant operation of the measure, as well as evidence that there was no way to 
prevent or identify such operation. 
7.65.  In writing the above, we do not mean to suggest that Mexico can establish a violation of 
Article 2.1 of the TBT Agreement negatively , i.e. Mexico does not succeed merely because it 
cannot be shown that the measure at issue has never  resulted in less favourable treatment. To the 
contrary, in a case such as the present where the claimed discrimination is de facto  rather than 
de jure162, the complainant must, in accordance with the burden of proof, show positively  that the 
measure is designed or applied in a manner that detrimentally modifies the conditions of 
competition. To establish this fact, the complainant must provide evidence of the measure's design, architecture, and revealing structure, and link these aspects of the measure to the 
detrimental impact that it claims its imports are suffering. A complainant, especially in a case of 
de facto  discrimination, cannot simply point to the measure at issue and then expect the panel to 
find a violation where the respondent fails to show that the measure at issue never could  result in 
a violation of one or more WTO obligations.
163 In cases of de facto  discrimination, the complainant 
must provide evidence and argument sufficient to show why a measure that appears to be 
non-discriminatory on its face nevertheless in fact provides less favourable treatment to imported products in a way that is repugnant to WTO law. This is not to say, however, that the complainant 
is expected to prove that a measure always has and always will, in each and every transaction, 
result in discrimination. 
7.66.  Before concluding our discussion of the bu rden and standard of proof, we wish to emphasize 
that, as the Appellate Body has affirmed on num erous occasions, a panel "enjoy[s] a margin of 
discretion in [its] assessment of the facts",
164. A Panel is "not required to accord to factual 
                                               
158 Appellate Body Report, US – Clove Cigarettes , para. 215. 
159 In this respect, we note that th e Appellate Body has instructed pane ls to consider "the totality of 
facts and circumstances" in the cases that come before them: Appellate Body Report, US – Clove Cigarettes , 
para. 206. 
160 Appellate Body Report, Argentina – Textil es and Apparel , para. 62. 
161 Appellate Body Reports, EC – Seal Products , para. 5.328 (emphasis added). 
162 Mexico's first written submission, para. 233 ("Accordingly, it is clear that the operation of the 
Amended Tuna Measure in the relevant market has a de facto  detrimental impact on the group of like imported 
products"). 
163 Appellate Body Report, US – Gambling , para. 140. 
164 Appellate Body Reports, China – Raw Materials , para. 341. WT/DS381/RW 
 
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  evidence of the parties the same mean ing and weight as do the parties";165 and, provided that it 
provides "reasoned and adequate explanations"166 of its treatment of the evidence, a panel does 
not violate Article 11 of the DSU merely because on e of the parties disagrees with its treatment of 
the evidence or would have preferred the panel to come to a different conclusion.   
7.67.  Having set out our understanding of the ru les on burden and standard of proof that must 
guide our analysis, we now turn to consider Mexico's claims under Article 2.1 of the TBT Agreement and Articles I: 1 and III:4 of the GATT 1994. 
7.5  Article 2.1 of the TBT Agreement 
7.68.  Having discussed certain preliminary matters in the preceding paragraphs, the Panel now 
turns to consider the merits of Mexico's case against the amended tuna measure. As explained 
above, we begin by considering Mexico's claim under Article 2.1 of the TBT Agreement. 
7.5.1  Legal test under Article 2.1 of the TBT Agreement 
7.69.  Article 2.1 of the TBT Agreement provides that: 
Members shall ensure that in respect of tec hnical regulations, products imported from 
the territory of any Member shall be accorded treatment no less favourable than that 
accorded to like products of national origin and to like products originating in any other country. 
7.70.  Article 2.1 sets out a three-step test. In order to fall foul of Article 2.1, a measure must: 
(a) Be a "technical regulation" within the meaning of Annex 1.1 of the 
TBT Agreement; 
(b) Concern or cover "like products"; and 
(c) Accord to like products of the complaining Member treatment less favourable than 
that accorded to domestic like products or like products from any other Member.
167 
7.71.  The present dispute does not raise question s under either (a) or (b) above. Both parties 
agree that, as the original panel found and the Appellate Body accepted, the tuna measure is a 
"technical regulation" for the purposes of the TBT Agreement.168 Moreover, both parties agree 
that, as the original panel also found169, Mexican and United States "tuna" and "tuna products" are 
like products.170 Accordingly, this Panel accepts that the amended tuna measure is a technical 
regulation within the meaning of Annex I of th e TBT Agreement, and that United States and 
Mexican "tuna" and "tuna products" are like. 
7.72.  The main issue that falls for decision under Article 2.1 of the TBT Agreement is thus whether 
the amended tuna measure accords to Mexican tuna and tuna products "treatment less 
favourable" than that which it accords to like tuna and tuna products from the United States and other WTO Members. We recall that, in accordance with our findings above about the scope of 
these Article 21.5 proceedings, our duty is not re stricted to assessing the WTO-consistency of the 
2013 Final Rule, but rather extends to considering whether the amended tuna measure as a whole, including but not limited to the 2013 Final Rule, is WTO-consistent, or whether it continues to 
accord less favourable treatment to Mexican tuna and tuna products. 
7.73.  The Appellate Body has developed a two-tier test for determining whether a technical 
regulation accords less favourable treatment to imported products than to domestic products or like products from other WTO Members. First, the Panel must assess whether the measure at issue 
                                               
165 Appellate Body Reports, US – COOL , para. 403. 
166 Appellate Body Reports, Philippines – Distilled Spirits , para. 136. 
167 Appellate Body Report, US – Tuna II (Mexico) , para. 202. 
168 Mexico's first written submission, para. 205; United States' first written submission, para. 181. 
169 Panel Report, US – Tuna II (Mexico) , para. 7.251 (confirmed in Appellate Body Report, US – Tuna II  
(Mexico) , para. 202 (noting that the United States did not challenge this finding on appeal). 
170 Mexico's first written submission, para. 208; United States' second written submission, para. 181. WT/DS381/RW 
 
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  modifies the conditions of competition in the US market to the detriment of Mexican tuna and tuna 
products as compared to like US tuna and tuna products or tuna and tuna products originating in any other Member.
171 Second, if the Panel finds that detrimental impact exists, it will proceed to 
examine whether the detrimental impact on imports stems exclusively from a legitimate regulatory 
distinction rather than reflects discriminat ion against the group of imported products. 172  
7.74.  In the following paragraphs, we briefly review the Appellate Body's guidance on the legal 
steps comprising these two tiers.  
7.75.  With respect to the first tier, i.e. the question whether the amended tuna measure modifies 
the conditions of competition in the US market to the detriment of Mexican tuna and tuna products, we recall that "Article 2.1 of the TBT Agreement prohibits both de jure  and de facto  
discrimination between domestic and like imported products".
173 Accordingly, the amended tuna 
measure may modify the conditions of competition in the US market to the detriment of Mexican 
tuna and tuna products even if it does not, on its face, single out tuna for differential treatment on the basis of the flag under which it was caught and/or processed.
174 Moreover, detrimental 
treatment may exist even in the absence of differential treatment, and, in fact, a "formal 
difference in treatment between imported and like domestic products is … neither necessary, nor sufficient, to show a violation of" Article 2.1.
175 Where a complainant argues that a measure has a 
de facto  detrimental impact on its exports, the reviewing panel should consider "the totality of the 
facts and circumstances before it, including any implications for competitive conditions discernible from the design and structure of the measure itself, as well as all features of the particular market 
at issue that are relevant to the measure's operation within that market". The Appellate Body has 
also made clear that " any adverse impact on competitive opportunities for imported products 
vis-à-vis  like domestic products that is caused by a particular measure may potentially be relevant 
to a panel's assessment of less favourable treatment under Article 2.1".
176 
7.76.  One of the major issues that arose for consideration in the original proceedings concerned 
the extent to which any proven detrimental impact must be shown to "result[] from the [challenged] measure itself rather than from the actions of private parties".
177 Reviewing the legal 
findings of the original panel on this issue, the Appellate Body clarified that, to succeed under 
Article 2.1 of the TBT Agreement, a complain ant must show the existence of "a genuine 
relationship between the measure at issue and an adverse impact on competitive opportunities for 
imported products".178 Reaffirming its earlier findings in Korea – Various Measures on Beef179, the 
Appellate Body concluded that "[t]he relevant question is … whether the governmental  
intervention [i.e. the measure itself] affects the conditions under which like goods, domestic and imported, compete in the market within a Member's territory".
180 In answering this question, the 
presence or existence of "some element of priv ate choice" will not relieve a respondent of 
responsibility under the TBT Agreement181 where the challenged measure has restricted or 
otherwise conditioned the exercise of that choice in a way that cannot be considered "normal" in 
the relevant market.182 
7.77.  With respect to the second tier of the less favourable treatment test, i.e. the question 
whether any detrimental treatment reflects illegitimate discrimination, the Appellate Body has 
                                               
171 Appellate Body Report, US – Tuna II (Mexico) , para. 268. 
172 Appellate Body Report, US – Clove Cigarettes , para. 215. 
173 Appellate Body Reports, US – COOL , para. 286. 
174 Appellate Body Report, US – Tuna II (Mexico) , para. 225 ("a measure may be de facto  inconsistent 
with Article 2.1 even when it is  origin neutral on its face"). 
175 Appellate Body Reports, US – COOL , para. 277 (citing Appellate Body Report, Korea – Various 
Measures on Beef , para. 137). 
176 Appellate Body Reports, US – COOL , para. 286. See also Appellate Body Reports, US – Tuna II 
(Mexico), para. 225 and US – Clove Cigarettes , para. 179. 
177 Appellate Body Report, US – Tuna II (Mexico) , para. 236. 
178 Appellate Body Report, US – Tuna II (Mexico) , para. 236. 
179 Appellate Body Report, Korea – Various Measures on Beef , para. 146. 
180 Appellate Body Report, US – Tuna II (Mexico) , para. 237 (citing Appellate Body Report, Korea – 
Various Measures on Beef , para. 149). 
181 Appellate Body Report, US – Tuna II (Mexico) , para. 239. 
182 Appellate Body Report, Korea – Various Measures on Beef , para. 146. Having said that, we also 
recognize that, as the Appellate Body made clear in US – COOL , "detrimental effects caused solely by the 
decisions of private actors cannot suppo rt a finding of inconsistency with Ar ticle 2.1": Appellate Body Reports, 
US – COOL , para. 291 (emphasis original). WT/DS381/RW 
 
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  explained that panels must "carefully scrutinize the particular circumstances of the case, that is, 
the design, architecture, revealing structure, operation, and application of the technical regulation at issue, and, in particular, whether the technical regulation is even-handed".
183 In essence, this 
inquiry requires the Panel to analyse whether the detrimental treatment found to exist under the 
first tier "stems exclusively from a legitimate regulatory distinction rather than reflecting 
discrimination against the group of imported products".184  
7.78.  In terms of the burden of proof , and as explained above, we will assess first whether Mexico 
has shown  prima facie both  that the amended tuna measure modifies the conditions of competition 
in the US market to the detriment of Mexican tuna and tuna products, and second  that such 
detrimental impact does not stem exclusively from a legitimate regulatory distinction. If Mexico 
succeeds in making this showing, the burden will shift to the United States to rebut Mexico by 
showing that, despite Mexico's prima facie  case, the detrimental treatment in fact does stem 
exclusively from a legitimate  regulatory distinction. 
7.79.  With the above in mind, how should panels assess whether a detrimental impact stems 
exclusively from a legitimate regulatory distinction, rather than reflecting discrimination in a 
manner inconsistent with Article 2.1 of the TBT Agreement? The Appellate Body has provided some guidance on this issue in the recent "trilogy" of TBT cases
185 and in EC – Seal Products . Most 
importantly, the Appellate Body has explained th at an analysis of whether detrimental impact 
stems exclusively from a legitimate regulatory distinction (or whether a technical regulation that causes detrimental impact is even-handed) must take account of whether the technical regulation at issue is "applied in manner that would constitute a means of arbitrary or unjustifiable 
discrimination between countries where the same conditions prevail or a disguised restriction on 
international trade".
186  
7.80.  This language is, of course, similar to the language of the chapeau of Article XX of the 
GATT 1994.187 Should panels, then, draw on the jurisp rudence elaborated under the chapeau in 
interpreting and applying Article 2.1 of the TBT Agreement? We now turn our attention to this 
question, which is highly contested by the parties in the present proceedings.  
7.81.  According to Mexico, "[a]lmost identical language [to that used by the Appellate Body in 
describing the test under Article 2.1 of the TBT Agreement] is included in the chapeau of Article XX of the GATT 1994. Accordingly, the interpretation of  "arbitrary discrimination" in the chapeau of 
Article XX sheds light on the interpretation of "arbitrary discrimination" within the meaning of 
Article 2.1 of the TBT Agreement".
188 In particular, Mexico argues that the question "whether the 
discrimination can be reconciled with, or is rationally related to, the relevant policy objective" pursued by the technical regulation is central to a panel's analysis under Article 2.1 of the 
TBT Agreement. In Mexico's view, "[w]here the a lleged rationale for the distinction created by the 
measure in question is inconsistent with, or actively undermines, its stated policy objective, it is reflective of arbitrary discrimination".
189 Thus, says Mexico, "the degree to which the resulting 
regulatory distinction can be reconciled to the poli cy objective pursued by the measure will provide 
a clear indication of whether arbitrary discrimination and a lack of even-handedness results".190 
7.82.  Mexico also argues that, read in light of the Appellate Body's interpretation of the chapeau 
of Article XX, the concept of "arbitrary or unjustifiable discrimination" under Article 2.1 of the 
TBT Agreement must be read as prohibiting, in the design or application of a technical regulation, 
"ambiguity that creates the potential for its [i.e. the technical regulation's] abuse and 
                                               
183 Appellate Body Report, US – Tuna II (Mexico) , para. 225 (citing Appellate Body Report, US – Clove 
Cigarettes , para. 182). 
184 Appellate Body Report, US – Tuna II (Mexico) , para. 215 (citing Appellate Body Report, US – Clove 
Cigarettes , para. 182). See also Appellate Body Reports, US – COOL , para. 271. 
185 Appellate Body Report, US – Clove Cigarettes ; US – Tuna II (Mexico) ; and US – COOL . 
186 Appellate Body Report, US – Clove Cigarettes , para. 94; See also Appellate Body Report, US – Tuna 
II (Mexico) , para. 213. 
187 The chapeau of Article XX of the GATT 1994 relevantly reads: "Subject to the requirement that such 
measures are not applied in a manner which would constitute a means of arbitrary or unjustifiable 
discrimination between countries where the same conditions prevail, or a disguised restriction on international trade." 
188 Mexico's second written submission, para. 123. 
189 Mexico's second written submission, para. 132. 
190 Mexico's second written submission, para. 132. WT/DS381/RW 
 
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  misapplication, regardless of whether or not the body responsible for applying the measure is 
acting in good faith".191 Moreover, according to Mexico, "a regulatory system that does not provide 
an effective means of verifying whether a measure is being applied in an accurate and diligent manner will also give rise to arbitrary discrimination. Where the design of the measure is such that 
it is impossible to audit or assess the degree to which it is being applied appropriately, the 
measure cannot be said to be even-handed".
192 
7.83.  The United States disagrees with Mexico's interpretation of "arbitrary discrimination".193 
Specifically, it submits that Mexico's approach "artificially graft[s] the analysis used in the context 
of the chapeau of Article XX of the GATT 1994 onto Article 2.1 of the TBT Agreement", and 
concludes that this is "surely wrong" because "the two provisions are entirely different".194 The 
United States also submits that "the Appellate Body reversed  the EC – Seal Products  panel's GATT 
Article XX chapeau analysis for considering the two analyses to be the same".195 
7.84.  The parties elaborated on these positions in response to a question from the Panel. In its 
response, Mexico emphasized that "the Appellate  Body did not find that the analysis under 
Article 2.1 was irrelevant to the analysis under  the chapeau. Rather, the Appellate Body only 
indicated that an independent analysis must be do ne under the chapeau and, if the analysis under 
Article 2.1 is used, then an explanation must be provided as to why this analysis is relevant and 
applicable".196 According to Mexico, the Appellate Body has made clear that "there are important 
parallels between the analyses under Articl e 2.1 of the TBT Agreement and the chapeau"197, and, 
indeed, that, "'arbitrary discrimination' is a common concept" shared by the two provisions.198 
Mexico concludes that it is "clearly appropriate to use the meaning of 'arbitrary discrimination' 
developed under the chapeau of Article XX as co ntext for interpreting … Article 2.1 of the 
TBT Agreement".199 
7.85.  The United States' maintained its opposition to this interpretive approach in its response to 
the Panel's question. The United States explained that in  EC – Seal Products  the Appellate Body 
"refused to find that the analysis under the seco nd step of Article 2.1 merely incorporates the 
analysis under the chapeau of Article XX, as Mexico would have the Panel believe". Although it 
acknowledged that "the 'balance' set out within  the TBT Agreement is not, in principle, different 
from the balance set out in the GATT 1994"200, the United States reasserted that Mexico's 
approach is "surely wrong," and submitted that "Mexico is unable to cite even one paragraph  of 
the three TBT disputes for the proposition that th e most important factor in an even-handedness 
analysis is whether the discrimination can be reconciled with, or is rationally related to, the 
relevant policy objective".201 
7.86.  We note that all third-parties that respon ded to the Panel's question on this issue agreed 
that the case-law on the chapeau of Article XX informs the interpretation of Article 2.1 of the 
TBT Agreement. New Zealand appeared to agree wi th Mexico's approach, and submitted that the 
Panel should consider whether "the rationale for the distinction [giving rise to the detrimental 
                                               
191 Mexico's second written submission, para. 129 (citing Appellate Body Reports, EC – Seal Products , 
paras. 5.326-5.328). 
192 Mexico's second written submission, para. 131. 
193 United States' second written submission, para. 83. The United States phrases its arguments in 
terms of the meaning of "even-handedness", but the substa nce of its claims concern Me xico's use of the law of 
the chapeau of Article XX of the GATT 1994 in interpreti ng "arbitrary discrimination" under Article 2.1 of the 
TBT Agreement. As we noted above,  and as we will explain in more detail below, we think that "even-
handedness", as an analytical tool that may be useful in assessing whether detrimental impact stems exclusively from a legitimate regulatory  distinction, may have a wider mean ing that "arbitrary discrimination", 
although there is certainly some overlap. 
194 United States' second written submission, para. 84. 
195 United States' second written submission, para. 84. 
196 Mexico's response to Pane l question 5(c), para. 12 (cit ing Appellate Body Reports, EC – Seal 
Products , para. 5.310). 
197 Mexico's response to Pane l question 5(c), para. 13 (cit ing Appellate Body Reports, EC – Seal 
Products , para. 5.310). 
198 Mexico's response to Pane l question 5(c), para. 13 (cit ing Appellate Body Reports, EC – Seal 
Products , para. 5.310). 
199 Mexico's response to Pane l question 5(c), para. 13. 
200 United States' response to Panel question No. 5(c), para. 36 (emphasis original). 
201 United States' response to Panel question No. 5(c), para. 36 (internal citations omitted). WT/DS381/RW 
 
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  treatment] [is] consistent with the measure's overall objective".202 Similarly, Japan considered that 
"the assessment of even-handedness under Article 2.1 of the TBT Agreement involves 
consideration of whether the regulatory distinctions in question drawn in the technical regulation have rationales which are legitimate and rationally connected with the stated policy objective 
pursued by the technical regulation". In Japan's opin ion, "a technical regulation that is designed in 
such a way that its provisions contradict each other and even undermine the stated policy objective pursued by the technical regulation would be difficult to be justified under Article 2.1 of 
the TBT Agreement".
203 The European Union also agreed that "the 'rationale' or 'objective' or 
'purpose' or 'objective intent' of the regulatory distinction criticised by Mexico is indeed relevant to the assessment, just as it would be relevant in an assessment under Articles III:4 and XX of the GATT 1994".
204 And Canada, too, indicated that "in examining the even-handedness of the 
regulatory distinction, a panel should examine the rationale for the regulatory distinction advanced 
by the responding Member in light of the identifi ed policy objective, to determine whether there is 
a rational connection between the regulatory distinction and the identified policy objective. A 
regulatory distinction cannot be even-handed wher e it hinders or undermines the overall objective 
of the technical regulation".205 
7.87.  We begin our analysis by expressing our disagreement with the United States' claim that 
"the two provisions [i.e. Article 2.1 of the TBT Agreement and the chapeau of Article XX of the 
GATT 1994) are entirely different". The United States is, of course, correct that the text of Article 2.1 does not contain the words "arbitrary or unjustifiable discrimination". Nevertheless, as we noted above, the Appellate Body has consistently instructed panels to look for "arbitrary or 
unjustifiable discrimination" as one indication that a technical regulation provides less favourable 
treatment to imported products in contrave ntion of Article 2.1 of the TBT Agreement.
206 This 
language is drawn directly from the sixth recital of the TBT Agreement's preamble, which provides 
that technical regulations must "not [be] applied in a manner which would constitute a means of 
arbitrary or unjustifiable discrimination between countries where the same conditions prevail or a disguised restriction on international trade". By instructing panels to interpret TBT Article 2.1 in 
light of this recital, we believe the Appellate Bo dy clearly intended that panels would apply the 
"less favourable treatment" requirement in Arti cle 2.1 of the TBT Agreement in light of the 
jurisprudence developed in the context of the chap eau of Article XX. We agree with Mexico that 
there is no "basis to interpret the meaning of this term differently in different agreements".
207  
7.88.  We also do not agree with the United States that the Appellate Body's recent ruling in EC – 
Seal Products  prevents us from having recourse to Arti cle XX chapeau jurisprudence in interpreting 
Article 2.1 of the TBT Agreement. In that case, the Appellate Body faulted the panel for "applying 
the same legal test  to the chapeau of Article XX as it applied under Article 2.1 of the 
TBT Agreement".208 According to the Appellate Body, the panel "should have provided more 
explanation as to why and how its analysis under Article 2.1 of the TBT Agreement was relevant 
and applicable to the analysis under th e chapeau of Article XX of the GATT 1994"209, instead of 
finding a violation of the chapeau merely because the measure at issue had previously been found 
to violate Article 2.1 of the TBT Agreement.210  
7.89.  We note that the Appellate Body found that the panel in EC – Seal Products  had erred in 
importing its analysis under Article 2.1 of the TBT Agreement into the chapeau of Article XX; it did 
not say that the jurisprudence developed in the context of the chapeau could not be used to interpret Article 2.1 of the TBT Agreement. This fi nding is fully explicable on the basis that while 
                                               
202 New Zealand's oral statement, para. 6. 
203 Japan's response to Panel third-party question No. 1, para. 2. Japan also argued that "a technical 
regulation may contain elements that are in tension, or possibly even in conflict, with the particular policy objective pursued by the measure because such elements  are seeking to accommodate  other policy objectives. 
Japan believes that this, by itself, is insufficient to  support a finding that the technical regulation is not 
even-handed": para. 4. 
204 European Union's response to Pa nel third-party question No. 1, pa ra. 1. The European Union also 
submitted that "[i]t is possible th at the regulatory distinction neithe r "assists" nor "hinders" the overall 
objective, but merely reflects  a calibration of the different measures to  different risks. The mere existence of 
such differences does not necessarily mean that there is discrimination, or unjustified discrimination": para. 2. 
205 Canada's response to Panel thir d-party question No. 1, para. 1. 
206 Appellate Body Reports, US – Clove Cigarettes , para. 173; US – COOL , para. 268. 
207 Mexico's comments on the Un ited States' response to Panel question No. 5(c), para. 30. 
208 Appellate Body Reports, EC – Seal Products , para. 5.313 (emphasis added). 
209 Appellate Body Reports, EC – Seal Products , para. 5.310. 
210 Appellate Body Reports, EC – Seal Products , para. 3.507. WT/DS381/RW 
 
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  the tests in the chapeau of Article XX and Article 2.1 of the TBT Agreement overlap, they are not 
identical. Whereas Article 2.1 asks whether detrimental treatment stems from a legitimate regulatory distinction, and while the existence of "arbitrary or unjustifiable discrimination" is one 
way in which inconsistency with this aspect of Article 2.1 of the TBT Agreement can be shown, the 
chapeau of Article XX is focused solely  on whether a measure is applied in an arbitrarily or 
unjustifiably discriminatory manner (or is a disguised restriction on international trade).
211 
Additionally, analysis under Article 2.1 requires consideration of both the design and the 
application of the measure at issue212, whereas the chapeau focuses only on the application  of the 
measure at issue.213 As we understand it, then, the error of the EC – Seal Products  panel was in 
assuming that a violation of Article 2.1 of th e TBT Agreement, which may involve analysis of 
factors that are not be germane to the anal ysis under Article XX of the GATT 1994, would 
automatically give rise to a violation of that latter provision. To our minds, this reasoning does not 
deny the possibility that jurisprudence concerning the chapeau of Article XX could be used to inform those aspects of the test under Articl e 2.1 of the TBT Agreement that call for an 
examination of whether an instance of detrimenta l treatment constitutes "arbitrary discrimination". 
7.90.  Moreover, we cannot ignore the Appellate Body's confirmation that "important parallels" 
exist between the chapeau of Article XX and the "l ess favourable treatment" limb of Article 2.1 of 
the TBT Agreement. Indeed, the Appellate Body sp ecifically recognized that "the concepts of 
'arbitrary or unjustifiable discrimination between countries where the same conditions prevail' and of a 'disguised restriction on trade' are found bo th in the chapeau of Article XX of the GATT 1994 
and in the sixth recital of the preamble of the TBT Agreement".
214 To us, these statements clearly 
indicate that, while the tests under Article 2. 1 of the TBT Agreement and Article XX of the 
GATT 1994 should not be conflated, there are ne vertheless important similarities and overlaps 
between them, and Appellate Body jurisprudence de veloped in the context of one may be used to 
interpret similar concepts in the other. 
7.91.  Accordingly, we are not convinced by the United States' argument that Mexico's approach to 
"arbitrary discrimination" in the context of Arti cle 2.1 of the TBT Agreement is "surely wrong".215 
To the contrary, we agree with Mexico that, in considering whether detrimental impact caused by a 
technical regulation reflects "arbitrary discrimination", we may consider, among other things, whether the detrimental treatment can be reconciled with, or is rationally related to, the policy pursued by the measure at issue. This analysis may help the Panel determine whether the 
detrimental impact complained of (that is, if such impact is found by the Panel to exist) stems 
exclusively from a legitimate regulatory distinction – although, as we have said, the "legitimate regulatory distinction" may involve examination of more than just the existence (or not) of 
"arbitrary discrimination". 
7.92.  In addition, we note that, contrary to the United States' claim that there is no authority 
supporting this approach, the Appellate Body in US – Clove Cigarettes , the first of the "TBT trilogy" 
cases,  did indeed  base its finding that the United States' ban on clove cigarettes violated 
Article 2.1 on the fact that the exemption of menthol cigarettes from the ban was difficult to reconcile with the United States' purported goal of "prevent[ing] youth smoking" by banning flavoured cigarettes.
216 In the course of its findings, the Appellate Body explicitly noted that 
"menthol cigarettes have the same product characteristic [i.e. flavouring] that, from the 
perspective of the stated objective of [the challenged measure, i.e. discouraging youth smoking], justified the prohibition of clove cigarettes".
217 In other words, a central element of the Appellate 
                                               
211 Appellate Body Reports, EC – Seal Products , para. 5.311 (noting that Article 2.1 of the 
TBT Agreement analyses whether detrimental treatment stems exclusively from a legitimate regulatory distinction whereas the chapeau of Article XX is sole ly concerned with the existence of "arbitrary or 
unjustifiable discrimination"). 
212 Appellate Body Reports, US – COOL , para. 271 (finding that detrimental treatment cannot be found 
to stem exclusively from a legitimate regulatory distinction where a regulatory distinction is " designed or 
applied  in a manner that constitutes a means of arbitrary or unjustifiable discrimination" (emphasis added)). 
213 As we explain in more detail below, the analysis under Article XX of the GATT 1994 is "two-tiered: 
first, provisional justification by reason of charac terization of the measure under [a subparagraph of 
Article XX]; second, further appraisal of the same me asure under the introductory clauses of Article XX": 
Appellate Body Report, US – Gasoline , p. 22, DSR 1996:I, p. 3 at at 20. 
214 Appellate Body Reports, EC – Seal Products , para. 5.310. 
215 United States' second written submission, para.84; United States' response to Panel question 
No. 5(a), para. 28. 
216 This is noted by Canada in its response to Panel third-party question No. 1, para. 2. 
217 Appellate Body Report, US – Clove Cigarettes , para. 225. WT/DS381/RW 
 
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  Body's finding was the fact that the detrimental treatment at issue in that case could not be 
reconciled with or justified by reference to the policy objective of the technical regulation under review. In our view, the Appellate Body's approach in this case closely resembles the type of analysis conducted under the chapeau of Article XX of the GATT 1994, and confirms that there are 
important similarities between the analysis under Article XX and the analysis under Article 2.1 of 
the TBT Agreement.
218 
7.93.  We turn now to the meaning of the term "even-handed". In our understanding, 
even-handedness is not a separate criterion whose existence must be proved in addition  to a 
showing that the technical regulation at issue accords less favourable treatment to imported 
products. Rather, as we read the case-law, even-handedness is properly understood as an analytical tool, a kind of rhetorical measure or test that deploys a fluid, broadly equitable concept 
as a proxy or gauge to help a panel determine whether identified detrimental treatment stems 
exclusively from a legitimate regulatory distin ction. In our view, the proposition that even-
handedness is not an additional test follows clearly from the Appellate Body's statement that a 
panel must consider the even-handedness of a measure " in order to  determine"
219 whether or not 
the detrimental impact caused by that measure stems exclusively from a legitimate regulatory distinction. 
7.94.  In our view, the notion of even-handedne ss is especially closely related to the question 
whether detrimental impact stems exclusively  from a legitimate regulatory distinction. In 
particular, we think that asking whether a measure is even-handed can help a panel to determine whether the identified detrimental treatment is fu lly explainable as a consequence of a legitimate 
regulatory distinction – in which case it could be said to stem exclusively  from that distinction – or 
whether the detrimental treatment, while perhaps connected to or broadly based on a legitimate 
regulatory distinction, is nevertheless not fully or precisely accounted for, in terms of both its 
nature and its scope, by the regulatory distinctio n that the responding Member seeks to pursue – 
in which case it could not be concluded that the detrimental treatment stems exclusively  from the 
distinction pursued.   
7.95.  In other words, in our view even-handedness directs a panel's attention to what might be 
called the "fit" of the measure at issue, includ ing the detrimental treatment caused by that 
measure, with the legitimate regulatory distinction pursued. Thus, even if a measure were based 
on a legitimate regulatory distinction, the measure would nonetheless not stem exclusively  from 
that legitimate regulatory distinction if the detrimental impact were disproportionate, or if the 
measure otherwise reflected, for example, protectionism, and thus was not clearly justifiable by reference only to the legitimate regulatory distinctions invoked. 
7.96.  In our view, "even-handedness" directs our attention to what can perhaps best be called the 
"fairness" of a technical regulation. The plain mean ing of "even-handed" is "i mpartial, fair". "Fair", 
in turn, means "just, unbiased, equitable".  Terms li ke "fair" and "just" are notoriously difficult to 
define a-contextually; accordingly, the specific criteria or indicia through which the fairness of a 
technical regulation should be assessed are no t comprehensively enumerable in the abstract. 
Instead, a panel's analysis must "take into consideration the totality of the facts and circumstances of the case".
220 In our view, "even-handedness" may overlap with the concept of "arbitrary 
discrimination". We think, however, that "even-handedness" is conceptually distinct from "arbitrary 
discrimination", and may be broader in terms of the features of a measure that it may take into account. Thus, while a showing of "arbitrary discrimination" is one way of demonstrating that a 
measure is not even-handed (as we explained above), the concept of "even-handedness", and the 
range of facts and circumstances that could lead a panel to find that a measure is not "even-handed" (and, therefore, to conclude that the detrimental impact in question, does not stem 
                                               
218 We wish to clarify one point. In  finding that Article 2.1 requires, inter alia , an assessment of whether 
any proven detrimental impact is related to or otherwis e explicable on the basis of the policy pursed by the 
technical regulation at issue, we are not suggesting that panels should, in the context of Article 2.1, inquire into either the legitimacy of that policy or the effectiv e contribution that the technical regulation makes to it.  
These inquiries may be relevant under Article 2.2 of the TBT Agreement, which is not at issue in these proceedings. 
219 Appellate Body Report, US – Clove Cigarettes , para. 215. 
220 Appellate Body Reports, US – COOL , para. 286. We note our agreement with the United States that 
"[t]he particular set of facts that a Me mber is required to establish in orde r to prove that a technical regulation 
is not even-handed will depend on the particular fact s and circumstances". United States' response to Panel 
question No. 5(a), para. 24. WT/DS381/RW 
 
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  exclusively from a legitimate regulatory distinction) is wider than those that could give rise to a 
finding of "arbitrary discrimination".   
7.5.2  Application of Articl e 2.1 of the TBT Agreement 
7.5.2.1  Mexico's claim 
7.97.  Having considered certain preliminary issu es, and having set out our understanding of the 
legal test under Article 2.1 of the TBT Agreemen t, we now proceed to examine the merits of 
Mexico's Article 2.1 claims. As we have noted, our task is to determine whether the amended tuna 
measure as a whole affords "less favourable treatment" to Mexican tuna and tuna products than to 
tuna and tuna products from the United States and other WTO Members. 
7.98.  In its first written submission, Mexico explained that the analysis under TBT Article 2.1 "is 
on the regulatory distinction that accounts for the detrimental treatment on Mexican tuna products 
as compared to US tuna products and tuna products originating in other countries".221 According to 
Mexico, the following are the central regulatory dist inctions whose design and application give rise 
to the detrimental treatment of which Mexico complains:222 
 First, Mexico complains about "[t]he disqualification of setting on dolphins in accordance 
with AIDCP as a fishing method that can be used to catch tuna in the ETP in a dolphin-safe manner and the qualification of other fishing methods to catch tuna in a dolphin-safe 
manner". We refer to this aspect of the amende d tuna measure as the "eligibility criteria". 
 Second, Mexico highlights "[t]he mandatory independent observer requirements for tuna 
caught in the ETP by setting on dolphins in accordance with the AIDCP and the absence of such requirements for tuna caught outside the ETP using the same and different fishing 
methods". We refer to this aspect of th e amended tuna measure as the "different 
certification requirements". 
 Third and finally, Mexico draws the Panel's attention to "[t]he record-keeping and 
verification requirements for tuna caught in the ETP by setting on dolphins in accordance 
with the AIDCP and the different requirements for tuna caught outside the ETP using both the same and different fishing methods". We refer to this aspect of the amended tuna 
measure as the "different tracking and verification requirements". 
7.99.  Mexico refers to these conditions and requirements collectively as "the difference in labelling 
conditions and requirements".
223 According to Mexico, "[w]hen the facts and circumstances related 
to the design and application of these conditions and requirements are examined, it is clear that 
the detrimental impact on imports of Mexican tuna products does not stem exclusively from a 
legitimate regulatory distinction".224 Specifically, Mexico argues that "[a]s a consequence of the 
difference in labelling conditions and requirements, all like US tuna products and most tuna 
products of other countries have access to the dolphin-safe label, while, at the same time, the 
amended tuna measure denies access to this label for most Mexican tuna products".225 
7.100.  The United States has at various stages in these proceedings urged the Panel to ignore 
Mexico's claims concerning the different certification and tracking and verification requirements. 
According to the United States, the relevant detrimental impact does not stem from either of these two regulatory distinctions. Rather, "Mexico's first element [i.e. the eligibility criteria] is the 
detrimental impact", and since "Mexican tuna product containing tuna caught by setting on 
dolphins would still be ineligible for the 'dolphin safe' label" even if the different certification 
requirements did not exist, "Mexico simply cannot establish a causal connection between the detrimental impact" and the different certification and tracking and verification requirements".
226 
                                               
221 Mexico's first written submission, para. 235. 
222 Mexico's first written submission, para. 236. 
223 Mexico's second written submission, para. 112. 
224 Mexico's first written submission, para. 237. 
225 Mexico's second written submission, para. 112. 
226 United States' first written submission, para. 223 (emphasis original). WT/DS381/RW 
 
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  7.101.  The United States repeats this contention in  its second written submission. There, it argues 
that the certification and tracking and verification requirements "are not relevant to this analysis (under Article 2.1 of the TBT Agreement), in that neither aspect accounts for the detrimental impact … Simply put, the requirements regarding record-keeping/verification and observers do not 
cause the detrimental impact that was the basis for the DSB's recommendations and rulings".
227  
7.102.  The Panel acknowledges that Mexico's argu mentation on the detrimental treatment caused 
by the different certification and tracking and veri fication requirements appears to have developed 
over the course of its written submissions. In its first written submission, Mexico described the 
detrimental impact caused by the amended tuna measure as a whole as follows:  
While all like US tuna products and most tuna products of other countries have access 
to the "dolphin-safe" label, the Amended Tuna Measure denies access to this label for 
most Mexican tuna products.228 
7.103.  It seems to us that this description identifies, at least primarily, the detrimental impact 
caused by the eligibility criteria , because, as the United States argued in its own first written 
submission, even if the different certification and tracking and verification requirements were 
eliminated, "Mexican tuna product containing tuna caught by setting on dolphins would still be ineligible for the 'dolphin safe' label, and tuna product containing tuna caught using other methods 
would still be potentially eligible for the label".
229 
7.104.  In its second written submission, however, Mexico elaborated on and clarified its 
arguments on the detrimental impact caused by the different certification and tracking and verification requirements. Mexico explained that:  
[T]he absence of sufficient fishing method qualification, record keeping, verification 
and observer requirements for tuna that is used to produce tuna products from the 
United States and other countries means that Mexican tuna products are losing 
competitive opportunities to tuna products that may be inaccurately labelled as 
dolphin-safe.230 
7.105.  This passage clearly identifies a distinct ty pe of detrimental impact that, in Mexico's view, 
is caused by the different certification and trac king and verification requirements. Whereas the 
different eligibility requirements are responsible for the fact that most Mexican tuna products are ineligible to receive the label (in Mexico's words denying a competitive opportunity to Mexican tuna),
231 the different certification and tracking and verification requirements, on Mexico's 
argument, provide or "confer[]"232 a "competitive advantage" to non-Mexican tuna products, and 
so detrimentally modify the conditions of competition. In our view, Mexico's arguments on the different certification and tracking and verification requirements constitute a clear and cognizable 
claim of detrimental impact separate from  the detrimental impact identified by Mexico as the result 
of the eligibility criteria.
233 The Panel notes that although Mexico maintained in its first written 
submission that it is the "key elements of the de sign and structure of the measure" that "together" 
deny Mexican products competitive opportunities,234 in the Panel's view Mexico's argumentation 
throughout these proceedings made clear that di fferent elements of the amended tuna measure 
negatively affect Mexican tuna in different ways. 
7.106.  In its responses to the Panel's questions, the United States suggested that, by developing 
its argument on detrimental impact in its second written submission, "Mexico is now attempting to 
fundamentally alter all three of its claims, alleging that the tracking and verification and certification requirements of the amended measure modify the conditions of competition in the 
relevant market to the detriment of the group of Mexican tuna products via-à-vis  the group of like 
                                               
227 United States' second written submission, paras. 75 and 76. 
228 Mexico's first written submission, para. 232. 
229 United States' first written submission, para. 223. 
230 Mexico's second written submission, para. 117 (emphasis original). 
231 Mexico's second written submission, para. 117. 
232 Mexico's second written submission, para. 117. 
233 Mexico articulated its argument in this way thro ughout these proceedings. See Mexico's response to 
Panel question No. 9, para. 36; Mexico's second writ ten submission, paras. 147, 163; Mexico's response to 
Panel question No. 7, paras. 19 and 21. See also section 6.2.6 of this Report. 
234 Mexico's first written submission, para. 223. WT/DS381/RW 
 
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  US tuna product and like tuna product originating in other Members".235 T h e  i m p o r t  o f  t h i s  
statement is not entirely clear: the United Stat es has not, for example, argued that Mexico's 
arguments concerning the different certification and tracking and verification requirements are barred by Article 6.2 of the DSU. At any rate, in  our view, parties in WTO dispute settlement are 
fully entitled to develop and clarify their argumentation over the course of their written 
submissions. In our opinion, the very purpose of  having successive rounds of written submissions, 
followed by an oral hearing, is to enable the parties to refine, clarify, and develop their arguments. 
This is an essential element of the due process "implicit in the DSU"
236, according to which "each 
party [must] be afforded a meaningful opportunity to comment on the arguments and evidence adduced by the other party".
237 We are of the view that Mexico's elaboration in its second written 
submission is a fully acceptable clarification of Mexico's claim and argument.  
7.107.  Additionally, the Panel notes that at variou s stages in this litigation, Mexico has argued 
that it is the "differences in these labelling conditions and requirements together " that "account for 
the detrimental impact on imports".238 In other words, as Mexico explained in its response to a 
question from the Panel:  
[I]t is only the combined operation of the labelling conditions and requirements for 
tuna products containing tuna caught by setting on dolphins in the ETP, together with 
the labelling conditions and requirements for tuna products containing tuna caught 
outside the ETP, that gives rise to the regulatory distinction that affects the conditions of competition to the detriment of tuna products imported from Mexico vis-à-vis  like 
tuna products of U.S. origin and like tu na products imported from other countries.
239  
7.108.  Despite this, both parties have structured their arguments throughout these proceedings 
on the basis of the three regulatory distinctions identified by Mexico. That is, while Mexico has argued that the relevant less favourable treatment emerges only or at least most clearly when all 
three distinctions are considered together, it has nevertheless presented its arguments on a 
distinction-by-distinction basis. The United Stat es has followed suit, and presented its arguments 
on the three regulatory distinctions separately. We have decided to follow the approach of the 
parties in presenting our own analysis. Although we will indicate the connections between these 
distinctions where relevant, we conduct our analysis in three parts, considering first the eligibility criteria; second, the different certification requirements; and third, the different tracking and verification requirements. 
7.5.2.2  The eligibility criteria 
7.5.2.2.1  Arguments of the parties 7.109.  In its first written submission, Mexico de scribes the eligibility criteria in the following 
terms: 
Under the Amended Tuna Measure, the labe lling conditions and requirements differ 
depending on the fishing method used to ca tch tuna. Setting on dolphins is a fishing 
method that is "disqualified" from being used to catch dolphin-safe tuna, even if the 
utilization of this method complies with the stringent AIDCP requirements and there are no dolphin mortalities or serious injuries in the set in which the tuna is caught, as confirmed by an independent on-board observer and certified under the 
comprehensive tracking and verification system established by the AIDCP and Mexican 
law. … 
                                               
235 United States' response to Panel question No. 58, para. 288. 
236 Appellate Body Report, India – Patents , para. 94. 
237 Appellate Body Report, Thailand – Cigarettes (Philippines), para. 150. 
238 Mexico's second written submission, para. 113 (emphasis added). 
239 Mexico's response to Panel ques tion No. 8, para. 32: Mexico's comments on the United States' 
response to Panel question No. 4, para. 20 ("Mexico [h as] highlighted that the th ree labelling conditions – 
i.e. (i) the disqualification of setting on dolphins and the qualification of other fishing methods to catch tuna; 
(ii) the record-keeping, tracking, and verification requ irements; and (iii) the mandatory independent observer 
requirement – operating together, account for the detrimental impact on Mexican imports"). WT/DS381/RW 
 
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  The situation is different for fishing methods used to catch tuna outside the ETP. With 
the exception of driftnet fishing on the high seas by the Italian fleet, all of the other tuna fishing methods (including other driftnet fishing) are qualified to be used to catch tuna in a dolphin-safe manner, even though … these methods cause substantial 
dolphin mortalities and serious injuries. 
… Notwithstanding these substantial adverse effects on dolphins, the other fishing 
methods are not disqualified from being used to catch 'dolphin-safe' tuna. They are 
qualified to be used to catch dolphin-safe tuna, subject only to the requirement that there are no dolphin mortalities or serious injuries observed in the gear deployments in which the tuna is caught.
240 
7.110.  As we understand it, Mexico's claim is that the amended tuna measure distinguishes 
between tuna caught by setting on dolphins and tuna caught by any other method. On the one hand, tuna caught by setting on dolphins is never eligible to receive the dolphin-safe label, even if 
no dolphins were actually killed or seriously injured in a particular net set. On the other hand, tuna 
caught by other fishing methods is, in principle , eligible to receive the dolphin-safe label, provided 
that no dolphins were killed or seriously injured in the particular gear deployment. 
7.111.  In Mexico's opinion, this regulatory distinction modifies the conditions of competition in the 
United States' market to the detriment of Mexican tuna products. Mexico recalls the Appellate Body's finding in the original proceedings that "the lack of access to the 'dolphin-safe' label of tuna products containing tuna caught by setting on dolphins has a detrimental impact on the 
competitive Mexican opportunities of Mexican tuna products in the US market"
241 because, 
although the label has "significant commercial  value on the US market for tuna products"242, "most 
tuna caught by Mexican vessels, being caught in the ETP by setting on dolphins, would not be 
eligible for inclusion in a dolphin-safe product under the US dolphin-safe labelling provisions".243 In 
Mexico's view, the fact that tuna caught by setting on dolphins is ineligible to receive the label while tuna caught by other methods is, in principle, eligible is "clearly … not even-handed"
244 for a 
number of reasons. First, Mexico argues that the el igibility of tuna caught other than by setting on 
dolphins and the ineligibility of tuna caught by setting on dolphins "is not rationally connected to the objective of the measure"
245 because those fishing methods eligible to fish dolphin-safe tuna in 
fact "cause substantial dolphin mortalities and serious injuries".246 To support this view, Mexico 
submitted evidence arguing that "tens to hundreds of thousands of [marine mammals] are killed 
each year through entanglement in fishing gear".247 Indeed, Mexico maintains that "these 
'qualified' fishing methods have adverse effects on dolphins that are equal to or greater than the 
disqualified tuna fishing method of setting on dolphins in an AIDCP-compliant manner",248 although 
it also argues that to prove its case it need only show that "other fishing methods also cause 
mortalities and serious injuries to dolphins".249 The Panel notes that a number of the exhibits 
submitted in these proceedings were also submitted in the original proceedings. 
7.112.  Second, Mexico maintains that the distinction is not even-handed because it "assumes that 
setting on dolphins in an AIDCP-compliant manne r has adverse effects on dolphins that justify 
disqualification, and this assumption is perm anent and will not change, even if evidence 
establishes that dolphin stocks are not being adversely affected. … At the same time, the Amended 
Tuna Measure assumes that catching tuna using other fishing methods does not have adverse 
                                               
240 Mexico's first written submission, paras. 247-249. 
241 Appellate Body Report, US – Tuna II (Mexico) , para. 235 (cited in Mexic o's first written submission, 
para. 227). 
242 Appellate Body Report, US – Tuna II (Mexico) , para. 233. 
243 Mexico's first written submission, para. 226. 
244 Mexico's first written submission, para. 250. 
245 Mexico's first written submission, para. 252. 
246 Mexico's first written submission, para. 248. 
247 Mexico's first written submission, para. 109. On dolphin mortality and injury caused by gillnets, see 
Mexico's first written submission, paras. 126-131; on dolphin mortality and injury caused by longlines, see Mexico's first written submission, paras. 132-151; on dolphin mortality and injury caused by trawling, see 
Mexico's first written submission, paras. 152-155. 
248 Mexico's first written submission, para. 248. 
249 Mexico's comments on the Un ited States' response to Pane l question No. 5, para. 26. WT/DS381/RW 
 
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  effects on dolphins. However, the evidence presented by Mexico … contradicts this assumption and 
proves that other fishing methods have substantial adverse effects on dolphins that are equal to or greater than those of setting on dolphins in an AIDCP-compliant manner."
250 
7.113.  In light of these arguments, Mexico maintains that "[t]here is no justification for the 
different treatment", and urges the Panel to find th at "[i]n the circumstances of this dispute, all 
tuna fishing methods should be either qualified or disqualified"251 from accessing the dolphin-safe 
label. 
7.114.  The United States asks the Panel to reject Mexico's claims for a number of reasons, both 
procedural and substantive. On the procedural front, the United States argues that "the Appellate Body has already rejected Mexico's claim" that the eligibility criteria violate Article 2.1 of the TBT Agreement.
252 According to the United States, "Mexico's misguided attempt to claw back what 
Mexico failed to achieve in its appeal of the original panel's Article 2.1 analysis should be 
rejected".253 
7.115.   On the substantive front, while the United States accepts that, as the Appellate Body 
found in the original proceedings, the eligibility criteria have "a detrimental impact on Mexican 
tuna products"254, it rejects the claim that this impact does not stem exclusively from a legitimate 
regulatory distinction. In the opinion of the United States, " all tuna product containing tuna caught 
by setting on dolphins is ineligible for the label, regardless of the fishery, nationality of the vessel, 
and nationality of the processor "255; accordingly, "[t]he requirements are equal  for all products 
and nothing in the design or structure of the amended measure indicates that Mexican producers 
are disadvantaged in any way vis-à-vis  their competitors in the United States … or elsewhere".256 
In the view of the United States, any detrimental impact felt by Mexican producers stems from the 
fishing practices chosen by Mexican tuna fishers, and not from the amended tuna measure itself.
257  
7.116.  Additionally, the United States argues that "the science supports  the distinctions of the 
amended measure, and directly contradicts  Mexico's approach".258 In support of this position, the 
United States submitted evidence that, in its view, demonstrated that dolphin mortalities and 
serious injuries due to dolphin sets by large purse seine vessels in the ETP were many times 
greater than dolphin mortalities and serious injuries due to sets other than dolphin sets by large purse seine vessels.
259 In the original proceedings and in this dispute, the United States also 
presented evidence that, in its view, showed that dolphin mortalities and serious injuries in purse 
seine and longline fisheries outside the ETP were significantly lower, on a per set basis, than 
dolphin mortalities and serious injuries due to sets on dolphins by large purse seine vessels in the ETP.
260 Finally, the United States submitted evidence that, according to the United States, 
established that interactions with dolphins were much more frequent, and involved a much larger 
number of animals, in dolphin sets in the ETP large purse seine fishery than in other fisheries.261 In 
the view of the United States, Mexico failed to present evidence that dolphins were being chased 
to catch tuna in any fishery other than the ETP large purse seine fishery.262 The United States 
therefore concludes that "[t]here is nothing about setting on dolphins that is safe for dolphins, and 
                                               
