UNITED STATES – MEASURES CONCERNING THE IMPORTATION, MARKETING AND SALE OF TUNA AND TUNA PRODUCTS RECOURSE TO ARTICLE 21.5 OF THE DSU BY THE UNITED STATES UNITED STATES – MEASURES CONCERNING THE IMPORTATION, MARKETING AND SALE OF TUNA AND TUNA PRODUCTS SECOND RECOURSE TO ARTICLE 21.5 OF THE DSU BY MEXICO AB-2017-9
Document: MARKETING AND SALE OF TUNA AND TUNA PRODUCTS SECOND RECOURSE TO ARTICLE 21.5 OF THE DSU BY MEXICO AB-2017-9 Report of the Appellate Body
Date: 14 December 2018
Document codes: WT/DS381/AB/RW/USA; WT/DS381/AB/RW2
Complainant: Mexico
Respondent: U.S.
Third parties: Australia, Brazil, Canada, China, Ecuador, EU, Guatemala, India, Japan, South Korea, New Zealand, Norway
Dispute stage: Implementation & Compliance
Agreements cited: Art. I:1, III:4  GATT 1994Art. 2.1, 2.2, 2.3, 2.4  Technical Barriers to Trade (TBT)

UNITED STATES – MEASURES CONCERNING THE IMPORTATION,
MARKETING AND SALE OF TUNA AND TUNA PRODUCTS
RECOURSE TO ARTICLE 21.5 OF THE DSU BY THE UNITED STATES
UNITED STATES – MEASURES CONCERNING THE IMPORTATION,
MARKETING AND SALE OF TUNA AND TUNA PRODUCTS
SECOND RECOURSE TO ARTICLE 21.5 OF THE DSU BY MEXICO
AB-2017-9
Report of the Appellate Body
 •

ABBREVIATIONS USED IN THIS REPORT
Abbreviation Description
2013 Rule USDOC, NOAA, Enhanced Document Requirements to Support Use of the
Dolphin Safe Label on Tuna Products, United States Federal Register, Vol. 78,
No. 131 (9 July 2013), pp. 40997-41004
2013 Tuna Measure DPCIA; United States Code of Federal Regulations, Title 50, Part 216,
Subpart H (Dolphin Safe Tuna Labeling), as amended by the 2013 Rule; and
the Hogarth ruling
2016 implementing
regulations
United States Code of Federal Regulations, Title 50, Part 216, Subpart H
(Dolphin Safe Tuna Labeling), as amended by the 2013 Rule and the
2016 Rule
2016 Rule Enhanced Document Requirements and Captain Training Requirements to
Support Use of the Dolphin Safe Label on Tuna Products, United States Federal
Register, Vol. 81, No. 56 (23 March 2016)
2016 Tuna Measure DPCIA; the 2016 implementing regulations; and the Hogarth ruling
AIDCP Agreement on the International Dolphin Conservation Program
Assistant Administrator United States Assistant Administrator for Fisheries, NMFS, NOAA, or his/her
designee
Captain Training Course NMFS Tuna Tracking and Verification Program dolphin-safe training course
CC catch certificate
CDS catch documentation scheme
CFR United States Code of Federal Regulations
DML dolphin mortality limit
DPCIA Dolphin Protection Consumer Information Act of 1990, codified in
United States Code, Title 16, Section 1385
DSB Dispute Settlement Body
DSU Understanding on Rules and Procedures Governing the Settlement of Disputes
ETAO Eastern Tropical Atlantic Ocean
ETP Eastern Tropical Pacific
FAD fish aggregating device
FAO Food and Agricultural Organization of the United Nations
First Compliance Panel
Report
Panel Report, United States – Measures Concerning the Importation, Marketing
and Sale of Tuna and Tuna Products – Recourse to Article 21.5 of the DSU by
Mexico, WT/DS381/RW, Add.1 and Corr.1
GATT 1994 General Agreement on Tariffs and Trade 1994
Hogarth ruling United States Court of Appeals for the Ninth Circuit, Earth Island Institute v.
Hogarth, 494 F.3d 757 (9th Cir. 2007); United States Court of Appeals for the
Ninth Circuit, Earth Island Institute v. Hogarth, 494 F.3d 1123 (9th Cir. 2007)
IATTC Inter-American Tropical Tuna Commission
IDCP International Dolphin Conservation Program
IDCPA International Dolphin Conservation Program Act
ISSF International Seafood Sustainability Foundation
IUU illegal, unreported, and unregulated
Mexico's panel request Request for the Establishment of a Panel by Mexico pursuant to Article 21.5 of
the DSU, WT/DS381/38
NMFS National Marine Fisheries Service
NOAA National Oceanic and Atmospheric Administration
Original Panel Report Panel Report, United States – Measures Concerning the Importation, Marketing
and Sale of Tuna and Tuna Products, WT/DS381/R
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Abbreviation Description
Original Tuna Measure DPCIA; United States Code of Federal Regulations, Title 50, Sections 216.91
and 216.92 (Dolphin Safe Tuna Labeling), as of 13 September 2004; and the
Hogarth ruling
Panel Reports Panel Reports, United States – Measures Concerning the Importation,
Marketing and Sale of Tuna and Tuna Products – Recourse to Article 21.5 of
the DSU by the United States, WT/DS381/RW/USA and Add.1 /
United States – Measures Concerning the Importation, Marketing and Sale of
Tuna and Tuna Products – Second Recourse to Article 21.5 of the DSU by
Mexico, WT/DS381/RW2 and Add.1
PBR Potential Biological Removal
RFMO Regional Fishery Management Organization
TBT Agreement Agreement on Technical Barriers to Trade
TTF Tuna Tracking Form
United States' panel request Request for the Establishment of a Panel by the United States pursuant to
Article 21.5 of the DSU, WT/DS381/32
USDOC United States Department of Commerce
WCPO Western and Central Pacific Ocean
Working Procedures Working Procedures for Appellate Review, WT/AB/WP/6, 16 August 2010
WTO World Trade Organization
WTO Agreement Marrakesh Agreement Establishing the World Trade Organization