250 Mexico's first written submission, para. 263 (emphasis original). 
251 Mexico's first written submission, para. 263. 
252 United States' first written submission, para. 214. 
253 United States' first written submission, para. 201. 
254 United States' first written submission, para. 215 (citing Appellate Body Report, US – Tuna II 
(Mexico) , paras. 234 and 235). 
255 United States' first written submission, para. 228; United States' second written submission, para. 89 
(emphasis original). 
256 United States' first written submission, para. 231 (emphasis original). 
257 United States' first written submission, para. 232. 
258 United States' first written submission, para. 237. 
259 United States' response to Panel question No. 19, paras. 111–113; United States' second written 
submission, para. 23; United States' first written submission, para. 92. 
260 United States' response to Panel question No. 21.  Paras. 136-142; United States' response to Panel 
question No. 19, paras. 116-118; United States' first written submission, paras. 132-134 and 145. 
261 United States' response to Panel question No. 17, paras. 88-89. 
262 United States' response to Panel question No. 20, paras. 121-130. WT/DS381/RW 
 
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  the measure rightly denies access to the label for tuna products containing tuna caught by this 
method".263 
7.5.2.2.2  Analysis by the Panel 7.117.  We begin by recalling that we have addressed the United States' claims on jurisdiction 
above.
264 In that discussion, we disagreed with the United States' argument that Mexico's "claim 
falls outside this Panel's terms of reference because [it] is premised entirely on the elements of the 
measure that the DSB did not find to be in breach of Article 2.1 and that are unchanged from the 
original measure".265 We noted that the Appellate Body's findings, and the DSB's rulings and 
recommendations, concerned the original tuna measure as a whole , so that the United States was 
not "entitled to assume" that any aspect of the measure was automatically and uncontestably consistent with the covered agreements.
266  
7.118.  Nevertheless, in our opinion, the United States' argumentation on the eligibility criteria 
raises an additional (though certainly related) issue that we dealt with only briefly above: the place and role in this report of findings made by the panel and the Appellate Body in the original 
proceedings. The eligibility criteria were, after al l, at the very heart of the original proceedings, 
and in the United States' view "the original pa nel has already fully addressed Mexico's argument 
[on this point] and found it lacking".
267 According to the United States, the Panel should not give 
Mexico the opportunity to "appeal" the Appellate Body's report268, since doing so would upset the 
finality of DSB rulings and recommendations. In the opinion of the United States, adopted 
Appellate Body findings "must be treated by the parties to a particular dispute as a final resolution 
to that dispute ".269 
7.119.  As we explained above in our discussion  of the legal test under Article 2.1 of the 
TBT Agreement, it is appropriate for this Panel, as a compliance panel composed under Article 21.5 of the DSU to review compliance with a ruling made  by the DSB in previous proceedings, to rely 
upon factual and legal conclusions made by the original panel and the Appellate Body, at least in 
the absence of compelling new evidence that would render those previous findings unsustainable. The Panel agrees with the United States that, as a matter of principle, parties in compliance 
proceedings should not be afforded the opportunity to re-litigate questions that have already been 
"definitively settled" by the Appellate Body.
270 The question for us, however, is what precisely was 
"definitively settled" by the Appellate Body in the original proceedings in this matter. 
7.120.  In the Panel's view, it is quite clear that the Appellate Body in the original proceedings 
settled the question whether the United States can disqualify tuna caught by setting on dolphins 
from accessing the dolphin-safe label. The Appellate Body found that setting on dolphins is "particularly harmful to dolphins"
271, because:  
[V]arious adverse impacts can arise from setting on dolphins, beyond observed 
mortalities, including cow-calf separation during the chasing and encirclement, threatening the subsistence of the calf and adding casualties to the number of 
observed moralities, as well as muscular damage, immune and reproductive system 
failures, and other adverse health consequences.  
7.121.  Importantly, the Appellate Body also accepted that these harms arise as a result of the 
"chase itself". Consequentially, it affirmed the original panel's conclusion that "the US objectives … 
                                               
263 United States' second written submission, para. 93. 
264 See section 7.3 above. 
265 United States' first written submission, para. 202. 
266 Cf United states' first written submission, para. 207.  Indeed, as we explained, the fact that aspects 
of the measure remain unchanged may be problematic  precisely because the Appellate Body found that the 
original tuna measure as a whole  was inconsistent with Article 2.1 of the TBT Agreement. Th e question before 
us is whether, by modifying one pa rt of the original measure (i.e. the implementing regulations), the 
United States has been able to bring the entire measure, which consists of the (unchanged) DPCIA and the Hogarth ruling as well as the relevant implementing regulations, into conformity with the WTO Agreement. 
267 United States' first written submission, para. 230. 
268 United States' first written submission, para. 202. 
269 United States' first written submission, para. 198 (emphasis original). 
270 Appellate Body Report, EC – Bed Linen (Article 21.5 – India) , para. 98. 
271 Appellate Body Report, US – Tuna II (Mexico) , para. 289. WT/DS381/RW 
 
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  to minimize unobserved consequences of setting on dolphins" would not be attainable if tuna 
caught by setting-on dolphins were eligible for the dolphin-safe label272, because "'to the extent 
that it would not discourage these unobserved effects of setting on dolphins and their potential consequences on dolphin populations … [allowing tuna caught by setting on dolphins to be labelled 
dolphin-safe] … could potentially provide a lesser degree of protection than the existing 
US dolphin-safe provisions", even where setting on dolphins is conducted in an AIDCP-compliant manner.
273 The Appellate Body thus concluded that the disqualification of tuna caught by setting 
on dolphins from accessing the dolphin-safe label "fully addresse[s]" the risks posed to dolphins by 
setting on dolphins, and made clear that requiring th e United States to remove that disqualification 
would undermine the United States' achievement of its desired level of protection.274 
7.122.  As the Panel reads it, then, the Appellate Body clearly found that setting on dolphins 
causes observed and unobserved harm to dolphi ns. However, as we understand it, what makes 
setting on dolphins particularly harmful is the fact that it causes certain unobserved effects  beyond  
mortality and injury "as a result of the chase itself".275 These harms would continue to exist "even 
if measures are taken in order to avoid the taking and killing of dolphins on the nets".276 It is 
precisely because these unobserved harms cannot be  mitigated by measures to avoid killing and 
injuring dolphins that the original panel and the Appellate Body found that the United States is 
entitled to treat setting on dolphins differently from other fishing methods. 
7.123.   Therefore, we reaffirm the Appellate Body's  finding that the United States is entitled, in 
pursuit of its desired level of protection, to disqua lify tuna caught by that method from ever being 
labelled as dolphin-safe.   We recall that the original US measure was considered WTO-inconsistent 
(and in particular inconsistent with Article 2.1 of the TBT), not because it disqualified tuna caught 
by setting on dolphins from accessing the dolphin-safe label, but because the original tuna measure was not even-handed with respect to other methods of fishing  which may also cause 
harm to dolphins – a fact that was not reflected in the original dolphin labelling regime.  
7.124.  In our view, a careful reading of the Appe llate Body report also shows that the Appellate 
Body considered and answered the question whethe r the failure of the tuna labelling regime to 
disqualify other  methods of tuna fishing necessarily deprives the measure of even-handedness. 
Importantly, the Appellate Body found that "impos ing a requirement that an independent observer 
certify that no dolphins were killed or seriously injured in the course of fishing operations in which the tuna was caught would [not] be the only way for the United States to calibrate its 'dolphin-
safe' labelling provisions to the risks that … [are] posed by fishing techniques other than setting on 
dolphins".
277 As we read it, this statement has a number of important implications. First, it 
recognizes that, although "the risks to dolp hins from other fishing techniques are [not] 
insignificant"278, nevertheless the United States may distinguish between setting on dolphins, 
which, as we noted, it found was "particularly harmful", and other methods of tuna fishing.  
7.125.  Secondly, and crucially for the question befo re us, the statement indicates that, in the view 
of the Appellate Body, the United States may bring its dolphin-safe labelling regime into 
conformity with Article 2.1 of the TBT Agreement without disqualifying methods of tuna fishing 
other than setting on dolphins . This is so because the question of observer certification only arises 
in respect of tuna fishing methods that are, in principle, qualified to catch dolphin-safe tuna. 
Certification requirements are simply not relevant to fishing methods that are disqualified from 
catching dolphin-safe tuna, because tuna caught by those methods are always  and under all 
circumstances ineligible  to receive the label. Certification, which is the documentary precondition 
to accessing the label, is thus only relevant in respect of tuna that is in principle eligible to be 
labelled dolphin-safe. In stating that the United States could "calibrate" its measure without necessarily requiring  observer coverage for tuna caught other than by setting on dolphins, the 
Appellate Body implicitly recognized that tuna fishing methods other than setting on dolphins do 
not need to be disqualified in order for the United States to bring its measure info conformity with the TBT Agreement . Put simply, we do not believe that the Appellate Body would even have 
touched upon the issue of certification, which is only relevant to tuna fishing methods that are, at 
                                               
272 Panel Report, US – Tuna II (Mexico) , para. 7.613. 
273 Panel Report, US – Tuna II (Mexico) , para. 7.613. 
274 Appellate Body Report, US – Tuna II (Mexico) , para. 287. 
275 Panel Report, US – Tuna II (Mexico) , para. 7.504. 
276 Panel Report, US – Tuna II (Mexico) , para. 7.504. 
277 Appellate Body Report, US – Tuna II (Mexico) , para. 296 (emphasis original). 
278 Appellate Body Report, US – Tuna II (Mexico) , para. 289. WT/DS381/RW 
 
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  least in principle, eligible  to catch dolphin-safe tuna, if it had considered that the United States 
must necessarily disqualify methods of fishing other than setting on dolphins in order to make its measure even-handed. 
7.126.  Accordingly, in the Panel's opinion, the original proceedings have settled the question 
whether the disqualification of tuna caught by setting on dolphins, together with the qualification 
of tuna caught by other fishing methods, is incons istent with Article 2.1 of the TBT Agreement. The 
Appellate Body found that it is not. In light of this finding, we do not think it is appropriate for us 
to re-open this inquiry. Rather, we respect and re affirm the finding of the Appellate Body that, to 
the extent that they modify the conditions of competition in the US market to the detriment of Mexican tuna and tuna products, the eligibility criteria are even-handed, and accordingly are not inconsistent with Article 2.1 of the TBT Agreement. 
7.127.  Of course, we note that the Appellate Body  ultimately found that the original tuna measure 
was inconsistent with Article 2.1 of the TBT Agreement. This finding was based, however, not on 
the fact that the United States disqualified tuna caught by setting on dolphins from accessing the 
dolphin-safe label, but rather on the fact that the regulatory scheme imposed by the United States 
on tuna fishing methods other  than setting on dolphins, which are eligible to catch dolphin-safe 
tuna, did not sufficiently address the risks posed to dolphins by those methods.
279 The measure 
was therefore not "even-handed", in violation of Article 2.1.  
7.128.  Accordingly, the question for this Panel is not whether the United States can, consistently 
with Article 2.1 of the TBT Agreement, disqualify  all tuna caught by setting on dolphins from 
accessing the dolphin-safe label while qualifying all other methods. The question for us is rather 
whether the amended tuna measure, including thro ugh or by way of the modifications made by 
the 2013 Final Rule, sufficiently addresses the risks posed to dolphins from methods of tuna fishing other than setting on dolphins, that is, fishing methods that are qualified to catch dolphin-
safe tuna. It is, therefore, only the regulatory regime that currently applies to those  other fishing 
methods, which are qualified to catch dolphin-safe tuna, that this Panel should examine. 
7.129.  In the course of arguing about this issue, both parties have made reference to a range of 
exhibits. Some were presented in the original proceedings, and some were new. In our view, the 
new evidence presented by both parties on this question ultimately supports our decision to 
reaffirm the conclusions in the original dispute that the United States is entitled to treat setting on dolphins differently from other tuna fishing methods. The evidence presented by Mexico, especially 
in its first written submission, certainly suggests that very significant numbers of dolphins are 
killed in tuna fishing operations outside of the ETP large purse seine fishery.
280 Like the original 
panel and the Appellate Body281 (and, we note, the United States itself)282, we accept that tuna 
fisheries other than the ETP large purse seine fish ery may, and in fact have, caused significant 
harms to dolphins. 
7.130.  In our view, none of the new evidence submitted by Mexico is sufficient to undermine the 
Appellate Body's finding that no fishing method other than setting on dolphins has effects on 
dolphins as consistently harmful as those caused by setting on dolphins.283 With respect to gillnet 
fishing, Mexico has submitted substantial evidence  showing that gillnets kill and seriously injure 
dolphins. None of this evidence, however, sugg ests that gillnets have the same kind of 
unobservable effects as setting on dolphins. The closest that the evidence comes to making such 
an allegation is the finding by Gomercic et al284 that "[e]ven when dolphins do not immediately 
drown in a gillnet, interactions with the net causes dolphins to die later".285 Specifically, the report 
suggests that gillnets may cause eventual strangulation even of dolphins that manage to break 
free from the net. Accompanying this statement is a photograph of a dolphin with a "gillnet 
part…protruding from [its] mouth".286 While it may be that dolphins injured in gillnets die at some 
                                               
279 Appellate Body Report, US – Tuna II (Mexico) , para. 298. 
280 See generally Mexico's first written submission, section III.A. 
281 Appellate Body Report, US – Tuna II (Mexico) , para. 289. 
282 United States' response to Pa nel question no. 15, para. 81. 
283 Appellate Body Report, US – Tuna II (Mexico) , para. 289 (noting that other fishing methods may give 
rise to the "same level of risk" only "in some circumstances"). 
284 M. Gomercic et. al., "Bottlenose Dolphin (Tursiops Truncatus) Depredation resulting in Larynx 
Strangulation with Gill-net Parts", 25 Marine Mammal Science  392 (2009) (Exhibit MEX-52), p. 396. 
285 Mexico's first written submission, para. 131. 
286 Mexico's first written submission, para. 131. WT/DS381/RW 
 
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  later time, injuries such as those leading to gillnet parts "protruding from the mouth" of dolphins 
would seem clearly to be the kind of "serious in jury" that is observable and that must, under the 
amended tuna measure, be certified. Accordingly, while the evidence presented by Mexico suggests that gillnets caused delayed death or serious injury, it does not suggest that such nets 
cause the same kind of unobservable harms as are caused by setting on dolphins.  
7.131.  With respect to longline fishing, Mexico has presented convincing evidence that "longline 
fishing operations kill and maim dolphins".
287 Mexico's evidence also suggests that, at least in 
some fisheries, longlining is having a negative effect on the sustainability of dolphin populations.288 
Here again, however, none of Mexico's evidence  suggests that longline fishing has unobservable 
effects similar to those caused by setting in dolp hins. Mexico claims that "even when dolphins do 
not immediately die from an interaction with a longline, they are at risk to suffer from maiming of 
their mouths, dorsal fins, and other body parts, as well as from eventual drowning when they 
cannot free themselves from the lines".289 In its second written submission, Mexico submits that 
"dolphins suffer observed and unobserved adverse effects – including serious injury or death – as 
a result of commercial tuna fishing operations throughout the fisheries of the world (i.e., both 
within and outside the ETP) by every country with a commercial tuna fishing fleet".290 In support of 
this claim, Mexico cites to section II.A.2 of its second written submission. This section concerns 
"Mexico's evidence of risks to dolphins in non- ETP fisheries". While the evidence summarized in 
this section clearly establishes that tuna fishing methods other than setting on dolphins pose serious threats to dolphins, we have been unable to find any indication in this evidence that fishing methods other than setting on dolphins cause the kinds of unobservable harms that are caused by 
setting on dolphins. 
7.132.  In order to help the Panel understand whether fishing methods other than setting on 
dolphins cause unobservable harms similar to those caused by setting on dolphins – that is, harms 
of which no evidence is present at the time of the catch – the Panel asked the parties to explain 
whether "fishing methods other than setting on dolphins cause unobserved harms".
291 In its 
response, Mexico summarized a substantial numb er of reports and studies testifying to the 
deleterious effects that tuna fishing methods other than setting on dolphins may have on dolphins. 
This evidence presents a compelling case that various tuna fishing methods around the world are negatively impacting the health and well-being of dolphin populations.
292 None of it, however, 
suggests that fishing methods other than setting on dolphins inflict the same kinds of 
unobservable harms that are caused by net sets. To the contrary, Mexico's evidence concerns the 
extent of mortality and serious injury caused by tuna fishing methods including FAD fishing,293 
longline fishing,294 gillnet fishing,295 trawl fishing,296 and driftnet fishing.297 These, however, are 
precisely the kind of interactions that can an d, under the amended tuna measure, must be 
certified, and whose occurrence renders ineligible for the dolphin-safe label any tuna caught in the set in which the harmful interaction (i.e. the death or serious injury) occurred. They are not the 
                                               
287 Mexico's first written submission, para. 138. 
288 D. Hamer, S. Childerhous and N.  Gales, "Odontocete Bycatch and De predation in Longline Fisheries: 
A Review of Available Literature  and of Potential Solution", 28 Marine Mammal Science  345 (2012) 
(Exhibit MEX-55), p. 345. 
289 Mexico's first written submission, para. 149. 
290 Mexico's second written submission, para. 319. 
291 Panel's question No. 15. 
292 See Mexico's response to Pane l question No. 15, paras. 85-92. 
293 K.S.S.M. Yousuf et. al., "Observations on Incide ntal Catch of Cetaceans in Three Landing Centres 
Along the Indian Coast", 2 Marine Biodiversity Records  1 (Exhibit MEX-50), p 4. 
294 Kobe II Bycatch Workshop Background Paper (Exhibit MEX-39), p. 2; D. Hamer, S. Childerhous and 
N. Gales, "Odontocete Bycatch and Depredation in Longline  Fisheries: A Review of Available Literature and of 
Potential Solution", 28 Marine Mammal Science  345 (2012) (Exhibit MEX-55); Pelagic Longline Take Reduction 
Team, Key Outcomes  (NOAA Memorandum, 21-23 August 2012) (Exhibit MEX-62), pp. 4 and 5; Turtle 
Restoration Project, Pillaging the Pacific: Pelagic Longline Fishing Captures About 4.4 Million Sharks, Billfish, 
Seabirds, Sea Turtles, and Marine Mamm als Each Year in the Pacific Ocean  (November 16, 2004) 
(Exhibit MEX-64); R. Baird and A. Gogone, "False Killer Whale Dorsal Fin Disfiguremen ts as a Possible Indicator 
of Long-Line Fishery Interact ions in Hawaiian Waters", 59 Pacific Science  592 (2005) (Exhibit MEX-66, p. 597). 
295 Kobe II Bycatch Workshop Background Paper (Exhibit MEX-39), p. 2. 
296 A. Ross and S. Isaac, The Net Effect? A Review of Cetacean Bycatch in Pelagic Trawls and other 
Fisheries in the North-East Atlantic  (Exhibit MEX-71), p. 15; L. Nunny, The Price of Fish: A Review of Cetacean 
Bycatch in Fisheries in the North-East Atlantic (Exhibit MEX-72), p. 16. 
297 Z. Smith et. al., Net Loss: The Killing of Marine Mammals in Foreign Fisheries  (NRDC Report 
R:13-11-B, January 2014) (Exhibit MEX-103), p. 29. WT/DS381/RW 
 
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  kind of unobservable harm that we have found occurs as a result of setting on dolphins, and which 
cannot be certified because it leaves no observable evidence. 
7.133.  We note Mexico's argument that the United States has "expressly agreed that fishing 
methods other than setting on dolphins cause unobserved harms".298 In support of this claim, 
Mexico cites footnote 20 of the United States' second written submission, which reads:299 
[T]he United States does not suggest that fishing methods other than setting on 
dolphins do not cause any unobserved harms to dolphins. As we have said, many 
fishing techniques have the potential to harm marine mammals, including dolphins, 
and direct harms will have indirect (and unobserved) effects. If a mother dolphin is accidentally drowned in a FAD purse seine set, for example, that observed harm may result in unobserved harm to her calf, namely increased vulnerability to predators and 
starvation. But Mexico puts forward no evidence that other fishing methods produce 
anywhere close to the level of unobserved harm that setting on dolphins causes as a result of the chase in itself. 
7.134.  In the Panel's opinion, footnote 20 is not, as Mexico argues, a concession that fishing 
methods other than setting on dolphins cause the kind of unobservable harms that dolphins suffer as a "result of the chase in itself". Footnote 20 recognizes that indirect and unobservable harms 
may follow consequentially from observable  harms caused by tuna fishing methods other than 
setting on dolphins. Where, for example, a mother dolphin is killed or seriously injured in a gear set, her calf may also suffer as a result of her (the mother's) inability to provide care, including food and protection. The key point, however, is that these harms flow from mortalities or injuries 
that are themselves observable, and whose occurrence renders non-dolphin-safe all tuna caught in 
the set or gear deployment in which the injury or mortality was sustained. These harms may be 
serious. However, because they flow directly from observable harms, such as serious injury, all of 
which could be detected and reported, unlike the kinds of unobservable harms caused by setting 
on dolphins, these types of indirect harms are thus qualitatively different from the kind of 
unobservable harms caused by setting on dolphins. As explained above, these latter harms (i.e. 
caused by setting on dolphins) are unobservable in the sense that no evidence of their occurrence 
is produced during the set. They may be inflicted even in cases where no dolphin is caught in the net, or where any caught dolphin is released without apparent injury. Accordingly, they are harms whose occurrence cannot be recorded. Obviously, this would undermine the United States' 
objectives, which, as Mexico acknowledges, are "( i) ensuring that consumers are not misled or 
deceived about whether tuna products contain tu na caught in a manner that adversely affects 
dolphins; and (ii) contributing to the protection of  dolphins by ensuring the US market is not used 
to encourage fishing fleets in a manner that adversely affects dolphins".
300  
7.135.  In light of the above, our view is that  Mexico has not provided evidence sufficient to 
demonstrate that setting on dolphins does not cause observed and unobserved harms to dolphins, 
or that other tuna fishing methods consistently cause similar harms. Rather, the Panel agrees with 
the United States that " even if  there are tuna fisheries using…gear types that produce the same 
number of dolphin mortalities and serious injuries allowed or caused in the ETP…it is simply not the 
case that such fisheries are producing the same level of unobserved harms, such as cow-calf 
separation, muscular damage, immune and reproductive system failures, which arise as a result of 
the chase in itself".301 As we understand it, this position was also the basis of the original panel 
and Appellate Body's holding on this issue. Theref ore, we find that the new evidence presented in 
these proceedings merely supports the conclusion reached by the panel and the Appellate Body in 
the original proceedings. 
7.5.2.3  Mexico's remaining claims of less favourable treatment: the different 
certification and tracking an d verification requirements 
7.136.  In the original proceedings, the panel found, and the Appellate Body accepted, that 
disqualifying tuna caught by setting on dolphins from accessing the dolphin-safe label "fully 
                                               
298 Mexico's response to Pane l question No. 15, para. 88. 
299 United States' second written su bmission, para. 17, footnote 20. 
300 Mexico's second written submission, para. 3. 
301 United States' first written submission, para. 113 (internal citations omitted).  WT/DS381/RW 
 
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  addresses the adverse effects on dolphins resulting from setting on dolphins in the ETP".302 The 
Appellate Body also found, however, that "'the use of certain fishing methods other than setting on 
dolphins 'outside the ETP may produce and has produced significant levels of dolphin bycatch', and that 'the US dolphin-safe provisions do not address observed mortality', and any resulting adverse 
effects on dolphin populations, for tuna not caught by setting on dolphins".
303 Because the original 
measure fully addressed the risks posed to dolphins by the ETP large purse seine fishery, but did not sufficiently address the risks to dolphins arising in other fisheries, the Appellate Body found 
that the measure was inconsistent with Article 2.1 of the TBT Agreement.  
7.137.  As we understand it, then, the Appellate Body required the United States to modify its 
dolphin-safe labelling regime so as to ensure that it sufficiently addresses similar risks posed to dolphins by all fishing methods in all oceans. In  the present proceedings, Mexico argues that the 
United States has not done so. In support of this position, as we set out above, it points to three 
regulatory distinctions that, in its view, continue not to adequately address the risks posed to dolphins by methods of fishing other than setting on dolphins in the ETP: the eligibility criteria, the 
different certification requirements, and the different tracking and verification requirements. We 
explained above that the eligibility criteria were found by the Appellate Body in the original proceedings not to violate Article 2.1 of the TBT Agreement. Our analysis now turns to the 
remaining two distinctions. Our task in respect of  these is to determine whether the amended tuna 
measure sufficiently addresses the various risks arising to dolphins as a result of different fishing methods in different oceans, or whether it contin ues "not [to] address observed mortality … for 
tuna" caught other than by setting on dolphins in the ETP. 
7.138.  We note that this determination arises only insofar as the United States has chosen to 
address risks arising to dolphins as a result of tuna fishing. In other words, there is no general obligation under WTO law for the United States to protect dolphins. The United States' obligation 
under the WTO Agreement is, speaking generally, not to discriminate against imported products. 
But insofar as the United States has chosen – and succeeded – to fully address the risks posed to dolphins by setting on dolphins in the ETP, the A ppellate Body found that it must also address risks 
to dolphins arising from other fisheries if it is to be non-discriminatory.
304 
7.139.  In the original proceedings, the Appellate Body accepted that "the use of certain tuna 
fishing techniques other than setting on dolphins may … cause harm to dolphins".305 It also found 
that even though "certain environmental conditions in the ETP (such as the intensity of tuna-
dolphin association) are unique, the evidence … suggests that the risks faced by dolphin 
populations in the ETP are not".306 The Appellate Body was "not persuaded that at least some of 
the dolphin populations affected by fishing techniques other than setting on dolphins are not facing 
risks at least equivalent to those currently faced by dolphin populations in the ETP".307 
7.140.  Importantly, the Appellate Body found that the certification required by the original tuna 
measure for methods of fishing other than setting on dolphins – that "no purse seine net was 
intentionally deployed on or used to encircle do lphins during the fishing trip" – did "not address 
risks from other fishing methods, such as FADs".  The Appellate Body explained that "risks to 
dolphins resulting from fishing methods other than setting on dolphins could 'only be monitored by imposing a different substantive requirement, i.e. that no dolphins were killed or seriously injured 
in the sets in which tuna was caught'".
308 
7.141.  Of course, imposing a new substantive requirement is precisely what the United States has 
done by way of the 2013 Final Rule. As the Panel no ted in the descriptive part of its report, the 
2013 Final Rule requires that, from the date of its entry into force, all tuna, wherever and however 
caught, can only be labelled as dolphin-safe if it  was not caught in a set or other gear deployment 
                                               
302 Appellate Body Report, US – Tuna II (Mexico) , para. 297. 
303 Appellate Body Report, US – Tuna II (Mexico) , para. 298. 
304 Appellate Body Report, US – Tuna II (Mexico) , para. 298. 
305 Appellate Body Report, US – Tuna II (Mexico) , para. 288 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.520). 
306 Appellate Body Report, US – Tuna II (Mexico) , para. 288 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.552) (emphasis original). 
307 Appellate Body Report, US – Tuna II (Mexico) , para. 288 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.617). 
308 Appellate Body Report, US – Tuna II (Mexico) , para. 292 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.561). WT/DS381/RW 
 
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  in which one or more dolphins was killed or seriously injured. This means that the substantive 
certification required for all tuna, regardless of where or how it was caught, is now the same. In the Panel's view, this new uniformity in the required substantive certification addresses the specific concern identified by the Appellate Body at pa ragraph 292 of its report, and moves the amended 
measure towards compliance with WTO law. 
7.142.  While Mexico has not challenged the new substantive certification requirements, it argues 
that the continued differences in who must make the substantive certifications in what 
circumstances, and the different tracking and verifi cation requirements applied inside the ETP large 
purse seine fishery and outside it, mean that the amended tuna measure does not address similar risks posed to dolphins in different fisheries in an even-handed manner, and therefore continues to violate Article 2.1 of the TBT Agreement.  
7.143.  Before proceeding, the Panel recalls that the two distinctions at issue in this section of our 
Report are relevant only to tuna eligible and intended to receive the dolphin-safe label. The amended tuna measure does not prohibit  non-dolphin-safe tuna from being sold in the 
United States, but only controls access to the US dolphin-safe label.
309 Accordingly, tuna that is 
either ineligible to access this label (i.e. tuna caught by setting on dolphins) or not intended to be sold under the dolphin-safe label is not affected by these regulatory distinctions. 
7.144.  Regarding our order of analysis, the Panel notes that in its submissions Mexico deals first 
with the different tracking and verification requirements and second with the different certification requirements. In our report, however, we deal wi th the different certification requirements first 
and the different tracking and verification requirements second, to reflect what we understand to 
be the chronological order in which the requir ements imposed by the relevant regulatory 
distinctions arise.
310 This is simply a matter of presentation , and we do not believe that it has any 
significance for the content of our analysis. 
7.5.2.4  The different certification requirements 
7.145.  Mexico describes the different certification requirements as follows: 
The mandatory independent observer requirements for tuna caught in the ETP by 
setting on dolphins in accordance with the AIDCP and the absence of such 
requirements for tuna caught outside the ETP using the same and different fishing methods.
311 
7.146.  Before proceeding to our substantive analysis, we note that Mexico's description of the 
regulatory distinction in its first written submission is not entirely complete, insofar as it may seem 
to suggest that tuna fishing vessels outside the ETP and vessels other than large purse seine vessels inside the ETP are never  subject to mandatory observer requirements. Such suggestion 
would be incorrect. As we explained in the descriptive part of the report, such vessels may indeed 
be subject to mandatory observer requirements if certain conditions are met.
312  
7.147.  Additionally, Mexico's description of the dist inction in its first written submission refers to 
observer requirements for "tuna caught in the ETP by setting on dolphins". As we understand it, 
however, the amended tuna measure requires an observer certification for all tuna caught by large purse seine vessels in the ETP. What is decisive for the observer certification requirement is thus not the method actually used to catch tuna (e.g. setting on dolphins) but the type of vessel and 
the location of its fishing operation. Large purse seine vessels in the ETP are, under the amended 
tuna measure, required to present proof of an AIDCP-compliant observer certification (and therefore to carry observers) whether or not they intend to or actually do set on dolphins. 
7.148.  Accordingly, the relevant regulatory dist inction could, in our view, be more accurately 
articulated as being: The mandatory independent observer certification requirements for all tuna caught in the ETP large purse seine fishery and the absence of such requirements (unless certain 
                                               
309 See para. 3.2 above. 
310 Thus, the certification obligations arises first, at the time catch; and the record-keeping obligations 
arise only subsequently, once the tuna catch has been stored on board the fishing vessel. 
311 Mexico's first written submission, para. 236. 
312 See para. 3.45 above. WT/DS381/RW 
 
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  determinations have been made with respect to the fishery in which the tuna was caught) for all 
tuna caught in all other fisheries.  
7.149.  Indeed, Mexico itself revised its description of this regulatory distinction over the course of 
the proceedings. In its opening statement at the Panel's meeting with the parties, Mexico 
described the distinction in the following terms: 
In the case of Mexican tuna, the initial designation of dolphin-safe status is subject to 
mandatory independent observer requirements at the point when the tuna is 
harvested from the ocean, which prevents non-dolphin-safe tuna from being 
mislabelled as dolphin-safe, while, in the case of tuna from other countries, the initial designation of dolphin-safe status is no t made by independent observers, thereby 
allowing the tuna to be mislabelled as dolphin-safe when, in fact, it is not.
313 
7.150.  In our view, this formulation more accurate ly captures the regulatory distinction at issue 
(although we note that all tuna caught in the ETP large purse seine fishery, including tuna caught by vessels belonging to countries other than Mexi co, is subject to the observer requirement, so 
that the distinction is de facto  rather than de jure ). This formulation is consistent with our 
understanding as explained in paragraph 7.148 ab ove. Therefore, our analysis proceeds on the 
basis of this description of the relevant regulatory distinction. 
7.151.  In the following paragraphs, we consider, first, whether the different certification 
requirements modify the conditions of competition in the United States' tuna market to the detriment of Mexican tuna and tuna products. If Mexico is able to convince us that such detrimental impact exists, we will continue to  examine whether the detrimental impact stems 
exclusively from a legitimate  regulatory distinction. 
7.5.2.4.1  Whether the different certificatio n requirements modify the conditions of 
competition in the United States' market to the detriment of like Mexican tuna and tuna 
products 
7.5.2.4.1.1  Argume nts of the parties 
7.152.  As the Panel noted in the context of its di scussion above of the eligibility criteria, the core 
of Mexico's claim on detrimental treatment is th at, under the amended tuna measure, the majority 
of Mexican tuna and tuna products – being caught or made from tuna caught by setting on dolphins – is ineligible to receive the United States dolphin-safe label, while the majority of tuna and tuna products caught or manufactured by the United States and other WTO Members – being 
caught or made from tuna caught other than by setting on dolphins – are eligible.  In light of this 
central claim, Mexico's argument about the detrimental impact caused by the different certification requirements is not that these requirements in themselves block or hinder Mexican access to the 
dolphin-safe label. Rather, Mexico's complaint is that:  
[T]he absence of sufficient … observer requir ements for tuna that it used to produce 
tuna products from the United States and other countries means that Mexican tuna 
products are losing competitive opportunities to tuna products that may be 
inaccurately labelled as dolphin-safe. This difference is what is creating the detrimental impact.
314  
7.153.  According to Mexico, the detrimental impact caused by the different certification 
requirements does not stem from the "denial of a competitive opportunity" – that is, beyond or 
additional to the denial inherent in the disqualification of tuna caught by setting on dolphins315 – 
but rather from the granting of "a competitive advantage" to tuna and tuna products from the 
United States and other WTO Members.316 
7.154.  As we understand it, then, Mexico's claim is  that by requiring observer certification for all 
tuna caught by large purse seine vessels in the ETP while not requiring the same for tuna caught 
                                               
313 Mexico's opening st atement, para. 52. 
314 Mexico's second written submission, para. 117 (emphasis original). 
315 Mexico's opening st atement, para. 50. 
316 Mexico's second written submission, para. 117. WT/DS381/RW 
 
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  other than by large purse seine vessels in the ETP, the amended tuna measure imposes a lighter 
burden, in terms of accessing the dolphin-safe label, on tuna caught in fisheries other than by setting on dolphins in the ETP.
317 By making it easier for tuna caught other than by setting on 
dolphins in the ETP to access the label, the different certification requirements provide such tuna 
with a competitive advantage. This modifies the conditions of competition to the detriment of 
Mexican tuna and tuna products. Mexico also alleges that the different certification requirements create an opportunity for tuna caught in a set or other gear deployment in which a dolphin was 
killed or seriously injured to be incorrectly labelled as dolphin-safe. As a result, tuna that is not in 
fact dolphin-safe could enjoy the commercial advantage of bearing the dolphin-safe label. In contrast, "[i]n the case of Mexican tuna, the initial designation of dolphin-safe status is subject to mandatory independent observer requirements at the point when the tuna is harvested from the 
ocean, which prevents  non-dolphin-safe tuna from being mislabeled as dolphin-safe".
318 
7.155.  The United States rejects Mexico's arguments. As we noted above, the United States' 
primary submission is that "the detrimental impact does not stem from either" the different 
certification requirements or the different tracking  and verification requirements. Rather, "Mexico's 
first element [i.e. the eligibility criteria] is the detrimental impact", and since "Mexican tuna 
product containing tuna caught by setting on dolphins would still be ineligible for the 'dolphin safe' 
label" even if the different certification and trac king and verification requirements did not exist, 
"Mexico simply cannot establish a causal connection between the detrimental impact" and the different certification and tracking and verification requirements". 
7.156.  In support of this claim, the United States argues that "Mexico has put forward zero 
evidence to prove" that either the different certification or the different tracking and verification 
requirements modify the conditions of competition in the United States tuna market to the detriment of Mexican tuna and tuna products. According to the United States:  
[W]hat Mexico appears to be asserting is that its market access would increase if 
either one of two things happen: 1) the United States eliminates the need for the Form 370 that accompanies Mexican tuna product to list the AIDCP mandated tracking 
number and a Mexican government certification that an observer was on board the 
vessel; or 2) the United States requires all tuna product containing tuna to adhere to AIDCP-equivalent record-keeping/verificati on and observer coverage requirements. 
But Mexico puts forward no evidence that more Mexican non-dolphin safe tuna 
product would be sold in the US market under either scenario. Consumer preferences 
have not changed in the United States. Consumer demand for non-dolphin safe tuna product remains low. No causal connection exists between these requirements and 
denial of "access" to the label that the Appellate Body determined constituted the 
detrimental impact.
319  
7.157.  Additionally, in its opening statement at the Panel's meeting with the parties, the 
United States submitted that "Mexico [has not] put forward any evidence that even if one could 
find any illegal marketing, this unfortunate occurrence would be happening at a higher rate than for tuna product containing ETP tuna".
320 
7.158.  As such, the United States asks the Panel to reject Mexico's arguments.  
7.5.2.4.1.2  Analysis by the Panel 
7.159.  As the Panel explained in its discussion of the legal test under Article 2.1321, less 
favourable treatment within the meaning of Articl e 2.1 of the TBT Agreement arises where (a) the 
measure at issue modifies the conditions of competition in the relevant market to the detriment of 
imported products; and (b) at least where that detrimental treatment is de facto , the detrimental 
                                               
317 Mexico's second written submission, para. 193 (arguing that the amended tuna measure imposes 
"one standard for tuna caught inside the ETP, and a se parate and lower standard fo r tuna caught outside the 
ETP"). 
318 Mexico's opening statement,  para. 52 (emphasis added). 
319 United States' second written submission, paras. 76-77. 
320 United States' opening statement, para. 26. 
321 See section 7.5.1 above. WT/DS381/RW 
 
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  treatment identified in (a) does not stem exclusiv ely from a legitimate regulatory distinction. A 
panel must necessarily make a finding on the existence of detrimental treatment before proceeding to consider whether such detrimental treatment stems exclusively from a legitimate regulatory distinction. If a complainant is unable to make a prima facie  case for the existence of 
such treatment, a panel cannot proceed to the second step of the less favourable treatment 
analysis, since, as the Appellate Body has said, on ly those aspects of a technical regulation giving 
rise to detrimental treatment must be examined under the legitimate regulatory distinction test.
322 
Accordingly, if Mexico is unable to show prima facie  that the different certification requirements 
afford detrimental treatment to its tuna products in the United States' market, we do not need to proceed to the second part of the analysis under Article 2.1 of the TBT Agreement.  
7.160.  The Panel has already found above that Mexico has put forward a distinct claim of less 
favourable treatment in respect of the different certification and tracking and verification 
requirements, and that it is appropriate for us to  consider that claim, even though it developed 
over the course of Mexico's first and second wr itten submissions. Accordingly, we now turn to 
consider the merits of Mexico's case.  
7.161.  The first question we must address is whether Mexico has succeeded in proving, 
prima facie , that the different certification requirements modify the conditions of competition to 
the detriment of like tuna and tuna products from Mexico. In particular, we must determine 
whether, as Mexico has argued, the absence of an observer coverage requirement for fishing vessels other than large purse seine vessels in the ETP does grant a competitive advantage by imposing a lighter burden, in terms of accessing the dolphin-safe label, on tuna and tuna products 
made from tuna caught other than by large purse seine vessels in the ETP, including by increasing 
the likelihood that such tuna may be labelled as dolphin-safe even if caught in a set or other gear deployment in which dolphins we re killed or seriously injured. 
7.162.  In the Panel's view, it is clear that by not requiring observer coverage outside of the ETP 
large purse seine fishery, the amended tuna measure imposes a lighter burden on tuna and tuna products made from tuna caught other than by large purse seine vessels in the ETP. The 
United States has recognized that observer co verage involves the expenditure of significant 
resources
323, and both parties in their oral responses at the Panel meeting and in their written 
responses to the Panel's questions made clear that the costs of implementing observer coverage can be significant.
324 Indeed, the United States explicitly re cognized that the resource expenditure 
required to establish and maintain observer programs "impose[s] [an] enormous barrier to entry" 
into the US tuna market, and may cost hundreds of millions of dollars.325 In our view, these facts 
clearly point to the conclusion that the different certification requirements impose a lesser burden 
on tuna and tuna products made from tuna caught outside the ETP large purse seine fishery, and 
thus modify the conditions of competition to the detriment of Mexican tuna and tuna products. 
7.163.  With respect to Mexico's allegation that the different certification requirements 
detrimentally modify the conditions of competition because they make it more likely that tuna 
caught outside the ETP large purse seine fishery will be inaccurately labelled, we agree with the United States that Mexico has not provided specific "evidence that non-dolphin safe tuna product produced outside the ETP is being illegally marketed in the United States as dolphin safe".
326 We 
are not convinced, however, that Mexico is, as a matter of law, required to produce such evidence 
to sustain its claim. As we explained in our discussion of the standard of proof327, it is well 
established that, to make out a claim of detrimental impact, a complainant is not expected to show 
that the measure at issue will "give rise to less favourable treatment for the like imported products 
in each and every case".328 In fact, the Appellate Body has repeatedly held, in the context of the 
less favourable treatment analysis under Article III:4 of the GATT 1994, that "the examination [of 
                                               
322 Appellate Body Report, US – Tuna II (Mexico) , para. 286. 
323 United States' first written submission, paras. 265 and 266. 
324 United States' first written submission, para. 265;  United States' and Mexi co's responses to Panel 
questions Nos. 48, 49 and 50. See especially Mexico's response to Panel question No. 48, paras. 137 and 138 
(explaining the costs borne by Mexico). 
325 United States' response to Panel question No. 49, para. 266. 
326 United States' opening statement, para. 26. 
327 See section 7.4.2 above. 
328 Appellate Body Report, US – FSC (Article 21.5 – EC) , para. 221. WT/DS381/RW 
 
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  whether a measure modifies the conditions of competition to the detriment of imported products] 
need not be based on the actual effects  of the contested measure in the marketplace".329  
7.164.  This observation applies with special force in the context of the detrimental treatment 
analysis under Article 2.1, concerning which the Appellate Body has instructed panels to pay close 
attention to the "design, architecture, revealing structure, operation, and application" of the 
technical regulation at issue.330 According to this instruction, panels are both entitled and, indeed, 
required to carefully consider what  might be called the "objective" features or characteristics of the 
measure – that is, not only how the measure in fact operates, but how it is designed, how its 
various parts fit together, and what consequences might flow from its overall structure and architecture. Accordingly, although we would not be barred from considering evidence of actual 
instances of incorrect labelling had Mexico submitted it, we do not believe that Mexico's failure to 
submit such evidence is fatal to its claim that the different certification requirements modify the 
conditions of competition in the United States' market to the detriment of Mexican tuna and tuna products.  
7.165.  This, of course, does not mean that Mexico need not provide any evidence to substantiate 
its claims: a finding of detrimental treatment "cannot rest on mere assertion".
331 Mexico may, 
however, make its case on the basis of evidence and arguments going to the "design, architecture, 
and revealing structure" of the amended tuna measure. And this is, in fact, what Mexico has 
attempted to do.  
7.166.  The core factual assertion underlying Mexico's allegation that the different certification 
requirements make it easier for tuna caught outside the ETP large purse seine fishery to be 
incorrectly labelled is that "captains are neither qualified nor able to make" an accurate 
designation that no dolphins were killed or seriously injured in a particular gear deployment.332 
Accordingly, in Mexico's view, "it is both appropriate and necessary to have an independent 
observer requirement for tuna fishing outside the ETP".333 According to Mexico, the incapacity of 
captains to accurately certify the dolphin-safe status of tuna "create[s] a very real risk that tuna may be improperly certified as dolphin-safe", with the consequence that "tuna caught in the ETP, 
which is accurately certified as dolphin-safe by independent observers, will lose competitive 
opportunities to tuna caught outside the ETP, which has received an inherently unreliable dolphin-safe certification".
334  
7.167.  The United States rejects these allegations. In its view, "[t]he simple fact is that a 
captains' statement is an effective vehicle to determine the eligibility of tuna for the label".335 
According to the United States, "Mexico's argument assumes  that captains operating outside the 
ETP are fraudulently certifying tuna as dolphin safe when it is not"336, but "Mexico has not provided 
any evidence of such fraud".337 The United States concludes that "Mexico cannot hope to prove its 
claim based simply on its insistence – without more – that certifications by captains operating outside the ETP are inherently unreliable".
338 
7.168.  We note that the United States has itself recognized that observer certification 
"strengthens" the dolphin-safe certification.339 As we understand it, this is a concession that 
observer certification heightens or increases the accuracy and reliability of the label. Such 
                                               
329 Appellate Body Report, US – FSC (Article 21.5 – EC) , para. 215. See also Appellate Body Report, 
Thailand – Cigarettes  (Philippines) , para. 129 ("This analysis need not be based on empirical evidence as to the 
actual effects of the measure at issue in the internal  market of the Member conc erned. Of course, nothing 
precludes a panel from taking such evidence of actual effects into account") and 134 (Such scrutiny may well involve – but does not require – an assessment of the contested measure in light of evidence regarding the 
actual effects of that measure in the market"). 
330 Appellate Body Report, US – Clove Cigarettes , para. 206; see also Appellate Body Report, US – 
Tuna II (Mexico) , para. 225. 
331 Appellate Body Report, Thailand – Cigarettes (Philippines) , para. 130. 
332 Mexico's first written submission, para. 285; Mexico's second written submission, para. 168. 
333 Mexico's second written submission, para. 167. 
334 Mexico's second written submission, para. 182. 
335 United States' first written submission, para. 267. 
336 United States' second written submission, para. 122 (emphasis original). 
337 United States' second written submission, para. 100. 
338 United States' second written submission, para. 122. 
339 See United States' responses to Panel question  No. 31, para. 175 and Panel question No. 32, 
para. 180. WT/DS381/RW 
 
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  concession does not entail the conclusion that, without observers, captains' certifications are 
always and necessarily "inherently unreliable"340; but by recognizing that the observer certification 
"strengthens" the dolphin-safe certification341, the United States has acknowledged that observer 
certification may heighten the veracity, reliability and, importantly, the accuracy of the relevant 
certification. Thus, even the United States' own argument appears to recognize that it may be 
easier  or more likely  for dolphin-safe certifications made only by captains to be inaccurate than it 
is for dolphin certifications made by captains and observers. And of course, the consequence of 
this is that it may be more likely that tuna caught by vessels other than large purse seine vessels 
in the ETP will be inaccurately labelled as dolphin-safe than it is that tuna caught by large purse seine vessels in the ETP will be.  
7.169.  In the Panel's view, however, it is not necessary to make a definitive finding on this point. 
The Panel's finding that the different requirements impose a lighter burden, in terms of accessing 
the dolphin-safe label, on tuna and tuna products made from tuna caught other than by large purse seine vessels in the ETP is sufficient to justify a finding that this aspect of the measure 
modifies the conditions of competition to the detriment of Mexican tuna and tuna products. In light 
of what we understand to be the United States' concession, the Panel does see some merit in Mexico's allegation that the different certification requirements may make it more likely that tuna 
caught outside the ETP could be inaccurately labelled. Ultimately, however, a definitive finding on 
this point would require a complex and detailed analysis of all of the various factors that may lead to tuna being inaccurately labelled. Such an analysis is not necessary in the context of the present dispute. 
7.170.  Accordingly, the Panel accepts Mexico's claim that the different certification requirements 
detrimentally modify the conditions of competition because they impose a significantly lighter burden on tuna and tuna products made from tuna caught outside the ETP large purse seine 
fishery than on tuna caught within it. 
7.171.  Before concluding our consideration of whether the different certification requirements 
modify the conditions of competition in the United States' market to the detriment of Mexican tuna 
and tuna products, the Panel must address the United States' contention that any detrimental 
impact suffered by Mexican tuna and tuna products on account of the different observer requirements stems from the AIDCP regime and not the amended tuna measure
342, with the 
consequence that there is no "genuine relationsh ip between the measure at issue and the adverse 
impact on competitive opportunities for imported products".343 Although the United States first 
raised this issue in the section of its first written submission entitled "Mexico Fails to Prove that Detrimental Impact does not Stem Exclusively from a Legitimate Regulatory Distinction", the 
United States explicitly acknowledged that the question of "genuine relationship" is relevant to the 
question whether "the US measure has a detrimental impact on the conditions of competition".
344 
Accordingly, we think it is appropriate to deal wi th this issue in the present context, although we 
will revisit it as well in the course of our discussion on whether any detrimental treatment caused 
by the different certification requirements stems exclusively from a legitimate regulatory distinction. 
7.172.  According to the United States, there is no genuine connection between the amended tuna 
measure and any detrimental impact suffered by Mexican tuna and tuna products on account of 
the different certification requirements because these different requirements are not "establishe[d]"
345 by the amended tuna measure, but rather  by the AIDCP, an international treaty 
that Mexico joined in the free exercise of its sove reignty. The proof of this assertion, according to 
the United States, is the fact that even "if the United States eliminated all references to the AIDCP (and its requirements) from the amended meas ure, the differences in record-keeping and 
observers that Mexico complains about would still exist ".
346 As the United States explains:  
                                               