PANEL EXHIBITS CITED IN THIS REPORT
Exhibit Number Short Title
(if applicable) Description
Original Panel Record
Original Panel Exhibit
MEX-11
AIDCP Agreement on the International Dolphin Conservation
Program (Annexes I, IV(I)(3)(c), and VII(6))
Original Panel Exhibit
MEX-29
 United States District Court for the Northern District of
California, Earth Island Institute et al. v. Donald Evans et
al., 34 ELR 20069 (N.D. Cal. 2004)
Original Panel Exhibit
MEX-30
 United States Court of Appeals for the Ninth Circuit, Earth
Island Institute et al. v. William T. Hogarth, 484 F.3d 1123
(9th Cir. 2007)
Original Panel Exhibit
MEX-31
 United States Court of Appeals for the Ninth Circuit, Earth
Island Institute et al. v. William T. Hogarth, 494 F.3d 757
(9th Cir. 2007)
Original Panel Exhibit
MEX-55
 AIDCP, Resolution to Adopt the Modified System for
Tracking and Verification of Tuna (20 June 2001)
Original Panel Exhibit US-5 DPCIA Dolphin Protection Consumer Information Act of 1990,
codified in United States Code, Title 16, Section 1385
Original Panel Exhibit US-6 United States Code of Federal Regulations, Title 50,
Sections 216.91 and 216.92
Original Panel Exhibit
US-58
 United States Code of Federal Regulations, Title 50,
Sections 216.91-216.95
First Compliance Panel Record
First Compliance Panel
Exhibit MEX-7
2013 Rule USDOC, NOAA, Enhanced Document Requirements to
Support Use of the Dolphin Safe Label on Tuna Products,
United States Federal Register, Vol. 78, No. 131
(9 July 2013), pp. 40997-41004
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Exhibit Number Short Title
(if applicable) Description
First Compliance Panel
Exhibit MEX-8
DPCIA Dolphin Protection Consumer Information Act of 1990,
codified in United States Code, Title 16, Section 1385
First Compliance Panel
Exhibit MEX-20
 United States Code of Federal Regulations, Title 50,
Section 216
First Compliance Panel
Exhibit MEX-30
 AIDCP, as amended October 2009, Article I:8 and Annex II,
paras. 1-3
First Compliance Panel
Exhibit MEX-36
 AIDCP, Resolution to Adopt the Modified System for
Tracking and Verification of Tuna (20 June 2001)
First Compliance Panel
Exhibit US-2
2013
implementing
regulations
USDOC, NMFS/NOAA, Dolphin Safe Tuna Labeling, United
States Code of Federal Regulations, Title 50, Part 216,
Subpart H (Sections 216.90-216.95)
First Compliance Panel
Exhibit US-113
 Determination of Observer Programs as Qualified and
Authorized by the Assistant Administrator for Fisheries,
United States Federal Register, Vol. 79, No. 134 (14 July
2014), pp. 40718-40720
First Compliance Panel
Exhibit US-114
 NMFS, National Observer Program FY 2012 Annual Report
(2013)
Panel Record in these Compliance Proceedings
Panel Exhibit MEX-1 DPCIA Dolphin Protection Consumer Information Act of 1990,
codified in United States Code, Title 16, Section 1385
Panel Exhibit MEX-2 2016
implementing
regulations
USDOC, NMFS/NOAA, Dolphin Safe Tuna Labeling,
United States Code of Federal Regulations, Title 50,
Part 216, Subpart H, Sections 216.90-216.95
Panel Exhibit MEX-3 Hogarth ruling United States Court of Appeals for the Ninth Circuit, Earth
Island Institute et al. v. William T. Hogarth, 484 F.3d 1123
(9th Cir. 2007) and United States Court of Appeals for the
Ninth Circuit, Earth Island Institute et al. v. William
T. Hogarth, 494 F.3d 757 (9th Cir. 2007)
Panel Exhibit MEX-8 AIDCP, Report on the International Dolphin Conservation
Program, Doc. MOP-28-05, 18 October 2013
Panel Exhibit MEX-15 Food and Agricultural Organization of the United Nations,
"Tuna Drifting Gillnet",
http://www.fao.org/fishery/fishtech/1011/en, accessed
17 March 2014
Panel Exhibit MEX-18 Natural Resources Defense Council, Net Loss: The Killing of
Marine Mammals in Foreign Fisheries (New York, January
2014)
Panel Exhibit MEX-26 Food and Agricultural Organization of the United Nations,
"Industrial Tuna Longlining",
http://www.fao.org/fishery/fishtech/1010/en, accessed
17 March 2014
Panel Exhibit MEX-37 Food and Agricultural Organization of the United Nations,
"Trawl Nets", http://www.fao.org/fishery/geartype/103/en,
accessed 23 March 2014
Panel Exhibit MEX-38 Food and Agricultural Organization of the United Nations,
"Tuna Handlining,"
http://www.fao.org/fishery/fishtech/1012/en, accessed
5 September 2016
Panel Exhibit MEX-47 Enhanced Document Requirements and Captain Training
Requirements to Support Use of the Dolphin Safe Label on
Tuna Products, United States Federal Register, Vol. 81,
No. 56 (23 March 2016), pp. 15444-15449
Panel Exhibit MEX-104 National Oceanic and Atmospheric Administration, 2015
NOAA Marine Debris Program Report, Impact of "Ghost
Fishing" via Derelict Fishing Gear (Charleston, March 2015)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Exhibit Number Short Title
(if applicable) Description
Panel Exhibit MEX-127 ISSF, RFMO Catch Documentation Schemes: A Summary
(Washington, DC, 14 September 2016)
Panel Exhibit USA-1 DPCIA Dolphin Protection Consumer Information Act of 1990,
codified in United States Code, Title 16, Section 1385
Panel Exhibit USA-2 2016
implementing
regulations
USDOC, NMFS/NOAA, Dolphin Safe Tuna Labeling, United
States Code of Federal Regulations, Title 50, Part 216,
Subpart H, Sections 216.90-216.95
Panel Exhibit USA-3 Taking and Related Acts Incidental to Commercial Fishing
Operations by Tuna Purse Seine Vessels in the Eastern
Tropical Pacific Ocean, United States Code of Federal
Regulations, Title 50, Section 216.24 (2016)
Panel Exhibit USA-4 NOAA Form 370 NOAA, Form 370: Fisheries Certificate of Origin (2016)
Panel Exhibit USA-12 T. Gerrodette, "The Tuna-Dolphin Issue", in Perrin, Wursig,
and Thewissen (eds.), Encyclopedia of Marine Mammals,
2nd edn (Elsevier, 2009), pp. 1192-1195
Panel Exhibit USA-15 AIDCP, Report on the International Dolphin Conservation
Program, Doc. MOP-32-05, 20 October 2015
Panel Exhibit USA-60 Food and Agriculture Organization of the United Nations,
FAO Fisheries and Aquaculture Technical Paper 568,
Bycatch and Non-Tuna Catch in the Tropical Purse Seine
Fisheries of the World (Rome, 2013)
Panel Exhibit USA-90 International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015)
Panel Exhibit USA-111 Dolphin Mortalities Per Set Due to ETP Dolphin Sets and in
Other Fisheries
Panel Exhibit USA-166 United States Code, Title 18, Section 545
Panel Exhibit USA-167 United States Code, Title 18, Section 3571
Panel Exhibit USA-169 United States Code, Title 16, Section 3372
Panel Exhibit USA-170 Civil Monetary Penalty Adjustments for Inflation,
United States Federal Register, Vol. 81, No. 109
(7 June 2016), pp. 36454-36458
Panel Exhibit USA-171 United States Code, Title 16, Section 3373
Panel Exhibit USA-172 United States Code, Title 16, Section 3374
Panel Exhibit USA-173 United States Code, Title 18, Section 1001
Panel Exhibit USA-174 United States Code, Title 16, Section 1375
CASES CITED IN THIS REPORT
Short Title Full Case Title and Citation
Argentina – Footwear (EC) Appellate Body Report, Argentina – Safeguard Measures on Imports of
Footwear, WT/DS121/AB/R, adopted 12 January 2000, DSR 2000:I, p. 515
Australia – Salmon Appellate Body Report, Australia – Measures Affecting Importation of Salmon,
WT/DS18/AB/R, adopted 6 November 1998, DSR 1998:VIII, p. 3327
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 – 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
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Short Title Full Case Title and Citation
China – HP-SSST (EU) Appellate Body Report, China – Measures Imposing Anti-Dumping Duties on
High-Performance Stainless Steel Seamless Tubes ("HP-SSST") from the
European Union, WT/DS460/AB/R and Add.1, adopted 28 October 2015,
DSR 2015:IX, p. 4573
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, DSR 2014:III, p. 805
Colombia – Textiles Appellate Body Report, Colombia – Measures Relating to the Importation of
Textiles, Apparel and Footwear, WT/DS461/AB/R and Add.1, adopted
22 June 2016, DSR 2016:III, p. 1131
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