340 Cf e.g. Mexico's second written submission, para. 147. 
341 United States' response to Panel question No. 31, para. 175; United States' response to Panel 
question No. 32, para. 180. 
342 United States' first written submission, para. 226. 
343 United States' first written submission, para. 295 (citing Appellate Body Reports, EC – Seal Products , 
para. 5.101). 
344 United States' first written submission, para. 195. 
345 United States' first written submission, para. 226. 
346 United States' first written submission, para. 226 (emphasis original). WT/DS381/RW 
 
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  [T]he requirement of the AIDCP observer coverage program are contained in the 
AIDCP and related documents. These requirements are not repeated in US law.  
Rather, the amended measure requires that , for … [non-US-flagged large purse seine 
vessels in the ETP], the tuna must be accompanied by a Form 370 and valid 
documentation, signed by the representative of the appropriate IDCP member nation, 
that certifies, among other things, that there was an IDCP-approved observer on board for the entire trip.
347 
7.173.  As such, "[t]he requirement for large purse seine vessels operating in the ETP to carry 
observers (while other vessels are not similarly required) stems from the AIDCP , not US law".348 In 
fact, says the United States, the requirement is not even "repeated in US law".349 
7.174.  Mexico appears to recognize that the differe nt certification requirements stem from, in the 
sense of having their origin in, the AIDCP. However, in Mexico's view "[t]he US argument seeks to 
avoid the fact that the amended tuna measure expressly incorporates the AIDCP requirements".350 
Mexico explains that:  
Section (d)(2)(B) of the DPCIA establishes th at, for a tuna product containing tuna 
caught in the ETP to qualify as dolphin-safe, it must be accompanied by a written statement executed by (i) a Commerce Department official, (ii) a representative of the 
IATTC [i.e. the Inter-American Tropical Tuna Commission], or (iii) an authorized 
representative of a participating nation whose national program meets the requirements of the AIDCP, which states th at there was an observer approved by the 
AIDCP on board the vessel during the entire trip and that the observer certified that 
no dolphin sets were made during the entire voyage and no dolphins were killed or 
seriously injured during the set in which the tuna were caught. There is no such requirement for non-ETP tuna products.
351   
7.175.  In Mexico's view, because the requiremen ts of the AIDCP are embedded in the amended 
tuna measure, "[t]he US argument that there is no connection between the Amended Tuna Measure and the AIDCP is … unsupportable".
352 
7.176.  It is well established that, as the Appellate Body has held in the context of both Article 2.1 
of the TBT Agreement and Article III:4 of the GATT 1994, "there must be in every case a genuine 
relationship between the measure at issue and its adverse impact on competitive opportunities for imported versus like domestic products".
353 In considering whether there is a "genuine connection" 
between the amended tuna measure and the detrimen tal impact alleged by Mexico, we also recall 
the Appellate Body's explanation, given in the course of the original proceedings in this matter, that "[i]n assessing whether there is a genuine relationship between the measure at issue and an 
adverse impact on competitive opportunities for imported products, the relevant question is 
whether governmental action 'affects the condit ions under which like goods, domestic and 
imported, compete in the market within a Member's territory'".
354 This statement directs our 
attention to the question whether the detrimental impact is attributable  to government action, or 
whether it stems from some other source. 
7.177.  In our view, although the observer coverage requirement for large purse seine vessels 
fishing in the ETP has its origin in the AIDCP, the different certification requirements – that is, the 
regulatory distinction  between the requirements for tuna caught by large purse seine vessels on 
the one hand and the requirements for other vessels on the other hand – stem from the amended 
                                               
347 United States' first written submission, paras. 253 and 254 (emphasis original). See also 
United States' second written submission, para. 111 ("For Mexican large purse seine vessels operating in the ETP, any tuna sold as dolphin safe must be accompanied by a Form 370 and valid documentation signed by a representative of the Government of  Mexico that certifies, among othe r things, that there was an AIDCP-
approved observer on board for the entire trip"). 
348 United States' first written submission, para. 256 (emphasis original). 
349 United States' second written submission, para. 112. 
350 Mexico's second written submission, para. 80. 
351 Mexico's second written submission, para. 80. 
352 Mexico's second written submission, para. 83. 
353 Appellate Body Report, Thailand – Cigarettes (Philippines) , para. 134. 
354 Appellate Body Report, US – Tuna II (Mexico) , para. 236. WT/DS381/RW 
 
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  tuna measure itself. The AIDCP imposes certain certification requirements on large purse seine 
vessels fishing in the ETP, but it has nothing to say about other methods of fishing in the ETP or about fishing in other oceans. The amended tuna measure, by contrast, imposes certain certification requirements on the ETP large purse seine fishery and certain, different certification 
requirements on other fisheries. It is the amended tuna measure that provides for two sets of 
rules for access to the dolphin-safe label – one set for tuna caught by large purse seine vessels in the ETP, and another set for all other tuna. And it is therefore the amended tuna measure itself 
that sets up a distinction, within a single regu latory framework (i.e. the amended tuna measure) 
between large purse seine vessels in the ETP and other vessels. That the requirements imposed on large purse seine vessels in the ETP are themselves adapted from the AIDCP cannot detract from the fact that it is the design and structure of the amended tuna measure itself that establishes the 
regulatory distinction about which Mexico complains. 
7.178.  As such, the United States' insistence that "if the United States eliminated all references to 
the AIDCP (and its requirements) from the amended measure, the differences in record-keeping 
and observers that Mexico complains about would still exist "
355 is somewhat beside the point. In 
one sense, the United States is correct: the certification requirements that the AIDCP imposes on large purse seine vessels fishing in the ETP exist, of course, in the AIDCP itself, and will continue 
to exist as a matter of international law regardless of whether they are incorporated into the 
domestic legal system of the United States. But as we have explained above, Mexico's complaint is not directed at the existence of these AIDCP-mandated requirements under international law, or at its own acceptance of these conditions as an adherent to the AIDCP. Rather, Mexico's complaint is 
based on the fact that the amended tuna measure does not require observer coverage on vessels 
other than large purse seine vessels fishing in the ETP. In not doing so, the amended tuna measure imposes a lighter burden on vessels other than large purse seine vessels in the ETP, and 
may make it easier for tuna and tuna products made from tuna caught by such vessels to access 
the dolphin-safe label, thus distorting the conditions of competition on the United States' tuna market to the detriment of Mexican tuna and tuna products. 
7.179.  In light of the foregoing, we conclude that Mexico has made a prima facie case that the 
different certification requirements in the am ended tuna measure modify the conditions of 
competition in the United States' tuna market to the detriment of like Mexican tuna and tuna products. The United States has not rebutted this case. The Panel now proceeds to consider 
whether this detrimental impact stems exclusively from a legitimate regulatory distinction, or 
whether it rather reflects discrimination in vi olation of Article 2.1 of the TBT Agreement. 
7.5.2.4.2  Whether the detrimental treatmen t caused by the different certification 
requirements stem exclusively from a legitimate regulatory distinction 
7.5.2.4.2.1  Argume nts of the parties 
7.180.  According to Mexico, the different certification requirements cannot be said to stem 
exclusively from a legitimate regulatory distinction because "captain self-certification for tuna 
caught outside the ETP does not provide reliable or accurate information on the dolphin-safe status of the tuna products comprising this tuna because captains are not trained, educated, or qualified to identify whether tuna are caught in a dolphin-safe manner, captains may not be directly 
involved in the setting of nets and the capturing of fish, and captains will not reliably declare 
non-dolphin-safe sets or non-compliance with dolphin-safe requirements".
356 Mexico submits that 
"[a]s a consequence, the initial designation of the dolphin-safe status of tuna caught outside the 
ETP is unreliable and inaccurate", and theref ore "consumers are receiving unreliable and 
inaccurate information on such products".357  
7.181.  As such, in Mexico's view, the effect of the different certification requirements is to create 
"two distinct and conflicting standards for the accuracy of information regarding the dolphin-safe 
status of tuna: one standard for tuna caught inside the ETP, and a separate and much lower standard for tuna caught outside the ETP".
358 G i v e n ,  h o w e v e r ,  t h a t  o n e  o f  t h e  g o a l s  o f  t h e  
amended tuna measure is "ensuring that consum ers are not misled or deceived about whether 
                                               
355 United States' first written submission, para. 226 (emphasis original). 
356 Mexico's first written submission, para. 297. 
357 Mexico's first written submission, para. 298. 
358 Mexico's second written submission, para. 193. WT/DS381/RW 
 
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  tuna products contain tuna caught in a manner that adversely affects dolphins"359, Mexico 
concludes that the amended tuna measure's system of captain self-certification "does not bear a rational connection to", and is "entirely inconsistent"
360 and "irreconcilable"361 with, the objectives 
of the amended tuna measure, and accordingly cannot be considered to be "even-handed".362 
7.182.  Moreover, in Mexico's view, the two di fferent standards of accuracy created by the 
different certification requirements cannot be explained or justified on the basis of "calibration" of the different risks to dolphins arising in different areas of the ocean and resulting from the use of 
different tuna fishing method s. According to Mexico:  
The United States' calibration argument implies that it is acceptable and even-handed 
to provide consumers with unreliable, unveri fied, and inaccurate information regarding 
the dolphin-safe status of tuna where the tuna originates from all ocean regions save 
the ETP, but to ensure that such information is independently certified and accurate 
where the tuna originates specifically in the ETP.
363 
7.183.  However, according to Mexico: 
Under the Amended Tuna Measure, the terms "dolphins … killed or seriously injured" 
are clearly designed and applied in an absolute way in the context of observed adverse effects. Tuna caught in a fishing set or gear deployment cannot be labelled as 
dolphin-safe if only a single dolphin mortality or serious injury is observed during the 
set or deployment. It is not a question of the relative number of dolphins that are killed or seriously injured during fishing sett or gear deployments. It is simply a question of whether or not such adverse effects merely exist.
364 
7.184.  In light of this "zero tolerance benchmark for risk" embodied in the amended tuna 
measure, Mexico argues that "a comparison of the magnitude of dolphin mortalities and serious injuries in different fisheries is not relevant to, and does not affect, Mexico's arguments regarding 
the lack of even-handedness in the design and application of the different labelling conditions".
365  
7.185.  In other words, in Mexico's view, the differences in the nature and degree of risk to 
dolphins from setting on dolphins in the ETP or from other methods in the ETP or other fisheries in 
no way explain or justify the different certific ation requirements. The amended tuna measure is 
designed so as to disqualify from accessing the label any and every tuna catch as soon as even a single dolphin is killed or seriously injured. Both parties accept that dolphins are at some risk from all tuna fishing methods  and in all fisheries.
366 As such, the amended tuna measure should require 
the same level of accuracy in reporting regardle ss of whether one or 1,000 dolphins are killed. And 
for this reason, "calibration" does not respond to Mexico's claim that the different certification requirements are inconsistent with the amended tuna measure's objectives.
367 
7.186.  Additionally, Mexico attacks the differen t certification requirements on the basis that 
captain self-certification "permits or requires a private industry party to participate in the administration of [a law] which affect[s] the party's own commercial interests".
368 In Mexico's 
view, there is a "financial incentive for captains to  declare the tuna caught by their vessels to be 
'dolphin-safe', and a corresponding financial disincentive to declare any tuna caught by their vessels to be non-dolphin-safe", because "if a captai n were to decline to certify tuna caught by his 
or her own vessel as dolphin-safe … the value of the tuna would be significantly diminished".
369 
According to Mexico, the different certification requirements place captains "in an inherent conflict 
                                               
359 Mexico's second written submission, para. 3. 
360 Mexico's second written submission, para. 194. 
361 Mexico's second written submission, para. 195. 
362 Mexico's first written submission, para. 298. 
363 Mexico's second written submission, para. 173. 
364 Mexico's response to Pane l question No. 11, para. 50. 
365 Mexico's response to Pane l question No. 11, para. 52. 
366 Except for pole-and-line fishin g: see Mexico's response to Pa nel question No. 11, para. 51; 
United States' first written submission, para. 236. 
367 Mexico's response to Panel qu estion No. 11, paras. 51 and 52. 
368 Mexico's second written submission, para. 178 (citing Panel Report, Thailand – Cigarettes 
(Philippines) , paras. 7.902 and 7.904). 
369 Mexico's second written submission, para. 181. WT/DS381/RW 
 
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  of interest", because they "have a vested commercial and financial interest in securing dolphin-
safe certification for the tuna that they catch". In Mexico's opinion, this creates "a very real risk 
that the tuna may be improperly certified as dolphin-safe", which would be inconsistent with the amended tuna measure's stated objectives.
370 
7.187.  According to Mexico, the risk that captains will make improper or inaccurate statements is 
heightened by the fact that "there are no safeguards in the form of effective legal sanctions or enforcement mechanisms for fishing vessel captains who inaccurately or improperly certify the 
dolphin-safe status of tuna that is caught by their own vessels".
371 As such, Mexico submits that 
"there are no incentives to accurately and properly administer the dolphin-safe certification requirements for tuna caught outside the ETP".
372 
7.188.  The United States rejects Mexico's allegations.  
7.189.  First, and simply, the United States argues that "Mexico puts forward not a single piece of 
evidence that any tuna product has been marketed in the United States as 'dolphin safe' when, in 
fact, it did not meet the conditions of US law".373 According to the United States', Mexico's 
argument is based "entirely on speculation and innuendo rather than any actual evidence".374 
7.190.  Secondly, the United States denies that ca ptains' statements are "inherently unreliable" or 
"meaningless".375 On the contrary, the United States observes that "captains statements, 
logbooks, and the like have always been a core implementation tool for Members to verify 
compliance with [a range of] applicable fishing rules".376 Additionally, "the United States also relies 
on the self-reporting by vessels for implementation of its domestic laws, such as the MMPA".377 In 
the view of the United States, "Mexico's suggesti on – that such an approach [e.g. reliance on 
captain self-certification to prove compliance with fishing laws and regulations] is inherently 
unreliable – would be hugely trade disruptive . Members simply do not have the resources to 
require the independent verification of all the activities of domestic and foreign producers".378 
7.191.  The United States also submits that Mexico's arguments concerning the reliability of 
captains "ignores the fact that this is a closely watched industry", as well as one that is "very risk averse".
379 Moreover, the United States notes that, contrary to Mexico's allegation, United States 
domestic law imposes various civil and criminal penalties on captains and other persons who make 
false dolphin-safe declarations.380 
7.192.  Thirdly, the United States suggests that the even-handedness of the different certification 
requirements is inherent in the very fact the "amended measure requires an observer certification 
where one particular international agreement requir es observers, and does not require an observer 
certification where the relevant authority for the fishery does not require observers to certify as to the tuna's eligibility for a 'dolphin safe' label".
381 According to the United States, Mexico's claim 
against the different certification requirements "ignores why the AIDCP was agreed to in the first 
place … [T]he IATTC Members agreed to different  requirements regarding record-
keeping/verification and observer coverage because the ETP is different ".382 
7.193.  Fourthly, and relatedly, the United States asserts that the difference about which Mexico 
complains does not stem from US law, but merely reflects that the AIDCP imposes requirements that differ from those of other RFMOs. According to the United States, even if the United States eliminated from its measure all reference to observers, "the difference that Mexico criticizes would 
                                               
370 Mexico's second written submission, para. 182. See also Mexico's first written submission, para. 286. 
371 Mexico's second written submission, para. 185. 
372 Mexico's second written submission, para. 185. 
373 United States' first written submission, para. 263 (emphasis original). 
374 United States' response to Panel question No. 18(b), para. 101. 
375 United States' first written submission, para. 264. 
376 United States' first written submission, para. 266. 
377 United States' first written submission, para. 266. 
378 United States' first written submission, para. 265 (emphasis original). 
379 United States' second written submission, para. 123. 
380 United States' second written submission, para. 124. 
381 United States' first written submission, para. 257. 
382 United States' second written submission, para. 126 (emphasis original). WT/DS381/RW 
 
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  still exist ".383 In the United States' view, Mexico's argument is essentially that it (i.e. the 
United States) can only make this element of the amended tuna measure "even-handed" by "unilaterally require[ing] 100 per cent observer coverage throughout the world".
384 According to 
the United States, this argument seeks to make Mexico's own international commitments the 
"floor" for the requirements that the United States must impose on itself and all other trading 
partners. This, the United States argues, is inconsistent with the principle that a Member may take measures "at the levels that it considers appropriate".
385 
7.194.  Finally, the United States observes that the Appellate Body in the original proceedings 
expressly noted that "nowhere in its reasoning did the [original] Panel state that imposing a requirement that an independent observer certify th at no dolphins were killed or seriously injured 
in the course of the fishing operations in which the tuna was caught would be the only way for the 
United States to calibrate its 'dolphin-safe' labelling provisions".
386 In the view of the 
United States, this statement represents an "explicit acknowledge[ment] that the United States could 'calibrate' its measure without requiring all its trading partners to put independent observers 
on their respective tuna fleets".
387 
7.5.2.4.2.2  Analysis by the Panel 7.195.  We begin our analysis by recalling that the question before us is whether the detrimental 
impact identified in the preceding section of this Report stems exclusively from a legitimate 
regulatory distinction, because, for instance, it is even-handed. In considering this question, we must constantly bear in mind that, pursuant to th e allocation of the burden of proof advanced by 
both parties and accepted by the Panel, it is for Mexico to show, at least prima facie , that the 
different certification requirements do not stem exclusively from a legitimate regulatory distinction. 
Only if Mexico makes this showing will the burden sh ift to the United States to show that, contrary 
to Mexico's case, the detrimental impact does in fact stem exclusively from a legitimate regulatory 
distinction. 
7.196.  Before proceeding, the Panel notes that in its discussion above of the legal test under 
Article 2.1 of the TBT Agreement, it set out th e factors that may be taken into account when 
considering whether identified detrimental impact stems exclusively from a legitimate regulatory 
distinction.
388 It is not necessary to repeat in full what was said there. Nevertheless, we would  
note again that, in our opinion, the jurisprudenc e developed by the Appellate Body in respect of 
the chapeau of Article XX of the GATT 1994 may be  relevant in elucidating the meaning of the 
discipline contained in the second tier  of Article 2.1 of the TBT Agreement.389 In particular, it is our 
opinion that in examining whether detrimental treatment stems exclusively from a legitimate regulatory distinction, a panel may take into account the extent to which the identified detrimental 
treatment is explained by, or at least reconcilable with, the objectives pursed by the measure at 
issue. We therefore reject the United States' suggestion that Mexico's arguments on the relationship between the different certification requirements and the objectives of the amended 
tuna measure are "not relevant to the analysis".
390 
7.197.  We turn now to the substance of the parties' arguments. Mexico appears to accept that, as 
the Appellate Body found, the system currently in place in the ETP fully addresses the risks posed 
to dolphins by setting on dolphins in the ETP.391 Its complaint is that the amended tuna measure, 
like the original measure before it, does not fully address the risks posed by other fishing methods 
in the ETP and other oceans, and therefore is not even-handed. Accordingly, the essence of 
Mexico's argument is not that the United States should remove  the certification requirements that 
exist in the ETP, but, conversely, that "it is both appropriate and necessary to have an 
independent observer requirement for tuna fishing outside the ETP"392 – and, indeed, that without 
imposing an observer requirement for vessels other than large purse seiners in the ETP, the 
                                               
383 United States' second written submission, para. 118 (emphasis original). 
384 United States' first written submission, para. 272. 
385 United States' first written submission, para. 273. 
386 Appellate Body Report, US – Tuna II (Mexico) , para. 296. 
387 United States' first written submission, para. 258. 
388 See section 7.5.1 above. 
389 See para. 7.87 above. 
390 United States' second written submission, para. 125. 
391 Appellate Body Report, US – Tuna II (Mexico) , para. 297. 
392 Mexico's second written submission, para. 167. WT/DS381/RW 
 
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  amended tuna measure cannot be even-handed as required under Article 2.1 of the 
TBT Agreement. 
7.198.  As we understand it, Mexico's claim that the different certification requirements are not 
even-handed rests on the fundamental factual premise that captains' certifications are "inherently 
unreliable"393 and "meaningless".394 This is so, in Mexico's view, for two distinct reasons: first, 
captains have a financial incentive to certify that their catch is dolphin-safe even when it is not, and the amended tuna measure contains no mechanism to check this incentive; and second , 
captains lack the technical expertise necessary to properly certify that no dolphins were killed or 
seriously injured in a given set or other gear deployment, and therefore their certifications do not ensure that tuna labelled dolphin-safe in fact meets the statutory and regulatory requirements. We will address each of these allegations separately. 
7.199.  We examine first Mexico's claim that captains' statements are unreliable because captains 
have a financial incentive to certify that tuna is dolphin-safe even when it is not. To help the Panel understand the possible incentives that might play into a captain's decision on certification, the 
Panel asked the parties to explain "[w]hat, if anything, is the relationship between, on the one 
hand, the number and/or dolphin-safe status of tuna caught, and, on the other hand, a captain's remuneration and/or other incentives".
395 
7.200.  In its response, Mexico argues that "the value of tuna caught by a purse seine vessel 
would range from approximately US$1.4 million  to US$2.2 million for skipjack tuna, and 
US$2.7 million to US$4 million for yellowfin tuna".396 According to Mexico, "canneries will not buy 
tuna that is not designated as dolphin-safe", and accordingly "[t]here is an extremely strong 
disincentive for a captain to self-report a dolphin set".397 Mexico submits this economic disincentive 
would exist even where captains are not paid on th e basis of the value or the volume of the tuna 
they catch. According to Mexico, "[i]f tuna cannot be sold to canneries, or if the catch volume of 
the vessel is low because it tried to avoid dolphins, those outcomes would be contrary to the 
economic interests of the companies that own and operate the vessels. A captain would not long be employed under such circumstances".
398 
7.201.  In support of this claim, Mexico cites to the decision in the Freitas  case399, a United States 
administrative law judgment concerning illegal sets on marine mammals. In particular, Mexico highlights the following statement by the Commerce Department judge: 
Given the incentives for making unlawful sets on marine mammals when the amount 
of potential economic gain associated with a catch of large tuna is so great, 
compliance with the mandates not to set on marine mammals is difficult to enforce. Here, Respondents knew not to intentionally set on whales and yet elected to do so 
anyway presumably because the economic benefits outweighed the potential cost 
under the MMPA.
400 
7.202.  The United States in its response argues that "[t]here is no evidence on the record to 
establish that a relationship exists between the number of fish caught on a particular trip or the 
dolphin-safe status of such fish and the vessel captain's remuneration (and/or other incentives)".
401 Indeed, contrary to Mexico's position, the United States suggests that vessel 
captains have economic incentives not to lie on their dolphin-safe declarations, because "[i]f a 
captain is untruthful about his catch, and a cannery discovers this, it would likely have a negative 
impact on the captain's income, because the cannery would no longer want to do business with 
                                               
393 Mexico's first written submission, para. 295. 
394 Mexico's first written submission, para. 285. 
395 Panel question No. 36. 
396 Mexico's response to Panel question No. 36, para. 106. 
397 Mexico's response to Panel question No. 36, para. 107. 
398 Mexico's response to Panel question No. 36, para. 110. 
399 In the Matter of Matthew James Freitas, et al (Exhibit MEX-46). 
400 In the Matter of Matthew James Freitas, et al (Exhibit MEX-46), p. 96. 
401 United States' response to Panel question No. 36, para. 190. WT/DS381/RW 
 
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  that captain".402 Additionally, the United States reiterates that "untruthfulness … could … provide 
an evidentiary basis for a captain to suffer civil and criminal penalties".403 
7.203.  To help the Panel explore this issue further, the Panel also asked the parties the following 
question:  
In both of its written submissions and in its oral statement to the Panel, the 
United States emphasizes that captain certifications are regularly relied upon by national and international regulators, and that such statements are generally accepted 
as being reliable. Is it international practice to accept captains' certifications to prove 
compliance with regulatory requirements? In other RFMOs, are captains' certifications sufficient to establish compliance with relevant regulatory requirements?
404 
7.204.  In its response, Mexico acknowledges that "captain's self-certifications might be reliable for 
certain purposes", but denies that they are "relia ble for the purpose of certifying the dolphin-safe 
status of the tuna caught by the captain's own fishing vessel".405 In support of this position, 
Mexico notes that a variety of academic, govern mental, and supra-governmental authorities have, 
in the past, expressed doubt about the extent to which captains accurately self-report. 
7.205.  Mexico notes, for instance, a 2006 study co nducted jointly by the Du ke University Marine 
Laboratory and the University of St. Andrews that found "that accurate estimation of bycatch rates 
in any fishery requires an independent observer scheme".406 Mexico also notes a technical 
memorandum prepared by the United States Commerce Department, which recognizes that "[d]espite fairly good outreach and the distribution of reporting forms to all state and Federally-permitted fishermen each year, compliance with the reporting requirement is thought to be very 
low".
407 To give one more example, Mexico observes that an "Observer Program Operations 
Manual" prepared by Canada and published by the United Nations Food and Agriculture Organization states that "under-reporting is common practice and … even now, after years of 
persistent enforcement, discrepancies between real and reported catch can be as high as … two to 
ten times higher for regulated bycatch species".
408 
7.206.  The United States takes the opposite position in its response to the Panel's question. 
According to the United States, "[c]aptain statemen ts and logbooks are an integral part of regional 
fishery management organisation (RFMO) regimes and other international regimes and agreements".
409 For example, both the IATTC and the WC PFC require that vessels keep detailed 
logbooks of information on various aspects of fishing operations. According to the United States, 
"the fact that most RFMOs rely on logbook data to manage fish stocks demonstrates that captains' 
statements, in the form of logbooks, are viewed as reliable".410 Additionally, the United States 
points to various international treaties whose implementation relies on captains' self-certifications 
and logbooks. To give one example, the Convention  for the Conservation of the Antarctic Marine 
Living Resources (CCAMLR), a treaty that "makes it unlawful to engage in harvesting Antarctic 
marine living resources in violation of any conservation measure in force under the Convention or 
to violate any regulation promulgated under the implementing statute", is implemented by the 
United States through "a catch documentation scheme, whereby captains have to supply fishing details to NOAA [i.e. the National Oceanic and Atmospheric Administration]".
411  
                                               
402 United States' response to Panel question No. 36, para. 193. 
403 United States' response to Panel question No. 36, para. 193. 
404 Panel question No. 39. 
405 Mexico's response to Panel question No. 39, para. 113. 
406 Andrew J. Read, Phebe Drinker and Simon Northridge , "Bycatch of Marine Mammals in US and Global 
Fisheries", 20 Conservation Biology 163 (2006) (Exhibit MEX-6), p. 167. 
407 United States Department of Commerce, "Evaluating Bycatch", NOAA Technical Memorandum 
NMFS-F/SPO-66 (October 2004) (Exhibit MEX-77), p. 28. 
408 United Nations Food and Agriculture Organi zation, "Observer Program Operations Manual" 
(Exhibit MEX-127). 
409 United States' response to Panel question No. 39, para. 205. 
410 United States' response to Panel question No. 39, para. 209. 
411 United States' response to Panel question No. 39, para. 214. WT/DS381/RW 
 
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  7.207.  In sum, the United States urges the Panel to find that:  
Captain statements and logbooks are an integral part of RFMO and other international 
regimes, as well as regimes of individual nations. These regimes depend on such documentation to regulate in a whole host of areas that are critical for the appropriate 
management of fisheries and the environment more broadly. These areas include 
closed area rules, fish stock management, and implementation of environment requirements … nations and international organizations depend on this information, 
despite that [ sic] it may be contrary to the narrow financial interests of the particular 
vessel to provide accurate information.
412 
7.208.  In the Panel's opinion, Mexico's argument concerning the reliability – and, indeed, the 
integrity – of vessel captains has significant implications. The Panel accepts the evidence 
submitted by the United States that many regional and international organizations and 
arrangements rely on captains' certifications and logbooks both to monitor compliance with regulatory requirements and as a means of data co llection. In the Panel's view, the fact that many 
domestic, regional, and international regimes rely on captains' self-certification raises a strong 
presumption that, from a systemic perspective, such certifications are reliable. RFMOs and other fisheries and environmental organizations are expert s in their respective fields, and the fact that 
they have relied, and continue to rely, on captains' statements in a variety of fishing and 
environmental areas strongly suggests that, as a general matter, they consider such certifications to be reliable. Of course, the Panel must make its own "objective assessment of the matter", and in this regard the fact that a particular practice is accepted by one or more domestic, regional, or 
even international organizations is not, by itself, determinative. But the Panel considers that such 
acceptance is a highly relevant and probative fact. 
7.209.  The Panel is not convinced that the evidence submitted by Mexico is sufficient to rebut this 
demonstration by the United States. The documents submitted by Mexico certainly suggest that 
there have been instances in which captains' certifications have been unreliable. Nevertheless, in the Panel's view, the fact that domestic, regional, and international regimes have continued to rely 
on captains' certifications and logbooks even though instances of non-compliance have been 
reported suggests to us that such instances of non-compliance should not be considered as seriously undermining the general reliability of ca ptains' certifications, as Mexico would have the 
Panel find. 
7.210.  Additionally, the Panel is not convinced by Mexico's argumentation concerning the 
economic incentives facing captains. As we noted above, Mexico asserted that, even where a captain's personal remuneration is not tied to the value of the fish caught, she or he is 
nevertheless unlikely to accurately report dolphin mortality and serious injury because doing so 
may result in dismissal from employment. But Mexico has provided no evidence that this would be the case, and the United States' alternative understanding of the economic incentives facing 
captains seems just as plausible to us.  
7.211.  In light of the above, the Panel finds that Mexico has not met its burden of making a 
prima facie  case that captains' certifications are unreliable because captains have a financial 
incentive not to report accurately on the dolphin-safe status of tuna caught in a given set or other 
gear deployment. Therefore, this argument does  not convince us that relying on captains' 
certifications outside the ETP deprives the amended tuna measure of even-handedness. 
7.212.  We now turn to consider Mexico's second argument, that captains' certificates are 
unreliable because captains may not have the technical expertise necessary to accurately certify 
that no dolphins were killed or seriously inju red in a particular set or gear deployment.  
7.213.  In considering whether captains can be assumed to have the technical expertise necessary 
to make an accurate dolphin-safe certification, we find it helpful to compare the kind of tasks 
expected to be carried out by observers in the ETP and other oceans with those that are customarily carried out by captains. Such a comparison should shine some light on whether captains are generally expected to have the kind of skills necessary to certify that no dolphins 
were killed or seriously injured in a given set or other gear deployment. 
                                               
412 United States' comments on  Mexico's response to Panel question No. 39, para. 93. WT/DS381/RW 
 
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  7.214.  We begin by noting that both parties have recognized that the task of observers in the ETP 
is complex.413 Both parties have also provided evidence indicating that observers under the IATTC 
Observer Program: 
[A]re biologists trained to collect a variety of data on the mortalities of dolphins 
associated with the fishery, sightings of dolphin herds, catches of tunas and by 
catches of fish and other animals, oceanographic and meteorological data, and other information used by the IATTC staff to assess the conditions of the various stocks of 
dolphins, study the causes of dolphin mortality, and assess the effect of the fishery on 
tunas and other components of the ecosystem.
414  
7.215.  We also take note of the evidence provid ed by both parties regarding the "Guidelines for 
Technical Training of Observers," which elaborat e on the training requirements expected from 
observers qualifying for the IATTC Observer Progra m; such requirements include: (i) candidates 
should be university graduates with a degree in biology or a related subject (zoology, ecology, etc.); (ii) training should include the identification of certain fish and animals, including tuna and 
those dolphins associated with tuna fishing; (iii) information on how to accurately fill out data 
forms; and (iv) information on identification, dealing with, and documenting "instances of  interference (including bribery attempts), intimidation or obstruction by vessel crew during a 
trip".
415  
7.216.  Significantly, we note that in the 2013 Final Rule, the National Marine Fisheries Service 
(NMFS) also recognized the complexity of accurately certifying that no dolphins were killed or seriously injured, and stated that it:  
[A]nticipates that qualified observers will undergo training programs that include such 
topics as recognizing an intentional set, dolphin species identification, and criteria for 
determining a serious injury. NMFS acknow ledges that these skills are complex, and 
t h a t  m a n y  e x i s t i n g  o b s e r v e r  p r o g r a m s  give little attention to marine mammal 
interactions. NMFS will determine an observer program is qualified and authorized only after rigorous scrutiny of the program's training programs, and a finding that the 
observers are able to make the requisite determinations.
416  
7.217.  We also recall that the NMFS Assistant Administrator has published a Qualified and 
Authorized Notice listing the criteria that must be met in order for observers to be considered as "qualified and authorized" for purposes of the dolphin-safe labelling program under the DPCIA.
417 
The NMFS Assistant Administrator has established, inter alia , the following criteria: (i) observers 
are trained and able to identify dolphins endemic to the area of the fishery; (ii) observers are 
trained and able to determine dolphin mortality and serious injury ('serious injury' meaning any 
injury likely to cause mortality); and (iii) observers are trained and able to collect written or 
photographic documentation sufficient for an authorized representative participating in the 
observer programme to verify or make a determination about the disposition of any dolphin. The 
Assistant Administrator also indicates that under NMFS observer programmes, observers 
participate in training programs that "include such topics as dolphin species identification, dolphin mortality recognition, data collection requirements for use in making a serious injury determination, and recognition of an intentional purse seine set".
418  
                                               
413 Mexico's first written submission , paras. 70-72. Mexico's response  to Panel additional question 
No. 61, paras. 10-11. United States' second written submission, paras. 126 and 128. United States' response to Panel additional question No. 61, paras. 22-23. 
414 Inter-American Tropical Tuna Commission, Quarterly Report (April-June 2013) (Exhibit MEX-29), 
p. 14. 
415  Agreement on the International Dolphin Conervation Program, "18th Meeting of the Parties: Minutes 
of the Meeting" (Exhibit US-243), p. 6. See also Inte rnational Dolphin Conservation  Program, "Guidelines for 
Technical Training of Observers" (Document. OBS-2-O3b) (Exhibits MEX-164), International Dolphin Conservation Program, "Directrices para la Selecció n de Candidatos de Observador del APICD" (Document 
OBS-2-03a) (MEX-165), and Inter-Amer ican Tropical Tuna Commission , "Manual de Campo" (MEX-166). 
416 2013 Final Rule, 78 Fed. Reg. 40997 (July 9 2013) (Exhibit MEX-7) (emphasis added). 
417 Determination of Observer Programs as Qualified and Authorized by the Assistant Administrator for 
Fisheries, 79 Fed. Reg. 40,718 (July 14 2014) (Exhibit US-113). 
418 Determination of Observer Programs as Qualified and Authorized by the Assistant Administrator for 
Fisheries, 79 Fed. Reg. 40,718 (July 14 2014) (Exhibit US-113). WT/DS381/RW 
 
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  7.218.  The evidence above strongly suggests that certifying whether a dolphin has been killed or 
seriously injured in a set or other gear deployment is  a highly complex task. It is especially telling, 
in the Panel's view, that the amended tuna measure itself recognizes the necessity of training and 
education in equipping persons with the necessary technical know-how to ensure that they can 
properly certify the dolphin-safety of a tuna catch. 
7.219.  The Panel has looked closely at the evidence submitted by the parties concerning the 
competencies and tasks generally expected of captains. This evidence includes the various regional 
and international treaties discussed above in the context of Mexico's argument concerning the 
financial incentives facing captains. As we explained above, this evidence indicates that captains are generally expected to conduct a wide variety of tasks on board the vessels they command. As we read the evidence, captains are generally expected to have the knowledge and ability to fulfil a 
range of activities that tends to extend to certif ying the existence of facts over which they have 
control and/or direct knowledge, e.g. port of entr y and exit, co-ordinates, date and time of gear 
deployment, and type of gear deployed.
419 In some cases captains are also expected to certify the 
species of fish caught, or the presence of whale or bird bycatch. In our opinion, however, these 
tasks are significantly different from those involved in certifying that no dolphins were killed or seriously injured in sets or other gear deployments.  
7.220.  The United States has also submitted evidence showing that, at least in some fisheries, 
captains are sometimes expected or enabled to record mammal, and specifically dolphin, bycatch. According to the United States, "minimum RFMO logbook standards may require tracking of marine mammal bycatch, including species identification, [but] such minimum standards may not 
require recording whether the marine mammal was killed or seriously injured. However, certain 
logbooks required by national programs covering fisheries in the WCPFC and IOTC areas do require determinations concerning the fate of any marine mammal bycatch".
420 
7.221.  In support of this claim, the United St ates has submitted seven documents. The first two 
of these documents are logbook templates produced by the United States National Marine Fisheries Service for use in the Western Paci fic Longline (Exhibit US-175) and Atlantic 
(Exhibit US-176) fisheries. Exhibit US-175 does indeed include a column in which captains are 
required to identify both the species and fate of dolphin bycatch. Specifically, captains are required to note whether a dolphin was released "uninjured", "injured", or "dead".
421 Similarly, 
Exhibit US-196 requires that captains indicate whether certain dolphin species were "involved", 
"injured", or "dead".422 
7.222.  The next two documents are logbook templates produced by Australia in the Australian 
pelagic longline (Exhibit US-197) and purse seine (Exhibit US-198) fisheries. Exhibit US-197 
provides space for the captain to note both the point during a fishing operation in which dolphins 
were caught ("haul", "set", or other"), as well as  the fate of dolphins caught ("alive", "dead", or 
"injured").423 The same information, as well as additional information on whether a protected 
species (including a dolphin) was "hooked" or "entangled", is required by the logbook in 
Exhibit US-198.424 
7.223.  The final three exhibits are logbook templates from China (Exhibit US-179), Japan 
(Exhibit US-180), and Korea (Exhibit US-181). Exhibit US-179 contains a box directing captains to 
record "dolphin and whale status".425 "Status" is not defined in the document. Additionally, the 
reference to dolphins is found in a section of the logbook headed "remarks". Accordingly, it is not clear whether this information is required to be provided. Exhibit US-180 does not mention 
dolphins at all.
426 It does, however, appear to require the captain to record the "condition after 
release" of "whales". A captain is required to indicate whether the whale was "survive – swim", 
                                               
419 United States' response to Panel question No. 37, paras. 194-196. Mexico's comments to 
United States' response to Panel question No. 37, paras. 130-134. 
420 United States' response to Panel question No. 37, para. 195. 
421 National Marine Fisheries Serv ice, "Western Pacific Longline Fishing Log" (Exhibit US-175). 
422 National Marine Fisheries Service, "2014 Atlantic Highly Migratory Species Logbook – Set Form" 
(Exhibit US-196), p. 3. 
423 Australian Fisheries Management  Authority, "Australian Pelagic Longline Daily Fishing Log" 
(Exhibit US-197), p. 6. 
424 Australian Fisheries Management Authority, "Purse Seine Daily Fish ing Log" (Exhibit US-198), p. 7. 
425 China, "Logsheet Form" (Exhibit US-179). 
426 Japan, "Reporting Form of Incidentally Encircled of Whale Shark (RHN) or Whales" (Exhibit US-180).  WT/DS381/RW 
 
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  "dead before release", or "other". Finally, Exhi bit US-181 appears to require a captain to provide 
certain information about "other species including sea birds, marine turtles, etc". Dolphins are not mentioned, and the document does not appear to require that captains indicate the state in which such "other species" were released.
427 
7.224.  In the Panel's view, this evidence does no t show that captains are generally expected, or 
regarded as having the skills necessary, to certify dolphin mortality and serious injury. The only documents suggesting that captains are expected to certify dolphin interactions come from two 
WTO Members – Australia and the United States it self – and even these documents do not appear 
to distinguish between "injury" and "serious injury", which distinction is embedded in the amended tuna measure. The remaining documents from China,  Japan, and Korea similarly do not show that 
captains are usually expected to be able to certify dolphin mortality and injury. Although 
Exhibit US-179 provides space for a captain to make "remarks" about "dolphin and whale status", 
it is not clear on the face of the document what such reporting entails and the United States has not provided any relevant explanation in this regard. Exhibits US-180 and US-181 do not mention 
dolphins at all, and accordingly we cannot attribute much probative value to them. 
7.225.  Taken as a whole, these documents suggest to the Panel that captains are generally not 
expected to certify dolphin mortality and serious injury. The United States has not convinced us 
that this evidence shows that certifying dolphin mortality or serious injury is the kind of task 
generally expected of captains or, for that matter, that captains necessarily have the skills to certify whether dolphins have b een killed or seriously injured. 
7.226.  Ultimately, therefore, the evidence suggests to us that certifying dolphin mortality and 
serious injury is a highly specialized skill, and one that has so far generally not been required of 
captains. None of the evidence before us suggests, nor has the United States explained why it believes, that captains (or, we would add, any other crew member) are always and necessarily in 
possession of those skills.  
7.227.  In the Panel's view, then, Mexico has su bmitted evidence and argumentation sufficient to 
show that certifying the dolphin-safety of a tuna catch is a highly complex task. 
7.228.  As part of its efforts to understand this issue more clearly, the Panel asked the 
United States the following question: 
According to the United States' own case, indi viduals require significant training before 
they can be authorized to certify that no dolphins were killed or seriously injured in a 
fishing set. In light of this fact, why does the United States believe that captains are 
qualified and authorized to make such certifications? Do captains undergo any kind of training that would enable them to certify that no purse seine nets was intentionally 
deployed on or used to encircle dolphins during the fishing trip?
428  
7.229.  The United States began its response by explaining that "training would not be necessary 
for a captain to understand whether he or she 'intentionally' set on dolphins. The captain should 
know his or her own intention without formal training".429 
7.230.  In the remainder of its response, the Un ited States provided details on the training 
required by the AIDCP for fishing vessels seek ing to operate purse seine vessels in the ETP.430 The 
United States also stated the following: 
The United States does not understand that the WCPCF, IOTC, or other RFMOs require 
training for operators of purse seine vesse ls of the type required by the AIDCP  
… 
                                               
427 Korea, "LL, PS / Bycatch Lognook (Ecologically Related Species) (Exhibit US-181). This document 
appears to require only that the captain indicate the nu mber of such "other species" "released', and not the 
state in which they were released. 
428 Panel question No. 40. 
429 United States' response to Panel question No. 40, para. 216 (emphasis original). 
430 United States' response to Panel question No. 40, paras. 217-221. WT/DS381/RW 
 
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  Similarly, the United States is not aware that the IATTC requires analogous training 
for captains of other types of vessels (longline, pole-and-line, etc.) operating inside the ETP. Likewise, the United States does not understand that the WCPFC or other RFMOs require analogous training for captains of non-purse seine vessels operating 
outside the ETP.
431 
7.231.  The Panel accepts, of course, that captains will have knowledge of their own intentions 
where they have ordered that a net be set on dolp hins. The Panel notes, however, that Mexico has 
submitted evidence showing that at least in some cases nets may be set without the explicit order 
or permission of a vessel captain, who may not be directly involved in every fishing operation.432 
7.232.  With respect to all other aspects of the responsibilities generally expected of dolphin-safe 
observers, the Panel considers that the Unit ed States did not answer the question. The 
United States' response shows that captains seeking to master a purse seiner in the ETP must 
undergo training; but the United States provided the Panel with no explanation why it expects that captains will always and necessarily have the technical expertise necessary to accurately certify 
whether a dolphin was killed or seriously injured in a set or other gear deployment when the 
amended tuna measure itself recognizes that these skills are highly complex and must be acquired through training. 
7.233.  In the Panel's view, the United States has not rebutted Mexico's showing that captains may 
not necessarily and always have the technical skills required to certify that no dolphins were killed or seriously injured in a set or other gear deployment, and this may result in inaccurate information being passed to consumers, in contradiction with the objectives of the amended tuna 
measure. The Panel therefore finds that the diffe rent certification requirements are not even-
handed, and so cannot be said to stem exclusively from a legitimate regulatory distinction. 
7.234.  We want to be clear that, in finding that Mexico has made a prima facie  case that captains 
may not always and necessarily have the technical skills necessary to ensure accurate dolphin-safe 
certification, we are not finding that the only way for the United States to make its measure even-
handed is to require observer coverage. To the contrary, as we found above, captains' 
certifications are relied upon by domestic, regional, and international regimes for a wide variety of 
purposes, and we see no reason why captains could not, in principle and as a general matter, accurately certify the dolphin-safe status of a tuna catch.
433 As we see it, the key problem with the 
amended tuna measure as currently designed is that the United States has not explained why its 
measure assumes that captains have at their disposal the skills necessary to ensure accurate 
certification. Accordingly, we are not convinced that the different certification requirements, as currently designed, sufficiently address "the risks to  dolphins arising from different fishing methods 
in different areas of the ocean".
434  
7.235.  Before concluding, the Panel will briefly sketch how it would approach the issue under 
consideration in this section if the burden of proof were allocated in the way suggested by the 
third-parties. 
7.236.  Having found that Mexico has made a prima facie  case that the different certification 
requirements modify the conditions of competition to the detriment of Mexican tuna and tuna products, the Panel would need to determine whether the United States has made a prima facie  
case that this detrimental treatment nevertheless stems exclusively from a legitimate regulatory 
distinction.  
7.237.  In our view, and taking into account our fa ctual findings above, we do not think we could 
find that the United States has successfully shown that the detrimental impact stems exclusively  
from a legitimate regulatory distin ction. Our reasons are as follows. 
                                               
431 United States' response to Panel question No. 40, paras. 222 and 223. 
432 Mexico's first written submission, paras. 180 and 181. 
433 In saying this, we are not suggesting that captains' certification is the only way for the United States 
to monitor the dolphin-safe status of tuna. There may well be other methods, including through the use of technology, by which such monitoring could be under taken. Nevertheless, because the United States has 
decided to rely on captains' certificatio n, our duty is only to assess whether this method could comply with 
Article 2.1 of the TBT Agreement. 
434 Appellate Body Report, US – Tuna II (Mexico) , para. 297. WT/DS381/RW 
 
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  7.238.  As we indicated above, we accept that, as the Appellate Body appears to have found in the 
original proceedings, requiring observer certification for vessels other than large purse seiners in the ETP was not the only way in which the United  States could have brought its measure into 
compliance with the rulings and recommendations of the DSB.435 Moreover, we accept the 
United States' argument that the 100 per cent observer requirement in the ETP is intricately tied 
to the special and, in some senses, "unique" na ture of the harms that the ETP large purse seine 
fishery poses to dolphins.  
7.239.  During the Panel's meeting with the parties, and again in its responses to the Panel's 
questions, the United States explained that obse rvers are necessary in the ETP large purse seine 
fishery because "it is those vessels that are capable and permitted to take advantage of the unique association of yellowfin tuna and dolphins in the ETP by engaging in multi-hour chases and 
captures of huge herds of dolphins".
436 As the United States explained: 
A large ETP purse seine vessel carries a crew of approximately 20 persons on any 
particular trip. The primary job of the crew is to harvest tuna. However, given the 
intensity and length of the interactions in a dolphin set between the dolphins, on the 
one hand, and the vessel, speed boats, helicopter, and purse seine net on the other, the AIDCP parties concluded that it was appropriate to require a vessel capable and 
permitted to engage in such a dangerous activity to carry a single person to observe 
the impact of the vessel on the dolphins that it was chasing and capturing.
437 
7.240.  In other words, as we understand it, the United States' position is that observers are 
necessary on ETP large purse seiners but may not be necessary on other vessels in other fisheries 
not because the risk of dolphin mortality or serious injury is somehow less important in other 
fisheries, but rather because the nature of the fi shing technique used by ETP large purse seiners, 
which essentially involves the chasing and encirclement of many dolphins over an extended period 
of time, means that it is necessary to have one single person on board with the responsibility of 
keeping track of those dolphins caught up in the chase and/or the purse seine nets set. Other fishing methods in other oceans may – and, as the United States recognizes, do – cause dolphin 
mortality and serious injury, but because the nature and degree of the interaction is different in 
quantitative
438 and qualitative439 terms (since dolphins are not set on intentionally, and interaction 
is only accidental), there is no need to have a single person on board whose sole task is to monitor the safety of dolphins during the set or other gear deployment. 
7.241.  The Panel notes that Mexico disagrees that the situation in the ETP is unique or different in 
any way that would justify the United States' different treatment of the ETP purse seine fishery and other fisheries. According to Mexico, "tuna dolphin associations have been sighted and 
deliberately set on" outside of the ETP,
440 and accordingly the absence of independent observers 
outside the ETP is unjustifiable. In the Panel's view , however, the evidence submitted by Mexico is 
not sufficient to rebut the United States' argumentation on this point. Most importantly, the 
evidence submitted by Mexico suggests that, even  though there may be some interaction between 
tuna and marine mammals, including dolphins, outside of the ETP, "dolphins in the Atlantic, Indian, and western Pacific Oceans [do not associate with tuna] as systematically as they do in the Eastern Tropical Pacific".
441 Thus, even according to conservative estimates, it appears that, in the 
WCPFC, only "3.2 per cent of all purse seine nets are deliberately set on cetaceans".442 Similarly, a 
recent paper submitted by Australia to the IOTC st ated that "[i]n observer data collected between 
1986-1992 from Soviet vessels in the Western Indian Ocean, 494 purse seine sets were observed 
                                               
435 Appellate Body Report, US – Tuna II (Mexico) , para. 296. 
436 United States' response to Panel question No. 30, para. 166. 
437 United States' response to Panel question No. 30, para. 168.  
438 United States' response to Panel question No. 20,  paras. 120-121; United States' response to Panel 
question No. 21, paras. 136-142. 
439 United States' response to Panel question No. 20,  paras. 120-125; United States' response to Panel 
question No. 22, paras. 147-149. 
440 Mexico's first written submission, para. 113. 
441 National Marine Fisheries Service, "An Annotate d Bibliography of Availa ble Literature Regarding 
Cetacean Interactions with Tuna Purse-Seine Fisheries Outside of the Eastern Tropical Pacific Oceans" 
(November 1996) (Exhibit MEX-40), p. 2. 
442 New York Times, "A Small Victory for Whale Sharks" (December 6, 2012) (Exhibit MEX-44). WT/DS381/RW 
 
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  over the seven year period, with 27 intentionally set on whale sharks and cetaceans".443 These 
numbers are entirely consistent with the finding by the original Panel that there are "no records of consistent or widespread fishing effort on tuna-d olphin associations anywhere other than in the 
ETP".
444 On the other hand, evidence submitted by  the United States suggests that "9220 
intentional sets on dolphins inside the ETP in 2012"445, amounting to 40 per cent of all sets in that 
ocean.  
7.242.  These statistics confirm for the Panel that although dolphins may occasionally and 
incidentally be set on outside the ETP, it is only inside the ETP that setting on dolphins is practiced 
consistently or "systematically", in the words of the original Panel. Thus the Panel find the United States' position on this point compelling. Indeed, in our view, the United States' arguments on this point would be sufficient to raise a presumption that the different certification requirements 
stem from a legitimate regulatory distinction, assuming that other fishing methods are treated 
even-handedly.  
7.243.  The Panel is also aware of Mexico's argument that because both parties agree that tuna 
fishing methods other that setting dolphins have the potential to kill and injure dolphins, 
"[w]hether or not the operators of the vessel claim the mortalities were an accident is not relevant"
446, and cannot explain the different certification requirements.  In the Panel's opinion, 
however, Mexico has misunderstood the United States' point in recalling the "accidental" or 
"incidental" nature of dolphin interactions with fishing methods other than setting on dolphins. As we understand it, the United States is not arguing that "accidental" dolphin mortality or injury is less serious than "intentional" mortality or injury. Neither is it arguing that tuna can be considered 
dolphin-safe where it is caught in a gear deployment that accidentally kills or mains dolphins, or 
that tuna can or should only be considered non-dolphin-safe only when a dolphin is intentionally killed or injured. On the contrary, the amended tuna measure makes clear that tuna cannot be 
considered dolphin-safe whenever  a dolphin is killed or seriously injured in the gear deployment in 
which the tuna was caught, regardless of whether such death or injury was intentional.
447 
7.244.  Rather, as we understand it, the United States' invocation of the accidental nature of 
dolphin interactions with fishing methods other than setting on dolphins goes to difference 
between fishing methods that cause harm to dolphins only incidentally and those, like setting on, that interact with dolphins "in 100 per cent of dolphin sets".
448 This distinction is especially 
important where, as the United States argues is the case with setting on – the particular nature of 
the interaction is itself "inherently dangerous"449 to dolphins, even where no dolphin is seen to be 
killed or seriously injured, because it has unobservable deleterious effects on dolphins' physical and emotional well-being. 
7.245.  On the basis of the above, we would find that the United States has made a prima facie  
case that the different certification requirements stem exclusively from a legitimate regulatory distinction. 
7.246.  Nevertheless, in light of the evidence submitted by Mexico concerning the complexity of 
certifying the dolphin-safe status of tuna catch
450 - which evidence was not rebutted by the 
United States - we would find that the United States has not explained sufficiently why it assumes that captains are capable of carrying out an ac tivity that the amended tuna measure itself 
recognizes as highly complex and for which training and education are required. In the absence of 
such explanation, we would be compelled to find that while the United States may legitimately draw distinctions between the ETP large purse se ine fishery and other fisheries, the lack of 
explanation concerning the technical capacities of captains means that the different certification 
                                               
443 Australia and Maldives, "On the Conservation of  Whale Sharks (Rhincodon Typus)" (IOTC-2013-S17-
PropD[E]) (April 5, 2013) (Exhibit MEX-45). 
444 Panel Report, US – Tuna II  (Mexico) , para. 7.520. 
445 AIDCP, "Fishing Mortality Limits 2012-2014" (Exhibit US-22). 
446 Mexico's second written submission, para. 142. 
447 See e.g. United States' second written submissi on, para. 22 ("any tuna product containing tuna 
caught where a dolphin was killed or seriously injured would not be eligible for the dolphin safe label"). 
448 United States' response to Pa nel question no. 17, para. 88. 
449 United States' second written submission, para. 23. 
450 Mexico's first written submission, paras. 70-72; Mexico's second written submission, para. 168; 
Mexico's response to Panel question No. 13, para. 79; Mexico's response to  Panel question No. 61, 
paras. 10-11. WT/DS381/RW 
 
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  requirements cannot be said to be even-handed, and as such to stem exclusively  from a legitimate 
regulatory distinction.  
7.247.  Before concluding our analysis of the different certification requirements, we think it is 
worthwhile to briefly note one additional aspect of the amended tuna measure that bears on the 
certification distinction and that, while not discussed extensively by the parties, nevertheless 
seems to us to be of some importance.  
7.248.  In one of the questions sent by the Panel to the parties, the parties were asked to 
comment on a table prepared by the Panel that summarized the various eligibility, certification, 
and tracking and verification requirements that apply in different fisheries.451 The Panel prepared 
this table and sought comments on it to help clarify its understanding of the amended tuna measure. 
7.249.  In its response to the Panel's question, the United States clarified a number of issues.
452 
Most importantly for present purposes, the United States explained that "the determination provided for under section 216.91(a)(4)(iii)
453 only applies to those fisheries not otherwise covered 
by sections 216.91(a)(1)-(3). As purse seine vessels operating outside the ETP are covered by 
(a)(2), this determination does not apply to purse seine fisheries outside the ETP".454 The 
United States also explained that "the determination made pursuant to section 216.91(a)(2)(i)455 
only applies to non-ETP purse seine fisheries".456 
7.250.  In its comments on the United States' response, Mexico addressed these clarifications. It 
submitted that: 
[T]he United States interprets the statute to authorize small purse seine vessels in the 
ETP to be made subject to mandatory observer requirements with a determination 
that they are causing regular and significant mortality (unrelated to tuna-dolphin association), while both large and small purse seine vessels outside the ETP are not 
subject to such a possibility.  
… [Additionally,] [t]he US response highlights that the Amended Tuna Measure is 
unconcerned with tuna-dolphin associations in any fisheries other than purse seine 
fisheries. Especially in light of the association of dolphins with longline fisheries, that is yet another indication or arbitrariness.
457 
7.251.  The United States' response and Mexico's comments thereon thus appeared to raise issues 
of some importance in respect of the system whereby observer certifications could be required 
outside the ETP large purse seine fishery in certain circumstances. To further explore this matter, the Panel sent an additional question the parties in the following terms:  
To both Parties:  In its response to Panel question no. 59, the United States clarified 
that "the determination provided for under section 216.91(a)(4)(iii) [of the 2013 Final Rule, i.e. that a fishery is causing "regular and significant dolphin mortality or serious 
injury of dolphins"] only applies to those fisheries not otherwise covered by 
sections 216.91(a)(1)-(3). As purse seine vessels operating outside the ETP are covered by (a)(2), this determination does not apply to purse seine fisheries outside the ETP".  In its comments on this response, Mexico noted that "the United States 
interprets the statute to authorize small purse seine vessels in the ETP to be made 
                                               
451 Panel question No. 59. 
452 United States' response to Panel question No. 59. 
453 This provision states "In any othe r fishery that is identified by th e Assistant Administrator as having 
a regular and significant mortality or serious injury of dolphins"; See para. 3.45 above. 
454 United States' response to Panel question No. 59, para. 295. 
455 This provision states "In a non-ETP purse seine fishery in which the Assistant Administrator has 
determined that a regular and signif icant association occurs between dolphins and tuna (similar to the 
association between dolphins and tuna in the ETP)"; See para. 3.45 above.  
456 United States' response to Panel question No. 59, para. 301. 
457 Mexico's comments on the United States' response to Panel question No. 59, para. 198. WT/DS381/RW 
 
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  subject to mandatory observer requirements with a determination that they are 
causing regular and significant mortality (unrelated to tuna-dolphin association), while both large and small purse seine vessels ou tside the ETP are not subject to such a 
possibility".  
In light of the above, the Panel understan ds that (a) large and small purse seine 
fisheries outside the ETP can never be requir ed to have observers on board because of 
"regular and significant mortality or serious injuries of dolphins".  Rather, observers 
can only be required in such fisheries where there is "regular and significant 
association between dolphins and tuna similar to the ETP".  Conversely, the Panel understands that non-purse seine fisheries outside the ETP, as well as small purse seine fisheries inside the ETP, can only be required to have observers in board in 
cases where they are causing "regular and significant mortality or serious injury of 
dolphins".  A determination of "regular and significant association" cannot be made in respect of these fisheries. 
a. Is the Panel's understanding correct? If so, why is the amended tuna measure 
structured in this way? Why, in other words, can no determination of "regular and significant mortality or serious injury" be made in respect of large and small purse 
seine vessels outside the ETP, and why can no determination of "regular and 
significant association of dolphins and tuna" be made with respect to non-purse seine fisheries outside the ETP and small purse seine fisheries inside the ETP?  The Panel is aware that small purse seine vessels in the ETP are not allowed to set on dolphins 
under the AIDCP. 
b. If the Panel's understanding of the above-mentioned provisions is correct, could 
the fact that no determination of "regular and significant mortality or serious injury" 
can be made in respect of large and small purse seine vessels outside the ETP, or that 
no determination of "regular and significant association of dolphins and tuna" can be made with respect to non-purse seine fisheries outside the ETP and small purse seine 
fisheries inside the ETP result in non-dolphin safe tuna fishing?
458 
7.252.  In its response, the United States confirmed the Panel's understanding as set out in its 
question to the parties. The United States expl ained that the two determinations in question 
"allow[] for the possibility " that conditions in fisheries other than the ETP large purse seine fishery 
may be such as to justify requiring an observer certification (in addition to a captain's statement) 
for tuna caught outside the ETP. On the issue of why the DPCIA only allows a determination of "regular and significant tuna-dolphin association" to be made in respect of purse seine fisheries 
outside the ETP, the United States stated that: 
[I]n contrast to purse seine fisheries, it would seem to make little sense to connect an 
observer requirement to the existence of an association between tuna and dolphins 
similar to the one that exists in the ETP fo r purposes of non-purse seine fishing. That 
is to say, while it is undisputed in this proceeding that the unparalleled harm to dolphins caused by large purse seine vessels in the ETP is directly related to the existence of the association between ye llowfin tuna and dolphins, there is no evidence 
that a similar correlation exists between association and harm to dolphins from other 
fishing  methods. The reason for this is simple – other gear types cannot take 
advantage of such an association.
459 
7.253.  The United States did not explain why, under the DPCIA, a determination of "regular and 
significant dolphin mortality" cannot be made in respect of purse seine fisheries outside the ETP. 
7.254.  In its comments on the United States' response, Mexico argued that "[t]he United States is 
also wrong to claim that there is no evidence that  there is a correlation between harm to dolphins 
from non-purse seine fishing methods and an association between tuna and dolphins". In Mexico's view: 
                                               
458 Panel question No. 60. 
459 United States' response to  Panel question No. 60, para. 11 (emphasis original). WT/DS381/RW 
 
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  Mexico has presented uncontested evidence th at dolphins are attracted to longlines to 
eat the fish on the hooks, and that this attraction results in dolphin mortalities and serious injuries. Mexico has also submitted evidence that many thousands of dolphins die in gillnets, indicating that dolphins are "associated" with that the [ sic] tuna caught 
with that fishing method. The United States cannot reasonably deny the role that the 
association plays in dolphin mortalities outside the ETP.
460 
7.255.  Mexico thus urges the Panel to accept that "it is irrational to exclude outright non-purse 
seine fishing methods from the determination of regular and significant association between 
dolphins and tuna and to exclude purse seine fishing from the determination of regular and 
significant mortality or serious injury of dolphins".461 For Mexico, this irrationality "is further proof 
that the Amended Tuna Measure is arbitrary and not even-handed".462  
7.256.  The Panel recognizes that the aspect or feature of the amended tuna measure at issue 
here – which we call the "determination provisions" – was not explicitly argued by Mexico as a separate ground of WTO-inconsistency prior to the Panel's raising this issue. Indeed, even in its 
response to the Panel's question Mexico did not ask the Panel to find that the determination 
provisions in themselves give rise to inconsis tency with Article 2.1 of the TBT Agreement or 
Articles I and III of the GATT 1994. Rather, as we understand it, Mexico's view is that the 
determination provisions are simply one more example or manifestation of the uneven-handed 
nature of the different certification requirements, which, as we have discussed above, have a detrimental impact on Mexican tuna and tuna products.
463 
7.257.  The determination provisions are an integral part of the certification system put in place by 
the amended tuna measure, and therefore they are relevant to the Panel's analysis of whether the 
United States has brought its measure into conformity with the rulings and recommendations of the DSB by developing procedures and requirements  that adequately address the risks to dolphins 
caused by tuna fishing methods other than setting on dolphins inside the ETP. This, indeed, is 
precisely why the Panel sent an additional question  to the parties seeking further information once 
the issue emerged clearly.  
7.258.  In the Panel's opinion, the determination provisions appear to reduce the range of 
circumstances in which observers can be required outside of the ETP large purse seine fishery (or in small purse seine fisheries inside the ETP), further entrenching the less favourable treatment 
caused by the different certification requirements. This is so because the design of the 
determination provisions is such that like tuna products may be subject to different requirements 
even where, as a matter of fact, the conditions in a non-ETP fishery (or a small purse seine fishery inside the ETP) are the same as those in the ETP large purse seine fishery. They thus seem to us 
to represent a further way in which the amended tuna measure lacks even-handedness in its 
treatment of different tuna fishing methods in di fferent oceans, and may also make it easier for 
tuna caught other than by large purse seine vessel in the ETP to be incorrectly labelled as dolphin-
safe, thus modifying the conditions of competition in the US tuna market to the detriment of 
Mexican tuna and tuna products.
464    
7.259.  Moreover, in the Panel's opinion, the determination provisions appear to be arbitrary in the 
sense that they are difficult to reconcile with, or justify by reference to, the objectives pursued by 
the amended tuna measure itself.  
7.260.  We note first that the United States did not explain to the Panel why purse seine vessels 
outside the ETP cannot be subject to a declaration that they are causing "regular and significant 
dolphin mortality". Accordingly, the Panel is not in a position to assess whether this determination 
provision stems exclusively from a legitimate regulatory distinction. 
                                               
460 Mexico's comments on the Un ited States' response to Panel question No. 60, para. 4. 
461 Mexico's comments on the Un ited States' response to Panel question No. 60, para. 5. 
462 Mexico's comments on the Un ited States' response to Panel question No. 60, para. 5. 
463 Mexico's comments on the Un ited States' response to Panel question No. 60, para. 7. 
464 The Panel recalls that, as it expl ained above, it is not necessary in  this proceeding to undertake the 
kind of extensive and detailed analys is that would be required in order to conclude definitively that the 
different certification requir ements make it easier for tuna caught ot her than by large purse seine vessels in 
the ETP to be inaccurately labelled: see para. 7.169 above. WT/DS381/RW 
 
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  7.261.  Secondly, we have doubts about the United States' argument that the existence and 
nature of tuna-dolphin association has no impact on the degree of mortality or serious injury caused by fishing methods other than setting on dolphins. As a matter of common-sense, it appears to the Panel that the risk of mortality or serious injury is necessarily heightened where 
dolphins associate with tuna, even if the fishing method in question does not deliberately target 
that association, as does setting on dolphins. Where dolphins associate with tuna, it seems to the Panel that they are more likely to interact with tuna fishing gear, even if such interaction is 
accidental or unintentional. This is simply a question of numbers: the more dolphins there are in 
the vicinity, the more likely that one or more dolp h i n s  w i l l  b e  k i l l e d  o r  s e r i o u s l y  i n j u r e d .  F o r  
instance, as Mexico explains in its response to and comments on the Panel's question on this issue, it seems far more likely that dolphins will be killed or seriously injured by longlines in areas where 
there is a "regular and significant" tuna-dolphin association, since in such circumstances dolphins 
will be in close physical proximity to the tuna th at are attracted to the longlines and are thus more 
likely to be hooked themselves.  
7.262.  Moreover, in the Panel's opinion, the Unit ed States' own explanation as to why observers 
are necessary in the ETP seems to suggest that observers may be necessary whenever there is a "regular and significant" tuna-dolphin association, regardless of whether the association occurs in 
a purse seine fishery or any other type of fishery. It  will be recalled that the United States argued 
(and the Panel accepted) that observers are need ed in the ETP large purse seine fishery because 
the intensity of the tuna-dolphin interaction in that fishery makes it indispensable to have a single individual charged with monitoring the safety an d well-being throughout the fishing operation. In 
the Panel's view, it is difficult to see why that logic does not apply equally in the cases of other 
fisheries where there is "regular and significant tuna-dolphin association", even if the fishing 
method used in that fishery does not intentionally target the association. Insofar as a "regular and 
significant" tuna-dolphin association is likely to increase the chance of dolphin mortality or serious 
injury, it may make sense to require observers wherever  a "regular and significant" tuna-dolphin 
association exists, in order to ensure that consumers receive accurate dolphin-safe information.  
7.263.  For the foregoing reasons, the Panel believes that the determination provisions open up a 
gap in the certification procedures applied ou tside the ETP large purse seine fishery. These 
provisions appear to be designed to enable the United States to impose conditions on fisheries other than the ETP large purse seine fishery where the conditions in the former approach those of 
the latter. This would help ensure that similar situations are treated similarly under the amended 
tuna measure. However, a determination of regular and significant mortality
465  cannot be made in 
respect of purse seine fisheries outside the ETP,  and a determination of regular and significant 
tuna-dolphin association466 cannot be made in respect of non-purse seine fisheries. This means 
that, in some cases, fisheries other than the ETP large purse seine fishery may be treated differently, and less stringently, under the amende d tuna measure even where the conditions in 
that fishery mirror those in the ETP large purse seine fishery, either in terms of the level of dolphin 
mortality or the degree of tuna-dolphin association. The United States has not provided sufficient explanation as to why this aspect of the amended t una measure is structured in this way, or how it 
relates to the objectives pursued by the labelling regime. The Panel is therefore not convinced that 
this gap stems exclusively from a legitimate regulatory distinction.  
7.5.2.4.2.3  Separate opinion of one panelist 7.264.  One of the panelists is unable to agree with the reasoning and conclusions in 
paragraphs 7.233-7.246 above. This section reflects the views of that panelist.  
7.265.  While I agree with many of the intermedia te factual findings made by the majority in 
respect of the different certification requirements, I do not agree with the legal reasoning or 
conclusions that my colleagues have developed on the basis of those findings. Most importantly, I 
do not agree that the different certification requ irements lack even-handedness. On the contrary, 
in my opinion any detrimental treatment caused by the different certification requirements does stem exclusively from a legitimate regulatory distinction, and accordingly is not inconsistent with 
Article 2.1 of the TBT Agreement.  
                                               
465 Section 216.91(a)(4)(iii) of the Implementing Regulations. 
466 Section 216.91(a)(2)(i) of the Implementing Regulations. WT/DS381/RW 
 
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  7.266.  I begin by noting my agreement with the majority that a central question in the 
assessment of even-handedness under Article 2.1 of  the TBT Agreement is whether or not, and the 
extent to which, identified detrimental treatment is justifiable on the basis of the policy objective 
pursued by the technical regulation at issue. In the present case, this means it is necessary to 
consider whether the different certification requirements imposed by the amended tuna measure 
are fully in line with, or capable of achieving, the amended tuna measure's objectives.  
7.267.  In my view, the overall goal or objective of the amended tuna measure is to minimize the 
risk that consumers who prefer dolphin-safe tuna – that is, tuna caught in a manner not harmful 
to dolphins – will nevertheless end up consuming tuna that was, in fact, caught in sets or other gear deployments in which dolphins were killed or seriously injured. To achieve this goal, the amended tuna measure develops and implements mechanisms to enable detection of dolphin 
mortality and serious injury during fishing trips. Whenever these mechanisms detect that a dolphin 
was killed or seriously injured in a particular set or other gear deployment, all tuna caught in that set or gear deployment becomes ineligible to receive the United States dolphin-safe label.  
7.268.  Mexico argues that the detection mechanisms put in place outside the ETP large purse 
seine fishery are less sensitive, and so less accurate or reliable, than those in place for large purse seine vessels in the ETP. According to Mexico, the mechanisms in place outside the ETP large 
purse seine fishery are less likely to detect dolphin mortality and serious injury than are the 
mechanisms in place in the ETP large purse seine fishery. Accordingly, in Mexico's argument, there is a greater chance, or a higher likelihood, that tuna caught outside the ETP large purse seine fishery will be labelled dolphin-safe even if it was caught in a set in which, as a matter of fact, 
d o l p h i n s  w e r e  k i l l e d  o r  s e r i o u s l y  i n j u r e d .  H o w e v e r ,  t h e  r i s k  o r  l i k e l i h o o d  t h a t  t u n a  i s  l a b e l l e d  
dolphin-safe even if it was caught in a set in which, as a matter of fact, dolphins were killed or seriously injured, depends not only on the sensitivity of the mechanism to detect dolphin mortality 
or injury, but also on the probability of such mortality or injury, i.e. the magnitude of the risk 
posed to dolphins either by a specific fishing method or because of the specific situation in a fishery such as close interaction between dolphins and tuna. 
7.269.  Mexico argues that the mechanisms in place outside the ETP large purse seine fishery are 
less accurate because (a) captains have financial incentives to under-report mortality and serious injury; and (b) captains may not have the same degree of expertise as independent observers, and accordingly may be less capable of detecting mortality and serious injury occurring during 
fishing operations. 
7.270.  I agree fully with the majority's factual finding on point (a): in my view, Mexico has not 
provided sufficient evidence to show that capt ains are inherently unreliable due to perverse 
financial incentives.   
7.271.  I also agree with the majority on point (b), that is, that captains may not have the same 
degree of expertise as independent observers. The evidence shows quite clearly that observers in 
the ETP undergo extensive training on a range of topics and activities related to dolphin-safety, 
and that captains may not always and necessarily have the same degree of specialized knowledge.
467 Accordingly, captains may be less capable than independent and specially-trained 
observers of detecting mortality and serious injury occurring during fishing operations. 
7.272.  In my view, however, this is not fatal, be cause captains are often called upon to certify the 
existence of facts of which they do not have di rect knowledge. Captains are in many instances 
expected to certify the existence of facts on the basis of information provided to them by their 
crew. Similarly, it is reasonable to expect that many activities entrusted to captains under 
national, regional, and international fisheries regulations are in fact carried out by the crew, under the captain's overall or general supervision, even though it is the captain him or herself who 
ultimately bears responsibility for certifying that the activity in question was properly carried out. 
This suggests that the mere fact that captains may not themselves have expertise or specialised knowledge about dolphin biology and safety does not necessarily render unreliable their certifications that no dolphins were killed or seriously injured in a given set or other gear 
deployment. Even where the captain does not have such expertise, one of the crew members may, 
                                               
467 Indeed, in my opinion, the United States has not even claimed that captains always and necessarily 
have the same technical expertise as independent observers. WT/DS381/RW 
 
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  and there is no reason to think that a captain certification on the basis of information provided by 
that crew member would be necessarily or inherently inaccurate. 
7.273.  Additionally, and perhaps more importantly, I think that even assuming  captains' 
certification is less likely to detect instances of mortality and serious injury, this fact does not lead 
to the conclusion that the different certification requirements lack even-handedness. This is so for 
the following reasons. 
7.274.  First, neither captain nor observer certification is capable of detecting every  instance of 
dolphin mortality or serious injury. The language of the certification notwithstanding, all that can 
really be certified, by either a captain or an observer, is that no dolphin mortality or serious injury was detected  – that is, observed - in a set or other gear deployment. The capacity for human error 
being what it is, it is simply impossible for even the most highly qualified observer to say with 
certainty that no dolphin was killed or seriously injured during a fishing operation. Both the 
observers' and captains' certificate should be seen as reliable indication of whether dolphin mortality or injury was detected or not. However, it is obvious that when there is no independent 
observer on board, the probability that dolphin mortality or serious injury is detected is less likely 
than in situations where a specially trained independent observer is on board. 
7.275.  The consequence of this is that, in respect of both captain and observer certification, a 
certain degree or margin of error is necessarily tolerated. The margin of error may be smaller in 
the case of observer certification than in the case of captain certification; but in both cases there is 
always some chance that a dolphin death or serious injury will go unobserved. Accordingly, we can talk of the difference between captain and observer certification not only in terms of how accurate 
or sensitive  each one is, but also in terms of how large a margin of error  each one allows. 
7.276.  Now, accepting that certification, whether by captain or observer, always allows a certain 
margin of error, the question is whether it is acceptable, under Article 2.1 of the TBT Agreement, 
for the United States to tolerate a greater margin of error in the mechanisms in place outside the 
ETP large purse seine fishery than inside it. In my view, it is. Put simply, my opinion is that where the probability of dolphin mortality or serious injury is smaller – because, for instance, the degree 
of tuna-dolphin association is less likely - the United States may accept a proportionately larger 
margin of error. Conversely, where the risks are higher, it may be appropriate to tolerate only a smaller margin of error. Provided that the tolerated margin of error is, to use a term from the original proceedings, "calibrated" to the risks face d by dolphins in a particular fishery, the mere 
fact that the detection mechanisms inside the ETP large purse seine fishery and outside of it are 
not the same does not deprive the amended tuna measure of even-handedness. Indeed, 
understood in this sense, "calibration" of the accept able margin of error to the degree of risk in a 
particular fishery seems to me to be at the very heart of the even-handedness analysis in this 
case.  
7.277.  A hypothetical may help to clarify my view . Say a city imposes a speed limit of 80 km/h on 
all roads. Say also that to detect violations of this speed limit, the city has developed a system of 
police observation. Now, assume that suburb A has a higher incidence of speeding than does 
suburb B. As a result, the city requires police observation every day on major roads in suburb A with highly sensitive detectors, but only four days a week in suburb B with less sensitive machines. 
Could such a set-up be described as lacking even-h andedness? In my view, it could not. As I see 
it, it is entirely reasonable for governments, in the course of enforcing regulations, to vary the intensity of their detection mechanisms in accordance with the historical incidence of and future 
potential for violations. Provided that there is a rational connection between the variation in 
intensity and the difference in risk, I would not find  that the implementation of different detection 
mechanisms lacks even-handedness or is otherwise discriminatory. 
7.278.  As the Panel explained in its discussion of  the eligibility criteria, both the panel and the 
Appellate Body in the original proceedings found that setting on dolphins is "particularly harmful" to dolphins. Setting on dolphins is the only tuna fishing method that deliberately targets dolphins, and so interacts with dolphins in a way that is uniquely intense, both in terms of the number of 
dolphins affected and the frequency of interaction. In my view, the United States has put forward 
evidence sufficient to show that the risks in fish eries other than the ETP large purse seine fishery 
are, as a general matter, significantly less serious than those posed in the ETP large purse seine WT/DS381/RW 
 
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  fishery.468 This, of course, is not to say that other fishing methods do not cause mortality or 
serious injury. They do, and that is why the United States requires captains in such fisheries to certify that no dolphin was killed or seriously injured. However, given the higher degree of risk in the ETP large purse seine fishery, it is in my opin ion entirely even-handed for the United States to 
tolerate a smaller margin of error in that latter fishery, and accordingly to require observers in that 
fishery but not in others.  
7.279.  As should be clear, my reasoning is base d on the proposition that where the degree of risk 
is different, it is acceptable for the United States  to tolerate different margins of error in their 
detection mechanisms. This corollary of this position is that it could not be said to be acting even-handedly if it tolerated a different margin of error in two (or more) fisheries whose risk profiles were the same. In such circumstance, even-handedness would necessitate that the same detection 
mechanisms be implemented. 
7.280.  In my view, the amended tuna measure responds to this necessity through 
sections 216.91(a)(4)(iii) and 216.91(a)(2)(i) (the "determination provisions"). These provisions 
allow the Assistant Administrator to make a determination that a particular fishery is causing 
"regular and significant dolphin mortality" or has a "regular and significant tuna-dolphin association" akin to that in the ETP. Where such a determination is made, independent observer 
certification will be required in those fisheries. In other words, the amended tuna measure 
contains sufficient flexibility to enable the Unit ed States to impose the same requirements in 
fisheries where the same degree of risk prevails. In my view, this flexibility is further evidence of 
the even-handedness of the different certification requirements as designed in the amended tuna 
measure. 
7.281.  Now, if it were shown that some other fishery is, as a matter of fact, causing "regular and 
significant mortality or serious injury", or that another fishery does, as a matter of fact, have "a 
regular and significant tuna-dolphin association" akin to that in the ETP, then it might be argued 
that the failure of the Assistant Administrator to make the relevant determination foreseen in sections 216.91(a)(4 )(iii) and/or 216.91(a)(2)(i) it self gives rise to a la ck of even-handedness. 
This would be so because the failure to make a de termination would have the result that fisheries 
in which the same risks exist are being treated differently. However, Mexico has not asked the Panel to find that the Assistant Administrator's failure to make a determination is itself a violation of Article 2.1 of the TBT Agreement. Nor, in my view, has it put forward evidence sufficient to 
make out such an argument.  
7.282.  As such, in my view, the general rule that captains' certifications are sufficient outside the 
ETP large purse seine fishery while observers are required inside the ETP large purse seine fishery 
is even-handed. I think that this distinction represents a fair response to the different risk profiles 
existing in different fisheries, as established by the evidence.  
7.283.  Having said that, I agree fully with the majority's reasoning concerning the determination 
provisions, explained in paragraphs 7.247-7.263 abov e. In my view, the fact that a determination 
of regular and significant mortality cannot be made in respect of purse seine fisheries outside the ETP, and the fact that a determination of regula r and significant tuna-dolphin association cannot 
be made in respect of non-purse seine fisheries, ha s not been explained or justified. This aspect of 
the different certification requirements is th erefore inconsistent with Article 2.1 of the 
TBT Agreement. 
7.5.2.5  The different tracking and verification requirements 
7.284.  The third instance of less favourable trea tment raised by Mexico under Article 2.1 of the 
TBT Agreement concerns the different record keeping and verification requirements that apply to tuna caught by large purse seine vessels in the ETP on the one hand and all other tuna on the 
other hand.  
                                               
468 See section C of United States' first written submission and Tabl e Summarizing Fishery-by-Fishery 
Evidence on Record (Exhibit US-127). WT/DS381/RW 
 
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  7.285.  In its first written submission, Mexico describes the regulatory distinction as follows: 
The record-keeping and verification requirements for tuna caught in the ETP by setting 
on dolphins in accordance with the AIDCP and the different requirements for tuna caught outside the ETP using both the same and different fishing methods.
469 
7.286.  In these findings, we will refer to this regulatory distinction as the "different tracking and 
verification requirements". 
7.287.  As we did in respect of the different certification requirements, we begin by considering 
whether the different tracking and verification re quirements modify the conditions of competition 
in the United States' tuna market to the detriment of Mexican tuna and tuna products. If we find that they do, we will proceed to determine whethe r this detrimental impact stems exclusively from 
a legitimate regulatory distinction. 
7.5.2.5.1  Whether the different tracking and verification requirements modify the 
conditions of competition in the United Stat es' market to the detriment of like Mexican 
tuna and tuna products 
7.5.2.5.1.1  Argume nts of the parties 
7.288.  The content of Mexico's allegation that th e different tracking and verification requirements 
have a detrimental impact on the competitive opportunities of Mexican tuna and tuna products is 
essentially the same as that of its claim concerning the different certification requirements. 
Mexico's argument is not that the different tracking and verification requirements in themselves block or hinder Mexican access to the dolphin-safe label. Rather, its complaint is that "the absence of sufficient … record-keeping [and] verification … requirements for tuna that is used to produce 
tuna products from the United States and other countries means that Mexican tuna products are 
losing competitive opportunities to tuna products that may be incorrectly labelled as dolphin-safe. This difference is what is creating the detrimental impact".
470 According to Mexico, the detrimental 
impact caused by the different tracking and verification requirements does not stem from the 
"denial of a competitive opportunity" – that is, beyond or additional to the denial inherent in the disqualification of tuna caught by setting on dolphins – but rather from the granting of "a 
competitive advantage" to tuna and tuna products from the United States and other WTO 
Members.
471  
7.289.  The United States rejects Mexico's arguments for much the same reasons as it rejected 
Mexico's arguments on the different certification requirements. Its primary submission is that "the 
detrimental impact does not stem from" the different record-keeping and tracking and verification 
requirements.472 Rather, "Mexico's first element [i.e. the eligibility criteria] is the detrimental 
impact", and since "Mexican tuna product containing tuna caught by setting on dolphins would still 
be ineligible for the 'dolphin safe' label" even if  the different observer requirements did not exist, 
"Mexico simply cannot establish a causal connection between the detrimental impact" and the different record keeping and tracking and verification requirements".
473 
7.290.  Additionally, as in the context of the different certification requirements, the United States 
notes that Mexico's claim against the different tracking and verification requirements is based on the notion that "producers are disadvantaged vis-à-vis  their non-AIDCP competitors to the extent 
that the competitors are allowed to inaccurately designate their tuna products as 'dolphin safe' … 
whereas Mexican producers, due to the strict record-keeping requirements of AIDCP, are not able 
to commit this same level of fraud".
474 However, in the view of the United States, "Mexico puts 
forward no evidence to support the assertion that the US Government and its citizens have been 
defrauded on an industry-wide scale for over the past two decades".475 
                                               
469 Mexico's first written submission, para. 236. 
470 Mexico's second written submission, para. 117. 
471 Mexico's second written submission, para. 117. 
472 United States' first written submission, para. 223. 
473 United States' first written submission, para. 223 (emphasis original). 
474 United States' first written submission, para. 246. 
475 United States' first written submission, para. 247 (emphasis original). WT/DS381/RW 
 
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  7.291.  Further, and as it argued in the contex t of the different certification requirements, the 
United States argues that the distinction about which Mexico complains is "created by the AIDCP, not the US measure. Indeed, if the United States eliminated all references to the AIDCP (and its requirements) from the amended measure, the regulatory distinction that Mexico criticizes would 
still exist ".
476 Accordingly, in the view of the United States, there is no "genuine connection" 
between the different tracking and verification requirements and any detrimental impact suffered by Mexican tuna and tuna products.  
7.292.  Finally, according to the United States, Mexico's position means that the United States is 
obliged to require of itself and all its trading partners whatever international commitments Mexico has made with respect to tracking and verification, "irrespective of the science or any other consideration". The United States asserts that this is inconsistent with principle that Members may 
choose their appropriate levels of protection with respect to legitimate objectives.
477 
7.5.2.5.1.2  Analysis by the Panel 7.293.  As a preliminary matter, we recall again our finding above that Mexico has made a distinct 
claim in respect of the different tracking and veri fication requirements, and that it is appropriate 
for us to consider that claim.  
7.294.  We also recall that in the context of our analysis above of the different certification 
requirements, we explained why, in our opinion, the regulatory distinction about which Mexico 
complains is properly seen as stemming from th e amended tuna measure itself, even though it 
incorporates requirements imposed by the AIDCP.
478 Without prejudice to the question whether 
the different tracking and verification requirements in fact have a detrimental impact on the 
competitive opportunities of imported Mexican tuna and tuna products – a question that we 
analyse in detail in the following paragraphs – we note that our analysis of the relationship between the AIDCP requirements and the amende d tuna measure applies with equal force in 
respect of the different tracking and verification requirements. Although the tracking and 
verification requirements that the amended tuna measure imposes on tuna caught by large purse seine vessels in the ETP themselves stem from the AIDCP, the regulatory distinction about which 
Mexico complains, is the distinction made by the amended tuna measure itself in imposing 
different tracking and verification requirements on different tuna as a condition of accessing the United States' dolphin-safe label. Thus, while it is true that "[w]hat US law requires is that Mexican producers provide Form 370s that list the AIDCP-mandated tracking number", whereas "[t]he 
actual record-keeping and verification requirements Mexico complains of are contained in the 
AIDCP"
479, it is nevertheless the case that by incorporating these AIDCP requirements into the 
tuna measure, the tuna measure itself creates a regulatory distinction that conditions access to the 
United States dolphin-safe label on different criteria depending on where and how the tuna was 
caught.  
7.295.  The Panel now turns to the substance of th e parties' arguments. Before carrying out our 
legal assessment, it is necessary to consider in some detail the rather complex factual situation 
with which we are confronted. 
The Panel's understanding of the US system  for tracking and verifying tuna caught 
other than by large purse seine vessel in the ETP 
7.296.  As Mexico puts it in its first written submission, "[c]ompliance with the AIDCP brings with it 
strict obligations to comply with the tuna tracking system of the AIDCP".480 In its first submission, 
Mexico cites extensively from the AIDCP's Resolution to Adopt the Modified System for Tracking 
and Verification of Tuna, adopted in 20 June 2001481, which describes in great detail the tracking 
and verification requirements that apply to tuna caught by large purse seine vessels in the ETP. We agree with Mexico that this detailed description is "crucial to understanding the steps that are 
                                               
476 United States' first written submission, para. 226 (emphasis original). 
477 United States' second written submission, para. 105. 
478 See paras. 7.171-7.179 above. 
479 United States' second written submission, para. 98. 
480 Mexico's first written submission, para. 89. 
481  Agreement on the International Dolphin Conserva tion Program, "Resolution to Adopt the Modified 
System for Tracking and Verification of Tuna" (20 June 2001) (Exhibit MEX-36). WT/DS381/RW 
 
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  necessary to ensure that a tuna product validly contains tuna that was caught without harm to 
dolphins"482, and refer to the descriptive part of this Re port where we describe this system in some 
detail.483 
7.297.  The various steps are implemented in Mexican law through a series of measures.484 We 
need not, however, concern ourselves with the details of Mexico's domestic law.485 
7.298.  Mexico contrasts the detailed tracking and verification requirements that apply to large 
purse seine vessels in the ETP with the absence of similar requirements for tuna caught other than 
by large purse seine vessel in the ETP. As Mexico puts it, for such tuna "[t]here are no 
documentation requirements for any type of non-ETP tuna products other than the captain's self-certification. In particular, there is no requirement for a tuna tracking system at all".
486 
7.299.  The United States concedes that these AIDCP requirements are incorporated, indirectly at 
least, in the tuna measure. It explains that Form 370 "requires that tuna harvested in the ETP by 
large purse seine vessels be accompanied by documentation from the appropriate IDCP-member country certifying that there was an IDCP observer on the vessel at all times and listing the 
numbers for the associated TTF(s)".
487   
7.300.  However, the United States rejects Mexico's allegation that, contrary to the situation in the 
ETP large purse seine fishery, the amended tuna measure imposes no tracking and verification 
requirements on tuna caught other than by large purse seine vessels in the ETP. To the contrary, 
according to the United States, the amended tuna measure does impose at least two488 tracking 
and verification requirements to "protect the integrity of the dolphin safe label for tuna harvested by vessels other than large purse vessels operating in the ETP".
489 According to the United States, 
both of "[t]hese requirements implement, and in deed go beyond, the record-keeping requirements 
of RFMOs  governing tuna fisheries other than the ETP"490 – that is, the record requirements 
developed in the context of the various international agreements that regulate fishing in particular 
oceanic regions. 
7.301.  First, the United States explains that: 
[E]very imported tuna product, regardless of where the tuna was caught and whether 
the dolphin safe label is used, must be accompanied by a NOAA Form 370 which 
designates the gear type with which the tuna was caught and, if the product is to be labelled dolphin safe, contains the necessary certifications. At the time of importation, one copy of this form is submitted to Cu stoms and Border Protection and another is 
submitted, within 10 days of importation, to the Tuna Tracking and Verification 
Program (TTVP).
491 
7.302.  Second, the United States contends that: 
[T]the amended measure requires that tuna, to be contained in a tuna product 
labelled dolphin safe, be segregated from non-dolphin safe tuna at the time it was 
caught through unloading and processing. Section 216.93(c)(1) implements this 
requirement for tuna caught by large purse seine vessels in the ETP, requiring that 
dolphin safe tuna be loaded into designated wells and offloaded to trucks, storage facilities, or carriers in such a way as to safeguard the distinction between dolphin safe and non-dolphin safe tuna. Sections 216.93(c)(2) and (3) apply the same 
                                               
482 Mexico's first written submission, para. 90. 
483 See paras. 3.47-3.52 above. 
484 Norma Oficial Mexicana de Emergencia NOM-EM-002-PESC-1999, Pesca responsable de túnidos. 
Especificaciones para la protección de delfines. Requisitos para la come rcialización de túnidos en territorio 
nacional (Exhibit MEX-31) and Norma Oficial Mexicana NOM-001-SAG/PESC-2013, Pesca responsable de túnidos. Especificaciones para las operacione s de pesca con red de cerco (Exhibit MEX-32). 
485 See Mexico's first writte n submission, paras. 91-93. 
486 Mexico's first written submission, para. 94 (emphasis original). 
487 United States' first written submission, paras. 44-46. 
488 United States' first written submission, paras. 49 and 50. 
489 United States' first written submission, para. 48. 
490 United States' first written submission, para. 51. 
491 United States' first written submission, para. 49. WT/DS381/RW 
 
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  requirement to tuna caught by purse seine vessels outside the ETP and to tuna caught 
in other fisheries. Any mixing in the affected wells or storage areas results in the tuna being designated non-dolphin safe.
492 
7.303.  Additionally, the United States explains that certain US government agencies carry out 
various checks in US canneries493, including spot checks494, to ensure compliance with these 
requirements. Thus, whenever a US cannery receives a shipment of either domestic or imported tuna for processing, a representative from the National Marine Fisheries Service may be present to 
monitor delivery and verify the dolphin-safe designations.
495 Additionally, US canneries are 
required to submit monthly reports to the TTVP containing information about, inter alia , the 
species of tuna received by the cannery, its dolphi n-safe status, condition (including weight), as 
well as the ocean of capture, the gear type used , the type of catcher vessel, trip dates, carrier 
name, unloading dates, place of unloading, and, if  the tuna products are to be labelled dolphin-
safe, the required certifications that no dolphins were killed or seriously injured in the sets in which the tuna was caught. To facilitate these checks, all exporters, trans-shippers
496, importers, 
processors, and distributors of tuna and tuna products must maintain records related to the tuna 
shipment(s) with which they are involved for at least two years.497 
7.304.  According to the United States, various sa nctions may be applied if these requirements are 
not met. For instance, tuna products found to be incorrectly labelled are subject to forfeiture, re-
exportation, or even, in some cases, destruction.498 Additionally, the US importer of record for a 
particular batch or shipment of tuna is, under US domestic law, liable for the accuracy of the information contained in a Form 370. Persons who offer for sale or export tuna products falsely 
labelled as dolphin-safe – including producers, importers, exporters, distributors, and other sellers 
– may face civil sanctions or even criminal prosecutions under the DPCIA.
499 
7.305.  In its second written submission, Mexico raises concerns about the utility of the 
United States' tracking and verification requirements for tuna caught other than by large purse 
seine vessels in the ETP. In particular, Mexico notes that "[w]hen US authorities perform their 'verification' of US canneries, they can only check whether a cannery maintains records of the 
documentation that it receives; there is no way to check the validity of the documentation".
500 
Thus, according to Mexico, "the Amended Tuna Measure provides no requirements or procedures by which the dolphin-safe status of tuna caught by a vessel outside the ETP can be tracked or verified at any point while it is stored on board fishing vessels, consolidated with the tuna caught 
by other fishing vessels, unloaded at port, brokered through intermediaries, trans-shipped, 
partially processed into loins, processed into finished tuna products, or imported into the 
United States".
501 In Mexico's opinion, this is in stark contrast to the fact that "the Amended Tuna 
Measure requires a comprehensive and independentl y-verified record-keeping and tracking system 
for the dolphin-safe status of tuna caught within the ETP".502  
7.306.  In order to help it better understand the tracking and verification requirements imposed on 
tuna caught other than by large purse seine vessels, the Panel asked the parties a number of 
questions on this issue following the Panel's meeting with the parties.503 
7.307.  The Panel asked the United States to explain "[h]ow, if at all, is the United States able to 
verify that outside the ETP dolphin-safe and non-dolphin safe tuna has been kept separately, from 
the point of catch to the point of retail, as required under the amended tuna measure".504 In 
                                               
492 United States' first written submission, para. 50. 
493 The United States has conceded that it does not conduct checks in non-US canneries: United States' 
first written submission, para. 64. 
494 United States' first written submission, para. 53 ("NMFS regularly audits US tuna canneries and 
conducts "spot checks" of re tail market tuna products"). 
495 United States' first written submission, para. 52. 
496 On the complex issue of trans-shipment, see paras. 7.327-7.351 below. 
497 United States' first written submission, para. 52. 
498 United States' first written submission, para. 53. 
499 United States' first written submission, para. 53. 
500 Mexico's second written submission, para. 67. 
501 Mexico's second written submission, para. 145. 
502 Mexico's second written submission, para. 145. 
503 Panel questions Nos. 43, 44 and 45. 
504 Panel question No. 43. WT/DS381/RW 
 
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  response, the United States explained that "[t]here are several mechanisms by which the 
United States could verify whether dolphin safe and non-dolphin safe tuna caught outside the ETP had been kept separate from harvest, through processing, to retail sale".
505 These mechanisms 
include "inspections on the high seas or in US waters", during which "a captain's failure to 
segregate dolphin safe and non-dolphin safe tuna could be uncovered".506 Additionally, the 
United States argues that "routine inspections of shipments of tuna unloaded at US ports or US canneries could disclose a captain's failure to segregate dolphin safe from non-dolphin safe 
tuna". Such disclosure may come about as a result of documentary audits, or "an officer might be 
able to observe tuna being offloaded to trucks, storage facilities, or carrier vessels in a way that does not maintain segregation of dolphin safe and non-dolphin safe tuna".
507 Government audits of 
US canneries "could disclose systemic failures to maintain adequate procedures for segregating 
dolphin safe and non-dolphin safe tuna" or "inadequate systems for ensuring that all tuna 
purchased as dolphin safe is accompanied by the required certifications and is tracked through processing".
508 And the NMFS is authorized to engage in "retail spot checks", in which it "uses the 
product code" of a randomly selected retail can or pouch of tuna "to trace the product back 
through the importer or manufacturer all the way to the harvesting vessel and vessel trip".509 
Finally, the United States argues that "the tuna canning industry imposes its own oversight on 
vessel captains". According to the United States, "it is possible that canneries themselves could 
and would verify whether vessels have maintained the segregation required by the US measure, and … they might refuse to purchase tuna from vessels that had not complied with the amended 
measure".
510 
7.308.  In its response to another question from the Panel511, the United States provided the Panel 
with additional details on these tracking and verification mechanisms. For present purposes, the most important part of the United States' response concerns cannery audits, because it is through 
these audits that United States authorities can "acquire all the documents that track particular lots 
received by the canneries from the vessel trip on which the tuna was caught".
512 In other words, 
as we understand it, it is primarily through cannery audits that the United States ensures that all 
tuna has been properly tracked and verified so as to ensure that non-dolphin-safe tuna is not 
incorrectly labelled. 
7.309.  [[BCI513 514]] 
7.310.  [[BCI515 516]] 
7.311.  [[BCI517]] In the view of the United States, audits  can therefore "disclose discrepancies in 
documentation and procedural irregularities leading to inaccurate or fraudulent dolphin-safe certifications. Specifically, an audit could uncover missing Form 370s or captains' statements, 
inadequate record keeping linking captains' certifications to canned tuna lots, or mixing of dolphin-
safe and non-dolphin-safe tuna".
518 
                                               