(Article 21.5 – Ecuador II) /
EC – Bananas III
(Article 21.5 – US)
Appellate Body Reports, European Communities – Regime for the Importation,
Sale and Distribution of Bananas – Second Recourse to Article 21.5 of the DSU
by Ecuador, WT/DS27/AB/RW2/ECU, adopted 11 December 2008, and Corr.1 /
European Communities – Regime for the Importation, Sale and Distribution of
Bananas – Recourse to Article 21.5 of the DSU by the United States,
WT/DS27/AB/RW/USA and Corr.1, adopted 22 December 2008,
DSR 2008:XVIII, p. 7165
EC – Bed Linen
(Article 21.5 – India)
Appellate Body Report, European Communities – Anti-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
EC – Fasteners (China) Appellate Body Report, European Communities – Definitive Anti-Dumping
Measures on Certain Iron or Steel Fasteners from China, WT/DS397/AB/R,
adopted 28 July 2011, DSR 2011:VII, p. 3995
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 – Sardines Appellate Body Report, European Communities – Trade Description of
Sardines, WT/DS231/AB/R, adopted 23 October 2002, DSR 2002:VIII, p. 3359
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, DSR 2014:I, p. 7
EC – Selected Customs
Matters
Appellate Body Report, European Communities – Selected Customs Matters,
WT/DS315/AB/R, adopted 11 December 2006, DSR 2006:IX, p. 3791
EC – Tube or Pipe Fittings Appellate Body Report, European Communities – Anti-Dumping Duties on
Malleable Cast Iron Tube or Pipe Fittings from Brazil, WT/DS219/AB/R,
adopted 18 August 2003, DSR 2003:VI, p. 2613
EC and certain member
States – Large Civil Aircraft
(Article 21.5 – US)
Appellate Body Report, European Communities and Certain Member States –
Measures Affecting Trade in Large Civil Aircraft – Recourse to Article 21.5 of
the DSU by the United States, WT/DS316/AB/RW and Add.1, adopted
28 May 2018
EU – Biodiesel (Argentina) Appellate Body Report, European Union – Anti-Dumping Measures on Biodiesel
from Argentina, WT/DS473/AB/R and Add.1, adopted 26 October 2016, DSR
2016:VI, p. 2871
EU – Fatty Alcohols
(Indonesia)
Appellate Body Report, European Union – Anti-Dumping Measures on Imports
of Certain Fatty Alcohols from Indonesia, WT/DS442/AB/R and Add.1, adopted
29 September 2017
EU – PET (Pakistan) Appellate Body Report, European Union – Countervailing Measures on Certain
Polyethylene Terephthalate from Pakistan, WT/DS486/AB/R and Add.1,
adopted 28 May 2018
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
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Short Title Full Case Title and Citation
Indonesia – Iron or Steel
Products
Appellate Body Report, Indonesia – Safeguard on Certain Iron or Steel
Products, WT/DS490/AB/R, WT/DS496/AB/R, and Add.1, adopted
27 August 2018
Japan – Agricultural
Products II
Appellate Body Report, Japan – Measures Affecting Agricultural Products,
WT/DS76/AB/R, adopted 19 March 1999, DSR 1999:I, p. 277
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
Japan – Apples Appellate Body Report, Japan – Measures Affecting the Importation of Apples,
WT/DS245/AB/R, adopted 10 December 2003, DSR 2003:IX, p. 4391
Korea – Alcoholic Beverages Appellate Body Report, Korea – Taxes on Alcoholic Beverages, WT/DS75/AB/R,
WT/DS84/AB/R, adopted 17 February 1999, DSR 1999:I, p. 3
Korea – Dairy Appellate Body Report, Korea – Definitive Safeguard Measure on Imports of
Certain Dairy Products, WT/DS98/AB/R, adopted 12 January 2000,
DSR 2000:I, p. 3
Mexico – Anti-Dumping
Measures on Rice
Appellate Body Report, Mexico – Definitive Anti-Dumping Measures on Beef
and Rice, Complaint with Respect to Rice, WT/DS295/AB/R, adopted
20 December 2005, DSR 2005:XXII, p. 10853
US – Carbon Steel Appellate Body Report, United States – Countervailing Duties on Certain
Corrosion-Resistant Carbon Steel Flat Products from Germany,
WT/DS213/AB/R and Corr.1, adopted 19 December 2002, DSR 2002:IX,
p. 3779
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)
Appellate Body Reports, United States – Certain Country of Origin Labelling
(COOL) Requirements – Recourse to Article 21.5 of the DSU by Canada and