505 United States' response to Panel question No. 43, para. 229. 
506 United States' response to Panel question No. 43, para. 230. 
507 United States' response to Panel question No. 43, para. 231. 
508 United States' response to Panel question No. 43, para. 232. 
509 United States' response to Panel question No. 43, para. 233. 
510 United States' response to Panel question No. 43, para. 234. 
511 Panel question No. 44. The question read as follows: "To the United States: How can the 
United States determine whether an importer, proc essor, or captain has made a false dolphin-safe 
declaration?" 
512 United States' response to Panel question No. 44, para. 240. 
513 United States' response to Panel question No. 44, para. 241. 
514 United States' response to Panel question No. 44, para. 241. 
515 United States' response to Panel question No. 44, para. 242. The United States argues that, in some 
cases, the can code may also enable the authorities to  trace back to an associated captain's statement. 
However, in the Panel's view the evidence relied upon by the US in support of th is point is ambiguous. In 
particular, the Panel is pu zzled by the fact that [[BCI]] . As such, the Panel declines to find that the evidence 
before it establishes that can codes enable US authorities to track tuna contained in a retail product back to its associated captain's statement.  
516 United States' response to Panel question No. 44, paras. 242 and 243. 
517 United States' response to Panel question No. 44, para. 243. 
518 United States' response to Panel question No. 44, para. 244. WT/DS381/RW 
 
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  7.312.  It is important to note that the retail spot checks that the United States authorities may 
carry out work in essentially the same way as ca nnery audits. For US-processed tuna, the relevant 
authority will trace the can back to the cannery re sponsible for production, and that cannery will 
then be expected to provide the documentation mentioned in the preceding paragraphs in order to 
establish the identity of the tuna – that is, the vessel and trip on which it was caught, and its 
dolphin-safe certification. For non-US-processed tuna, the relevant authorities will use the can to identify the importer, who will then have to provide the relevant documentation. In such cases, the 
importer him/herself will be liable for any inaccuracy or fraud detected.
519 Thus, "[t]he same 
internal traceability systems that enable canneries to comply with cannery audits also allow canneries to comply with the requirements of retail spot checks".
520 
7.313.  The United States' response to the Panel's question concludes in the following way: "Of 
course, NOAA does not verify the dolphin safe certification on every can of tuna imported to the 
United States. However, the detailed records kept by importers and canneries, and the fact that dolphin safe certifications have been translated into and provided in many languages by vessels of 
different nationalities, demonstrates that the US and foreign canneries and fishing vessels that 
supply tuna product for the US market are conscious of and take steps to comply with the US measure".
521 
7.314.  Mexico provided the Panel with detailed comments on the United States' response. The 
thrust of these is that "[t]he United States' responses to Questions 43 and 44 are disingenuous".
522 
7.315.  With respect to inspections on the high seas and at the dock-side, Mexico argues that 
"such inspections are incapable of detecting whether nets were set on dolphins or whether 
dolphins were killed or seriously injured during a set or gear deployment". According to Mexico, "the United States has submitted no evidence to show that any fishing vessel outside the ETP has 
a procedure for tracking tuna by the well in which it was stored". In Mexico's view, these 
shortcomings are exacerbated because "the United States does not conduct such inspections on vessels outside its jurisdiction".
523 
7.316.  With respect to cannery audits, Mexico's view is that "[t]he United States' evidence of the 
Commerce Department's audits of canneries reveals significant flaws in the US system and confirms Mexico's argument".
524 Mexico begins by recalling that "the Commerce Department only 
conducts dolphin-safe compliance audits of US canneries. It does not audit foreign canneries, 
foreign loining processors, foreign carrier companies, or foreign fishing vessel operators". 
Additionally, Mexico notes that the United Stat es' submissions on the possibility of auditing 
importers, trans-shippers, processors, and distributors are couched in terms of the Commerce 
Department's authority , and concludes on the basis of this language that "the Commerce 
Department does not periodically audit importers, trans-shippers, processors, or distributors".525 
7.317.  Mexico also rejects the reliability and the relevance of the United States' exhibits 
concerning cannery audits.  
7.318.  With respect to reliability, Mexico notes that in respect of all four exhibits, "the 
United States provided no explanation of these documents to verify their source, when they were prepared, and by whom".
526 
                                               
519 See United States' response to Panel question No . 18, explaining the various "legal consequences" 
stemming from fraudulent or otherwise inaccurate import activity. 
520 United States' response to Panel question No. 44, para. 246. 
521 United States' response to Panel question No. 44, para. 248. 
522 Mexico's comments on the United States' response to Panel question No. 43, para. 152. 
523 Mexico's comments on the United States' response to Panel question No. 43, para. 153. 
524 Mexico's comments on the United States' response to Panel question No. 43, para. 154. 
525 Mexico's comments on the United States' response to Panel question No. 43, para. 155 (emphasis 
original). 
526 Mexico's comments on the United States' response to Panel question No. 43, para. 156. WT/DS381/RW 
 
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  7.319.  As for relevance, Mexico notes first that [[BCI527 528 529]]. 
7.320.  [[BCI530 531]] 
7.321.  [[BCI532]] 
7.322.  [[BCI533 534]] 
7.323.  As regards retail spot checks, Mexico argues that the process described by the 
United States "can only trace a can from a US retail store to a US cannery or US importer. Such checks can provide no additional information on the source and dolphin-safe status of tuna than 
the superficial audits of US canneries".
535  
7.324.  Finally, Mexico takes issue with the United States' description of "industry oversight". 
According to Mexico: 
The key point is the following statement by the United States: "It is possible  that 
canneries themselves could and would verify whether vessels have maintained the 
segregation required by the US measure, and that they might refuse to purchase tuna 
from vessels that had not complied with the amended measure". The United States 
therefore admits that it does not know whether canneries perform such verifications 
or purchase non-dolphin safe tuna.536 
7.325.  Mexico sums up its rebuttal in the following terms: 
In summary, the evidence establishes that th e US tracking and verification system for 
non-ETP tuna is meaningless. US canneries can trace tuna once it arrives at their plants in the United States, but they have no method to verify that the information they receive from foreign exporters is accurate – both with regard to the truthfulness 
of the captain's statement, and with regard to whether a statement matches to a 
particular shipment of tuna.
537 
7.326.  Thus, according to Mexico, while tuna caug ht by large vessels fishing in the ETP can be 
tracked "from the moment the tuna is captured and stored in a fishing vessel's well", the system 
applied by the amended tuna measure to tuna caught other than by large purse seine vessels in the ETP "is limited to checking whether US canneries have the correct paperwork in their files". In 
Mexico's view, such checks do "not provide any assurance to consumers that the labels on 
non-ETP tuna products are accurate".
538 
The Panel's understanding of the trans-shipping issue  
7.327.  Our analysis of the different tracking and verification requirements applicable to tuna and 
tuna products is further complicated by the comp lex practice known as "trans-shipping". "Trans-
shipping" is defined in the Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean as "the unloading of all or any of the fish on 
board a fishing vessel to another fishing vessel at sea or at port".
539 According to Mexico, the key 
                                               
527 Company Traceability Procedure (Exhibit US-190) (BCI). 
528 Cannery Reference Reports for National Marine Fisheries Service Periodic Audit (Exhibit US-191) 
(BCI). 
529 Mexico's comments on the United States' response to Panel question No. 43, para. 158. 
530 Cannery Slides on Tuna Trace Systems (Exhibit US-189) (BCI). 
531 Mexico's comments on the United States' response to Panel question No. 43, para. 159. 
532 Mexico's comments on the United States' response to Panel question No. 43, para. 159. 
533 Cannery Traceability Flowchart (Exhibit US-192) (BCI). 
534 Mexico's comments on the United States' response to Panel question No. 43, para. 163. 
535 Mexico's comments on the United States' response to Panel question No. 43, para. 164. 
536 Mexico's comments on the United States' response to Panel question No. 43, para. 165 (emphasis 
original; internal citations omitted). 
537 Mexico's comments on the United States' response to Panel question No. 43, para. 166. 
538 Mexico's comments on the United States' response to Panel question No. 43, para. 167. 
539 See Mark A. McCoy, A Survey of Tuna Transshipment in Paci fic Island Countries: Opportunities for 
Improving Benefits and Increasing Monitoring  (Gillet, Preston and Associates, 2012) (Exhibit MEX-75), p. 12. WT/DS381/RW 
 
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  problem of "trans-shipping" is that it is "particularly vulnerable to 'tuna laundering', where 'black 
boats' may conduct illegal, unauthorized and unrestricted (IUU) fishing and then transfer their catch to licensed vessels to trans-ship".
540 
7.328.  In its first written submission, Mexico noted that some types of vessels, for instance purse 
seine vessels operating in the Western and Central Pacific Ocean, are prohibited from trans-
shipping, subject to certain exceptions.541 Mexico also acknowledged that "[s]ome reporting is 
required for unloading vessels and carriers, including a trans-shipment declaration".542 
Nevertheless, Mexico submits that "[i]n any event … observers likely cannot detect IUU fishing and 
fish laundering", and "the reporting required for transshipments does not address the US dolphin-safe requirements. There are no authorities with responsibility to monitor whether captains' certifications match to particular lots of tuna, or whether tuna has been mixed with uncertified 
tuna in a storage well".
543 
7.329.  According to Mexico, the risks associated with trans-shipping, including "tuna laundering", 
are much greater in the context of tuna fishing indu stries that are not vertically integrated – that 
is to say, where producers of tuna products do not have their own fishing fleets that deliver tuna 
directly to their processing plants, than where the "chain of ownership over the tuna caught … is maintained from the time of harvesting through the processing of the tuna and the eventual 
marketing of the tuna products".
544 In Mexico's view, in the context of a vertically integrated 
industry, "the chain of ownership over the tuna caught … is maintained from the time of harvesting through the processing of the tuna into tuna products and the eventual marketing of the tuna products". Consequently, the likelihood of "tuna laundering" is greatly reduced.
545 Mexico explains 
that while "the major Mexican producers are vertically integrated", "most major tuna products 
companies in other countries are not vertically integrated. They purchase tuna from third-party companies, and in many cases the tuna has passed through at least two parties before it is 
processed". The consequence of this, says Mexico, is that tuna products produced by non-Mexican 
producers are more likely to be made from tuna that cannot properly be tracked, and therefore cannot be reliably shown to be dolphin-safe. Where multiple catches are consolidated at sea, it is 
far harder to ensure that captains' certificates match particular batches of tuna (and that they are 
not incorrectly assigned to non-dolphin-safe tuna), and that dolphin-safe tuna and non-dolphin-safe tuna are properly segregated.
546 
7.330.  Mexico's allegations raise serious questions concerning the possibility of meaningfully 
tracking tuna caught other than by large purse seine vessels in the ETP where such tuna is trans-
shipped rather than being unloaded and transferred to a cannery directly from the fishing vessel. 
To explore this issue in more detail, the Panel asked the parties a number of questions concerning 
trans-shipping and its possible consequences. 
7.331.  In question 18(b), the Panel asked the United States to comment on Mexico's description 
of the trans-shipping problem, and to identify "[w]hat instruments enable the United States to 
identify and respond to the risk of tuna laundering". 
7.332.  The United States responded to this question in detail. According to the United States, 
"Mexico's argument ignores the interlocking international and national requirements regarding trans-shipments". Indeed, in the view of the United States, "[t]rans-shipment is one of the 
activities most highly regulated by RFMOs and port states".
547  
7.333.  With respect to international regulation , the United States notes that different RFMOs 
require various kinds of declarations and advance notice of trans-shipment. In the Western and 
Central Pacific Fisheries Commission (WCPFC), for instance, all incidents of trans-shipping in port 
must be documented through a "Trans-shipment Declaration", which must contain information including the identity of the fish being trans-sh ipped, the carrier vessels, the quantity and state 
                                               
540 Mexico's first written submission, para. 166. 
541 Mexico's first written submission, para. 167. 
542 Mexico's first written submission, para. 168. 
543 Mexico's first written submission, paras. 169 and 170. 
544 Mexico's first written submission, para. 159. 
545 Mexico's first written submission, para. 159. 
546 Mexico's first written submission, para. 170. 
547 United States' response to Panel question No. 18(b), para. 103. WT/DS381/RW 
 
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  (i.e. frozen or fresh) of the fish to be trans-sh ipped, the date and location of the trans-shipment, 
and the quantity of product already on board the receiving vessel.548 In the Indian Ocean Tuna 
Commission (IOTC), prior notification of intent to trans-ship at port must be provided to the relevant port state authorities before trans-shipment may occur. This notification must include 
information concerning the fishing and carrier vessels, the tonnage of the product, the major 
fishing grounds of the catch, and the date and location of the intended trans-shipment.
549 
7.334.  The United States explains that, in addi tion to these treaty-based requirements, port 
states where trans-shipment occurs impose additional requirements to protect the integrity of the 
process. In the WCPFC, for example, trans-shipping  may be undertaken at one of five designated 
ports, and "the procedures for clearing arriving fishing and carrier vessels are standard across" the ports. The United States explains the process as follows: 
A boarding party of representatives from relevant government offices boards the 
vessels, checks the vessel documents, conducts customs inspections, and collects the documents relevant to trans-shipment including the well plan showing the stowage of 
fish, the voyage memorandum showing previo us ports visited, and a sheet of general 
information on the vessel and the catch. When the vessel has been cleared, trans—shipment may begin, and is subject to monitoring by the government fisheries 
department and, periodically, by other monitoring or enforcement agencies. 
Government authorities collect the required documentation and monitor part or all of the trans-shipment, which takes place 12-14 hours per day for several days.
550 
7.335.  With respect to trans-shipment at sea, the United States observes that this is "subject to 
even more stringent regulation than trans-shipment  at port". Trans-shipment at sea is prohibited 
for purse seine vessels, and is permitted for large long line vessels only where such vessels have been authorized by their flag country. Under both the WCPFC and the IOTC regimes, trans-
shipment at sea must be overseen by an observer, whose responsibility it is to confirm that the 
quantities of transferred fish are consistent with the Trans-shipment Declaration, the relevant log book(s), and other available information.
551 Vessels involved in trans-shipping are also required to 
submit a declaration immediately following the trans-shipment to their flag state and the relevant 
international fisheries management organization.552 
7.336.  The United States also argues that, in a ddition to the extensive national and international 
regulation of trans-shipping, fishing and carrier vessels themselves have strong economic 
incentives to properly monitor trans-shipments and to ensure that all trans-shipped tuna can be 
properly tracked. According to the United States, "[c]anneries may reject tuna on various grounds (e.g. spoiling, smashed fish, or small size). Conseq uently, any tuna broker or carrier vessel has an 
incentive to track the harvest of each vessel, including during trans-shipment, to ensure that the 
cannery is not left paying for fish that they cannot use".
553 Additionally, in the view of the 
United States, port states have an economic incentive to carefully monitor trans-shipment that 
takes place in their territorial waters because "fee calculations are often based on volumes of 
trans-shipped fish, giving them an incentive (even apart from complying with RMFOs) to monitor trans-shipments in port".
554 
7.337.  Finally, the United States also rejects Mexico's argument that the risks of tuna laundering 
arise only in the context of tuna industries that are not vertically integrated. In the view of the 
United States, "Mexico's argument provides no basis for its assumption that a vertically integrated cannery would be less likely to launder tuna than one that is independently owned. The motivation 
                                               
548 Western and Central Pacific Fisheries Commission, "Conservation and Management Measure on the 
Regulation of Transhipment" (CMM 2009-06, 7-11 December 2009) (Exhibit US-152); see also United States' response to Panel question No. 18(b), para. 103. 
549 Indian Ocean Tuna Commission, "Resolution 12/05 Establishing a Programme for Transhipment by 
Large-Scale Fishing Vessels (2012) (Exhibit US-138); s ee also United States' response to Panel question 
No. 18(b), para. 104. 
550 United States' response to Panel question No. 18(b), para. 105 (internal citations omitted). 
551 United States' response to Panel question No. 18(b), para. 106. 
552 United States' response to Panel question No. 18(b), para. 106. 
553 United States' response to Panel question No. 18(b), para. 108. 
554 United States' response to Panel question No. 18(b), para. 107. WT/DS381/RW 
 
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  to act inconsistent [ sic] with national or international requirements is not impacted by ownership 
structure".555  
7.338.  In light of all this, the United States urge s the Panel to find that there is "no evidence to 
suggest that [tuna] laundering … is occurring on  a widespread basis in a way that impacts the 
US tuna product market".556 
7.339.  Mexico commented extensively on the United States' response to this question. 
7.340.  Mexico begins by recalling that the problem of illegal, unreported, and unregulated (IIU) 
fishing is real and serious, and has in fact been  recognized even by President Obama, who in 2014 
released a memorandum indicating, inter alia , that "IUU fishing continues to undermine the 
economic and environmental sustainability of fish eries and fish stocks" and warning that "[g]lobal 
losses attributable to the black market from IUU fishing are estimated to be [US]$10-23 billion 
annually, weakening profitability for legally caught sea food, fuelling illegal trafficking operations, 
and undermining economic opportunity for legitimate fishermen".557 Mexico notes that "[t]he 
United States has avoided responding to this point".558  
7.341.  Mexico also takes issue with the use made  by the United States of Exhibit MEX-75 in the 
course of its response to the Panel's question. According to Mexico, the United States has quoted this document selectively, and in particular has ignored the following key conclusion contained in 
the report: 
The legal framework for the regulation of trans-shipment is still evolving … If, as some 
expect, detailed reporting of high seas longline trans-shipment by flag states is poor and observer coverage does not result in significantly better understanding of the 
catches in the fishery, efforts will likely be made to ban high seas longline 
trans-shipment and require all trans-shipping to be done in [exclusive economic zones] or in port.
559 
7.342.  Mexico next submits that there are "reasons to question the United States' claim that there 
is comprehensive monitoring of trans-shipments".560 For instance, a 2014 IOTC report suggests 
that in 2013 over twenty-six per cent of trans-sh ipments on the high seas were not monitored by 
an observer.561 Moreover, Mexico suggests that even when  observers are present, the extent of 
their monitoring may be minimal. Thus, a 2013 IOTC report observed that:  
[O]ther than asking the fishing masters directly, there appears to be no other way to 
determine if transfers have taken place, as detailed examination of the log books are 
not possible in the time allocated. This would require a more detailed analysis of the 
data to determine the average catch rates of vessels, the frequency a vessel trans-ships and the amount trans-shipped each time.
562 
7.343.  The reliability of observer monitoring of trans-shipment is further undermined, in Mexico's 
view, by the fact that in 2013 many discrepancies were reported between information provided by observers and information obtained through subsequent verification
563, as well as by the fact 
                                               
555 United States' response to Panel question No. 18(b), para. 109. 
556 United States' response to Panel question No. 18(b), para. 110. 
557 Mexico's comments on the United  States' response to Panel questi on No. 18(b), para. 79. See also 
Mexico's second written submission, para. 62. 
558 Mexico's comments on the United States' response to Pa nel question No. 18(b), para. 79. 
559 Mexico's comments on the United States' response to Panel question No. 18(b), para. 81 (citing Mark 
A. McCoy, A Survey of Tuna Transshipment in Pacific Island  Countries: Opportunities for Improving Benefits 
and Increasing Monitoring  (Gillet, Preston and Associates, 2012) (Exhibit MEX-75), p. 60). 
560 Mexico's comments on the United States' response to Pa nel question No. 18(b), para. 82. 
561 Mexico's comments on the United  States' response to Panel ques tion No. 18(b), para. 82 (citing 
Indian Ocean Tuna Commission, "A Summary of th e IOTC Regional Observer Programme During 2013" 
(IOTC-2014-CoC11-04bE, March 2014) (Exhibit MEX-139), p. 8). 
562 Mexico's comments on the United  States' response to Panel ques tion No. 18(b), para. 83 (citing 
Indian Ocean Tuna Commission, "Summary of Region al Observer Programme During 2012" (March 2013) 
(Exhibit US-137, p. 10). 
563 Mexico's comments on the United States' response to Pa nel question No. 18(b), para. 84. WT/DS381/RW 
 
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  monitoring procedures for certain species of tuna appear to be less stringent than those that apply 
to other species.564  
7.344.  Finally, and most importantly, Mexico argues that:  
[T]he evidence submitted by both the United  States and Mexico confirms that, even 
when trans-shipments are properly monitored, the observers have no responsibility to 
keep track of dolphin-safe and non-dolphin-safe tuna, and there are no procedures for carriers to maintain records regarding from which well of a fishing vessel tuna was 
transferred. Tuna of any particular species is fungible and can be mingled for storage 
and shipment … [so] for non-ETP tuna products there is no way to verify or validate that a captain's certificate actually matches to the tuna with which it has been associated.
565  
7.345.  To help us better understand how dolphin-safe certifications are kept together with 
particular batches of tuna during trans-shipment, we asked the parties to explain whether "dolphin-safe certifications always follow or stay with the tuna catch that they describe", or 
whether such certifications are or can be "assigned at a later point (i.e. sometime after catch) to 
other batches of tuna that may not have been caught in a dolphin-safe manner".
566 
7.346.  Mexico submitted that although it is not aware of any specific instances of dolphin-safe 
certifications being sold so as to accompany a batch of non-dolphin-safe tuna, nevertheless "the 
US system allows for certifications to be assigned to batches of tuna that may not have been caught in a dolphin-safe manner".
567 In particular, Mexico argues that "the unreliability of the … 
tracking and verification procedures, make it simple to assign a captain's certificate to any 
shipment of tuna products".568 
7.347.  In support of these allegations, Mexico ci tes an article published in 2014 in the Journal of 
Marine Policy, according to which "[i]llegal and unreported catches represented 20-32% of wild-
caught seafood imported to the USA in 2011, as determined from robust estimates, including 
uncertainty, of illegal and unreported fishing activities". According to this study, "illegal fish products are often mixed into supply chains at the processing stage"; and, crucially:  
Illegal tuna fishing in the Indian and Pacific Oceans is facilitated by the lack of seafood 
traceability when supplies are consolidated during trans-shipping at sea. In particular, the frozen tuna market tends to trans-ship and re-supply at sea. Strong demand for tuna encourages brokers to amalgamate supplies from different origins to make 
orders. Because there is scant transparency at sea, even products carrying a 
traceability claim on the package could well derive from mixed shipments … Illegal activity by small and medium scale longliners and falsification of tuna documentation 
is also a concern.
569 
7.348.  The study states that, with respect to the: 
[H]ighly internationalized seafood supply chain feeding imports into the United States 
and other major markets … there is a lack of monitoring, transparency and 
accountability as to the sources of the seafood. There are no trace-back procedures to help companies avoid handling the products of poaching and illegal fish products enter [sic] the supply chain at multiple points.
570  
                                               
564 Mexico's comments on the United States' response to Pa nel question No. 18(b), para. 85. 
565 Mexico's comments on the United States' response to Pa nel question No. 18(b), para. 87. 
566 Panel question No. 42. 
567 Mexico's response to Panel question No. 42, para. 120. 
568 Mexico's response to Panel question No. 42, para. 121. 
569 Ganapathiraju Pramod et al, "Est imates of Illegal and Unreported Fish in Seafood Imports to the 
USA", 48 Marine Policy 102 (2014) (Exhibit MEX-131), p. 110. 
570 Ganapathiraju Pramod et al, "Est imates of Illegal and Unreported Fish in Seafood Imports to the 
USA", 48 Marine Policy 102 (2014) (Exhibit MEX-131), p. 106. WT/DS381/RW 
 
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  7.349.  It also notes that:  
[A] significant amount of fish is imported into the USA by first passing through one or 
more intermediary countries for post-harvest processing and subsequent re-export. These additional steps introduce additional challenges to traceability and allow for the 
mixing of legally and illegally-sourced fish, where illegal fish may be essentially 
"laundered" in the processing countries, and subsequently enter international trade as a legal product of the exporting nation.
571 
7.350.  In its own response to this question, the United States argues that Mexico has provided no 
evidence that any tuna and tuna products entering its market are the result of "tuna laundering".
572 In particular, the United States submits that "[t]here is no market – legal or 
otherwise – for dolphin-safe certifications. Dolphin-safe certifications are not alienable or 
transferable. Labels are specifically associated wi th the particular tuna caught. The United States 
has no reason to believe that there is a black market for such certifications".573 As such, according 
to the United States, "the documentation attesting to whether the tuna is dolphin safe or not stays 
with the tuna". Canneries keep track of this documentation and, as explained above, "use 
comprehensive tracking systems … that allow all the information related to [a] particular lot of fish … to be retrieved quickly in case of a NMFS audit".
574 
7.351.  The United States elaborated on this issue in its comments on Mexico's response. There, it 
expresses the view that "the global problem of ill egal, unreported, and unregulated fishing" is not 
"relevant" to this dispute.575 Additionally, with respect to the journal article cited by Mexico, the 
United States explains that "[w]hile … IUU fishing is a global problem … the United States does not 
agree with the statistics that are being highlighted in the study, which are based on suspect, 
unverifiable data".576 
Legal assessment 
7.352.  We begin by recognizing the complex and contested nature of the facts before us. The 
structure and operation of the international tuna industry is characterized by an overlapping series of domestic and international regulatory regimes, as well as more or less consistent practices 
across vessels, oceans, and domestic and international waters. As one peer-reviewed study 
submitted by Mexico says: 
The highly internationalized seafood supply chain feeding imports into the 
United States and other major markets is on e of the most complex and opaque of all 
natural commodities. It involves many actors between the fisherman and the 
consumer, including brokers, traders, whol esalers, and other middlemen, often distant 
from the consumer markets they supply.
577 
7.353.  Our task is to determine, in light of all of the factual issues discussed above, whether the 
tracking and verification systems applied by th e amended tuna measure to different fisheries 
modify the conditions of competition to the detriment of Mexican tuna and tuna products.  
7.354.  In the Panel's view, Mexico's evidence suggests that there are three crucial differences 
between the tracking and verification system that applies to tuna caught by large purse seine vessels inside the ETP and that which applies to  other tuna. In the Panel's understanding, these 
differences can be said to relate broadly to the depth, accuracy, and degree  of government 
oversight  of the tracking and verification systems.  
                                               
571 Ganapathiraju Pramod et al, "Est imates of Illegal and Unreported Fish in Seafood Imports to the 
USA", 48 Marine Policy 102 (2014) (Exhibit MEX-131), pp. 106 and 107. 
572 United States' comments on Mexi co's response to Panel question No. 42, para. 99; United States' 
response to Panel question No. 42, para. 227. 
573 United States' response to Panel question No. 42, para. 227. 
574 United States' response to Panel question No. 42, para. 228. 
575 United States' comments on  Mexico's response to Panel question No. 42, para. 99. 
576 United States' comments on Mexico's response to Panel question No. 42, para. 103. 
577 Ganapathiraju Pramod et al, "Est imates of Illegal and Unreported Fish in Seafood Imports to the 
USA", 48 Marine Policy 102 (2014) (Exhibit MEX-131), p. 106. WT/DS381/RW 
 
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  7.355.  By depth , we mean to refer to the point to which tuna can be traced back. Mexico has 
shown that tuna caught by large purse seine ve ssels in the ETP can, pursuant to the record-
keeping requirements embedded in the AIDCP and incorporated into the amended tuna measure, 
be tracked back all the way to the particular set  in which the tuna was caught and the particular 
well in which it was stored .578  
7.356.  In contrast, on the basis of the evidence submitted to us by the United States, it appears 
that outside the ETP, tuna can be traced back to the vessel  and trip on which it was caught.579 For 
instance, [[BCI580]]. 
7.357.  [[BCI]]  
7.358.  [[BCI581 582]] 
7.359.  [[BCI]]  
7.360.  By accuracy, we mean the degree of confidence that a particular captain (or, where 
applicable, observer) statement properly describes the lot of tuna to which it is assigned. Mexico's evidence suggests that the tuna tracking forms required for tuna caught by large purse seine 
vessels in the ETP accompany particular catches of tuna throughout the fishing and production 
process, from the point of catch right through to the point of retail.
583 The form must accompany a 
particular batch of tuna at each production stage, and accordingly the identity of a particular batch 
of tuna can, in principle, always be established.  
7.361.  In contrast, and crucially, [[BCI]] . It is not clear to the Panel how particular certificates 
are kept with particular lots of tuna up until the tuna reaches the canning plant. The United States asserts that "[t]he documentation attesting to whether the tuna is dolphin safe or not stays with 
the tuna"
584, but the Panel has not been provided with evidence showing how this is ensured in 
practice. At one point in its responses to the Panel's questions the United States appears to suggest that canneries could or should have "adequate record keeping linking captains' 
certifications to canned tuna lots"
585, but the nature of this record keeping, or whether canneries 
actually implement sufficient systems, does not emerge clearly from the United States' 
explanations. The United States has said that "it is possible that canneries … could and would 
verify whether vessels have maintained the segregation required by the US measure, and that 
they might refuse to purchase tuna from vessels that had not complied with the amended measure";
586 but, judging by the United States' use of the words "might" and "could", this appears 
to be speculation, and the United States has submitted no evidence showing that canneries 
actually do ensure that the tuna they receive matches a particular captains' statement.  
7.362.  The difficulty of ensuring that a particular certification matches an identified batch of tuna 
is compounded, in the Panel's view, by the fact that in many cases tuna appears to pass through a 
number of parties before it reaches a US cannery. [[BCI]] . Additionally, as noted above, a recent 
study published in the Journal of Marine Policy  found that "a significant amount of fish is imported 
into the USA by first passing through one or more intermediary countries for post-harvest 
                                               
578 See AIDCP, "Resolution to Adopt the Modified System for Tracking and Verification of Tuna 
(20 June 2001) (Exhibit MEX-36). 
579 We note again the United States' has stated that in some cases, the can code may also enable the 
authorities to trace back to an associated captain's stat ement. As we have explained above, in the Panel's view 
the evidence relied upon by the US in support of this po int is ambiguous. In particular, the Panel is puzzled by 
the fact that [[BCI]] . As such, the Panel declines to find that the evidence before it establishes that can codes 
enable US authorities to track tuna contained in a reta il product back to its associated captain's statement. 
580 United States' response to Panel question No.44, para. 241. 
581 United States' response to Panel question No. 42, para. 228. 
582 Appellate Body Report, US – Gambling , para. 140. 
583 Mexico's first written submission , paras. 80-93; AIDCP, "Resolution to Adopt the Modified System for 
Tracking and Verification of Tuna" (20 June 2001) (Exhibit MEX-36); Norma Oficial Mexicana NOM-001-
SAG/PESC-2013 (Exhibit MEX-32); Statement of Mario G. Ag uilar, Commissioner of Fisheries and Aquaculture 
(CONAPESCA) (Exhibit MEX-37); Statement of Mexican Industry (Exhibit MEX-73). 
584 United States' response to Panel question No. 42, para. 228. 
585 United States' response to Panel question No.44, para. 244. 
586 United States' response to Panel question No. 43, para. 234. WT/DS381/RW 
 
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  processing and subsequent re-export".587 The United States has not provided any evidence 
explaining how canneries are able to ensure that captains' certifications remain with the tuna batches they identify throughout this process.  
7.363.  Moreover, it does not appear that  there is any additional or explicit legal requirement  in 
the amended tuna measure that US canneries ensure or otherwise satisfy themselves, at the time 
they receive a batch of tuna, of either the validity of a dolphin-safe certificate or whether such certificate in fact describes the batch of tuna with which it is associated. 50 FCR § 216.93(g)(1) 
requires canneries to "maintain records", but there does not appear to be any legal requirement 
that the canneries verify the accuracy of the records, or that the records in fact correctly describe the particular batches of tuna to which they are assigned.  
7.364.  Finally, by  government oversight , we mean the extent to which a national, regional, or 
international authority is involved in the tracking and verification process. Mexico's evidence shows 
that, in respect of tuna caught by large purse seine vessels in the ETP, information concerning every stage of the tuna catch and canning process is made available to national and regional 
authorities, which must be sent copies of tuna tracking forms and are thus able to verify at any 
stage of the catch and canning process whether a particular batch of tuna is dolphin-safe. Various national and regional authorities are also requir ed to be notified whenever ownership of tuna 
changes.  
7.365.  For tuna caught other than by large purse seine vessels in the ETP, however, 
US authorities receive information concerning the origin and history of tuna only from US tuna canneries themselves, through the monthly reports that such canneries are required to submit
588, 
and when they (the authorities) carry out an audit or spot check; and even then it seems that they 
a r e  o n l y  a b l e  t o  v e r i f y  t h a t  p r o p e r  t r a c k i n g  m e c h a n i s m s  w e r e  i m p l e m e n t e d  f r o m  t h e  t i m e  t h e  cannery received the tuna.
589 It appears, then, that the United States must rely on the canneries 
for information about the movement of the tuna prior to arrival at the cannery, and is not able to 
go "behind the documents", as it were, to verify that a particular dolphin-safe certification describes the batch of tuna with which it is associated. The US authorities are not, it seems, able 
to ensure that they receive information that would enable them to track the movement and 
dolphin-safe status of tuna from the time of catc h up to the point of delivery to a US cannery.  
7.366.  Similarly, where tuna products are imported from non-US canneries, it appears that the 
United States relies on US importers of tuna products for information about the movement of tuna 
prior to arrival at a US port. As in the case of US  canneries, it appears that the United States is not 
able to directly track the movement and dolphin-safe status of tuna from the time of catch up the point of delivery to a non-US cannery and subsequent shipment to the United States, but must 
rely on documentation provided by the importer. 
7.367.  The issue of government oversight and control is in fact broader than identified in the 
previous paragraphs, and it goes to the very de sign of the different tracking and verification 
systems. As we understand it, every step of the catch and canning process for tuna caught by 
large purse seine vessels in the ETP is prescribed and can be monitored by national and regional agencies. In contrast, in respect of tuna caught in all other fisheries, it appears to us that the United States has, as it were, delegated responsibility for developing tracking and verification 
systems to the tuna industry itself, including canneries and importers, and has decided to involve 
itself only on a supervisory and ad hoc  basis through the review of monthly reports and the 
conduct of audits and spot checks. 
7.368.  In the Panel's view, there is nothing inherently problematic, from the perspective of WTO 
law, about governments delegating functions to private entities, including industry. However, 
delegation to industry (or to other entities) must not have the result of modifying the conditions of 
competition to the detriment of imported products, and such delegation must provide certainty and 
legal security. In the present case, while we do not fault the United States for leaving the tuna 
                                               
587 Ganapathiraju Pramod et al, "Est imates of Illegal and Unreported Fish in Seafood Imports to the 
USA", 48 Marine Policy 102 (2014) (Exhibit MEX-131), pp. 106 and 107. 
588 Dolphin Safe Tuna Labelling Regulations, 50 C.F.R § 216.93(d) (Exhibit US-2). 
589 National Marine Fisheries Service, "TTVP Verification Components" (March 20 2014) (Exhibit US-222) 
("examination of documents and records of internal flows of specific shipments from re ceipt to cold storage to 
production and to finished goods at a US cannery"). WT/DS381/RW 
 
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  industry to develop the tracking and verification systems necessary to ensure compliance with the 
amended tuna measure, it appears to us that in doing so the United States has created a situation 
in which, as Mexico alleges, the system in place outside the ETP large purse seine fishery is less burdensome than the system inside the ETP large purse seine fishery,  and therefore modifies the 
conditions of competition to Mexico's detriment. In particular, we see some merit in Mexico's 
argument that the system in place outside the ETP large purse seine fishery may contribute to inaccurate labelling of tuna caught in sets or other gear deployments in which dolphins were killed 
or seriously injured.  As we understand it, the United States essentially relies upon the canneries 
themselves and other importers to ensure that the requirements of the amended tuna measure, 
including that dolphin-safe tuna and non-dolphin-safe tuna be segregated, are properly observed from the time of catch through to delivery to  the cannery. However, as we explained above,
590 we 
have seen no evidence suggesting that canneries and other importers in fact do this, and, as we 
understand the measure, canneries and other importers are not legally required  to conduct such 
checks.  
7.369.  The result of this systemic architecture is that, while every step of the catch and canning 
process for tuna caught by large purse seine vessels in the ETP is subject to some sort of governmental (including regional and international) oversight, there appears to be, as Mexico 
demonstrated, "major gaps in coverage"
591 in the system that applies to tuna caught other than by 
large purse seine vessels in the ETP. The existence of these gaps strongly suggests to the Panel that the tracking and verification system imposed on fisheries other than the ETP large purse seine 
fishery is significantly less burdensome than that imposed in the ETP large purse seine fishery. 
7.370.  In the Panel's view, these three differences show that the different tracking and 
verification requirements modify the conditions of  competition. They clearly show that the system 
imposed outside the ETP large purse seine fishery is  significantly less burdensome than the system 
imposed inside the ETP large purse seine fishery. In particular, the fact that outside the ETP large 
purse seine fishery tuna need only be traceable back to the vessel and trip on which it was caught, rather than to the particular well in which it was stored, [[BCI
592]] suggest to us that compliance 
with the system outside the ETP large purse se ine fishery is less demanding than the system 
imposed on the ETP large purse seine fishery.  
7.371.  In the Panel's view, the fact that the Un ited States carries out inspections on the high 
seas, at the dock-side, and in US canneries is not sufficient to rebut Mexico's showing that the 
tracking and verification requirements imposed on tuna caught outside the ETP large purse seine 
fishery are less burdensome than those imposed on tuna caught inside that fishery.  
7.372.  We also see some merit in Mexico's argument that the different tracking and verification 
requirements may make it more likely that tuna caught other than by large purse seine vessels in 
the ETP could be incorrectly labelled. Ultimately, however, in order for the Panel to reach a definite conclusion as to whether the system outside the ETP large purse seine fishery actually allows for 
incorrect labelling, the Panel would need to undertake a detailed technical analysis of the system's 
effective operation. In the Panel's view, such analysis is not necessary in order to conclude that the different tracking and verification requirements modify the conditions of competition to the detriment of Mexican tuna and tuna products. The fact that the system in place outside the ETP 
large purse seine fishery is less onerous than that inside is sufficient grounds for finding that this 
aspect of the amended tuna measure has a detrimental impact. 
7.373.   We turn now to the issue of trans-shipping because the parties have argued about this 
practice in great detail. The Panel accepts that, as the United States and Mexico argue, trans-
shipping is a highly regulated practice.  
7.374.  For instance, the Conservation and Management Measure on the Regulation of Trans-
shipment
593, which appears to establish the trans-sh ipping system for the WCPFC, makes no 
                                               
590 See para. 7.363 above. 
591 Mexico's comments on the United States' response to Panel question No. 43, para. 172. 
592 United States' response to Panel queston No. 44,  para. 141; Cannery Slides on Tuna Trace Systems 
(Exhibit US-189), pp. 1 and 2 (BCI). 
593 Western and Central Pacific Fisheries Commission, "Conservation and Management Measure on the 
Regulation of Transhipment" (CMM 2009-06, 7-11 December 2009) (Exhibit US-152). WT/DS381/RW 
 
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  mention of the dolphin-safe status of tuna being trans-shipped. Its Annex I lists the following as 
information that must be contained in all trans-shipment declarations: 
1. A unique document identifier 2. The name of the fishing vessel and its WIN 
3. The name of the carrier vessel and its WIN 
4. The fishing gear used to take the fish 5. The quantity of product (including species and its processed state) to be trans-
shipped 
6. The state of fish (fresh or frozen)  7. The quantity of by-product to be trans-shipped 8. The geographic location of the highly migratory fish stock catches 
9. The date and location of the trans-shipment 
10. If applicable, the name and signature of the WCPFC observer  11. The quantity of product already on board the receiving vessel and the 
geographic origin of that product. 
7.375.  And its Annex II, which lists information to be reported annually by contracting parties, 
lists the following:  
1. the total quantities, by weight, of high ly migratory fish stocks covered by this 
measure that were transhipped by fishing vessels the CCM is responsible for reporting against, with those quantities broken down by: 
a. offloaded and received; 
b. transhipped in port, transhippe d at sea in areas of national 
jurisdiction, and transhipped beyond areas of national jurisdiction; 
c. transhipped inside the Convention  Area and transhipped outside the 
Convention Area; 
d. caught inside the Convention Area and caught outside the 
Convention Area; 
e. species; 
f. product form; and g. fishing gear used. 
2. the number of transhipments involving highly migratory fish stocks covered by 
this measure by fishing vessels that is responsible for reporting against, broken down 
by [sic]: 
a. offloaded and received; 
b. trans-shipped in port, transhipped at sea in areas of national 
jurisdiction, and transhipped beyond areas of national jurisdiction; WT/DS381/RW 
 
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  c. trans-shipped inside the Convention Area and transhipped outside 
the Convention Area; 
d. caught inside the Convention Area and caught outside the 
Convention Area; and 
e. fishing gear. 
7.376.  In our view, none of this information is relevant to the question whether tuna is dolphin-
safe or whether tuna identified as dolphin-safe is  kept segregated from tuna that is not dolphin-
safe. As might be expected on the basis of this instruction, the WCPFC Trans-shipment 
Declaration594 does not appear to contain any reference to the dolphin-safe status of tuna being 
trans-shipped. Neither does it appear to allow the contents of specific wells to be tracked as they 
are moved from the fishing vessel to the carrier vessel. 
7.377.  The same is true of the IOTC's Resolu tion 12/05 on Establishing a Programme for Trans-
shipment by Large Scale Fishing Vessels.595 Section 4 includes a subsection entitled "Notification 
Obligations". It provides: 
Fishing vessel 
12. To receive the prior authorisation mentioned in paragraph 11 above, the master 
and/or owner of the LSTLV must notify the following information to its flag State 
authorities at least 24 hours in advance of an intended transhipment: 
a) The name of the LSTLV and its number in the IOTC Record of Vessels; b) The name of the carrier vessel and its number in the IOTC Record of Carrier 
Vessels authorised to receive transhipments in the IOTC area of competence, and the 
product to be transhipped; 
c) The tonnage by product to be transhipped; d) The date and location of transhipment; 
e) The geographic location of the catches. 
… Receiving carrier vessel 
14. Before starting transhipment, the master of the receiving carrier vessel shall 
confirm that the LSTLV concerned is participating in the IOTC programme to monitor transhipment at sea (which includes payment of the fee in paragraph 13 of Annex III) and has obtained the prior authorisation from their flag State referred to in 
paragraph 11. The master of the receiving carrier vessel shall not start such 
transhipment without such confirmation. 
15. The master of the receiving carrier vessel shall complete and transmit the IOTC 
transhipment declaration to the IOTC Secret ariat and the flag CPC of the LSTLV, along 
with its number in the IOTC Record of Carrier Vessels authorised to receive transhipment in the IOTC area of competen ce, within 24 hours of the completion of 
the transhipment. 
16. The master of the receiving carrier vessel shall, 48 hours before landing, 
transmit an IOTC transhipment declaration, along with its number in the IOTC Record 
                                               
594 Western and Central Pacific Fisheries Commission, "WCPFC Transshipment Declaration" 
(Exhibit US-157). 
595 Indian Ocean Tuna Commission, "Resolution 12/05 Establishing a Programme for Transhipment by 
Large-Scale Fishing Vessels" (2012) (Exhibit US-138). WT/DS381/RW 
 
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  of Carrier Vessels authorised to receive tran shipment in the IOTC area of competence, 
to the competent authorities of the State where the landing takes place.596 
7.378.  As the United States notes in its argument, the IOTC Resolution also establishes an 
observer program. However, even assuming that  such program is effective, the observer's 
obligations do not include checking the dolphin-safe status of tuna being trans-shipped, ensuring 
that dolphin-safe certifications stay with the tuna they describe, or verifying that dolphin-safe and non-dolphin-safe tuna is kept segregated.
597  
7.379.  The Panel has closely examined the other three international trans-shipping regulations 
submitted in evidence by the United States – that of the Inter-American Tropical Tuna 
Committee598, the International Commission for the Conservation of Atlantic Tunas599, and the 
Commission for the Conservation of Southern Bluefin Tuna.600 The obligations therein concerning 
declarations and observers are essentially the same as those discussed above. Nowhere is the 
dolphin-safe status of tuna being transferred even mentioned. 
7.380.  As such, while trans-shipping is clearly an issue of some international concern, in its 
current state the regulation of trans-shipping does not extend to requiring that the dolphin-safe 
status of tuna be verified or tracked. 
7.381.  The Panel acknowledges that it is not the sole  responsibility of the United States either to 
regulate or to reform, if necessary, the current regimes governing trans-shipping. Nevertheless, 
we accept Mexico's argument that the practice of trans-shipping may increase the likelihood that tuna caught outside the ETP large purse seine fishery could be incorrectly labelled.
601  
7.382.  We conclude, therefore, that Mexico has established a prima facie  case that the different 
tracking and verification requirements modify the conditions of competition in the United States' 
tuna market to the detriment of like Mexican tuna and tuna products. The system in place outside the ETP large purse seine fishery is less burdensome than that inside the ETP, and may contribute 
to inaccurate labelling of tuna caught outside the ETP large purse seine fishery, although we make 
no definitive finding on this specific point, because it would require consideration of other factors that may result in tuna being incorrectly labelled. We want to be clear that this conclusion does not 
entail the finding that the tracking and verification system for tuna caught by large purse seine 
vessels in the ETP is itself infallible  or that tuna tracked under that system could never  be 
incorrectly labelled as dolphin-safe.  
7.383.  The Panel turns now to consider whether the differential treatment identified nevertheless 
stems exclusively from a legitimate regulatory distinction. 
7.5.2.5.2  Whether the detrimental impact  caused by the different tracking and 
verification requirements stem exclusively from a legitimate regulatory distinction 
7.384.  Having found above that the different trac king and verification requirements modify the 
conditions of competition in the United States tuna market to the detriment of Mexican tuna and tuna products, the Panel now turns to consider whether this detrimental impact stems exclusively 
from a legitimate regulatory distinction. 
                                               
596 These notification requirements apply to trans-sh ipment at sea. The notifi cation requirements for 
trans-shipment at port are listed in Annex II, and are identical in all relevant respects, except that 48 hours' notice must be given, instead of the 24 required for trans-shipping at sea. 
597 See Indian Ocean Tuna Commission, "Resolution 12/05 Establishing a Prog ramme for Transhipment 
by Large-Scale Fishing Vessels (2012) (Exhibit US-138), Annex III. 
598 Inter-American Tropical Tuna Commission, "Resolut ion on Establishing a Program for Transshipments 
by Large-Scale Fishing Vessels" (Res. C-08-02, 2008) (Exhibit US-153). 
599 International Commission for the Conservation of Atlantic Tunas, "Recommendation by ICCAT on a 
Programme for Transshipment" (Rec. 1206, 2012) (Exhibit US-154). 
600 Commission for the Conservation of Southern Bl uefin Tuna, "Resolution for Establishing a Program 
for Transshipment by Large-Scale Fi shing Vessels" (Adopted at the 15th Annual Meeting, 14-17 October 2008) 
(Exhibit US-155). 
601 As we explained above, we do not here make a de finitive finding that tuna caught outside the ETP 
large purse seine fishery would in  fact be incorrectly labelled. WT/DS381/RW 
 
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  7.5.2.5.2.1  Argume nts of the parties 
7.385.  As was the case in the context of the different certification requirements, Mexico's central 
argument on the different tracking an d verification requirements is that:602 
[T]he record-keeping and verification requirements for tuna caught inside the ETP are 
comprehensive and accurate. However, the requirements and procedures for tracking 
and verifying tuna caught outside the ETP are unreliable and do not provide accurate information on the dolphin-safe status of the tuna products comprising this tuna. 
Thus, US consumers are not receiving accurate information on such tuna products and 
could be misled or deceived … In this light, the difference in record-keeping and verification requirements for tuna caught inside and outside the ETP does not bear a rational connection to the objectives of the Amended Tuna Measure. 
7.386.  Thus, according to Mexico, because "[a]ccurate information is being provided on tuna 
caught in the ETP but not on tuna caught in other fisheries … the measure is clearly not even-handed".
603 
7.387.  The United States urges the Panel to reject Mexico's arguments. According to the 
United States: 
[T]he record-keeping and verification re quirements imposed by the challenged 
measure are entirely even-handed as to Mexican producers vis-à-vis  tuna producers 
from the United States and other Members. These requirements are, in fact, entirely neutral as to the nationality of the vessel and origin of the tuna product … To the extent that the regulations draw other dist inctions, they do so not between Members, 
or even the fishing methods of Members, but rather between tuna caught by AIDCP-
covered large purse seine vessels and tuna caught by all other vessels.
604 
7.388.  In the opinion of the United States, "[t]he mere fact that the US measure acknowledges 
the AIDCP requirements cannot be considered legally problematic".605 Indeed, as the United States 
sees it, "a Member does not act inconsistently with its WTO obligations by applying domestic measures that reflect the international agreements (or lack thereof) of different Members".
606 
Moreover, "[t]he fact that Mexico may consider that the US law imposes insufficient requirements 
and procedures for non-AIDCP-covered large purse seine vessels is entirely beside the point". In the view of the United States: 
The Appellate Body's legitimate regulatory distinction analysis is not meant to be a 
vehicle for any and all criticisms of the challenged measure that the complainant sees 
fit to make. Indeed, the sixth preambular re cital of the TBT Agreement recognizes that 
a Member shall not be prevented from taking measures necessary to achieve its 
legitimate objectives at the levels it considers appropriate … The fact that Mexico 
considers the level of record-keeping and verification the amended measure provides 
to be insufficient is simply irrelevant to Mexico's claim of discrimination.
607 
7.5.2.5.2.2  Analysis by the Panel 
7.389.  As we have done previously, we begin our present analysis by recalling that, according to 
the allocation of the burden of pr oof advanced by the parties and accepted by the Panel, it is for 
Mexico to show,  prima facie  and in the first instance, that the different tracking and verification 
requirements are not even-handed, because, for example, th ey reflect discrimination. Only if 
Mexico makes this showing will the burden shift to the United States to show that the different tracking and verification requirements in fact stem exclusively from a legitimate regulatory 
distinction. 
                                               
602 Mexico's first written submission, para. 275. 
603 Mexico's first written submission, para. 280. See also Mexico's second written submission, para. 147. 
604 United States' first written submission, para. 243. 
605 United States' first written submission, para. 245. 
606 United States' first written submission, para. 251. 
607 United States' first written submission, para. 249 (emphasis original). WT/DS381/RW 
 
- 104 - 
 
  7.390.  We also recall again that, in our understanding of the legal test under Article 2.1 of the 
TBT Agreement, the extent to which a particular in stance of detrimental treatment is reconcilable 
with or explicable by reference to the objectives pursued by a challenged measure may be a relevant consideration in the assessment whether that detrimental treatment stems exclusively 
from a legitimate regulatory distinction.  
7.391.  In the preceding section of this Report, the Panel dealt in some detail with the evidence 
submitted by both parties concerning the tracking and verification systems imposed by the 
amended tuna measure on tuna caught other than  by large purse seine vessels in the ETP. We 
concluded that the different tracking and verification requirements have a detrimental impact on Mexican tuna and tuna products, including because they may make it more likely that tuna caught other than by large purse seine vessel will be incorrectly labelled as dolphin-safe. This incorrect 
labelling would accord a competitive advantage to non-Mexican tuna products.  
7.392.  With respect to the second tier of Articl e 2.1 of the TBT Agreement, the Panel finds that 
Mexico has shown prima facie that there is no rational connection between the different burden 
created by the tracking and verification requir ements and the objectives of the amended tuna 
measure. We accept,  prima facie , Mexico's argument that there is no obvious connection between 
the imposition of a lighter burden on tuna caught  outside the ETP large purse seine fishery and the 
goals of the amended tuna measure.  Accordingly, Mexico has shown, prima facie , that the 
detrimental treatment does not stem exclusively from a legitimate regulatory distinction.  
7.393.  The United States attempts to rebut this showing in three ways: first, by pointing out that 
the different tracking and verification requirements  are origin neutral; second, by arguing that the 
amended tuna measure simply reflects international commitments undertaken by Mexico and the 
United States; and third, by submitting that Me mbers have the right to achieve their legitimate 
objectives "at levels they consider appropriate". We consider each of these arguments in turn. 
7.394.  The Panel begins by noting that it has dealt with the question of origin neutrality in the 
preceding section of its Report.
608 In the Panel's view, the fact that the measure is origin neutral 
on its face does not respond to Mexico's core alle gation that the different tracking and verification 
requirements lack even-handedness because the de trimental impact they cause is not reconcilable 
with the objectives of the amended tuna measure. That the measure does not distinguish, at least on its face, between tuna caught by different Members does not explain or otherwise justify why the different tracking and verification requiremen ts impose a lighter compliance burden on tuna 
caught other than in the ETP large purse seine fishery. It does not shed light on any possible 
connection between the detrimental impact caused by the different tracking and verification requirements and the measure's objectives.  
7.395.  Quite simply, the origin neutrality of the measure is not responsive to the point that the 
different tracking and verification requirements are inconsistent with the objectives pursued by the amended tuna measure. A technical regulation may very well be origin neutral; but where, under 
Article 2.1 of the TBT Agreement, it is found to de facto  modify the conditions of competition to the 
detriment of imported products, that detrimental treatment must stem exclusively from a legitimate regulatory distinction. And where a complainant has shown prima facie  that the 
detrimental treatment is not reconcilable with or explicable on the basis of one or more of the 
objectives pursed by the challenged technical regulation, the mere fact that the regulation is origin 
neutral cannot preclude a finding of violation of Article 2.1.  
7.396.  We turn next to the United States' justification that the different tracking and verification 
requirements simply reflect international commitments undertaken by the United States and 
Mexico. We have addressed this issue above in the context of the question whether there is a "genuine connection" between the amended tuna measure and the various instances of 
detrimental impact complained of by Mexico.
609 
7.397.  In the Panel's view, the United States' arguments on this point must be rejected. There is, 
of course, nothing wrong with the United States legislating or regulating to give effect to its various international obligations. The question be fore us, however, is not whether the amended 
tuna measure accurately reflects or implements the United States' international obligations, but 
                                               
608 See para. 7.75 above. 
609 See paras. 7.171-7.179 above. WT/DS381/RW 
 
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  rather whether the detrimental impact identified by Mexico stems exclusively from a legitimate 
regulatory distinction. In answering this question, the fact that the United States may or may not have international obligations vis-à-vis  Mexico or any other Member is, in our view, not relevant. 
This is because it is not responsive to Mexico's key allegation, namely, that the different tracking 
and verification requirements are not justifiable on the basis of the amended tuna measure's own 
objectives. That the United States is not required under any international agreement other than the AIDCP to enforce any particular system of tracking and verification is not an explanation or 
justification of why the amended tuna measure contains a regulatory distinction whose effect is to 
impose a significantly lighter compliance burden on tuna caught in one fishery than on tuna caught in others. The existence of the AIDCP may explain why tuna caught by large purse seine vessels in the ETP is subject to a certain tracking and verification regime, but it does not explain why the 
system imposed by the United States outside  of that fishery is less burdensome.  
7.398.  The Panel also does not accept the United States' claim that the tracking and verification 
requirements embodied in the AIDCP and inco rporated into the amended tuna measure are 
different because of the higher degree of risk to dolphins in the ETP. In our view, the higher risk 
posed to dolphins by setting on dolphins in the ETP does not explain why the tracking and verification requirements, which by their very nature concern the movement of fish subsequent to 
the time of catch , differ between fisheries to the detriment of like Mexican tuna and tuna products. 
The different risk profiles of different fisheries may, as we found above, explain regulatory 
differences concerning the eligibility criteria for fishing methods, as well as the need for an independent observer to monitor and certify during and immediately following the fishing activity 
itself. But tracking and verification is about what happens to tuna after it has already been caught , 
as it moves from the fishing vessel all the way to retail sale. In other words, in the Panel's view, the special risk profile of the ETP large purse se ine fishery simply does not explain or otherwise 
justify the fact that the post-catch tracking and verification mechanisms applied to tuna caught 
other than by large purse seine vessels in the ETP are significantly less burdensome. 
7.399.  Finally, the Panel recognizes that every WTO Member has the right to achieve its legitimate 
objectives at the levels it considers appropriate.
610 But this right cannot be exercised in a way that 
"would constitute a means of arbitrary or unjustifiable discrimination".611 Thus, while the 
United States is of course free to set its own level of protection, or to pursue its objectives at a level or to a degree that it considers appropriate, this is not a licence to modify the conditions of 
competition in a market to the detriment of impo rted products where such modification does not 
stem exclusively from a legitimate regulatory dist inction. In the Panel's view, the principle that 
Members may set their own appropriate levels of protection is therefore not, in itself, a complete 
response to a claim that a particular measure is inconsistent with Article 2.1 of the TBT Agreement 
because it accords less favourable treatment to imported products than to like domestic products or like products from other Members. Neither can this principle be used to preclude scrutiny of a 
measure claimed to be WTO-inconsistent.
612 
7.400.   In light of the above, we find the United States has not rebutted Mexico's prima facie  
showing that the different tracking and verification requirements do not stem exclusively from a legitimate regulatory distinction. The United States has failed to explain sufficiently why it imposes 
different tracking and verification requirements on  tuna depending on the fishery in which and the 
method by which it was caught. None of the explanations provided by the United States suggests a connection between the detrimental treatment and the policy objectives pursed by the amended 
tuna measure. Accordingly, we find that the different tracking and verification requirements accord 
less favourable treatment to Mexican tuna products than to like tuna products from the United States and other WTO Members in contravention of Article 2.1 of the TBT Agreement. 
7.401.  The Panel emphasizes that in making the above finding, it is not suggesting that there 
could not be a reason why the United States might impose different tracking and verification 
requirements on different tuna and tuna produc ts. An even-handed tracking and verification 
                                               
610 Cf United States' first written submission, para. 249. 
611 TBT Agreement, sixth preambular recital. 
612 Additionally, and without wishing to make any express findings on this issue, the Panel notes that, in 
the context of the TBT Agreement, the concept of "appropriate level of protec tion" has only been referred to by 
the Appellate Body in the course of analysis under Ar ticle 2.2. The Appellate Body has not, to date, made 
reference to the concept in an analysis  under Article 2.1. The extent to which this concept is directly relevant 
to the Article 2.1 analysis remains, therefore, an open question, but one on which we do not need to rule in the present proceedings. WT/DS381/RW 
 
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  system may well take into account the different circumstances that different tuna faces as it 
moves from the shipping vessel to the point of retail. In the present case, the Panel's point is simply that, in the absence of a sufficient explanation as to how the United States is able to verify the various movements of tuna from the point of catch to the point of receiving the label, the 
United States has not rebutted Mexico's showing that the system currently in place under the 
amended tuna measure is not even-handed, and therefore does not stem exclusively from a 
legitimate regulatory distinction. 
7.402.  Before concluding, we note that if the burden of proof were to be allocated as suggested 
by some of the third-parties, our finding woul d be the same. Having found that the different 
tracking and verification requirements modify the conditions of competition to the detriment of Mexican tuna and tuna products, we would proceed to find, for the reasons explained above that 
the United States has not made a prima facie  case that the different tracking and verification 
requirements stem exclusively from a legitimate regulatory distinction.  
7.6  Claims under the GATT 1994 
7.403.  The Panel now turns to consider Mexico's claims under the GATT 1994. 
7.6.1  Article I:1 of the GATT 1994 7.6.1.1  Legal test 
7.404.  Article I:1 of the GATT 1994 relevantly provides: 
With respect to all matters referred to in paragraphs 2 and 4 of Article III, any 
advantage, favour, privilege or immunity granted by any contracting party to any product originating in or destined for any other country shall be accorded immediately 
and unconditionally to the like product originating in or destined for the territories of 
all other contracting parties. 
7.405.  The following elements must be demonstrated to establish an inconsistency with 
Article I:1: 
(i) that the measure at issue falls within the scope of application of Article I:1; (ii) that 
the imported products at issue are "like" pr oducts within the meaning of Article I:1; 
(iii) that the measure at issue confers an "advantage, favour, privilege, or immunity" 
on a product originating in the territory of any country; and (iv) that the advantage so accorded is not extended "immediately" and "unconditionally" to "like" products originating in the territory of all Members.
613 
7.406.  There has been little debate in WTO disputes  about the types of measures that fall within 
the ambit of Article I:1. Both panels and the Appe llate Body have held that Article I:1 covers a 
broad range of measures. 
7.407.  With respect to the meaning of "like products", the Panel notes that this concept is not 
defined in the GATT 1994, and case law on the meaning of "like products" in the context of Article I:1 is not extensive. The concept has been discussed more often in the context of Article III 
of the GATT 1994. In the context of the first sent ence of Article III:2 of the GATT 1994 and of 
Article III:4 of the GATT 1994, the Appellate Body ha s explained that the determination of whether 
products are "like products", is fundamentally, a determination about the nature and extent of a 
competitive relationship between and among products.
614 
7.408.  Furthermore, the Appellate Body has expl ained that in determining whether products are 
"like", a panel must examine on a case-by-case basis all relevant characteristics of the products at issue, including (i) the products' properties, nature and quality, i.e. their physical characteristics; 
                                               
613 Appellate Body Reports, EC – Seal Products , para. 5.86. 
614 Appellate Body Report, EC- Asbestos , para. 99. See also Appellate Body Reports, Philippines – 
Distilled Spirits , para. 170. WT/DS381/RW 
 
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  (ii) the products' end-uses; (iii) consumers' tastes and habits, also referred to as consumers' 
perceptions and behaviour, in respect of the products; and (iv) the products' tariff classification.615 
7.409.  The Panel believes that it is not unreasonable to consider that previous interpretations of 
the concept of "like products" under Article III of  the GATT 1994 should inform our interpretation 
of the concept of "like products" in the context of Article I:1 of the GATT 1994. 
7.410.  With respect to third element - that is, whether the measure at issue confers an 
"advantage, favour, privilege or immunity" - the Panel notes that relevant case law has given a 
broad interpretation to the term "advantage[s]". In EC — Bananas III , the Panel considered that 
"advantage[s]" in the sense of Article I:1 of the GATT 1994 are those advantages that create 
"more favourable import opportunities" or affect the commercial relationship between like products of different origins.
616 
7.411.  In Canada – Autos , the Appellate Body also clarified that the words of Article I:1 refer not 
to some advantages granted "with respect to" the subjects that fall within the defined scope of the Article, but to "any advantage"; not to some products, but to "any product"; and not to like 
products from some other Members, but to like products originating in or destined for "all other 
Members".
617 
7.412.  As for the fourth and final element, namely  the question whether an advantage is accorded 
"immediately" and "unconditionally" to all like products originating in the territory of all Members, 
the Panel notes that there has been little debate in past disputes on the meaning of the term 
"immediately". The Panel understands the term to mean "without delay", "at once" and "instantly".
618 
7.413.  The Panel notes that in past disputes, panels have interpreted the term "unconditionally" in 
different ways. For instance, the panel in Indonesia – Autos  ruled that "unconditionally" means 
that the advantage cannot be made conditional on any criteria that are not related to the imported 
product itself.619 The panel in Canada – Autos  held that whether conditions attached to an 
advantage granted in connection with the importation of a product offend Article I:1 depends upon whether such conditions discriminate with respect to the origin of products.
620 In EC – Tariff 
Preferences , the panel concluded that the term should be given its ordinary meaning under 
Article I:1, that is, "not limited by or subject to any conditions".621 In Columbia – Ports of Entry , 
the panel reverted to the interpretation developed by the Appellate Body in Canada – Autos , that 
is, that conditions attached to an advantage granted in connection with the importation of a 
product will violate Article I:1 when such conditions discriminate with respect to the origin of 
products.622 
7.414.  In EC – Seal Products , the Appellate Body had occasion to clarify the meaning of the terms 
"immediately" and "unconditionally": 
Under Article I:1, a Member is proscribed from granting an "advantage" to imported 
products that is not "immediately" and "unconditionally" extended to like imported 
products from all Members. This means, in our view that any advantage granted by a 
Member to imported products must be made available "unconditionally", or without 
conditions , to like imported products from all Members. However, as Article I:1 is 
concerned, fundamentally, with protecting expectations of equal competitive 
opportunities for like imported products from all Members, it does not follow that 
Article I:1 prohibits a Member from attaching any conditions to the granting of an 
"advantage" within the meaning of Article I:1. Instead, it prohibits those conditions 
that have a detrimental impact on the competitive opportunities for like imported 
products from any Member. Conversely, Article I:1 permits regulatory distinctions to 
                                               
615 Appellate Body Report, Japan – Alcoholic Beverages II , p. 20, DSR 1996:I, p. 97 at 113. 
616 Panel Report, EC – Bananas III , para. 7.239. 
617 Appellate Body Report, Canada – Autos , para. 79. 
618 Shorter Oxford Dictionary , 6th edn (Oxford University Press, 2007), Vol. 1, p. 1330. 
619 Panel Report, Indonesia – Autos , paras. 14.145–14.147. 
620 Panel Report, Canada – Autos , para. 10.29. 
621 Panel Report, EC – Tariff Preferences , para. 7.59. 
622 Panel Report, Columbia – Ports of Entry , para. 7.366. WT/DS381/RW 
 
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  be drawn between like imported products, provided that such distinctions do not result 
in a detrimental impact on the competitive opportunities for like imported products from any Member.
623  
7.415.  In the Panel's view, this passage clearly indicates that benefits accruing under a measure 
must be accorded straight away, and without co nditions, to all WTO Members, except where the 
conditions imposed do not modify the competitiv e opportunities of imported products in the 
relevant market. Where, however, the conditions do modify the conditions of competition to the 
detriment of imported products, the mere fact that those conditions do not directly target the 
origin of imported products cannot prevent a finding of violation under Article I:1 (although that fact may be relevant in the context of assessing a defence under Article XX).  
7.416.  Thus, in determining whether the amende d tuna measure extends any benefit it offers 
"immediately and unconditionally" to all Members, the Panel will first consider what benefit, if any, 
is accorded by the amended tuna measure. It will then proceed to determine whether the benefit(s) (if any) is or are accorded to all Members without condition, or, if conditions are 
imposed, whether these conditions modify the competitive opportunities in the United States' 
market to the detriment of like Mexican tuna and tuna products. 
7.6.1.2  Application 
7.6.1.2.1  Arguments of the parties 
7.417.  Mexico argues that the amended tuna me asure is inconsistent with Article I:1 of the 
GATT 1994. Specifically, Mexico argues that access to the dolphin-safe label is an advantage, and that this advantage is not accorded immediately and unconditionally to the like tuna products 
originating in the territories of all other WTO Members, including Mexico.
624 
7.418.  Mexico argues that in the context of its "treatment no less favourable" analysis under 
Article 2.1 of the TBT Agreement, it has demonstr ated that the conditions and requirements set 
forth in the amended tuna measure result in de facto  detrimental impact on the competitive 
opportunities for like Mexican tuna products in the United States market vis-à-vis  like imported 
tuna products originating in other countries, by effectively denying the advantage of access to the 
dolphin-safe label to tuna products of Mexican origin.625 
7.419.  Mexico also notes that, in the original pr oceedings, the Appellate Body found that the lack 
of access to the advantage of the dolphin-safe label for tuna products containing tuna caught by setting on dolphins had a detrimental impact on the competitive opportunities of Mexican tuna 
products in the US market because it had the effect of denying eligibility to most Mexican tuna 
products while granting eligibility to most tuna products from the United States and other Members. In Mexico's view, these findings appl y equally to the amended tuna measure. Mexico 
argues that nothing in the amended tuna meas ure has reduced or minimized the detrimental 
impact on imported Mexican tuna products caused by the regulatory distinction created in the original tuna measure; rather, the regulatory distinction remains substantially the same, and, as a 
consequence, tuna products of Mexican origin co ntinue to be effectively excluded from the US 
market.
626 
7.420.  The United States argues that Mexico fails to establish that the amended tuna measure is 
inconsistent with Article I:1 of that GATT 1994.627 
7.421.  The United States also argues that Mexico's claim under Article I:1 of the GATT 1994 
relates only to the eligibility criteria, and that Mexico makes no claim in respect of any other 
                                               
623 Appellate Body Reports, EC – Seal Products , para. 5.88 (emphasis original) (internal citations 
omitted). 
624 Mexico's first written submission, para. 315. 
625 Mexico's first written submission, para. 315, referring to Section IV. B.3.a (2) of the submission; 
Mexico's second written submission, para. 202. 
626 Mexico's second written submission, para. 203. 
627 United States' first written submission, para. 277. WT/DS381/RW 
 
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  requirements of the amended measure, including those related to certification and tracking and 
verification.628 
7.422.  The United States emphasizes that, with re gard to the access to the dolphin-safe label, no 
tuna product of a Member has a right  to the label. The United States elaborates that no product 
(whether of US, Mexican, or any other origin) is entitled  to be labelled dolphin-safe under US law; 
rather, the advantage is subject to eligibility requirements that all tuna products must meet in order to access the label. These conditions are: (1) that no purse seine net was intentionally 
deployed on or used to encircle dolphins during the fishing trip in which the tuna was caught; and 
(2) that no dolphins were killed or seriously injured in the sets or other gear deployments in which the tuna were caught.
629 
7.423.  Furthermore, the United States stresses that the original panel made no findings under 
Article I:1 of the GATT 1994, and that therefor e "one should now undertake an objective 
assessment of the matter, namely the facts of th e dispute and the relevant provisions" in the 
context of that provision.630 
7.6.1.2.2  Analysis by the Panel 
7.424.  The Panel notes that the parties agree th at the amended tuna measure satisfies the first 
three elements for finding an inconsistency under Article I:1 of the GATT 1994, i.e. that the 
amended tuna measure falls within the scope of application of Article I:1; that Mexican tuna 
products and tuna products originating in other countries are like imported products within the meaning of Article I:1; and that access to the dolphin-safe label is an "advantage, favour, 
privilege, or immunity" conferred by the amende d tuna measure on the US market. The parties 
disagree, however, in respect of the application of the fourth and final element of the legal test, 
that is, as to whether the advantage of access to the dolphin-safe label is accorded "immediately and unconditionally" to like products originating in the territories of all WTO Members.
 631 
7.425.  Before proceeding, the Panel recalls that it is for Mexico, as the complaining party, to 
make a prima facie case that the amended tuna measure is inconsistent with Article I:1 of the 
GATT 1994. 
7.426.  As mentioned above, the fourth element of  the legal test of Article I:1 of the GATT 1994 
requires a panel to determine whether any conditions are imposed on the access of some Members to an advantage accorded by a measure. If a ccess is conditioned, the panel must proceed to 
consider whether those conditions modify the competitive opportunities of the complaining 
Members in the relevant market. We will therefore review whether, as Mexico alleges, access to 
the dolphin-safe label is subject to conditions, and if so, whether these conditions result in a detrimental impact on competitive opportunities for like Mexican tuna and tuna products. 
7.427.  At the outset, the Panel considers it is nece ssary to clarify the scope of the elements of the 
amended tuna measure that should be examined in  the context of Article I:1 of the GATT 1994. As 
the Panel noted above, the United States argues that Mexico's claim relates only to what we have 
called the eligibility criteria – that is, the per se  disqualification of tuna caught by setting on 
dolphins from accessing the label, and the in-principle qualification of tuna caught by all other fishing methods subject to certain requirements. In the view of the United States, Mexico has made no claim in respect of any other requirements of the amended measure, including those 
related to certification and tracking and verification.
632 
7.428.  In its responses to a question from the Panel, Mexico clarified that its claims under 
Articles I and III of the GATT 1994 relate to both the eligibility criteria and the different 
certification and tracking and verification requirements imposed on the ETP large purse seine 
fishery. Mexico argues that the amended tuna measure in its totality is inconsistent with Articles I:1 and III:4 of the GATT 1994, and explains that this inconsistency arises from the 
                                               
628 United States' first written submission, para. 277. 
629 United States' first written submission, para. 280. 
630 United States' second written submission, para. 133. 
631 Mexico's first written submission, paras. 310–314, referring to Appellate Body Report, US – Tuna II 
(Mexico), paras. 233 -235; United States' first written submission, para. 279. 
632 United States' first written submission, para. 277. WT/DS381/RW 
 
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  detrimental impact on the competitive opportunities of Mexican tuna products caused by the 
relevant regulatory distinction under the amended tuna measure.633 
7.429.  In its comments on Mexico's response, the United States contends that Mexico initially 
argued that the amended tuna measure violates Ar ticle I:1 of the GATT 1994 only with respect to 
the eligibility criteria, and not with respect to the different certification or tracking and verification 
requirements. In the view of the United States, Mexi co's response to the Panel's question alters its 
argument by alleging that its claim is not limite d to "access" to the label, but rather encompasses 
the alleged differing requirements for certification and tracking and verification imposed in the ETP 
large purse seine fishery. The United States argues that despite broadening its claim, Mexico has not made a similar adjustment to its evidence, and accordingly fails to prove its allegations.
634  
7.430.  The Panel notes that in its first written submission, Mexico explains that its claim under 
Article I:1 relates to the "differences in the labelling conditions and requirements".635 The Panel 
considers that Mexico's response to the Panel's question clarifies the scope of its claim under Article I:1 of the GATT 1994 by confirming  that it relates not only to the ineligibility of tuna caught 
by setting on dolphins to access the label, but also to the different certification and tracking and 
verification requirements, which, in Mexico's view, are additional "conditions" whose application to tuna caught by large purse seine vessels in the ETP means that the benefit of access to the label is 
not extended "unconditionally" to Mexican tuna products, as required under Article I:1 of the 
GATT 1994.
636 Therefore, similar to the Panel's approach in its analysis above under Article 2.1 of 
the TBT Agreement, the Panel will examine all thre e of the regulatory differences in the labelling 
conditions and requirements identified by Mexico: first, the eligibility criteria; second, the different 
certification requirements; and third, the different tracking and verification requirements. 
7.431.  The United States stresses that Article 2.1 of the TBT Agreement has different language 
from that of Article I:1 of the GATT 1994, and that it requires a distinct inquiry.637 For the Panel, 
this raises the question whether it is appropriate for the Panel to rely on factual findings made 
under Article 2.1 of TBT Agreement in the context of analysing Mexico's claims under Article I:1 of the GATT 1994. 
7.432.  The Appellate Body has determined that Article 2.1 of the TBT Agreement and Article I:1 of 
the GATT 1994 embody different legal standards.
638 As the Panel understands it, however, the key 
difference between these two provisions is that, whereas Article I:1 requires only an analysis of 
whether the conditions attached to an advantage detrimentally impact the competitive 
opportunities of imported products in the rele vant market, Article 2.1 of the TBT Agreement 
requires an additional consideration of whether any detrimental impact nevertheless stems 
exclusively from a legitimate regulatory distinction.639 This second element is not present in the 
legal test under Article I:1, and accordingly, as the Appellate Body has said, it is not appropriate to 
conflate the two provisions. 
7.433.  Having said that, we note that the focus under Article I:1 on the question whether 
conditions imposed on access to an advantage modify the conditions of competition to the 
detriment of imported like products is similar to the first part of the analysis under Article 2.1 of the TBT Agreement, which similarly looks to the effect of a measure on the competitive 
opportunities of imported products. In light of this similarity, the Panel thinks it is appropriate to 
have regard to the factual findings we made in the context of the first part of our analysis under 
Article 2.1 of the TBT Agreement when consider ing Mexico's claims under Article I:1 of the 
GATT 1994.  
7.434.  The Panel also notes that Mexico refers to its factual allegations under Article 2.1 of the 
TBT Agreement in support of its argument under Article I:1 of the GATT 1994.
640 We see no reason 
why factual findings made under Article 2.1 of the TBT Agreement could not be relevant under 
                                               
633 Mexico's response to Panel question No. 9, paras. 35-36. 
634 Comments by the United States to Mexico's responses, paras. 25-26. 
635 Mexico's first written submission, para. 313; Mexico's second written submission, para. 203. 
636 Mexico's response to Panel question No. 10, paras. 37-39. 
637 United States' second written submission, para. 133. 
638 Appellate Body Reports, EC – Seal Products , para. 5.94. 
639 Appellate Body Reports, EC – Seal Products , para. 5.93. 
640 See Mexico's second written submission, para. 202. WT/DS381/RW 
 
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  Article I:1 of the GATT 1994 where, as is the case here, the factual allegations relied upon to 
establish a violation of both provisions are essentially the same. While the legal import of those factual findings may change depending on the term s of the particular provision being considered, 
there is no reason why the factual findings themse lves should change. Indeed, in our view, a panel 
that reached different factual conclusions in different parts of its report on the basis of the same 
factual allegations may not be making an "objective assessment" of the matter as required under Article 11 of the DSU.  
7.6.1.2.2.1  Whether the eligibility criteria and the different certification and tracking 
and verification requirements are "conditions" for the purposes of the Article I:1 of the 
GATT 1994 
7.435.  The first question that the Panel must address is whether the eligibility criteria and the 
different certification and tracking and verification requirements are "conditions" within the 
meaning of Article I:1 of the GATT 1994. Put another way, we need to determine whether these criteria and requirements "condition" Mexico's access to the benefit of the dolphin-safe label, 
which, as we have found above, has a commercial advantage on the US tuna market. This is so 
because, as the Appellate Body made clear in EC – Seal Products , Article I:1 of the GATT 1994 is 
not concerned with the question whether a measure  as a whole  modifies the conditions of 
competition; rather, "the legal standard under Article I:1 … is expressed through an obligation to 
extend any 'advantage' granted by a Member to any product originating in or destined for any 
other country 'immediately and unconditionally' to the 'like product' originating in or destined for all other Members".
641 The focus of our analysis is thus on the existence of conditions  that limit or 
otherwise affect the access of imported products from some Members to a benefit accorded by a 
measure.  
7.436.  We begin by noting that the parties appear to have different views as to the type of 
condition that is relevant under Article I:1 of the GATT 1994. Mexico seems to believe that 
Article I:1 concerns the imposition of any conditions on access to a benefit, even if these 
conditions are applied to all WTO Members in a facially non-discriminatory manner. For Mexico, the 
sole question for the Panel is whether the conditio ns actually imposed on access to a benefit "have 
a detrimental impact on the competitive opportunities for like imported products from any 
Member".642  
7.437.  In contrast, the United States' position seems to be that Article I:1 is not directed towards 
conditions that are uniform and impartial, and that do not apply on the basis of nationality.643 
Thus, in the context of the present dispute, the Un ited States argues that while the amended tuna 
measure lays down conditions which must be satisfied before access to the dolphin-safe label is 
granted, "[t]he eligibility criteria – and therefore the opportunity  for the label – are the same for 
everyone".644 Accordingly, the conditions in no way upset the "equality of competitive 
opportunities for like imported products".645 
7.438.  In the Panel's view, it is clear that Article I:1 of the GATT 1994 allows, at least in principle, 
advantages to be conditioned on the satisfaction of certain criteria. One such criterion is the likeness of products: extending a particular advantage only to "like" products clearly would not violate the provision. Moreover, because only those conditions that upset the equality of 
competitive opportunities are proscribed under Article I:1 of the GATT 1994, the imposition of 
neutral conditions applicable equally to all like products may be consistent with Article I:1. To find that any condition on access to a benefit necessarily and automatically falls foul of Article I:1 
would not be consistent with the provision's overarching aim, which is "prohibiting discriminatory  
measures".
646  
7.439.  Nevertheless, in our view, the fact that conditions on accessing an advantage are facially 
non-discriminatory is not a complete response to an allegation that certain conditions upset the 
competitive opportunities of imported products, since such conditions may nevertheless have a 
                                               
641 Appellate Body Reports, EC – Seal Products , para. 5.81 (emphasis original). 
642 Mexico's second written submission, para. 200 (emphasis original) (internal citations omitted). 
643 United States' first written submission, para. 283. 
644 United States' first written submission, para. 288. 
645 United States' first written submission, para. 281. 
646 Appellate Body Reports, EC – Seal Products , para. 5.82 (emphasis added). WT/DS381/RW 
 
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  de facto  impact on competitive equality. Thus, while the mere existence of neutral conditions 
applicable to all like products does not in itself  give rise to an automatic violation of Article I:1, 
neither does it prevent a panel from carefully scrutinizing the conditions and other relevant circumstances to determine whether the conditions detrimentally impact the competitive 
opportunities of some imported like products de facto .  
7.440.  Thus, the mere fact that "the eligibility criteria … are the same for everyone" does not 
mean that they are automatically consistent with  Article I:1 of the GATT 1994. Rather, we must 
consider whether, even despite their general app lication, they modify the equality of competitive 
opportunities to the detriment of some like imported products. 
7.441.  The Panel also notes that, while the eligibi lity criteria apply to all imported (and, we would 
add, domestic) tuna products, the different tracking and verification requirements explicitly impose 
different conditions on tuna caught by large purse seine vessels in the ETP. Such tuna must meet 
additional documentary (that is, certification and tracking and verification) requirements before being able to access to the dolphin-safe label. These conditions do not  apply "to everyone". As 
such, while they may not fall foul of Article I:1 if they "do not result in a detrimental impact on the 
competitive opportunities for like imported products" from Mexico,
647 they seem to us clearly to be 
the type of "condition" that must be assessed under Article I:1. 
7.442.  As such, the Panel finds that the eligibility criteria and the different certification and 
tracking and verification requirements are "conditions" imposed on accessing the dolphin-safe label. The advantage of accessing the label is thus  not accorded "unconditionally". That, however, 
is not the end of our inquiry. Rather, we now proceed to consider whether the conditions modify 
the equality of competitive opportunities  for like products from any Member. 
7.6.1.2.2.2  Whether the eligib ility criteria modify the conditions of competition in the 
US tuna market to the detriment of Mexican tuna and tuna products 
7.443.  The Panel recalls that in the original proceedings, the panel found that because there is 
"limited demand for non-dolphin-safe tuna products" in the United States market
648, and because 
"the only means through which dolphin-safe status can be claimed" is via the dolphin-safe label 
regulated by the tuna measure649, "[a]n advantage is … afforded to products eligible for the 
label".650 The panel concluded that access to the label "has a significant commercial value on the 
US market for tuna"651, and that denial of such access could "place Mexican tuna products at a 
disadvantage on the US market".652 The United States did not contest this finding on appeal.653 
Although the original panel found that the detrimental commercial impact of the disqualification of 
tuna caught by setting on dolphins was "primarily the result of 'factors or circumstances unrelated to the foreign origin of the product', including the choices made by Mexico's own fishing fleet and 
canners"
654 and so not attributable to the tuna measure, the Appellate Body reversed this, and 
held that "it is the governmental action in the fo rm of adoption and application of the US 'dolphin-
safe' labelling provisions that has modified the conditions of competition in the market to the 
detriment of Mexican tuna products".655 The Appellate Body accordingly concluded that "the lack of 
access to the 'dolphin-safe' label of tuna products containing tuna caught by setting on dolphins has a detrimental impact on the competitive opportunities of Mexican tuna products in the 
                                               
647 Appellate Body Reports, EC – Seal Products , para. 5.88. 
648 Panel Report, US – Tuna II (Mexico) , para. 7.286. 
649 Panel Report, US – Tuna II (Mexico) , para. 7.289. 
650 Panel Report, US – Tuna II (Mexico) , para. 7.287. 
651 Panel Report, US – Tuna II (Mexico) , para. 7.289. 
652 Panel Report, US – Tuna II (Mexico) , para. 7.284. 
653 Appellate Body Report, US – Tuna II (Mexico) , para. 233. 
654 Panel Report, US – Tuna II (Mexico) , para. 7.378. The Panel had earlier found in para. 7.377 "that 
the measures at issue, in applying the same origin neut ral requirement to all tuna products, do not inherently 
discriminate on the basis of the origin of the products , and they also do not make  it impossible for Mexican 
tuna products to comply with this requirement". 
655 Appellate Body Report, US – Tuna II (Mexico) , para. 239. WT/DS381/RW 
 
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  US market".656 The Appellate Body further concluded that "it is the measure at issue that modifies 
the competitive conditions in the US market to the detriment of Mexican tuna products".657  
7.444.  In the context of its claim under 2.1 of the TBT Agreement, Mexico argues that "[t]he 
features of the relevant market remain unchanged" from those prevailing at the time the original 
case was decided.658 According to Mexico, "virtually all of Mexico's purse seine tuna fleet continues 
to fish in the ETP by setting on dolphins and is therefore fishing for tuna that would not be eligible to be contained in a dolphin-safe tuna product under the Amended Tuna Measure".
659 And because 
"US retailers and consumers are sensitive to the dolphin-safe issue, and tuna products labelled 
'dolphin-safe' have an advantage in the marketplace"660, Mexico contends that its tuna products 
"continue to be effectively excluded from the US market"661, which "has a detrimental impact on 
the competitive opportunities of Mexican tuna products in the US market".662 
7.445.  Mexico contrasts the situation facing its own tuna and tuna products with that facing tuna 
products made with tuna caught by the United States and other WTO Members. Mexico explains that "[t]he US tuna fleet continues not to fish in the ETP", and that the fishing fleets of other WTO 
Members are operating in different (i.e. non-ETP)  oceans or within the ETP but using fishing 
methods other than setting on dolphins. Mexico accordingly concludes that "virtually all tuna caught by US vessels"
663 and "most tuna products from other countries"664 are potentially eligible 
for the label"665, while "most tuna caught by Mexican vessels … would not be eligible for inclusion 
in a dolphin-safe product under the US dolphin-safe labelling provisions".666 
7.446.  The Panel also recalls that in the context of Mexico's claim under Article 2.1 of the 
TBT Agreement, the United States did not deny that  the disqualification of tuna caught by setting 
on dolphins from accessing the dolphin-safe label resulted in de facto  detrimental treatment of 
Mexican tuna and tuna products, and neither did it submit any evidence that might cast doubt on this finding.
 667   
7.447.  In the Panel's view, in denying access to the dolphin-safe label to tuna caught by setting 
on dolphins, the amended tuna measure has the effect of denying to certain tuna and tuna products a valuable market advantage (that is, access to the dolphin-safe label). And because, as 
both parties agree and the Appellate Body found in the original proceedings, tuna and products 
made from tuna caught by large purse seine vessel in the ETP and in other fisheries are "like", the clear and necessary consequence of this finding is that the amended tuna measure does not  
accord immediately and unconditionally to all like products the benefit embodied in the US dolphin-
safe labelling regime. Accordingly, it is inconsistent with Article I:1 of the GATT 1994. 
7.448.  Before concluding, the Panel must deal with the United States' argument that with regard 
to the access to the dolphin-safe label, no tuna product of a Member has a right  to the label. The 
United States contends that no product (whether of US, Mexican, or any other origin) is entitled  to 
be labelled dolphin-safe under US law; rather, the advantage is subject to origin-neutral eligibility requirements that all tuna products must meet in  order to be labelled consistent with US law.
668 
                                               
656 Appellate Body Report, US – Tuna II (Mexico) , para. 235. 
657 Appellate Body Report, US – Tuna II (Mexico) , para. 240. The Appellate Body explained that "[t]he 
fact that the detrimental impact on Mexican tuna prod ucts may involve some element of private choice does 
not, in our view, relieve the United States of responsibility under the TBT Agreement, where the measure it 
adopts modifies the conditions of competition to the detriment of Mexican tuna products": para. 239 (citing Appellate Body Report, Korea – Various Measures on Beef , para. 146). 
658 Mexico's first written submission, para. 224. 
659 Mexico's first written submission, para. 227. 
660 Mexico's first written submission, para. 225. 
661 Mexico's first written submission, para. 231. 
662 Mexico's first written submission, para. 226. In support of these assertions, Mexico has provided 
statements from Mexican tuna producers testifying to the effects of the tuna measure on the competitive 
opportunities of Mexican tuna in the US market : Statements on Behalf of Mexican Producers 
(Exhibits MEX-89-A, MEX-89- B, and MEX-89-C) (BCI). 
663 Mexico's first written submission, para. 227. 
664 Mexico's first written submission, para. 232. 
665 Mexico's first written submission, para. 227. 
666 Mexico's first written submission, para. 227. 
667 United States' first written submission, para. 215 (citing Appellate Body Report, US – Tuna II 
(Mexico) , paras. 234-235). 
668 United States' first written submission, para. 280. WT/DS381/RW 
 
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  According to the United States, nothing prevents Mexican canneries or Mexican vessels from 
producing tuna product that would be eligible for the dolphin-safe label. Indeed, other countries that fish in the ETP, and that were in the same position as Mexico when the DPCIA was passed, have chosen to do so.
669 
7.449.  The Panel is not persuaded by the United States' argument. The Panel notes that the 
Appellate Body found in the original proceedings, in the context of its analysis under Article 2.1 of the TBT Agreement, that whether a measure comports with the "treatment no less favourable" 
requirement in Article 2.1 does not hinge on whether the imported products could somehow get 
access to an advantage, for example, by comply ing with all applicable conditions. Rather, a 
determination of whether imported products are accorded "less favourable treatment" within the meaning of Article 2.1 of the TBT Agreement calls for an analysis of whether the contested 
measure modifies the conditions of competition to the detriment of imported products. The 
Appellate Body further explained that the fact that a complainant could comply or could have complied with the conditions imposed by a contes ted measure does not mean that the challenged 
measure is therefore consistent with Article 2.1 of the TBT Agreement.
670 
7.450.  In our view, the same reasoning applies with  equal force in the context of Article I:1 of the 
GATT 1994. Where a condition attached to an ad vantage is found to detrimentally modify the 
competitive opportunities of imported like produc ts, the fact that that the disadvantaged Member 
could modify its practices so as to conform to the condition in question in no way changes the fact that the condition has upset the competitive equality that Article I:1 protects. As we understand it, Article I:1 of the GATT 1994, like Article 2.1 of  the TBT Agreement, is concerned with the 
conditions of competition as they exist, and no t as they might exist if the Member whose like 
products have suffered a detrimental impact were to somehow modify its practices. Accordingly, the fact that a Member could modify its practices to ensure that its like products conform to the 
relevant conditions and thus gain access to the benefit does not mitigate the responsibility of a 
Member for maintaining a measure that is inconsistent with Article I:1 of the GATT 1994.     
7.451.   In light of the foregoing, the Panel concludes that the eligibility criteria modify the 
conditions of competition in the US tuna market to the detriment of Mexican like tuna and tuna 
products, in violation of Article I:1 of the GATT 1994.  
7.452.  Whereas in an analysis under Article 2.1 of  the TBT Agreement, a Panel is required go one 
step further and assess and determine whether the detrimental impact stems exclusively from a 
legitimate regulatory distinction, such additional step is not necessary in the context of Article I:1 
of the GATT 1994.
671  
7.6.1.2.2.3  Whether the differe nt certification requirements modify the conditions of 
competition in the United States' market to  the detriment of Mexican tuna and tuna 
products 
7.453.  Mexico essentially relies on its argumentation in the context of Article 2.1 of the 
TBT Agreement to establish that, insofar as it imposes different certification requirements on tuna 
caught in the ETP large purse seine fishery on th e one hand, and in other fisheries on the other 
hand, the amended tuna measure is inconsistent with Article I:1 of the GATT 1994.672 
7.454.  In its analysis under Article 2.1 of the TBT Agreement, the Panel found that the different 
certification requirements modify the conditions of competition to the detriment of Mexican tuna 
and tuna products. The different conditions impose a lighter burden, in terms of proving compliance with the relevant conditions and thus accessing the dolphin-safe label, on tuna and 
tuna products made from tuna caught by large purse seine vessels outside the ETP large purse 
seine fishery than by those within it. The Panel also found merit in Mexico's allegation that the different certification requirements may make it easier for tuna and tuna products made from tuna 
                                               
669 United States' second written submission, para. 132. 
670 See Appellate Body Report, US – Tuna (II) Mexico , para. 221. 
671 See Appellate Body Reports, EC – Seal Products , para. 5.117. 
672 See Mexico's second written submission, paras. 202 and 204. WT/DS381/RW 
 
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  caught outside the ETP large purse seine fishery to be inaccurately labelled673, although it did not 
think it necessary to make a definitive finding on that point. 
7.455.  In the context of the present analysis, the Panel considers that the fact that tuna caught 
by large purse seine vessels in the ETP must be accompanied by two certifications, including one 
from an observer, whereas fish caught by other methods need only be accompanied by one 
certification (by a captain), in itself strongly suggests that the amended tuna measure imposes certain conditions on access to the dolphin-safe label on only some  tuna products in contravention 
of Article I:1. Indeed, it is difficult to conceive how a measure that imposes a certain condition on 
some like products and additional, heavier or more burdensome conditions on other like products could be considered to be non-discriminatory within the meaning of Article I:1. Bearing in mind the significant expenditure associated with observer certification, it seems clear to us that the observer 
certification requirement represents an additional "condition" that detrimentally modifies the 
competitive opportunities of like tuna and tuna products. To the extent that the absence of observer certification outside the ETP large purse seine fishery may also make it easier for tuna 
caught in those fisheries to be incorrectly labelled – a point we do not rule on definitively – the 
additional observer certification condition would further upset the equality of competitive opportunities between like tuna and tuna products.  
7.456.  In sum, we find that, insofar as it requires observer coverage for purse seine vessels in the 
ETP and does not require the same for other vessels in the ETP and other fisheries, the amended tuna measure is inconsistent with Article I:1. 
7.6.1.2.2.4  Whether the diffe rent tracking and verification requirements modify the 
conditions of competition in the United Stat es' market to the detriment of Mexican tuna 
and tuna products 
7.457.  Mexico essentially relies on its argumentation in the context of Article 2.1 of the 
TBT Agreement to establish that, insofar as it imposes different tracking and verification 
requirements on tuna caught by large purse seine vessels in the ETP and tuna not so caught, the amended tuna measure is inconsistent with Article I:1 of the GATT 1994.
674 
7.458.  The Panel recalls that, in the context of its claim under Article 2.1 of the TBT Agreement, 
Mexico did not argue that the difference in th e tracking and verification requirements in 
themselves prevents Mexican tuna from accessing the dolphin-safe label. Rather, in Mexico's view, because of "the absence of sufficient … record-kee ping [and] verification … requirements for tuna 
that is used to produce tuna products from the United States and other countries means that 
Mexican tuna products are losing competitive opportunities to tuna products that may be inaccurately labelled as dolphin-safe".
675 
7.459.  In response, the United States argued that there is no causal connection between the 
detrimental impact and the different record keep ing and tracking and verification requirements.676 
7.460.  The United States also alleged that while Mexico's claim is based on the proposition that 
"producers are disadvantaged vis-à-vis  their non-AIDCP competitors to the extent that the 
competitors are allowed to inaccurately designate their tuna products as 'dolphin safe' … whereas Mexican producers, due to the strict record-kee ping requirements of AIDCP, are not able to 
commit this same level of fraud", Mexico had put forward no evidence to support the assertion that 
the US Government and its citizens have been defrauded on an industry-wide scale for over the 
past two decades.
677 
7.461.  Finally, the United States argued that the distinction about which Mexico complains is 
"created by the AIDCP, not the US measure. Indeed, if the United States eliminated all references 
                                               
673 See paras. 7.168–7.170 above. 
674 See Mexico's second written submission, paras. 202 and 204. 
675 Mexico's second written submission, para. 117. 
676 United States' first written submission, para. 223. 
677 United States' first written submission, para. 247; United States' second written submission, 
para. 96. WT/DS381/RW 
 
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  to the AIDCP (and its requirements) from the am ended measure, the regulatory distinction that 
Mexico criticizes would still exist".678 
7.462.  In its Article 2.1 analysis, the Panel rejected the United States' arguments. It found that 
while it is true that "[w]hat US law requires is that Mexican producers provide Form 370s that list 
the AIDCP-mandated tracking number", whereas "[ t]he actual record-keeping and verification 
requirements Mexico complains of are contained in the AIDCP"679, it is nevertheless the case that 
by incorporating these AIDCP requirements into the tuna measure, the tuna measure itself creates 
a regulatory distinction that conditions access to the United States dolphin-safe label on different 
criteria depending on where and how the tuna was caught.680  
7.463.  After reviewing all the evidence before it, the Panel ultimately concluded that the system in 
place outside the ETP large purse seine fishery is less burdensome than the system inside that 
fishery, and therefore modifies the conditions of competition to the detriment of Mexican tuna and 
tuna products. The Panel also saw merit in Mexico's argument that the system in place outside the ETP large purse seine fishery may contribute to inaccurate labelling of tuna caught in sets or other 
gear deployments in which dolphins were killed or seriously injured
681, although it did not find it 
necessary to make a definitive finding on that point. 
7.464.   In the Panel's view, these factual findings lead to the conclusion that the amended tuna 
measure is inconsistent with Article I:1 of the GATT 1994. Insofar as the different tracking and 
verification requirements impose less burdensome tracking and verification requirements outside the ETP large purse seine fishery, the amended t una measure grants a benefit to tuna caught 
other than by large purse seine vessels in the ETP that is not immediately and unconditionally 
granted to tuna caught by large purse seine ve ssels. The different tracking and verification 
requirements essentially subject tuna caught by large purse seine vessel in the ETP to additional conditions in order to access the dolphin-safe label, and insofar as the system in place outside the 
ETP large purse seine fishery is less burdensome, the additional conditions imposed in the ETP 
large purse seine fishery upset the equality of competitive opportunities that Article I:1 of the GATT 1994 protects. 
7.465.  Accordingly, we find that the different tracking and verification requirements contained in 
the amended tuna measure are inconsistent with Article I:1 of the GATT 1994. 
7.466.  Before concluding, we note that in its se cond written submission, Mexico argues that what 
it considers to be the United States' unilateral action in designing and applying the dolphin-safe 
labelling conditions and requirements of the am ended tuna measure provides further support its 
claim that the measure is inconsistent with Article I:1 of the GATT 1994. Specifically, according to Mexico, the amended tuna measure's unilateral dolphin-safe regime has the intentional effect of 
exerting pressure on Mexico to change its tuna fishing practices, even though these practices are 
already fully compliant with the highly successful AIDCP dolphin-safe labelling regime, as agreed through multinational negotiations between the United States, Mexico, and the other members of 
the IATTC. Mexico argues that to the extent that Mexico refuses to acquiesce to the unilateral 
extraterritorial pressure imposed by the United St ates, the vast majority of its tuna products are 
denied the advantage of access to the dolphin-safe label in the US market even while they are entirely qualified for the AIDCP dolphin-safe label elsewhere.
682  
7.467.  In response, the United States advanced three arguments. First, the United States argues 
that the DSB recommendations and rulings did not fi nd that the detrimental impact caused by the 
US measure was a factor of "unilateral" application and, thus, it is unclear what finding Mexico 
asks the Panel to make or what the proposed factual basis would be. Second, according to the 
United States, the argument lacks merit becaus e measures of Members are, by definition, 
                                               