Mexico, WT/DS384/AB/RW / WT/DS386/AB/RW, adopted 29 May 2015,
DSR 2015:IV, p. 1725
US – Countervailing
Measures on Certain EC
Products
Appellate Body Report, United States – Countervailing Measures Concerning
Certain Products from the European Communities, WT/DS212/AB/R, adopted
8 January 2003, DSR 2003:I, p. 5
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 (and 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 – Large Civil Aircraft
(2nd complaint)
Appellate Body Report, United States – Measures Affecting Trade in Large Civil
Aircraft (Second Complaint), WT/DS353/AB/R, adopted 23 March 2012, DSR
2012:I, p. 7
US – Lead and Bismuth II Appellate Body Report, United States – Imposition of Countervailing Duties on
Certain Hot-Rolled Lead and Bismuth Carbon Steel Products Originating in the
United Kingdom, WT/DS138/AB/R, adopted 7 June 2000, DSR 2000:V, p. 2595
US – Offset Act (Byrd
Amendment)
Appellate Body Report, United States – Continued Dumping and Subsidy Offset
Act of 2000, WT/DS217/AB/R, WT/DS234/AB/R, adopted 27 January 2003,
DSR 2003:I, p. 375
US – Oil Country Tubular
Goods Sunset Reviews
Appellate Body Report, United States – Sunset Reviews of Anti-Dumping
Measures on Oil Country Tubular Goods from Argentina, WT/DS268/AB/R,
adopted 17 December 2004, DSR 2004:VII, p. 3257
US – Shrimp Appellate Body Report, United States – Import Prohibition of Certain Shrimp
and Shrimp Products, WT/DS58/AB/R, adopted 6 November 1998, DSR
1998:VII, p. 2755
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Short Title Full Case Title and Citation
US – Steel Safeguards Appellate Body Report, United States – Definitive Safeguard Measures on
Imports of Certain Steel Products, WT/DS248/AB/R, WT/DS249/AB/R,
WT/DS251/AB/R, WT/DS252/AB/R, WT/DS253/AB/R, WT/DS254/AB/R,
WT/DS258/AB/R, WT/DS259/AB/R, adopted 10 December 2003,
DSR 2003:VII, p. 3117
US – Tax Incentives Panel Report, United States – Conditional Tax Incentives for Large Civil
Aircraft, WT/DS487/R and Add.1, adopted 22 September 2017, as modified by
Appellate Body Report WT/DS487/AB/R
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
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 – Tuna II (Mexico)
(Article 21.5 – Mexico)
Appellate Body Report, United States – Measures Concerning the Importation,
Marketing and Sale of Tuna and Tuna Products – Recourse to Article 21.5 of
the DSU by Mexico, WT/DS381/AB/RW and Add.1, adopted 3 December 2015,
DSR 2015:X, p. 5133
US – Tuna II (Mexico)
(Article 21.5 – Mexico)
Panel Report, United States – Measures Concerning the Importation, Marketing
and Sale of Tuna and Tuna Products – Recourse to Article 21.5 of the DSU by
Mexico, WT/DS381/RW, Add.1 and Corr.1, adopted 3 December 2015, as
modified by Appellate Body Report WT/DS381/AB/RW, DSR 2015:X, p. 5409
and DSR 2015:XI, p. 5653
US – Tuna II (Mexico)
(Article 21.5 – US) /
US – Tuna II (Mexico)
(Article 21.5 – Mexico II)
Panel Reports, United States – Measures Concerning the Importation,
Marketing and Sale of Tuna and Tuna Products – Recourse to Article 21.5 of
the DSU by the United States, WT/DS381/RW/USA and Add.1 /
United States – Measures Concerning the Importation, Marketing and Sale of
Tuna and Tuna Products – Second Recourse to Article 21.5 of the DSU by
Mexico, WT/DS381/RW2 and Add.1, circulated to WTO Members
26 October 2017
US – Tuna II (Mexico)
(Article 22.6 – US)
Decision by the Arbitrator, United States – Measures Concerning the
Importation, Marketing and Sale of Tuna and Tuna Products – Recourse to
Article 22.6 of the DSU by the United States, WT/DS381/ARB, 25 April 2017
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 – Wool Shirts and
Blouses
Appellate Body Report, United States – Measure Affecting 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 (Japan) Appellate Body Report, United States – Measures Relating to Zeroing and
Sunset Reviews, WT/DS322/AB/R, adopted 23 January 2007, DSR 2007:I, p. 3
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