678 United States' first written submission, para. 244. 
679 United States' second written submission, para. 98. 
680 See paras. 7.171-7.179 above. 
681 See para. 7.382 above. As the Panel noted above, it need not make a final determination of whether 
the system in place outside the ETP large purse seine fish ery does, in every instance, contribute to inaccurate 
labelling. Such a determination would require a detailed examination of the several factors that may also contribute to the possibility of inaccurate labelling. In  the Panel's view, such analysis is unnecessary in the 
present case. The mere fact that the burden imposed outside the ETP large purse seine fishery is lesser than 
that imposed inside is sufficient to justif y a finding of violation under Article I:1. 
682 Mexico's second written submission, para. 208. WT/DS381/RW 
 
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  unilateral, and the Appellate Body found in the original proceedings that the objective of the tuna 
measure is not to "coerce" Mexico. Finally, the United States asserts that Mexico's argument ignores that setting on dolphins, which under the AIDCP is qualified to catch dolphin-safe tuna, harms dolphins even if no dolphin is observed killed or seriously injured in a particular set, and 
that consequently the AIDCP regime does not meet the United States' chosen level of protection 
with respect to dolphin protection.
683 
7.468.  The Panel does not need to decide on this point, since it has already found for different 
reasons that the amended tuna measure is inconsistent with Article I:1.  
7.6.2  Article III:4 of the GATT 1994 7.6.2.1  Legal test 7.469.  Article III:4 relevantly provides: 
The products of the territory of any contracting party imported into the territory of 
any other contracting party shall be accorded treatment no less favourable than that accorded to like products of national origin in respect of all laws, regulations and 
requirements affecting their  internal sale, offering for sale, purchase, transportation, 
distribution or use. 
7.470.  There are three elements that must be demonstrated to establish that a measure is 
inconsistent with Article III:4: 
(i) that the imported and domestic products are "like products"; (ii) that the measure 
at issue is a "law, regulation, or requirement affecting the internal sale, offering for sale, purchase, transportation, distribution, or use" of the products at issue; and 
(iii) that the treatment accorded to imported products is "less favourable" than that 
accorded to like domestic products.
 684 
7.471.  The Panel notes that the parties agree on the legal test to be applied in respect of the first 
and second of these steps.685 
7.472.  With respect to the first element, the Appellate Body has explained that in making a 
determination of whether products are like, a pane l should examine, on a case-by-case basis, all 
relevant criteria, including (i) the products' properties, nature and quality, i.e. their physical 
characteristics; (ii) the products' end-uses; (iii) consumers' tastes and habits, also referred to as consumers' perceptions and behaviour, in respect of the products; and (iv) the products' tariff classification.
686 
7.473.  The Appellate Body has also clarified, however, that the aforementioned criteria are 
"neither a treaty-mandated nor a closed list of criteria that will determine the legal characterisation of products".
687 The Appellate Body has explained that in each case, all pertinent 
evidence, whether related to one of those criteria or not, must be examined and considered by 
panels to determine whether products are – or could be – in a competitive relationship in the marketplace, i.e. are "like". The Appellate Body ex plained that when all the relevant evidence has 
been examined, panels must determine whether that evidence, as a whole, indicates that the 
products in question are "like" in terms of the legal provision at issue.
688 
7.474.  With respect to the second element, the Panel notes that previous panels and the 
Appellate Body have interpreted broadly what falls  within the ambit of "laws and regulations" in 
the context of Article III:4. 
                                               
683 United States' second written submission, para. 77, footnote 141. 
684 Appellate Body Reports, EC – Seal Products , para. 5.99. 
685 Mexico's first written submission, paras. 317-319; United States' first written submission, 
paras. 292-293. 
686 Appellate Body Report, EC – Asbestos, para. 101. 
687 Appellate Body Report, EC – Asbestos , para. 101. 
688 Appellate Body Report, EC – Asbestos , para. 103. WT/DS381/RW 
 
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  7.475.  With respect to the third element, Mexico recalls the Appellate Body's findings in past 
disputes and stresses that (i) "what is relevant is whether such regulatory differences distort the conditions of competition to the detriment of imported products"; (ii) under Article III:4, a panel is not required to examine whether the detrim ental impact of a measure on competitive 
opportunities for like imported products stems exclusively from a legitimate regulatory distinction; 
and (iii) whether the detrimental impact of a measure is unrelated to the foreign origin of the imported products is irrelevant to the analysis of a claim under Article III:4, and hence, no 
"additional inquiry" in this respect is necessary.
689 
7.476.  The United States stresses that the Article III:4 non-discrimination obligation is 
"concerned, fundamentally, with prohibiting discriminatory measures," and that what it requires is "effective equality of opportunities for imported products to compete with like domestic products." 
In the United States' view, a measure cannot violate Article III:4 of the GATT 1994 unless there is 
a "genuine relationship between the measure at issue and the adverse impact on competitive opportunities for imported products."
690   
7.477.  The Panel recalls that the Appellate Body has established the following propositions in 
respect of Article III:4 of the GA TT 1994. First, the term "treatment no less favourable" requires 
effective equality of opportunities for imported products to compete with like domestic products. 
Second, a formal difference in treatment between imported and domestic like products is neither 
necessary, nor sufficient, to establish that imported products are accorded less favourable treatment than that accorded to like domestic products. Third, because Article III:4 is concerned with ensuring effective equality of competitive opportunities for imported products, a 
determination of whether imported products are treated less favourably than like domestic 
products involves an assessment of the implications of the contested measure for the equality of competitive conditions between imported and like domestic products; if the outcome of this 
assessment is that the measure has a detrimental impact on the conditions of competition for like 
imported products, then such detrimental impact w ill amount to treatment that is "less favourable" 
within the meaning of Article III:4. Finally, for a measure to be found to modify the conditions of 
competition  in the relevant market to the detriment of imported products, there must be a 
"genuine relationship" between the measure at issue and the adverse impact on competitive opportunities for imported products.
691 
7.478.  The Appellate Body has clarified that in  determining whether the detrimental impact on 
competitive opportunities for like imported products is attributable to, or has a genuine 
relationship with, the measure at issue, the relevant question is "whether it is the governmental measure at issue that 'affects the conditions under which like goods, domestic and imported, 
compete in the market within a Member's territory'".
692  
7.479.  Importantly, the Appellate Body has also stated that for the purposes of an analysis under 
Article III:4, a panel is not required to examine whether the detrimental impact of a measure on 
competitive opportunities for like imported products stems exclusively from a legitimate regulatory 
distinction.693 
7.480.  Thus, in assessing the third element of the legal test, i.e. whether the treatment accorded 
to imported products by the amended tuna measure is "less favourable" than that accorded to like 
domestic products, the Panel will examine whether the measure at issue has a detrimental impact 
on competitive opportunities for like imported products, or whether the adverse impact on competitive opportunities for imported products is attributable to, or has a genuine relationship 
with, the measure at issue. 
7.481.  Before proceeding, the Panel notes that the "less favourable treatment" test in Article III:4 
of the GATT 1994 is very similar to the first element of the "less favourable treatment" test in 
Article 2.1 of the TBT Agreement. Indeed, the Appe llate Body itself has recognised that although 
the legal test under the two provisions is not the same, nevertheless there is a close connection 
                                               
689 Mexico's second written submission, paras. 216-219 (citing Appellate Body Report, Thailand – 
Cigarettes (Philippines) , para. 128 and Appellate Body Reports, EC –Seal Products , paras. 5.117 and 5.104). 
690 United States' first written submission, para. 295. 
691 Appellate Body Reports, EC –Seal Products , para. 5.101. 
692 Appellate Body Reports, EC –Seal Products , para. 5.105. 
693 Appellate Body Reports, EC –Seal Products , para. 5.117. WT/DS381/RW 
 
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  between the test under Article III:4 and the detrimental impact analysis that must be carried out 
under the first tier of Article 2.1 of the TBT Agreement.694 As the Panel understands it, the key 
difference between the two provisions is that while a showing of detrimental impact is in itself sufficient to establish a violation of Article III:4 of the GATT 1994, a further analysis of whether 
detrimental treatment stems exclusively from a legitimate regulatory distinction may be required 
under Article 2.1 of the TBT Agreement, at leas t where the detrimental treatment identified is 
de facto . 
7.6.2.2  Application 
7.6.2.2.1  Arguments of the parties 7.482.  Mexico argues that the three challenged features of the amended tuna measure (the 
eligibility criteria and the different certification and tracking and verification requirements) accord 
like Mexican tuna and tuna products treatment less favourable than that accorded to US tuna 
products, and are therefore inconsistent with Article III:4 of the GATT 1994.
695 
7.483.  Mexico recalls that in the original proceedings, the Appellate Body found that access to the 
dolphin-safe label constituted an "advantage" on the US market; that lack of access to the dolphin-
safe label has a detrimental impact on the competitive opportunities of Mexican tuna and tuna products in the US market; and that government intervention, in the form of adoption and 
application of the US dolphin-safe labelling provisions, affects the conditions under which like tuna 
and tuna products, domestic and imported, compete in the market within the United States' market. Moreover, the panel and Appellate Body found that most tuna caught by Mexican vessels, being caught in the ETP by setting on dolphins, would not be eligible for inclusion in a dolphin-safe 
product under the US dolphin-safe labelling provis ions, while most tuna caught by US vessels, not 
being caught by setting on dolphins, is potentially eligible for the label.  
7.484.  Mexico argues that this continues to be the case.
696 According to Mexico, the findings of 
the panel and the Appellate Body apply equally in  respect of the amended tuna measure, because 
none of the amendments to the amended tuna  measure have reduced or eliminated the 
detrimental impact on imported Mexican tuna products caused by the differences in the dolphin-
safe labelling conditions and requirements. In Mexico's view, the amended tuna measure accords 
to imported Mexican tuna products treatment that is "less favourable" than that accorded to like domestic products in the US market.
697 
7.485.  The United States argues that Mexico fails to establish that the amended tuna measure is 
inconsistent with Article III:4 of the GATT 1994.698 
7.486.  In the first place, the United States cons iders that Mexico's claim under Article III:4 of the 
GATT 1994 is limited to the different eligibility requ irements that disqualify tuna caught by setting 
on dolphins from accessing the dolphin-safe label. The United States stresses that Mexico neither 
claims nor proves that any other aspects of the amended measure, certification and tracking and verification requirements, are inconsistent with Article III:4 of the GATT 1994.
699  
7.487.  Additionally, the United States argues that  Mexico fails to estab lish that the challenged 
measure accords different treatment to like US and Mexican tuna products. The United States stresses that the measure sets the same  eligibility requirements for all tuna products sold in the 
United States – to be eligible for the dolphin-safe label, no tuna may be caught by setting on 
dolphins and no tuna may be caught where a dolphin was killed or seriously injured. The 
United States reiterates that the requirements set by the amended tuna measure do not differ based on the nationality of the vessel or processor, the fishery where the tuna was caught, or the 
fishing gear used to catch the tuna.
700 
                                               
694 See e.g. Appellate Body Report, US – Clove Cigarettes , paras. 179 and 180. 
695 Mexico's first written submission, para. 317. 
696 Mexico's first written submission, para. 329. 
697 Mexico's second written submission, para. 221. 
698 United States' first written submission, para. 295. 
699 United States' second written submission, para. 139. 
700 United States' first written submission, para. 297. WT/DS381/RW 
 
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  7.488.  The United States recalls the original panel's findings and argues, inter alia , that the 
adverse impact felt by Mexican tuna products on the US market is not a consequence of the measure itself putting Mexican producers at a disadvantage vis-à-vis  producers in the 
United States, Thailand, the Philippines, etc. Rather, it is a consequence of the "fishing and 
purchasing practices, geographical location, relative integration of different segments of 
production, and economic and marketing choices" of the different tuna producers.
701  
7.489.  The United States also criticizes what it sees as Mexico's sole reliance on the effects of the 
amended tuna measure in its argumentation under Article III:4. In the view of the United States, 
this approach entails the absurd consequence that measures could become  inconsistent with 
Article III:4 based entirely on the private choices made by different Members' industries.702 For the 
United States, as a consequence of Mexico's appr oach, the basis of the regulatory requirements 
becomes wholly immaterial to the national treatment analysis under Article III:4 of the 
GATT 1994. The United States argues that Mexico's approach would greatly undermine a Member's ability to regulate in the public interest.
703 
7.6.2.2.2  Analysis by the Panel 
7.490.  The Panel's task in this part of its Report is to review whether Mexico has established, 
prima facie , that the amended tuna measure has a detrimental impact on competitive 
opportunities for like Mexican tuna products.  
7.491.  At the outset, the Panel considers it is nece ssary to clarify the scope of the elements of the 
amended tuna measure that should be examined in the context of Article III:4 of the GATT 1994. 
As noted above, the United States argues that Mexico's claim under Article III:4 relates only to the 
eligibility criteria, and does not concern either the different certification or the different tracking 
and verification requirements.704 
7.492.  As was the case in respect of Mexico's claim under Article I:1 of the GATT 1994, we note 
that Mexico has articulated its claim under Article III:4 of the GATT 1994 in terms of "the 
difference in labelling conditions".705 It is this "difference" that Mexico is challenging.706 In our 
view, the term "difference in labelling conditions" clearly encompasses more than just the eligibility 
criteria; the use of the plural "conditions" indicates that Mexico's challenge relates also to other 
aspects or features of the amended tuna measure that, in Mexico's view, treat Mexican tuna and 
tuna products differently from like domestic tuna and tuna products. As such, we will consider whether any of the three features of the measure id entified by Mexico – the eligibility criteria, the 
different certification requirements, and the different tracking and verification requirements – 
modify the conditions of competition to the detriment of Mexican tuna and tuna products, in violation of Article III:4. 
7.493.  The Panel now proceeds to consider the substance of the parties' arguments. We begin by 
noting that Mexico appears to rely on the argumentation it developed in the context of Article 2.1 of the TBT Agreement to support its claim that th e amended tuna measure is inconsistent with the 
requirements of Article III:4 of the GATT 1994.
707  
7.494.  As we noted above in the context of our analysis under Article I:1 of the GATT 1994, we 
think it is appropriate for us to make reference to factual and legal findings arrived at in the course of our analysis under Article 2.1 of the TBT Ag reement, because, as we have explained, the 
Appellate Body has made clear that even though  the "less favourable treatment" tests under 
Article 2.1 of the TBT Agreement and III:4 of th e GATT 1994 are not identical, both include the 
question whether the measure at issue "modifies the conditions of competition in the market of the 
regulating Member to the detriment of the group of imported products vis-à-vis  the group of like 
                                               
701 United States' first written submission, para. 299. 
702 United States' second written submission, para. 142. 
703 United States' first written submission, paras. 302-314; United States' second written submission, 
para. 142. 
704 United States' first written submission, para. 277. 
705 Mexico's second written submission, para. 220. 
706 Mexico's second written submission, para. 221. 
707 E.g. Mexico's second written submission, paras. 220 and 221. WT/DS381/RW 
 
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  domestic products".708 Indeed, we think it would be rare for a panel that had found that a measure 
detrimentally modifies the conditions of competition within the meaning of the first tier of Article 2.1 of the TBT Agreement to find that the same measure nevertheless does not accord less favourable treatment within the meaning of Article III:4 of the GATT 1994. 
7.495.  As the Panel's discussion of the legal test  under Article III:4 suggests, the inquiry required 
under Article III:4 is very similar to the inquiry required under first tier of Article 2.1 of the TBT Agreement. In fact, as the Panel understands it, the essential legal question that must be 
answered under both Article III:4 of the GATT 1994 and the first tier of Article 2.1 of the 
TBT Agreement is, for all intents and purposes, the same: namely, whether or not the measure at issue "modifies the conditions of competition in the market of the regulating Member to the detriment of the group of imported products vis-à-vis the group of like domestic products".
709 The 
Appellate Body has consistently used this formulat ion to describe both the first step of the inquiry 
under Article 2.1 of the TBT Agreement and the question at issue in Article III:4 of the GATT 1994.
710 In the Panel's opinion, therefore, it is appropriate to apply our findings made in the 
context of the first step of the analysis under Ar ticle 2.1 of the TBT Agreement in the context of 
Article III:4 of the GATT 1994.   
7.496.  The Panel begins by recalling its findings in the context of Article 2.1 of the TBT Agreement 
and Article I:1 of the GATT 1994 that, as the parties agree, the tuna and tuna products concerned 
in this dispute are "like". This factual finding applies equally in the context of Article III:4 of the GATT 1994, which similarly concerns the treatment of "like products". Accordingly, the Panel finds that for the purpose of Article III:4 of the GATT 1994, all tuna and tuna products are "like". 
7.497.  The Panel now proceeds to consider whet her the three features of the amended tuna 
measure identified by Mexico modify the conditions of competition to the detriment of like Mexican tuna and tuna products, contrary to Article III:4 of the GATT 1994. 
7.498.  With respect to the eligibility criteria, the Panel recalls its findings on this aspect of the 
amended tuna measure under Article 2.1 of the TBT Agreement and Article I:1 of the GATT 1994. 
The Panel has found in this respect, following a separate detrimental impact analysis under 
Article I:1 of the GATT 1994, that the eligibility criteria modify the conditions of competition in the 
US tuna market to the detriment of Mexican tuna  and tuna products because they deprive certain 
tuna products of access to the dolphin-safe label, which is a valuable economic benefit on the US market.  
7.499.  Applying this finding in the context of Article III:4 of the GATT 1994, the Panel finds that 
the eligibility criteria in the amended tuna measure modify the conditions of competition to the detriment of like Mexican tuna and tuna products.  
7.500.  With respect to the different certification requirements, the Panel similarly found in the 
context of the first part of its analysis under Arti cle 2.1 of the TBT Agreement that this feature of 
the amended tuna measure modifies the conditions of competition in the US tuna market to the 
detriment of like Mexican tuna and tuna products. This is so because they impose a lighter burden 
on tuna caught outside the ETP large purse seine fishery than inside it, and may contribute to inaccurate labelling.  
7.501.  Applying this finding in the context of Article III:4 of the GATT 1994, the Panel finds that 
the different certification requirements in the amended tuna measure modify the conditions of 
competition to the detriment of like Mexican tuna and tuna products.  
7.502.  Finally, with respect to the different tracki ng and verification requirements, the Panel found 
in the context of the first part of its analysis under Article 2.1 of the TBT Agreement that this 
feature of the amended tuna measure modifies th e conditions of competition in the US tuna 
market to the detriment of like Mexican tuna and tuna products. This is so because they impose a 
                                               
708 Appellate Body Report, US – Clove Cigarettes , para. 180. 
709 Appellate Body Report, US – Clove Cigarettes , para. 180. 
710 See, most recently, Appellate Body Reports, EC – Seal Products , para. 5.101 (finding that a measure 
will violate Article III:4 where it "has a detrimental im pact on the conditions of competition for like imported 
products"). WT/DS381/RW 
 
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  lighter burden on tuna caught outside the ETP large purse seine fishery than on tuna caught inside 
that fishery, and they may also contribute to inaccurate labelling.711  
7.503.  Applying this finding in the context of Article III:4 of the GATT 1994, the Panel finds that 
the different tracking and verification requirements in the amended tuna measure modify the 
conditions of competition to the detriment of like Mexican tuna and tuna products.  
7.504.  In light of these findings, the Panel concludes that the amended tuna measure, including 
the three regulatory distinctions identified by Mexico, is therefore inconsistent with Article III:4 of 
the GATT 1994. 
7.7  The United States' defence under Article XX of the GATT 1994 
7.505.  The United States submits that if the amen ded tuna measure is inconsistent with Articles I 
and/or III of the GATT 1994, it is nevertheless ju stified under Article XX of that Agreement. 
Article XX provides for certain exceptions to the substantive obligations set forth in the 
GATT 1994.712 The burden of establishing that an otherwise GATT-inconsistent measure satisfies 
the requirements of one of the exceptions in Article XX lies with the party invoking it, in this case 
the United States.713   
7.506.  Article XX of the GATT 1994 sets forth requirements both in its subparagraphs and in its 
chapeau. As noted by the Appellate Body in US – Gasoline , the analysis under Article XX is 
"two-tiered: first, provisional justification by reason of characterization of the measure under [one 
or more subparagraphs]; second, further appraisa l of the same measure under the introductory 
clauses of Article XX."714 
7.507.  In this dispute, the United States argues that if the tuna amended measure is found to be 
inconsistent with Articles I and/or III of the GATT 1994, it is nevertheless justified under 
Article XX(b), as a measure necessary to protect the health of dolphins, and under Article XX(g), as a measure relating to the conservation of natural resources.
715  
7.508.  Mexico rejects the United States' defence. Accord to Mexico, considering its objectives - (i) 
ensuring that consumers are not misled or deceived about whether tuna products contain tuna caught in a manner that adversely affects dolphins, and (ii) contributing to the protection of 
dolphins by ensuring that the US market is not used to encourage fishing fleets to catch tuna in a 
manner that adversely affects dolphins
716 - the amended tuna measure does not "fit" into the 
general exceptions provided in either subparagrap h (b) or subparagraph (g) of Article XX of the 
GATT 1994. Mexico also argues that the variou s components and requirements of the amended 
tuna measure do not comply with the prescriptions of the chapeau of Article XX.717 
7.509.  The Panel will first discuss the United St ates' invocation of Article XX(g) of the GATT 1994 
to justify the inconsistencies of the amended tuna measure with Articles I and III.  
7.7.1  Article XX(g) 
7.7.1.1  Legal test under Article XX(g) 7.510.  The Panel begins by noting that, as a general matter, the parties agree that it is the 
requirements that are found to cause the inconsistency with the particular GATT provision that 
                                               
711 As the Panel noted above, it need not make a fi nal determination of whet her the system in place 
outside the ETP large purse seine fishery does, in every instance, contribute to ina ccurate labelling. Such a 
determination would require a detailed examination of the several factors that may also contribute to the possibility of inaccurate labelling. In the Panel's view , such analysis is unnecessary in the present case. The 
mere fact that the burden imposed outside the ETP large purse seine fishery is lesser than that imposed inside is sufficient to justify a finding of violation under Article I:1. 
712 Appellate Body Report, US – Shrimp , para. 157. 
713 Appellate Body Report, US – Gasoline , pp. 22-23, DSR 1996:I, p. 3 at 20. 
714 Appellate Body Report, US – Gasoline , pp. 22-23, DSR 1996:I, p. 3 at 20. 
715 United States' first written submission, para. 317. 
716 United States' first written submission, para. 14. 
717 Mexico's second written submission, paras. 230-240; 311-340. WT/DS381/RW 
 
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  need to be justified under the subparagraphs of Article XX. We think that this is correct as a 
matter of law.718 Therefore, in the present context, th e Panel needs to determine whether the 
requirements of the amended tuna measure as a whole, including its eligibility criteria and 
different certification and tracking and verification requirements, are justified under 
Article XX(g).719   
7.511.  Article XX(g) concerns measures relating to the conservation of exhaustible natural 
resources. To determine if the amended tuna measure is justified under Article XX(g), the 
United States bears the burden of demonstrating that its measure: (i) relates to the conservation 
of (ii) an exhaustible natural resource, and (iii) is made effective in conjunction with restrictions on domestic production or consumption. Although it includes different components, Article XX(g) 
ultimately lays down a single test, and a measure's compliance with Article XX(g) can be 
determined only on the basis of a holistic assessment.
720 
7.512.  With respect to the first clause of Article XX(g), "relating to the conservation of exhaustible 
natural resources", the Appellate Body has em phasized, referring to the preamble of the 
Marrakesh Agreement, that the term "natural resources" in Article XX(g) is not "static" in its 
content or reference, but is rather, "by definition, evolutionary".721 The word "conservation", in 
turn, means "the preservation of the environment, especially of natural resources".722 The 
Appellate Body in China - Rare Earths  explained that  
[F]or the purposes of Article XX(g), the prec ise contours of the word conservation can 
only be fully understood in the context of the exhaustible natural resource at issue in a given dispute. In respect of the "conservation" of a living natural resource, such as a 
species facing the threat of extinction, the word may encompass not only limiting or 
halting the activities creating the danger of extinction, but also facilitating the replenishment of that endangered species.
723 
7.513.  The Appellate Body has also explained that for a measure to "relate" to conservation in the 
sense of Article XX(g), there must be "a close and genuine relationship of ends and means"724 
between that measure and the conservation objective. In this sense, we agree with Mexico that 
the challenged measure must maintain a certain "nexus" with the legitimate policy goal of 
conservation of exhaustible natural resources.  
7.514.  Moreover, Article XX(g) requires the regulating Member to show that its measure is "made 
effective in conjunction with restrictions on domestic production or consumption," which has been 
interpreted as a requirement that the challenged measure and the related domestic restrictions 
"work together".725 As the Appellate Body explained in China – Rare Earths : 
[T]he phrase "made effective in conjunction with" requires that, when international 
trade is restricted, effective restrictions are also imposed on domestic production or 
consumption. Just as GATT-inconsistent measures impose limitations on international trade, domestic restrictions must impose limitations on domestic production or 
consumption. In other words, to comply with the "made effective" element of the 
second clause of Article XX(g), a Member must impose "real" restrictions on domestic production or consumption that reinforce and complement the restriction on 
                                               
718 Appellate Body Report, US – Gasoline , p. 16, DSR 1996:I, p. 3 at 15. 
719 The Appellate Body has made clear that "the aspects of a measure to be justified under the 
subparagraphs of Article XX are those that give rise to the finding of inconsistency under the GATT 1994. " EC – 
Seal Products (AB) , para. 5.185 ("In US – Gasoline , the Appellate Body clarified th at it is not a panel's legal 
conclusions of GATT-inconsistency that must be justif ied under Article XX, but rather the provisions of a 
measure that are infringing the GATT 1994. Similarly, in Thailand – Cigarettes (Philippines) , the Appellate Body 
observed that the analysis of the Article XX(d) defence in that case should focus on the "difference in the 
regulation of imports of like domestic products" giving rise to the finding of less  favourable treatment under 
Article III:4. Thus the aspects of a me asure to be justified under the subparagraphs of Article XX are those that 
give rise to the finding of inconsistency under the GATT 1994"). 
720 Appellate Body Reports, China – Rare Earths , para. 5.94. 
721 Appellate Body Report, US – Shrimp , para. 130. 
722 Appellate Body Reports, China – Raw Materials , para. 355. 
723 Appellate Body Reports, China – Rare Earths , para. 5.89. 
724 Appellate Body Reports, US – Shrimp , para. 136; China – Raw Materials , para. 355. 
725 Appellate Body Reports, China-Rare Earths , paras. 5.88 and 5.94. WT/DS381/RW 
 
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  international trade, and particularly so in circumstances where domestic consumption 
accounts for a major part of the exhaustible natural resource to be conserved.726 
7.515.  In this dispute, the parties generally agre e on the elements of the legal test but disagree 
as to its application. 
7.7.1.2  Application 
7.7.1.2.1  Arguments of the parties 7.516.  The United States argues that dolphins are an exhaustible natural resource,
727 and that the 
amended measure clearly "relates to" the conservati on of dolphins. The United States points out 
that the original panel found, and the Appellate Body affirmed, that one of the tuna labelling 
regime's objectives is the protection of dolphins. In the view of the United States, that finding clearly establishes that the required "substantial relationship" between the amended tuna measure 
and the objective of conservation exists.
728 The United States recalls the original panel and the 
Appellate Body's finding that the original measure was capable of achieving its dolphin protection objective completely within the ETP and partially outside the ETP. According to the United States, 
by maintaining the disqualification of tuna caught by the "particularly harmful"
729 fishing method of 
setting on dolphins, whether inside or outside the ETP, from accessing the dolphin-safe label,  and 
in expanding the certification system outside the ET P to require a statement that no dolphins were 
killed or seriously injured in the set or other gear deployment in which tuna was caught, the 
amended measure "fully addresses" the risks caused by different tuna fishing methods in different oceans, and as such clearly contributes to the conservation of dolphins.
730  
7.517.  The United States emphasizes that, under the amended measure, all tuna products 
containing tuna caught by setting on dolphins are ineligible for the label, regardless of the fishery, 
nationality of the vessel, or nationality of the processor, and the same is true of all tuna products containing tuna caught in a set or gear deployment where a dolphin was killed or seriously 
injured.
731 The United States argues that the amended tuna measure goes even further than the 
original tuna measure in protecting dolphins by applying a certification mechanism (captain's' certification) that the original panel found was "capable of achieving" the US objective in the 
context of setting on dolphins outside the ETP.
732 The United States argues, therefore, that the 
amended tuna measure makes a contribution to the protection of dolphins (inside and outside the ETP) that satisfies the "relating to conservation" standard. Additionally, the United States submits that the measure's origin neutrality indicates th at the amended tuna measure imposes the same 
conservation-related burden on US tuna producers as it does on foreign tuna producers. 
7.518.  Mexico does not dispute that dolphins are an exhaustible natural resource. However, 
Mexico argues that the amended tuna measure does not relate to the conservation of exhaustible 
natural resources. For Mexico, the amended tuna measure is not intended to conserve dolphin 
stocks in the course of tuna fishing operations in the ETP or to promote recovery of dolphin stocks. Mexico asserts that the amended measure's connection to dolphin protection is so tenuous that it 
does not even "relate to" the conservation of dolphins. For Mexico, conserving dolphin populations 
is only an "indirect objective" of the measure,
733 as there is no "effective protection" outside the 
ETP.734 Therefore, for Mexico, dolphins are not being "conserved" in any way outside the ETP.735 In 
Mexico's view, the lack of protection afforded by the amended tuna measure to dolphins outside 
the ETP shows that the amended tuna measure does not have a substantial, close, and real 
relationship to the conservation or preservation of dolphins.736 
                                               
726 Appellate Body Reports, China – Rare Earths , para. 5.132 (internal citations omitted). 
727 United States' first written submission, para. 325. 
728 United States' first written submission, para. 327. 
729 United States' first written submission, para. 327. 
730 United States' second written submission, para. 190. 
731 United States' first written submission, para. 328. 
732 United States' second written submission, para. 187. 
733 Mexico's second written submission, para. 303. 
734 Mexico's second written submission, para. 299. 
735 Mexico's second written submission, para. 299. 
736 Mexico's second written submission, para. 303. WT/DS381/RW 
 
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  7.519.  Mexico also argues that the amended tuna measure is not made effective in conjunction 
with restrictions on domestic production or consumption. According to Mexico, the United States has not sufficiently explained what kind of restriction on domestic production or consumption is imposed by the amended tuna measure. Mexico ar gues that the amended tuna measure maintains 
insufficient tracking and verification requirements in relation to tuna caught outside the ETP and 
tuna products containing same. Furthermore, the dolphin-safe certification requirements for tuna products containing tuna caught other than by large purse seine vessel in the ETP are themselves 
inherently unverifiable, unreliable, inaccu rate, unenforceable and, thus, meaningless.
737 
7.7.1.2.2  Analysis by the Panel 7.520.  The Panel now examines whether the United States has demonstrated that the amended 
tuna measure (and in particular the three aspects of the measure challenged by Mexico: the 
eligibility criteria, the different certification requirements, and the different tracking and 
verification requirements) complies with subpa ragraph (g) of Article XX of the GATT 1994.  
7.521.  As we noted above, both parties agree that  dolphins are an "exhaustible natural resource". 
We agree. 
7.522.  Mexico argues, however, that the amended tuna measure, including the three conditions 
and requirements identified by Mexico, does not " relate to " the " conservation " of dolphins; it also 
adds that the amended tuna measure does not include any relevant domestic restrictions. Mexico's 
main argument is that the measure as a whole, and in particular its less-stringent requirements with respect to observers and tracking and verifica tion for tuna caught other than by large purse 
seine vessel in the ETP, does not have a sufficient nexus  with the goal of conserving dolphins.    
7.523.  The parties agree
738 that the general objectives of the amended tuna measure are the 
same as the objectives pursued by the original measure, namely: (i) ensuring that consumers are not misled or deceived about whether tuna products contain tuna caught in a manner that 
adversely affects dolphins; and (ii) ensuring that the US market is not used to encourage fishing 
fleets to catch tuna in a manner that adversely affects dolphins.   
7.524.  As we understand it, the original panel found, and the Appellate Body affirmed, that one of 
the original measure's objectives was to contribute to the "protection" of dolphins.
739 The Appellate 
Body noted that: 
[T]he Panel accepted these objectives as legitimate within the meaning of Article 2.2 
of the TBT Agreement .740 The Panel further noted that "as described by the 
United States itself, its measures seek to address a range of adverse effects of fishing 
techniques on dolphins", including "situations in which dolphins are killed or seriously injured".
741 
7.525.  In our view, this statement confirms that one of the goals of the US dolphin-safe labelling 
regime is to contribute to the protection of dolp hins. In this dispute, while the Panel accepts that 
the conservation of dolphins is a policy objective falling within the scope of subparagraph (g) of 
Article XX, the United States must nevertheless demonstrate that its measure pursues or 
otherwise "relates to" the conservation of dolphins.  
7.526.  According to Mexico, the amended tuna measure cannot be said to relate to conservation, 
even if it makes a marginal contribution to th e protection of dolphins. In Mexico's view, the 
amended tuna measure is not intended to conserve dolphin stocks in the course of tuna fishing 
operations in the ETP or to promote recovery of dolphin stocks, and since there is no "effective 
                                               
737 Mexico's second written submission, para. 308. 
738 Mexico's first written submission, para. 297; United States' first written submission, para. 319. 
739 Appellate Body Report, United States – Tuna II (Mexico) , para. 242 (citing the Panel Report, US – 
Tuna II (para. 7.401). 
740 (footnote original) Panel Report, US – Tuna II (Mexico) , para. 7.444. As we explain in the following 
section of our Report, a panel adjudicating a claim under Article 2.2 of the TBT Agreement  is required to 
objectively ascertain a measure's objective. A panel must  also determine whether the objective of the measure 
is "legitimate". 
741 (footnote original) Panel Report, US – Tuna II (Mexico) , para. 7.550. WT/DS381/RW 
 
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  protection" for tuna caught other than by large purse seine vessel in the ETP, the measure cannot 
and does not conserve dolphins.742   
7.527.  We recall the Appellate Body's clarification that the term "conservation" in 
subparagraph (g) is broad, and includes "not only limiting or halting the activities creating the 
danger of extinction, but also facilitating th e replenishment of that endangered species."743 We 
agree with the United States that the word conservation also includes "the action of keeping from harm, decay, or loss; careful preservation,"
744 and that this is not limited to preserving species or 
populations but also encompasses the protection of  individual members of a species or population. 
In our view, nothing in either the ordinary meanin g of the term "conservation" or Appellate Body 
jurisprudence indicates that conservation under subparagraph (g) of Article XX covers only measures that have as their primary goal the conservation of dolphins on a population-wide scale. 
To the contrary, we think that the preservation of individual dolphin lives is just as much an act of 
conservation as is a program to encourage recovery of a particular population. Indeed, in our view, there is an essential and inextricable link between the protection of dolphins on an individual scale 
and the "replenishment of [an] endangered species", for it is only through protecting individual 
dolphins that a population itself can be protected, replenished, and maintained. Accordingly, in our view, the fact that the amended tuna measure is more concerned with the effects of tuna fishing 
on the well-being of individual dolphins rather than  on the state of a particular dolphin population, 
considered globally or statistically, does not in itself negate the nexus between the measure and the goal of conserving exhaustible natural resources.  
7.528.  We note in this context that the original panel recognized that "the adverse effects on 
dolphins targeted by the US dolphin-safe provisio ns, as described by the United States, relate to 
observed and unobserved mortalities and serious inju ries to individual dolphins in the course of 
tuna fishing operations. In addition … to the extent that addressing such adverse effects 'might 
also be considered as seeking to conserve dolphin populations', the US objectives also incorporate, 
at least indirectly, considerations regarding the conservation of dolphin stocks."
745 
7.529.  We believe that measures designed to reduce the harm done to dolphins in commercial 
fishing practices concern the protection of dolphins, and as such can properly be said to relate to 
the conservation of dolphins. Accordingly, to the extent that the goal of the amended tuna 
measure is to contribute to the protection of do lphins, even on an individual scale, that measure 
can be said to relate to the conservation of dolphins. 
7.530.  As we understand it, Mexico's argument is  not only that the goal of the amended tuna 
measure is not the conservation of dolphins, but moreover that the measure does not function or operate in a way that effectively contributes to the protection of dolphins. In other words, for 
Mexico the link or nexus between the goal of conservation and the effective impact of the 
amended tuna measure on the conservation of dolphins is too remote.  
7.531.  In US – Gasoline , the Appellate Body stated that for a measure to "relate to" conservation 
there must be a "substantial relationship" be tween the challenged measure and the goal of 
conservation.
746 The Appellate Body repeated in China – Rare Earths  that in order for a measure to 
relate to conservation, there must exist "a close and genuine relationship of ends and means"747 
between the challenged measure and the conservation objective. 
7.532.  The original panel found that the US dolphin-safe labelling regime was capable of 
protecting dolphins by ensuring that the US market is not used to encourage fishing practices that may kill or seriously injure dolphins, but that th e measure was doing so only within the ETP. The 
Appellate Body, in confirming the original panel's determination that one of the two goals of the 
labelling measure was indeed to contribute to the protection of dolphins
748, in effect also accepted 
that the original tuna measure "related" to the conservation of dolphins. In particular, in 
                                               
742 Mexico's second written submission, para. 299. 
743 Panel Reports, China – Rare Earths , para. 7.258. 
744 See Oxford English Dictionary  (Clarendon Press, 1993), p. 485 (Exhibit US-119). 
745 Panel Report, US – Tuna II (Mexico) , paras. 7.485-7.486. 
746 Appellate Body Report , US – Gasoline , p. 19, DSR 1996:I, p. 3 at 18. 
747 Appellate Body Report, US – Shrimp , para. 136; Appellate Body Reports , China – Raw Materials , 
para. 355. 
748 Appellate Body Report, US – Tuna II (Mexico) , paras. 342-343. WT/DS381/RW 
 
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  concluding that the tuna measure "fully addresse[d]" the risks caused by the "particularly" harmful 
practice of setting on dolphins, the Appellate Body  confirmed that the tuna measure related to the 
conservation and protection of dolphins. The Ap pellate Body concluded that the measure did so 
effectively in respect of the harms caused by setting on dolphins, but it concluded that the 
US measure was not doing enough for the protection  of dolphins harmed by tuna fishing methods 
other than setting on dolphins.749   
7.533.  In this context, we note that the amended tuna measure disqualifies from the dolphin-safe 
label all tuna caught in a set or other gear deployment in which dolphins were killed or seriously 
injured, regardless of the fishing method used or the location in which the tuna was caught. Notwithstanding the possible merits of Mexico's arguments concerning the shortcomings of the 
certification and tracking and verification requirements imposed on tuna caught other than by 
large purse seine vessel in the ETP, it seems to us that the amended tuna measure remains 
centrally concerned with the pain caused to dolphins in the context of commercial fishing practices both inside and outside the ETP, and caused by both setting on dolphins and other methods of 
tuna fishing. Whatever may be the shortcoming of  one system of certification or tracking and 
verification vis-à-vis another, it seems clear to us that, considered in themselves, systems 
designed to identify, track, and, indirectly, to re duce dolphin mortality and injury, clearly "relate" 
to conservation.  Thus, we do not believe that the differences in the certification and tracking 
verification requirements that apply inside the ETP large purse seine fishery on the one hand and 
in other fisheries on the other hand undermine or otherwise cast doubt on the fact that the amended tuna measure "relates" to conservation.  
7.534.  At this juncture, we would recall that ou r task under subparagraph (g) of Article XX is to 
examine the features of the measure giving rise to discrimination under Articles I and III of the 
GATT 1994, and not the discrimination itself. Accordingly, the question before us is not whether 
the discrimination we identified above relates to conservation, but rather whether the features of 
the measure that cause that discrimination in themselves  – the eligibility criteria, certification and 
tracking and verification requirements – relate to  conservation. Accordingly, at this point of our 
analysis, we do not need to decide whether the differences in certification and tracking verification 
requirements relate to conservation. Rather, our task is only to determine whether the eligibility criteria, and the certification and tracking and verification requirements that are applied, 
considered in themselves, relate to conservation.  
7.535.  To put this another way, we think there is a difference between the question whether the 
amended tuna measure "relates to" the conservation of dolphins and the question whether the measure deals with or responds to harms caused to dolphins by different tuna fishing methods in a 
way that does not arbitrarily or unjustifiably discriminate between like products. The former 
question arises under subparagraph (g), whereas the latter question is properly dealt with under the chapeau of Article XX, which we address below. In  the present context, we think it is clear that 
requirements relating to the eligibility, certification and tracking of tuna that have as their goal the 
provision of accurate information to consumers concerning the dolphin-safe status of tuna can properly be said to "relate to" the goal of conserving dolphins, since, as the United States argues, they help to ensure that the US tuna market does not operate in a way that encourages dolphin 
unsafe fishing techniques. Thus, we think that the eligibility, tracking and verification, and 
certification requirements "relate to" the conservation of dolphins regardless of the level at which they are applied, and regardless also of whether that level is uniform across all fisheries.   
7.536.  In conclusion, we find that the amended tuna measure "relates" to the conservation of 
dolphins.   
7.537.  Mexico also claims that the amended tuna measure does not itself impose any real 
restrictions on the tuna that is harvested by the US fleet outside the ETP, and that the 
United States has not demonstrated that it imposes any kind of restriction on domestic production or consumption, as required by the second limb of subparagraph (g) of Article XX.
750  
7.538.  We understand that the amended tuna measure conditions access to the dolphin-safe label 
on the same requirements for both US vessels and foreign vessels: all tuna products containing 
tuna caught by setting on dolphins is ineligible for the label, regardless of the fishery, nationality of 
                                               
749 Appellate Body Report, US – Tuna II (Mexico),  paras. 289 and 297. 
750 Mexico's second written submission, para. 308. WT/DS381/RW 
 
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  the vessel, or nationality of the processor. Moreover, all tuna products containing tuna caught in a 
set or gear deployment in which a dolphin was killed or seriously injured is ineligible for the label, regardless of the fishery, gear type, nationality of the vessel, or nationality of the processor.
751 
Additionally, all tuna caught in large-scale driftnets on the high seas is ineligible for the label, 
regardless of the fishery and nationality of the vessel.752 Accordingly, we find that the amended 
tuna measure does impose real and effective restrictions on the US tuna industry within the meaning of subparagraph (g) of Article XX. 
7.539.  Mexico argues that the requirements of the amended tuna measure do not "distribute the 
burden of conservation between foreign and dome stic consumers in an even-handed or balanced 
manner."
753 In US – Gasoline , the Appellate Body said that identical treatment of domestic and 
imported products is not required by subparagraph (g), which is rather a requirement of 
even-handedness. The Appellate Body in China – Rare Earths  clarified the meaning of 
even-handedness under subparagraph (g), stating that that in no prior dispute had it ever 
"assessed whether the burden of conservation was evenly distributed between foreign producers, 
on the one hand, and domestic producers or consumers, on the other hand, nor suggested that 
such an assessment was required. … In other wo rds, the Appellate Body's reasoning does not 
suggest that Article XX(g) contains a requirement that  the burden of conservation be evenly 
distributed."754 For the Appellate Body, the relative impact of restrictions imposed on domestic and 
foreign production is rather to be assessed under the chapeau of Article XX:755 
In order to comply with Article XX, a measure needs to fulfil cumulatively the 
conditions specified both in subparagraph (g) and in the chapeau. If, however, 
subparagraph (g) itself required an analysis of whether the burden of conservation is 
evenly distributed, this could entail duplication of the analysis to be conducted under the chapeau, in particular in cases involving discriminatory measures. This would not 
comport with the principle of effective treaty interpretation. 
7.540.  Therefore, we will examine under the chap eau Mexico's claim that the impact of different 
restrictions imposed on domestic and foreign products is unbalanced.  
7.541.  In sum, the Panel finds that the features of the amended tuna measure that give rise to 
violations of Articles I and III of the GATT 1994 are nevertheless provisionally justified under subparagraph (g) of Article XX the GATT 1994. In our view, these features clearly "relate to" the 
goal of conserving dolphins, and are also made effective in conjunction with restrictions on 
domestic production of tuna products. 
7.7.2  Article XX(b) 7.542.  In addition to its defence under Article XX(g), the United States also claims that the 
amended tuna measure is justified under Article XX(b). That provision provides an exception for 
GATT-inconsistent measures that are "necessary to protect human, animal or plant life or health". 
7.543.  Having found that all three aspects of the amended tuna measure challenged by Mexico 
are provisionally justified under subparagraph (g) of Article XX, the Panel is of the view that it 
need not decide whether the amended tuna measure is justified under subparagraph (b) of Article XX. It is a well-established principle of WTO law that "panels may exercise judicial economy and refrain from addressing claims beyond those necessary to resolve the dispute".
756 The 
Appellate Body has on numerous occasions stated that "[p]rovided it complies with its duty to 
assess a matter objectively, a panel enjoys the freedom to decide which legal issues it must address in order to resolve a dispute".
757 Thus, where decision on a particular legal claim is not 
"necessary to secure a 'positive solution' to the dispute or a 'satisfactory settlement of the 
                                               
751 United States' second written submission, para. 328. 
752 See para. 3.37 above. 
753 Mexico's second written submission, para. 309. 
754 Appellate Body Reports, China – Rare Earths , paras. 5.133-5.134. 
755 Appellate Body Reports, China – Rare Earths , para. 5.135. 
756 Appellate Body Report, US – Upland Cotton , para. 718. 
757 Appellate Body Report, US – Gambling , para. 344. WT/DS381/RW 
 
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  matter'"758, a Panel may, in the exercise of its own discretion759, "exercise … restraint" and "refrain 
from addressing" one or more issues raised by the parties.760 
7.544.  In our view, the findings we have made with respect to Article XX(g) are sufficient to 
resolve the legal question before us. Moreover, in  the context of the present dispute, we do not 
believe that there is a meaningful difference be tween the goal of "conserving" dolphins under 
Article XX(g) and the goal of "protecting the life or health" of dolphins under Article XX(b). Nor has any party suggested otherwise. In the present case , the purported goal of the challenged measure 
is to reduce the harm suffered by dolphins during tuna fishing operations. Whether phrased in 
terms of "conservation of exhaustible natural resour ces" or "protecting animal life or health", the 
substance of the goal remains essentially the same, and as such we do not believe that a finding under both subparagraphs is necessary here. Our conclusion under subparagraph (g) suffices for a 
finding that, subject to meeting the test under  the chapeau of GATT Article XX, the amended 
measure is provisionally justified under Article XX, allowing us to move to an analysis of the amended measure under the chapeau.  
7.545.  Therefore, the Panel chooses to exercise ju dicial economy in respect of the United States' 
defence under Article XX(b).  
7.7.3  The chapeau of Article XX 
7.546.  Having found that the amended tuna measure is provisionally justified under Article XX(g), 
the Panel needs to determine whether it compli es with the requirements of the chapeau of 
Article XX of the GATT 1994. 
7.7.3.1  Legal test under the chapeau of Article XX 
7.547.  The chapeau of Article XX contains addition al requirements for measures that have been 
found to violate an obligation under the GATT 1994, but that have also been found to be provisionally justified pursuant to one of the exceptions set forth in the subparagraphs of 
Article XX. The chapeau does so by requiring th at such measures not be "applied in a manner 
which would constitute a means of arbitrary or unjustifiable discrimination between countries where the same conditions prevail, or a disguised restriction on international trade".
761 Whether a 
measure is applied  in a particular manner "can most often be discerned from the design, the 
architecture, and the revealing structure of a measure", which involves a consideration of "both substantive and procedural requirements" imposed by the measure at issue.
762  
7.548.  It is well established that the burden of demonstrating that a measure provisionally 
justified pursuant to one of the exceptions of Article XX is consistent with the chapeau rests with 
the party invoking the exception.763 
7.549.  For a measure to be applied in a manner that would constitute "arbitrary or unjustifiable 
discrimination between countries where the same conditions prevail", three elements must exist:  
First, the application of the measure must result in discrimination . Second, the 
discrimination must be arbitrary  or unjustifiable  in character. Third, this discrimination 
must occur between countries where the same conditions prevail .764 
7.550.  The type, nature, and quality of the discrimination addressed under the chapeau are 
different from the discrimination in the treatment of products found to be inconsistent with one of the substantive obligations of the GATT 1994. The Appellate Body has emphasized that a finding 
that a measure is inconsistent with one of the non-discrimination obligations of the GATT 1994, 
such as those contained in Articles I and III, is not dispositive of the question whether the measure gives rise to "arbitrary or unjustifiabl e discrimination between countries where the same 
                                               
758 Appellate Body Report, US – Zeroing (EC) , para. 250. 
759 Appellate Body Report, India – Patents (US) , para. 87. 
760 Appellate Body Report, Canada – Wheat Exports and Grain Imports , para. 133. 
761 Appellate Body Reports, EC – Seal Products , para. 5.296. 
762 Appellate Body Reports, EC – Seal Products , para. 5.302. 
763 Appellate Body Reports, EC – Seal Products , para. 5.297. 
764 Appellate Body Report, US – Shrimp , para. 150 (emphasis original). WT/DS381/RW 
 
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  conditions prevail" under the chapeau of Arti cle XX of the GATT 1994. This does not mean, 
however, that the circumstances, including relevant facts, which bring about the discrimination that is to be examined under the chapeau cannot be  the same as those that led to the finding of a 
violation of a substantive provision of the GATT 1994.
765 
7.551.  The Appellate Body has indicated that, when assessing a measure under the chapeau of 
Article XX, a panel should begin by determining whether the design of the measure causes discrimination. In answering this question, a panel should consider whether "countries in which the 
same conditions prevail are differently treated".
766 Where this is the case, a panel should proceed 
to analyse whether the resulting discrimination is "arbitrary or unjustifiable".  
7.552.  The Appellate Body has held that in exam ining whether the conditions prevailing in the 
countries between which the measure allegedly discriminates are the same, only conditions that 
are relevant  for the purpose of establishing arbitrary or unjustifiable discrimination in the light of 
the specific character of the measure at issue and the circumstances of a particular case should be 
considered under the chapeau.767 The Appellate Body has explained that, in determining which 
conditions prevailing in different countries are relevant in the context of the chapeau, the objective 
pursued by the measure at issue may provide pertinent context.768 In other words, conditions 
relating to the particular policy objective purs ued by the measure at issue are relevant for the 
analysis under the chapeau. Subject to the particular nature of the measure and the specific 
circumstances of the case, the provisions of th e GATT 1994 with which a measure has been found 
to be inconsistent may also provide useful guidance on the question of which conditions prevailing in different countries are relevant in the context of the chapeau. In particular, the type or cause of 
the violation that has been found to exist may inform the determination of which countries should 
be compared with respect to the conditions that prevail in them.
769  
7.553.  One of the most important factors in the assessment of arbitrary or unjustifiable 
discrimination is the question of whether the discrimination can be reconciled with, or is rationally 
related to, the policy objective with respect to which the measure has been provisionally justified under one of the subparagraphs of Article XX. The Appellate Body has explained that this analysis 
"should focus on the cause of the discrimination,  or the rationale put forward to explain its 
existence".
770   
7.554.  The parties agree generally on the elements  of the legal test under the chapeau, but they 
disagree as to its application to the facts of this dispute. Before we consider the parties' 
arguments, we recall that this dispute involves discrimination claims and arguments made 
pursuant to both the GATT 1994 and the TBT Agreement. The Panel has already made various findings pursuant to Article 2.1 of the TBT Agr eement and Articles I:1 and III:4 of the GATT 1994. 
Some of them (whether factual or legal findings) - in particular those relating to whether the 
detrimental impact caused by the amended tuna measure is even-handed and so stems 
exclusively from a legitimate regulatory distinction - are relevant to the assessment this Panel is 
required to make under the chapeau of Article XX of the GATT 1994. In this context the Panel 
makes the following general observations on the relationship between the analysis under Article XX of the GATT 1994 and Article 2.1 of the TBT Agreement on the basis of recent jurisprudence of the Appellate Body on this matter. 
7.7.3.2  Relationship between the chapeau of Article XX of the GATT 1994 and Article 2.1 
of the TBT Agreement 
7.555.  As we explained in our discussion of the le gal test under Article 2.1 of the TBT Agreement, 
the Appellate Body has said that in assessing whether detrimental impact stems exclusively from a 
legitimate regulatory distinction within the mean ing of Article 2.1 of the TBT Agreement, panels 
should take account  of whether the technical regulation at issue is "applied in manner that would 
constitute a means of arbitrary or unjustifiable discrimination between countries where the same 
                                               
765 Appellate Body Reports, EC – Seal Products , para. 5.298. 
766 Appellate Body Report, US – Shrimp , para. 165. 
767 Appellate Body Reports, EC – Seal Products , para. 5.299. 
768 Appellate Body Report, Brazil – Retreaded Tyres , para. 227. 
769 Appellate Body Reports, EC – Seal Products , para. 5.300. 
770 Appellate Body Reports, EC – Seal Products , para. 5.303. WT/DS381/RW 
 
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  conditions prevail or a disguised restriction on international trade".771 We noted that this language 
is identical to the language found in the chapeau of Article XX of the GATT 1994. We explained, however, that in our view, the question whether detrimental impact stems exclusively from a legitimate regulatory distinction, and the associated  question of whether the technical regulation is 
"even-handed", is broader  than the question whether the technical regulation is designed or 
applied in a manner that constitutes arbitrary or unjustifiable discrimination or a disguised restriction on trade. The latter is one way  in which the former may be shown, but a measure may 
be uneven-handed for the purposes of Article 2.1 of the TBT Agreement even if it is not designed 
or applied in a manner that is arbitrarily or unjustifiably discriminatory or a disguised restriction on international trade.  
7.556.  As the concept of "even-handedness" under Article 2.1 of the TBT Agreement is broader 
than the concept of arbitrary and unjustifiable discrimination and disguised restriction on trade 
under the chapeau of Article XX, a panel may not assume that a finding of violation under Article 2.1 necessarily or automatically implies or requires a finding of violation of the chapeau. For 
instance, where a panel has found that a measure is not even-handed for some reason other than  
that the measure is designed or applied in a manner that constitutes arbitrary or unjustifiable discrimination or a disguised restriction on trade, it will be necessary for that panel, if presented 
with a defence under Article XX of the GATT 1994, to conduct an independent analysis to 
determine whether the measure is arbitrarily or unjustifiably discriminatory, in addition to being 
uneven-handed for the reason(s) given in the co ntext of Article 2.1 of the TBT Agreement. 
7.557.  However, we tend to think that where a panel has analysed even-handedness under 
Article 2.1 of the TBT Agreement through the lens of, or using the analytical framework provided 
by, the phrase "applied in manner that would constitute a means of arbitrary or unjustifiable discrimination between countries where the same conditions prevail or a disguised restriction on 
international trade", it may be appropriate to rely on that reasoning in the context of assessing a 
measure's consistency with the chapeau of Articl e XX of the GATT 1994. Put another way, where a 
panel has found, in the context of Article 2.1 of the TBT Agreement, that a measure is not 
even-handed precisely because  it is "applied in manner that would constitute a means of arbitrary 
or unjustifiable discrimination between countries wh ere the same conditions prevail or a disguised 
restriction on international trade", it will generally be appropriate for that panel to use the reasoning underlying that finding in its analysis under the chapeau.  
7.558.  In  EC – Seal Products , the Appellate Body faulted the panel for automatically importing its 
analysis under Article 2.1 of the TBT Agreement into its analysis under the chapeau of Article XX.
772 In our opinion, however, the Appellate Body's ruling does not stand for the 
proposition that a panel can never  rely on its findings under Article 2.1 of the TBT Agreement in 
the context of the Article XX chapeau. Rather, as we understand it, the error of the EC – Seal 
Products  panel was in assuming that a violation of Article 2.1 of the TBT Agreement, which may 
involve analysis of factors that are not germane to the analysis under Article XX (since it may 
involve analysis of factors other than or beyond whether the measure is arbitrarily or unjustifiably discriminatory or a disguised restriction on trade), automatically gives rise to a violation of that latter provision. What the Appellate Body required was that panels should justify  their use of 
findings made under Article 2.1 of the TBT Agreem ent in the context of the chapeau, by showing, 
for example, that their Article 2.1 analysis wa s based entirely on the question whether the 
measure was applied in a manner that would constitute a means of arbitrary or unjustifiable 
discrimination between countries where the same conditions prevail or a disguised restriction on 
international trade. Where it is, we see nothing in the Appellate Body reasoning to suggest that a panel may not apply relevant aspects of its reasonin g developed in the context of Article 2.1 of the 
TBT Agreement to its analysis under the chapeau of Article XX of the GATT 1994. 
7.559.  It will be recalled that in the present proceedings, Mexico's arguments concerning the 
amended tuna measure's lack of even-handedne ss were premised entirely on the basis that 
various aspects of that measure arbitrarily and unjustifiably discriminate against Mexican tuna 
products. Moreover, the Panel's findings that the different certification and tracking and verification 
requirements did not stem exclusively from a legitimate regulatory distinction were all based on the conclusion that those aspects are arbitrarily discriminatory because they are not reconcilable 
                                               
771 Appellate Body Report, US – Clove Cigarettes , para. 94; Appellate Body Report, US – Tuna II 
(Mexico) , para. 213. 
772 Appellate Body Reports, EC – Seal Products , para. 5.310. WT/DS381/RW 
 
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  with the goal of the amended tuna measure. Simi larly, our finding that the eligibility criteria did 
stem exclusively from a legitimate regulatory distinction was based on the fact that distinction was fully justifiable on the basis of the measure's objectives.  
7.560.  As such, we think it is appropriate for us to rely on the reasoning we developed in the 
context of Article 2.1 in the course of our an alysis under the chapeau of Article XX of the 
GATT 1994. It is to that latter analysis that we now turn. 
7.7.3.3  Application 
7.7.3.3.1  Arguments of the parties 
7.561.  The United States argues that the amende d tuna measure is applied consistently with the 
chapeau of Article XX. According to the United States, the eligibility conditions under the amended tuna measure are the same for all tuna – that is, they are neutral as to nationality. Any tuna 
product containing tuna caught by setting on dolphins is ineligible for the label – the nationality of 
the vessel (or processor) is irrelevant.
773 The United States stresses that whether a tuna product is 
eligible for the dolphin-safe label depends on the choices made by vessel owners, operators, and 
captains.774 
7.562.  The United States also argues that, in any event, the eligibility conditions regarding setting 
on dolphins are neither arbitrary nor unjustified. For the United States, it is without question that 
the two relevant eligibility conditions (i.e. that the tuna was not caught by setting on dolphins and 
that the tuna was not caught in a set or other gear deployment in which dolphins were killed or seriously injured) are rationally related to the policy objective of conserving dolphins, because they provide consumers with the information necessary to ensure that the US tuna market does not 
operate in a way that encourages fishing methods that harm dolphins.
775  
7.563.  According to the United States, "[i]t could hardly be questioned whether the first eligibility 
condition [i.e. the disqualification of tuna caught by setting on dolphins] is rationally related to the 
objective" of protecting dolphins.776 Moreover, the United States argues that because other fishing 
methods that produce tuna for the US  market do not cause the same level of harm to dolphins that setting on dolphins does, treating them differently is not inconsistent with the chapeau of 
Article XX. Therefore, in the United States' view, the eligibility condition of not setting on dolphins 
is rationally related to the objective of the measure.
777 
7.564.  The United States also argues that the amended tuna measure is not applied so as to 
constitute a disguised restriction on trade. The United States argues that it has demonstrated that 
setting on dolphins is a "particularly harmful" fishing method, and other fishing methods do not 
cause the same level of harm to dolphins that setting on dolphins does.778 The United States notes 
that when the original tuna measure was adopted, it greatly affected the US industry – it was not, 
therefore, a measure that could have or in fact did protect US tuna production. Moreover, the 
amended tuna measure applies to tuna from all Members, including the United States, regardless of origin or nationality. Accordingly, the amended tuna measure is clearly not a disguised 
restriction on international trade.
779 
7.565.  In response to Mexico's argument that the United States has discriminated arbitrarily and 
unjustifiably by not working through the AIDCP to "address[] its remaining concerns about dolphins and tuna fishing"
780, the United States emphasizes that a Member may take measures "at 
the levels that it considers appropriate," and nothing in the covered agreements requires a 
                                               
773 United States' first written submission, para. 332. 
774 United States' first written submission, para. 333. 
775 United States' first written submission, para. 336. 
776 United States' first written submission, para. 337. 
777 United States' first written submission, paras. 339-340. 
778 United States' second written submission, para. 213. 
779 United States' first written submission, para. 342. 
780 Mexico's second written submission, para. 338. WT/DS381/RW 
 
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  Member to adhere to an international agreement,  a point that Article 2.4 of the TBT Agreement 
confirms.781 
7.566.  In its second written submission, the United States argues that the alleged differences in 
the certification and tracking and verification requir ements raised by Mexico are not relevant to the 
Panel's Article XX analysis. The United States argues that, first, Mexico has not alleged, much less 
proven, that those requirements result in a detrimental impact on Mexican tuna products. Second, these requirements stem from the AIDCP , not US law, and as such, no genuine relationship exists 
between the amended measure and any disadvantage that Mexico claims to be suffering vis-à-vis  
other Members that are selling tuna or tuna product in the US tuna market. Third, the "conditions prevailing" as they relate to the requirements are not the same, i.e. the ETP large purse seine 
fishery is different from other fisheries.
782 
7.567.  Mexico rejects the United States' arguments. It submits that the United States has not 
demonstrated that the amended tuna measure respects the requirements of the chapeau of Article XX.  
7.568.  Mexico argues that the chapeau of Article XX requires that Members in whose territory the 
same conditions prevail must be treated similarly. In Mexico's view, the conditions prevailing in the ETP are the same, in terms of risks to dolphins, as those in all other fisheries. In Mexico's view, 
dolphins are killed and seriously injured in all tuna fisheries, and the risk that tuna may be caught 
in a way that has detrimental effects on dolphins exists equally in all oceans and in respect of all fishing methods. Accordingly, in Mexico's opin ion, the amended tuna measure treats the same 
situation differently, in violation of the chapeau.
783 
7.569.  Mexico submits that the amended tuna measure is designed and applied in a manner that 
results in discrimination. According to Mexico, the application of the amended tuna measure continues to de facto  discriminate against Mexican tuna products in that the lack of access to the 
advantage of the dolphin-safe label for tuna products containing tuna caught by setting on 
dolphins has a detrimental impact on the competitive opportunities of Mexican tuna products in the US market. In Mexico's view, nothing in the amended tuna measure has reduced or minimized the 
detrimental impact on imported Mexican tuna products caused by the regulatory distinction 
imposed in the original tuna measure. Rather, the differences in labelling conditions and requirements remain substantially the same, and, as a consequence, tuna products of Mexican origin continue to be effectivel y excluded from the US market.
784 
7.570.  Mexico also argues that this discrimination is clearly demonstrated in the three labelling 
conditions and requirements of the amended tuna measure that Mexico previously identified in 
relation to the relevant regulatory distinction under Article 2.1 of the TBT Agreement, namely: 
disqualification of setting on dolphins in accord ance with the AIDCP as a fishing method that can 
be used to catch tuna in the ETP in a dolphin-safe manner, and the qualification of other fishing methods to catch tuna in a dolphin-safe manner; the different certification requirements for tuna 
caught by large purse seine vessels in the ETP and tuna caught outside the ETP by large purse 
seine and other vessels; and the different tracking and verification requirements for tuna caught in the ETP by large purse seine vessels and tuna caught outside the ETP caught by large purse seine and other vessels.
785 Mexico argues that, pursuant to each of these three labelling conditions and 
requirements, Mexican tuna products are denied access to the US dolphin-safe label while other 
countries, all of which produce at least some tuna products that may contain tuna caught outside the ETP in a manner that adversely affects dolphins, are permitted to use the label.
786 
7.571.  Finally, Mexico stresses that one of the policy objectives pursued by the amended tuna 
measure is to provide consumers with accurate information regarding the dolphin-safe status of tuna contained in the tuna products on the US market. However, according to Mexico, the 
amended tuna measure does just the opposite in that the three labelling conditions and 
requirements established pursuant to the amended tuna measure provide consumers with reliable 
                                               
781 United States' second written submission, paras. 219-220. 
782 United States' second written submission, paras. 207-210. 
783 Mexico's second written submission, para. 319. 
784 Mexico's second written submission, para. 323. 
785 Mexico's second written submission, para. 324. 
786 Mexico's second written submission, para. 325. WT/DS381/RW 
 
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  and objective information concerning the dolphin-safe status of tuna caught inside the ETP, while 
providing inherently unreliable and unverifiable information concerning the dolphin-safe status of tuna caught outside the ETP.
787 
7.7.3.3.2  Analysis by the Panel 
7.572.  The Panel considers now whether the United States has demonstrated that the amended 
tuna measure, and in particular the three challe nged aspects of the amended tuna measure that 
are inconsistent with Articles I and III of the GATT 1994 but provisionally justified under 
Article XX(g) of that Agreement, are applied in a manner that constitutes a means of arbitrary or 
unjustifiable discrimination between countries where the same conditions prevail, or a disguised restrictions on international trade. 
7.7.3.3.2.1  Arbitrary or unjustifiable disc rimination between countries where the same 
conditions prevail 
7.573.  The United States claims that the amended tuna measure does not impose any arbitrary or 
unjustifiable discrimination between countries where the same conditions prevail because the 
relevant conditions with respect to the protection of dolphins are not the same for all fisheries 
worldwide; the United States adds that if there is any discrimination resulting from its measure, it is justified and not arbitrary. 
7.574.  Under the chapeau, discrimination exists only where "countries in which the same 
conditions prevail are treated differently".
788 Thus, we need to review whether the amended tuna 
measure discriminates between countries in which the same conditions exist. 
Eligibility criteria 
7.575.  The first aspect of the amended tuna measure discussed by the parties is the eligibility 
criteria. We recall that the eligibility condition regarding setting on dolphins is applicable to all tuna, regardless of where it was caught. All tuna products containing tuna caught by setting on 
dolphins is ineligible for the label, regardless of the fishery, nationality of the vessel, and 
nationality of the processor. We agree with the United States that this provision has no carve-out whereby the products of certain Members automatically qualify for different regulatory treatment, 
as was the case in the measures challenged in Brazil – Retreaded Tyres  and EC – Seal Products .
789  
7.576.  The United States insists that its amended tuna measure is "neutral," and submits that 
whether tuna product is eligible for the dolphin-safe label depends on the choices made by vessel owners, operators, and captains.
790 As discussed extensively in both the original proceedings and 
before this Panel, there are many ways to catch tuna. Setting on dolphins is one such way, but it is 
not the only way. The United States submits that ev en in the ETP purse seine fishery, most sets by 
large purse seine vessels are not sets on dolphins.791   
7.577.  We note that the amended tuna measure does not impose different regulatory treatment 
between countries. The main regulatory distinct ion of the amended tuna measure concerns not 
countries but different fishing methods: accordingly, it is the fishing method of setting on dolphins 
– considered to be particularly harmful to dolphins because it necessarily entails the chasing of 
dolphins to find and catch tuna – that is regulated differently and more tightly than other fishing methods. In addition, if a tuna product contains t una caught during a set or other gear deployment 
                                               
787 Mexico's second written submission, para. 336. 
788 Appellate Body Reports, EC – Seal Products , para. 5.303 (citing Appellate Body Report, US – Shrimp , 
para. 165). 
789 Appellate Body Reports, EC – Seal Products , para. 5.316 (considering the different regulatory 
treatment to be the prohibition of seal products originating from "commercial hunts" in Canada and Norway and the allowance of seal products originating from in digenous communities in Greenland); Appellate Body 
Report , Brazil – Retreaded Tyres , paras. 226-33 (discussing the Mercosur exception). 
790 United States' first written submission, para. 333 (quoting Panel Report, US – Tuna II (Mexico) , 
para. 7.333 ("[T]he choice facing the fleets of the United States, of Mexico, and other foreign origin was the same, and that US and other fleets operating in the ETP could equally have chosen to continue to set on 
dolphins in the ETP under the conditions set out in the AIDCP … In that respect, the situation arising from the 
measure was the same for both fleets.")). 
791 United States' first written submission, para. 92. WT/DS381/RW 
 
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  in which a dolphin was killed or seriously injured, such tuna product is ineligible to be labelled 
dolphin-safe regardless of what fishing method was used. This latter eligibility requirement applies to all tuna, regardless of where or how it was caught. As such, these eligibility conditions do not distinguish between Members, or even between fi sheries, but between fishing methods. In this 
context, the United States suggests that the most appropriate "condition" to examine in this 
analysis is the different harms to dolphins caused by setting on dolphins, on the one hand, and by purse seine (other than setting on dolphins), long line, and pole-and-line fishing, on the other. We 
agree. 
7.578.  As we explained above, the Appellate Bo dy found in the original proceedings that the 
eligibility criteria were not inconsistent with Article 2.1 of the TBT Agreement.
792 We also recall 
that there are overlaps between the test in the chapeau of Article XX and the second step of the 
test under Article 2.1 of the TBT Agreement. The Appellate Body in the original proceedings did not 
address the consistency of the eligibility criteria with the chapeau of Article XX.793 However, the 
Panel believes that the factual findings made by the original panel and noted by the Appellate Body 
are relevant to the application of the chapeau of Article XX. 
7.579.  As we have explained above, in the original proceedings, the panel found that sufficient 
evidence had been put forward by the United St ates to raise a presumption that setting on 
dolphins not only causes observable harms, but also causes unobservable harms to dolphins 
beyond mortality and serious injury.  . These harms arise "as a result of the chase itself", and may occur even if no dolphin is actually killed or seriously injured in a way that is perceptible during the fishing operation.
794  As we understand it, this is why the Appellate Body concluded that setting on 
dolphins is "particularly harmful" to dolphins.795  
7.580.  The original panel also found that the observed and unobserved effects of setting on 
dolphins were "fully addressed" by the original measure precisely because it "disqualif[ied] all tuna 
products containing tuna harvested with that method from access to the 'dolphin-safe' label"796, 
and stated that "to the extent that it would not discourage these unobserved effects of setting on dolphins and their potential consequences on dolphin populations … the use of the AIDCP labelling 
requirements … could potentially provide a less er degree of protection than the existing 
US dolphin-safe provisions".
797  
7.581.  Applying these factual findings in the present case, the Panel is not convinced that fishing 
methods other than setting on dolphins cause the same or similar unobserved harms. Rather, the 
Panel agrees with the United States that " even if  there are tuna fisheries using … gear types that 
produce the same number of dolphin mortalities and serious injuries allowed or caused in the ETP … it is simply not the case that such fisheries are producing the same level of unobserved harms, 
such as cow-calf separation, muscular damage, immune and reproductive system failures, which 
arise as a result of the chase in itself".
798 
7.582.  As we noted above, the Appellate Body's conclusion in the original proceedings was not 
that the disqualification of setting on dolphins itself gave rise to a violation of Article 2.1 of the 
TBT Agreement. Rather, the original tuna meas ure was inconsistent with the WTO Agreement 
because, although it fully addressed the harms arising from setting on dolphins, it did not sufficiently address the harms caused to dolphins by other tuna fishing methods. In making this 
finding, the Appellate Body did not say, or even suggest, that the United States must disqualify all 
other fishing methods from accessing the dolphin-safe label, as Mexico suggests in the present proceedings, or that setting on dolphins and ot her methods of fishing must be regulated in the 
same manner. To the contrary, the Appellate Body accepted that, in principle, WTO law allows the 
United States to "calibrate" the requirements imposed by the amended tuna measure according to 
                                               
792 See paras. 7.126-7.135 above. 
793 This is because the original panel exercised judicial economy with respect to Mexico's GATT claims – 
an exercise that the Appellate Body found to be a violation of Article 11 of the DSU. Ultimately, however, 
Mexico did not request the Appellate Bo dy to complete the legal analysis, and accordingly it made no finding on 
this matter: see Appe llate Body Report, US – Tuna II (Mexico) , paras. 405 and 406. 
794 Appellate Body Report, US – Tuna II (Mexico), para. 246 (citing Panel Report, US – Tuna II (Mexico) , 
para. 7.504). 
795 Appellate Body Report, US – Tuna II (Mexico), para. 289. 
796 Appellate Body Report, US – Tuna II (Mexico), para. 287. 
797 Panel Report, US – Tuna II (Mexico), para. 7.613. 
798 United States' first written submission, para. 113 (internal citations omitted) (emphasis original). WT/DS381/RW 
 
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  "the likelihood that dolphins would be adversely affected in the course of tuna fishing operations in 
the respective conditions" of different fisheries.799 And insofar as it found that setting on dolphins 
is "particularly harmful" to dolphins, it implicitly acknowledged that the United States need not impose the same standards on all fishing methods in  order to ensure that its dolphin-safe labelling 
regime is consistent with the Article 2.1 of the TBT Agreement: 
In addition, we note that nowhere in its reasoning did the Panel state that imposing a 
requirement that an independent observer ce rtify that no dolphins were killed or 
seriously injured in the course of the fishing operations in which the tuna was caught 
would be the only way for the United States to calibrate its "dolphin-safe" labelling 
provisions to the risks that the Panel found were posed by fishing techniques other than setting on dolphins.  We note, in this regard, that the measure at issue itself 
contemplates the possibility that only the captain provide such a certification under 
certain circumstances.
800 
7.583.  Both parties argue that one of the most important factors in determining whether 
discrimination is "arbitrary or unjustifiable" is "whether the discrimination can be reconciled with, 
or is rationally related to, the policy objective with respect to which the measure has been provisionally justified under one of the subparagraphs of Article XX."
801   
7.584.  The relevant objectives of the amended measure are (i) ensuring that consumers are not 
misled or deceived about whether tuna products contain tuna caught in a manner that adversely 
affects dolphins, and (ii) contributing to the protec tion of dolphins by ensuring that the US market 
is not used to encourage fishing fleets to catch tuna in a manner that adversely affects dolphins.802 
In our view, the eligibility criteria are rationally related to the dolphin protection objective of the 
amended tuna measure. As the original panel found and the Appellate Body noted, setting on dolphins is a "particularly harmful" fishing method, and other fishing methods do not cause the 
same kinds of unobserved harms to dolphins as are caused by setting on dolphins.
803 In our view, 
the fact that other fishing methods do not cause the kind of unobservable harms as are caused by setting on dolphins means that, at least insofar as the eligibility criteria are concerned, the 
conditions prevailing in fisheries where tuna is caught by setting on dolphins and fisheries where 
that method is not used are not the same. Accordingly, in our view, the eligibility criteria are directly related to the objective of the amended measure. Any discrimination that they (i.e. the 
eligibility criteria) cause is directly connected to the main goal of the amended tuna measure, and 
accordingly we conclude that this aspect of the measure is not inconsistent with the requirements 
of the chapeau. 
7.585.  For the same reasons, we also believe that the United States has demonstrated that the 
eligibility criteria are applied in a manner that does not constitute a disguised restriction on trade. 
Indeed, setting on dolphins is a "particularly harmful" fishing method, and other fishing methods do not cause the same kinds of unobserved harms to dolphins as are caused by setting on 
dolphins
804, although according to the Appellate Body th ey may, in some circumstances, cause the 
same kinds of observed harms. The eligibility criter ia are in line with the fundamental rationale and 
objective of the amended tuna measure, i.e. to contribute to the protection of dolphins. Any 
restrictions they cause are directly connected to the main goal of the amended tuna measure and 
therefore cannot be considered "disguised". Accordingly we conclude that this aspect of the 
measure is not inconsistent with the requirements of the chapeau. 
Different certification requirements 
7.586.  In Mexico's view, the effect of the different certification requirements is to create "two 
distinct and conflicting standards for the accuracy of information regarding the dolphin-safe status of tuna: one standard for tuna caught inside the ETP, and a separate and much lower standard for 
tuna caught outside the ETP".
805 Given, however, that one of the goals of the amended tuna 
                                               
799 Appellate Body Report, US – Tuna II (Mexico), para. 286. 
800 Appellate Body Report, US – Tuna II  (Mexico) , para. 296. 
801 Appellate Body Reports, EC – Seal Products , para. 5.303. 
802 United States' first written submission, para. 14. 
803 United States' first written submission, paras. 89-101 and 110-61. 
804 United States' first written submission, paras. 89-101 and 110-61. 
805 Mexico's second written submission, para. 193. WT/DS381/RW 
 
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  measure is "ensuring that consumers are not misled or deceived about whether tuna products 
contain tuna caught in a manner that adversely affects dolphins"806, Mexico concludes that the 
amended tuna measure's system of captain self-certification "does not bear a rational connection to", and in fact is "entirely inconsistent"
807 and "irreconcilable"808 with, the objectives of the 
amended tuna measure, and accordingly the measure is applied in a manner that constitutes 
arbitrary discrimination, in contravention of the chapeau. 
7.587.  In Mexico's opinion, the differences in th e nature and degree of risk posed to dolphins by 
different fishing methods do not explain or ju stify the different certification requirements. 
According to Mexico, the amended tuna measure is designed so as to disqualify from accessing the label any and every tuna catch as soon as even a single dolphin is killed or seriously injured. Given that all parties agree that dolphins may be killed or seriously injured in every  fishery, Mexico 
concludes that all tuna fishing vessels must have an independent observer on-board if the 
United States is to ensure that the amended tuna measure operates to provide consumers with accurate and reliable information about th e dolphin-safe status of tuna products. 
7.588.  Mexico challenges the different certification requirements on the basis that captain self-
certification "permits or requires a private industry party to participate in the administration of [a law] which affect[s] the party's own commercial interests".
809 In Mexico's view, there is a "financial 
incentive for captains to declare the tuna caught by their vessels to be 'dolphin-safe', and a 
corresponding financial disincentive to declare any tuna caught by their vessels to be non-dolphin-safe", because "if a captain were to decline to certify tuna caught by his or her own vessel as dolphin-safe … the value of the tuna would be significantly diminished".
810 According to Mexico, the 
different certification requirements place captains "i n an inherent conflict of interest", because they 
"have a vested commercial and financial interest in securing dolphin-safe certification for the tuna that they catch". In Mexico's opinion, this creates "a very real risk that the tuna may be 
improperly certified as dolphin-safe", which would be inconsistent with the amended tuna 
measure's stated objectives.
811 
7.589.  According to Mexico, the risk that captains will make "false"812, incorrect, or improper 
statements is heightened by the fact that "there are no safeguards in the form of effective legal 
sanctions or enforcement mechanisms for fishing vessel captains who inaccurately or improperly certify the dolphin-safe status of tuna that is caught by their own vessels".
813 As such, Mexico 
submits that "there are no incentives to accurately and properly administer the dolphin-safe 
certification requirements for tuna caught outside the ETP".814 
7.590.  The United States rejects Mexico's allegations. It submits that the IATTC members agreed 
to different requirements regarding certification and tracking and verification, because the ETP is 
different  – nowhere else in the world has tuna fishing ca used the harm to dolphins that large purse 
seine vessels have caused in the ETP. The number of dolphins killed in the ETP tuna purse seine fishery since the fishery began in the late 1950s is the greatest known for any fishery.
815 In light of 
this unique history, the AIDCP parties agreed to unique  requirements, including the certification 
requirements that Mexico now insists the United States must require of itself and all of its trading partners, regardless of where or how they catch tuna, to come into compliance with its WTO obligations.  
7.591.  As we noted in the context of our anal ysis under Article 2.1 of the TBT Agreement, 
Mexico's argument is not that the United States should remove  the certification requirements that 
exist in the ETP, but, conversely, that "it is both appropriate and necessary to have an 
                                               
806 Mexico's second written submission, para. 3. 
807 Mexico's second written submission, para. 194. 
808 Mexico's second written submission, para. 195. 
809 Mexico's second written submission, para. 177 (citing Panel Report, Thailand – Cigarettes 
(Philippines) , paras. 7.902 and 7.904). 
810 Mexico's second written submission, para. 181. 
811 Mexico's second written submission, para. 182. See also Mexico's first written submission, para. 286. 
812 Mexico's second written submission, para. 185. 
813 Mexico's second written submission, para. 185. 
814 Mexico's second written submission, para. 185 
815 Tim Gerrodette, "The Tuna Dolphin Issue" in Perrin, Wu rsig and Thewissen (eds.), Encyclopedia of 
Marine Mammals  (2nd ed.) (Elservier: 2009), p. 1192 (Exhibit US-29). WT/DS381/RW 
 
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  independent observer requirement for tuna fishing outside the ETP"816 – and, indeed, that without 
imposing an observer requirement for vessels other than large purse seiners in the ETP, the amended tuna measure cannot be "even-handed " as required under Article 2.1 of the 
TBT Agreement. We believe that the eviden ce and arguments of the parties on the 
even-handedness of the regulatory distinction pu rsuant to Article 2.1 are also relevant for 
determining whether these aspects of the amended tuna measure impose arbitrary or unjustifiable discrimination between countries where the same conditions exist, in contravention of the chapeau 
of Article XX. Consequently, throughout our analysis of whether the United States has 
demonstrated that its certification and tracking and verification requirements are not applied in a manner that constitutes unjustifiable and arbitrary discrimination between countries where the same conditions prevail, we make reference to and use of the factual and legal assessments made 
in the course of our analysis under Article 2.1 of the TBT Agreement. 
7.592.  First, in the context of our analysis under Article 2.1 of the TBT Agreement, we were 
convinced by the United States' argument that ob servers are necessary on ETP large purse seiners 
but may not be necessary on other vessels in other fisheries because of the nature of the fishing 
technique used by ETP large purse seiners, which essentially involves the chasing and encirclement of many dolphins over an extended period of time. This means that it is necessary to have one 
single person on board with the responsibility of keeping track of those dolphins caught up in the 
chase and/or the purse seine net sets.
817 Other fishing methods in other oceans may – and, as the 
United States recognizes, do – cause dolphin mortality and serious injury, but because the nature and degree of the interaction is different in quantitative
818 and qualitative terms (since dolphins 
are not set on intentionally, and interaction is only accidental),819 there may be no need to have a 
single person on board whose sole task is to monitor the safety of dolphins during the set or other gear deployment. 
7.593.  In our view this argument is sufficient to demonstrate that maintaining different 
certification requirements does not necessarily amount to imposing unjustifiable or arbitrary discrimination. However, the fact that the United States may be entitled to have different 
certification requirements for tuna caught in the ETP large purse seine fishery and for tuna caught 
in other fisheries is not determinative of whether the system in place in fisheries other than the ETP large purse seine fishery – certification by captains only – is balanced and justified within the meaning of the chapeau of Article XX. We now consider whether the amended tuna measure's 
reliance on captains' certification in all fisheries other than the ETP large purse seine fishery is 
consistent with the chapeau of Article XX.  
7.594.  In the context of the Panel's application of  Article 2.1 of the TBT Agreement, we noted that 
Mexico's claim that the different certification requirements were not even-handed (and thus 
imposed unjustifiable discrimination) rested on the premise that captains' self-certifications are "inherently unreliable" and "meaningless".
820 Mexico submitted two reasons in support of this 
allegation: first, that captains have a financial incentive to certify that their catch is dolphin-safe 
even when it is not, and the amended tuna measure contains no mechanism to check this incentive; and second, that captains lack the technical expertise necessary to properly certify that no dolphins were killed or seriously injured in a given set or other gear deployment, and therefore 
their certifications do not guarantee that tuna labelled dolphin-safe in fact meets the statutory and 
regulatory requirements.  
7.595.  In the context of Article 2.1 of the TBT Agreement, the Panel was not convinced by 
Mexico's argumentation concerning the economic incentives facing captains. The Panel accepted 
the evidence submitted by the United States that  many regional and international organizations 
and arrangements rely on captains' certifications and logbooks both to monitor compliance with 
regulatory requirements and as a means of data co llection. The fact that many domestic, regional, 
and international regimes rely on captains' self-certification raised a strong presumption that such certifications are reliable. RFMOs and other fish eries and environmental organizations are experts 
                                               
816 Mexico's second written submission, para. 167. 
817 United States' response to Panel question No. 30, para. 168. 
818 United States' response to Panel question No. 20,  paras. 120-121; United States' response to Panel 
question No. 21, paras. 136-142. 
819 United States' response to Panel question No. 20,  paras. 120-125; United States' response to Panel 
question No. 22, paras. 147-149. 
820 Mexico's first written submission, paras. 271, 285 and 295; Mexico's second written submission, 
paras. 147, 172, 182, 188 and 193. WT/DS381/RW 
 
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  in their respective fields, and the fact that they have and continue to rely on captains' statements 
in a variety of fishing and environmental areas strongly suggests that, as a general matter, they consider such certifications to be reliable. The Panel considered that such acceptance was a highly relevant and probative fact.  
7.596.  The Panel was not convinced that the evidence submitted by Mexico was sufficient to rebut 
this fact. The documents submitted by Mexico certainly suggest that there have been instances in which captains' certifications have been unreliable. However, Mexico did not prove that there was 
a general practice of captains providing misstatem ents contrary to their domestic, regional, and 
international obligations. As the Panel explained, the fact that there have been cases of unreliable certification is not sufficient to conclude that captain statements are not, as a general matter of fact and law, sufficient to establish compliance with all kinds of fishing regulations. Several 
international instruments provide captains with multiple responsibilities and duties, and the Panel 
concluded that asking captains to perform dolphin-safe certification outside the ETP is, at least in principle, justified. 
7.597.  In light of the above, the Panel found that Mexico had not demonstrated that captains' 
certifications are inherently unreliable because captains have a financial incentive not to report accurately on the dolphin-safe status of tuna caught in a given set or other gear deployment. We 
concluded that in principle captains could be reliable to certify compliance with the requirements of 
the US dolphin-safe label requirements. In our view this means, in our current analysis, that the United States has demonstrated that requesting captains on boats outside the ETP to provide the same dolphin-safe certification that is requested from both the captain and an observer within the 
ETP, is not necessarily unjustifiable and inconsistent with the chapeau of Article XX.  
7.598.  However, we agreed with Mexico's second claim that captains' certificates may be 
unreliable because captains may not have the technical expertise necessary to accurately certify 
that no dolphins were killed or seriously inju red in a particular set or gear deployment.  
7.599.  We compared the kinds of tasks expected to be carried out by observers in the ETP and 
other oceans with those that are customarily carried out by captains. Such comparison helped us 
understand the kinds of skills necessary to certify that no dolphins were killed or seriously injured 
in a given set or other gear deployment.  
7.600.  On the basis of this evidence, we concluded that certifying whether a dolphin has been 
killed or seriously injured in a set or other gear deployment is a highly complex task. The Panel 
found it especially telling that the amended tuna measure itself recognizes the necessity of training 
and education in equipping persons with the necessary technical know-how to ensure that they can properly certify the dolphin-safety of a tuna catch. 
7.601.  Our analysis of the evidence also helped us understand the competencies and tasks 
generally expected of captains. This evidence, including the various regional and international treaties indicates that captains are generally expected to conduct a wide variety of tasks on board 
the vessels they command. As we read the evidence, captains are generally expected to have the 
knowledge and ability to fulfil a range of activities  that tends to extend to certifying the existence 
of facts over which they have control and/or di rect knowledge, e.g. port of entry and exit, co-
ordinates, date and time of gear deployment, and type of gear deployed.
821 In some cases 
captains are also expected to certify the species of fish caught, or the presence of whale or bird 
bycatch.822 In our opinion, however, these tasks may be rather different from those involved in 
certifying that no dolphins were killed or seriou sly injured in sets or other gear deployments. The 
evidence cited above suggests that this is a highly specialized skill, and none of the evidence 
before us suggests that captains (or, we would add, any other crew member) are always and necessarily in possession of those skills.  
                                               
821 United States' response to Panel question No. 37, paras. 194-196. Mexico's comments to 
United States' response to Panel question No. 37, paras. 130-134. 
822 As we noted above, the evidence  before us suggests that in a ve ry small number of  jurisdictions, 
captains may also be required or enabled to certify about marine mammal bycatch, although the amount of 
detail required and the mammals covered are different from the amended tuna measure: see paras. 7.220-7.225 above. WT/DS381/RW 
 
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  7.602.  Accordingly, the Panel concluded that the different certification requirements do not stem 
exclusively from a legitimate regulatory distin ction within the meaning of Article 2.1 of the 
TBT Agreement, because, to the extent that capt ains' could not be assumed to have the skills 
necessary to make an accurate dolphin-safe certification, this distinction makes it easier for 
non-dolphin-safe tuna caught other than by large purse seine vessel in the ETP to be incorrectly 
labelled as dolphin-safe, which inaccurate labelling would undermine the overall objectives of the amended tuna measure. 
7.603.  In our view, and taking into account our findings above, we do not think the United States 
has shown that the different certification requirements do not impose any arbitrary or unjustifiable discrimination. Requiring certification by captains only outside the ETP is not justifiable unless the United States can explain why it believes that captains have the necessary expertise to perform 
the duties necessary to certify compliance with the dolphin-safe label criteria. The United States 
has not explained sufficiently how captains can perform the duties inherent to the certification for the dolphin-safe label since they do not appear to  have the specific expertise required to do so 
thoroughly. 
7.604.  The Panel also found that the determination provisions in the amended tuna measure, 
which allow the Assistant Administrator to make certain determinations that have the effect of 
triggering an observer requirement outside the ET P large purse seine fishery, were inconsistent 
with Article 2.1 of the TBT Agreement (and Articl es I and III of the GATT 1994). This finding was 
based on the fact that such determinations are only possible in respect of certain fisheries, and the United States had not adequately explained how this limitation is rationally connected to the 
objectives pursed by the amended tuna measure. 
7.605.  In the Panel's view, the findings we made  in the context of Article 2.1 apply with equal 
force in the context of the chapeau of Article XX. Insofar as the different certification requirements 
are not justified by the objective of conserving dolphins by providing consumers with accurate 
information about the dolphin-safe status of tuna  p r o d u c t s ,  w e  f i n d  t h a t  t h i s  a s p e c t  o f  t h e  
amended tuna measure is unjustifiably and arbitrar ily discriminatory. We also find that, unlike in 
the context of the eligibility criteria, for the purposes of this element of the measure, the 
conditions prevailing among Members are the same, because dolphins may be killed or seriously injured by all fishing methods in all oceans, and accordingly accurate certification is necessary regardless of the particular fishery in which tuna is caught. Thus, the Panel finds that the different 
certification requirements are not applied consistently with the requirements of the chapeau of 
Article XX of the GATT 1994.  
Separate opinion of one panelist 
7.606.  As I explained in section 7.5.2.4.2.3 above,  the different certification requirements can be 
justified where the risks in different fisheries are different. In my view, the conditions inside the ETP are not the same as those in other fisheries. In my opinion, the United States has 
demonstrated that the different requirements as to who must make a dolphin-safe certification are 
rationally connected to the different risks facing dolphins in different areas and from different fishing methods, because those requirements are "calibrated" or otherwise proportionate to those risks. Accordingly, I do not agree with the majority view expressed in paragraph 7.603 above. In 
my view, requiring observers only in the ETP is not arbitrarily or unjustifiably discriminatory, 
contrary to the requirements of the chapeau of Article XX of the GATT 1994. 
7.607.  However, in the context of Article 2.1 of the TBT Agreement, I joined with the majority in 
finding that the United States has not explained or justified the discrimination caused by the so-
called "determination provisions", which only allow the Assistant Administrator to make certain determinations in respect of certain fisheries. These provisions unjustifiably limit the capacity of 
the amended tuna measure to respond to situations where the risks to dolphins are on a par with 
those in the ETP large purse seine fishery. Accord ingly, I agree with the majority's reasoning at 
paragraph 7.605 and would find that for this reason the United States has not succeeded in showing that the different certification requirements are not applied in a manner that gives rise to 
arbitrary or unjustifiable discrimination. WT/DS381/RW 
 
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  Different tracking and verification requirements 
7.608.  We turn finally to the different tracking  and verification requirements imposed by the 
amended tuna measure. 
7.609.  The Panel has already reached the conclusion that the different tracking and verification 
requirements are not even-handed within the meaning of Article 2.1 of the TBT Agreement 
because they cause a detrimental impact that the United States has not justified on the basis of the objectives pursued by the amended tuna measur e. In our opinion, the circumstances that gave 
rise to the breach of Article 2.1 of the TBT Agreem ent give rise also to arbitrary and unjustifiable 
discrimination under the chapeau of Article XX of  the GATT 1994. Our reasons are as follows. 
7.610.  In our findings under Article 2.1 of the TBT Agreement, we concluded that the different 
tracking and verification requirements impose a lighter burden on tuna caught other than in the 
ETP large purse seine fishery. We also saw merit in Mexico's arguments that the lighter tracking 
and verification requirements imposed outside of the ETP large purse seine fishery may make it more likely that tuna caught other than by large purse seine vessel will be incorrectly labelled as 
dolphin-safe, although we did not find it necessary to make a definitive finding on that point. In 
the context of the present analysis, the Panel agrees with Mexico that the lesser burden placed on tuna caught other than in the ETP large purse seine fishery, is not rationally related to the 
amended tuna measure's objective of conserving dolphins by providing information to consumers 
concerning the dolphin-safe status of tuna products. Moreover, to the extent that the different requirements may make it easier for tuna caught other than by large purse seine vessel in the ETP to be incorrectly labelled – a point on which we do not make a definitive finding – this would also 
be inconsistent with the measure's goal of providing accurate information to consumers. In the 
Panel's view, the United States has not provided  any explanation as to how this differential 
treatment is related to, let alone justified by, the objectives pursed by the amended tuna measure, 
which is to provide accurate information to consumers in order to conserve dolphins. 
7.611.  As such, the Panel concludes that the different tracking and verification requirements are 
applied in a manner that constitutes unjustifiable and arbitrary discrimination contrary to the 
chapeau of Article XX of the GATT 1994. 
7.7.3.3.2.2  Disguised restri ction on international trade 
7.612.  Mexico argues that the amended tuna measure is applied so as to constitute a disguised 
restriction on trade. For the United States the measure was adopted at a time when it affected the 
US industry – it was not a measure that would protect US production. And the dolphin-safe label is 
available regardless of nationality of the fishing vessel or the origin of the product. Mexico asserts that the United States has discriminated arbitrarily and unjustifiably by not working through the 
AIDCP to "address[] its remaining concerns about dolphins and tuna fishing."
823 The United States 
responds that it has engaged in multilateral negotiations with Mexico through the AIDCP process.  
7.613.  It seems to this Panel that the United States and Mexico have been debating the issue of 
tuna and dolphins for several years. Neverthele ss, it is not necessary to decide whether the 
amended tuna measure is applied in a manner that constitutes a disguised restriction on international trade. This is so because we alread y found that the United States has not been able 
to demonstrate that certain aspects of the amended tuna measure is not applied in a manner that 
constitutes arbitrary or unjustifiable discrimination. We need not discuss whether these same 
aspects of the amended tuna measure constitute a disguised restriction on international trade.  
8  CONCLUSIONS AND RECOMMENDATIONS 
8.1.  Mexico raised claims with regard to certain aspects of the United States' amended tuna 
measure under Article 2.1 of the TBT Agreemen t and Articles I:1 and III:4 of the GATT 1994. 
                                               
823 Mexico's first written submission, paras. 337-339. WT/DS381/RW 
 
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  8.2.  With respect to Mexico's claims under Arti cle 2.1 of the TBT Agreement, the Panel concludes 
that: 
a. the eligibility criteria in the amended tuna measure do not accord less favourable 
treatment to Mexican tuna and tuna products than that accorded to like products from 
the United States and to like products originating in any other country, and are thus 
consistent with Article 2.1 of the TBT Agreement;  
b. the different certification requirements in the amended tuna measure accord less 
favourable treatment to Mexican tuna and tuna products than that accorded to like 
products from the United States and to like products originating in any other country, in violation of Article 2.1 of the TBT Agreement; and  
c. the different tracking and verification requirements in the amended tuna measure accord 
less favourable treatment to Mexican tuna and tuna products than that accorded to like 
products from the United States and to like products originating in any other country, in violation of Article 2.1 of the TBT Agreement. 
8.3.  With respect to Mexico's claims under the GATT 1994, the Panel concludes that: 
a. the eligibility criteria in the amended tuna measure accord less favourable treatment to 
Mexican tuna and tuna products than that accorded to like products from the 
United States and to like products originating in any other country, in violation of 
Articles I:1 and III:4 of the GATT 1994; 
b. the different certification requirements in the amended tuna measure accord less 
favourable treatment to Mexican tuna and tuna products than that accorded to like 
products from the United States and to like products originating in any other country, in 
violation of Articles I:1 and III:4 of the GATT 1994; and 
c. the different tracking and verification requirements in the amended tuna measure accord 
less favourable treatment to Mexican tuna and tuna products than that accorded to like 
products from the United States and to like products originating in any other country, in violation of Articles I:1 and III:4 of the GATT 1994. 
8.4.  With respect to the United States' defence under Article XX(g) of the GATT 1994, the Panel 
finds that: 
a. the eligibility criteria in the amended tuna measure are provisionally justified under 
Article XX(g); 
b. the different certification requirements in the amended tuna measure are provisionally 
justified under Article XX(g); and 
c. the different tracking and verification requirements in the amended tuna measure are 
provisionally justified under Article XX(g). 
8.5.   With regard to the question of whether the challenged aspects of the amended tuna measure 
satisfy the requirements of the chapeau of Articl e XX of the GATT 1994, the Panel concludes that: 
a. the eligibility criteria in the amended tuna measure are applied in a manner that meets 
the requirements of the chapeau of Article XX of the GATT 1994; 
b. the different certification requirements are applied in a manner that does not meet the 
requirements of the chapeau of Article XX of the GATT 1994; and 
c. the different tracking and verification requirements are applied in a manner that does 
not meet the requirements of the chapeau of Article XX of the GATT 1994. WT/DS381/RW 
 
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  8.6.  Pursuant to Article 19.1 of the DSU, we recommend that the Dispute Settlement Body 
request the United States to bring its measure, which we have found to be inconsistent with Article 2.1 of the TBT Agreement and Articles I:1 and III:4 of the GATT 1994 and not justified 
under Article XX of the GATT 1994, into conformity  with its obligations under the TBT Agreement 
and the GATT 1994. 
 
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