APPELLATE BODY

United States – Measures Concerning the
Importation, Marketing and Sale of Tuna
and Tuna Products

Recourse to Article 21.5 of the DSU by the
United States

United States – Measures Concerning the
Importation, Marketing and Sale of Tuna
and Tuna Products

Second Recourse to Article 21.5 of the DSU by
Mexico

Mexico, Appellant
United States, Appellee

Australia, Third Participant
Brazil, Third Participant
Canada, Third Participant
China, Third Participant
Ecuador, Third Participant
European Union, Third Participant
Guatemala, Third Participant
India, Third Participant
Japan, Third Participant
Korea, Third Participant
New Zealand, Third Participant
Norway, Third Participant
AB-2017-9

Appellate Body Division:

Bhatia, Presiding Member
Graham, Member
Zhao, Member

1 INTRODUCTION
1.1. Mexico appeals certain issues of law and legal interpretations developed by the Panels in
United States – Measures Concerning the Importation, Marketing and Sale of Tuna and Tuna
Products – Recourse to Article 21.5 of the DSU by the United States and United States – Measures
Concerning the Importation, Marketing and Sale of Tuna and Tuna Products – Second Recourse to
Article 21.5 of the DSU by Mexico .1 The Panels were established pursuant to Article 21.5 of the
Understanding on Rules and Procedures Governing the Settlement of Disputes (DSU) to consider the
claims by the United States2 and Mexico3 concerning the measure taken by the United States to
comply with the recommendations and rulings of the Dispute Settlement Body (DSB) in the original
proceedings4 and first compliance proceedings5 in this dispute.6

1 WT/DS381/RW/USA; WT/DS381/RW2, 26 October 2017. The Panels explained that they decided to
issue their findings in a single document, with separate conclusions for each of the two proceedings. We refer
to both Reports collectively as the "Panel Reports". (See Panel Reports, para. 7.4)
2 Request for the Establishment of a Panel by the United States pursuant to Article 21.5 of the DSU,
WT/DS381/32 (United States' panel request).
3 Request for the Establishment of a Panel by Mexico pursuant to Article 21.5 of the DSU, WT/DS381/38
(Mexico's panel request).
4 The recommendations and rulings of the DSB resulted from the adoption by the DSB, on
13 June 2012, of the Appellate Body report (WT/DS381/AB/R) and the panel report (WT/DS381/R) in
US – Tuna II (Mexico).
5 The recommendations and rulings of the DSB resulted from the adoption by the DSB, on 3 December
2015, of the Appellate Body report (WT/DS381/AB/RW) and the panel report (WT/DS381/RW) in US – Tuna II
(Mexico) (Article 21.5 – Mexico).
6 In this Report, we refer to the panel that considered the original complaint brought by Mexico as the
"original panel" and to its report as the "original panel report". We refer to the panel that considered Mexico's
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

1.2. This dispute concerns the United States' labelling regime for dolphin-safe tuna products. In the
original proceedings, Mexico raised claims under the General Agreement on Tariffs and Trade 1994
(GATT 1994) and the Agreement on Technical Barriers to Trade ( TBT Agreement) challenging the
consistency with these Agreements of certain US measures relating to the importation, marketing,
and sale of tuna and tuna products. 7 Specifically, Mexico challenged: (i) the Dolphin Protection
Consumer Information Act of 1990, codified in United States Code, Title 16, Section 13858 (DPCIA);
(ii) United States Code of Federal Regulations (CFR), Title 50, Sections 216.91 and 216.929 (original
implementing regulations); and (iii) a ruling by a United States Federal Appeals Court in Earth Island
Institute v. Hogarth10 (Hogarth ruling).11 The original panel and the Appellate Body referred to these
measures, collectively, as the "measu re at issue" or the "US dolphin-safe labelling provisions". 12
In these compliance proceedings, we refer to them as the "original Tuna Measure".
1.3. The original Tuna Measure specified the conditions to be fulfilled in order for tuna products sold
in the United States to be labelled "dolphin -safe" or to make similar claims on their labels. 13 The
original Tuna Measure thus prohibited the use of the "dolphin-safe" label on a tuna product sold in
the US market unless the conditions specified in the measure are met. At the same time, it did not
make the use of a dolphin -safe label obligatory for the importation or sale of tuna products i n the
United States.14 Nonetheless, the preferences of retailers and cons umers are such that the
dolphin-safe label has "significant commercial value", and access to that label constitutes an
"advantage" on the US market for tuna products.15
1.4. Mexico alleged that the original Tuna Measure was inconsistent with Articles I:1 and III:4 of
the GATT 1994 and Articles 2.1, 2.2, and 2.4 of the TBT Agreement.16 The original panel found that:
(i) the US "dolphin-safe" labelling provisions constituted a "technical regulation" within the meaning
of Annex 1.1 to the TBT Agreement17; (ii) the measure was not inconsistent with Article 2.1 of the
TBT Agreement18; (iii) the measure was inconsistent with Article 2.2 of the TBT Agreement19; and
(iv) the Agreement on t he International Dolphin Conservation Program 20 (AIDCP) dolphin -safe
definition and certification were a relevant international standard within the meaning of Article 2.4
of the TBT Agreement 21, and the measure was not inconsistent with that provision.22 The original

complaint in the first compliance proceedings as the "first compliance panel" and to its report as the "first
compliance panel report".
7 In the original proceedings, Mexico clarified that its claims under Articles I:1 and III:4 of the
GATT 1994 and Article 2.1 of the TBT Agreement were made only in relation to tuna products, and not tuna.
For that reason, the original panel limited its findings in this respect to tuna products. (Original Panel Report,
para. 6.10)
8 Original Panel Exhibit US-5.
9 Original Panel Exhibit US-6 and US-58.
10 Earth Island Institute v. Hogarth, 494 F.3d 757 (9th Cir. 2007) (Original Panel Exhibit MEX-31); Earth
Island Institute v. Hogarth, 484 F.3d 1123 (9th Cir. 2007) (Original Panel Exhibit MEX-30). See infra, fn 104.
11 Original Panel Report, para. 2.1.
12 The original panel and the Appellate Body considered it appropriate to treat these legal instruments
as a single measure for the purpose of analysing Mexico's claims and reaching findings. (Original Panel Report,
para. 7.26. See also Appellate Body Report, US – Tuna II (Mexico), paras. 2 and 172 and fn 357 thereto)
13 Appellate Body Report, US – Tuna II (Mexico), para. 172. The original panel found that the DPCIA
defines "tuna product" as a food item "which contains tuna and which has been processed for retail sale,
except perishable sandwiches, salads, or other products with a shelf life of less than 3 days". (Original Panel
Report, paras. 2.5 and 7.60 (quoting DPCIA (Original Panel Exhibit US-5), Section 1385(c)(5)) See also
Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), fn 101 to para. 6.1)
14 Appellate Body Report, US – Tuna II (Mexico), paras. 172 and 196-199.
15 Appellate Body Report, US – Tuna II (Mexico), para. 233 (referring to Original Panel Report,
paras. 7.289-7.291). The factual aspects of the original proceedings are set forth in greater detail in
paragraphs 2.1-2.41 of the original panel report, and paragraphs 172-177 of the Appellate Body report in the
original proceedings.
16 Original Panel Report, para. 3.1.
17 Original Panel Report, paras. 7.62, 7.78, and 7.145. This finding was upheld on appeal. (See
Appellate Body Report, US – Tuna II (Mexico), para. 199)
18 Original Panel Report, paras. 7.374 and 8.1(a).
19 Original Panel Report, paras. 7.620 and 8.1(b).
20 Original Panel Exhibit MEX-11.
21 Original Panel Report, para. 7.707. (Both Mexico and the United States are parties to the AIDCP, an
agreement among 14 countries that entered into force in February 1999. (Original Panel Report, para. 2.35)
The AIDCP, administered by the Inter-American Tropical Tuna Commission (IATTC), addresses a particular
tuna-fishing method (purse seine fishing) in a specific area of the ocean, namely, the Eastern Tropical Pacific
(ETP). (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.4))
22 Original Panel Report, paras. 7.740 and 8.1(c).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

panel exercised judicial economy with respect to Mexico's claims under Articles I:1 and III:4 of the
GATT 1994.23
1.5. On appeal, the Appellate Body reversed the original panel's finding under Article 2.1 of the
TBT Agreement. The Appellate Body found, instead, that the United States had not demonstrated
that the detrimental impact of the measure on Mexican tuna products stemmed exclusively from a
legitimate regulatory distinction. The Appellate Body thus concluded that the original Tuna Measure
accorded less favourable treatment to Mexican tuna products than that accorded to like products
from the United States and other countries, and it was inconsistent with Article 2.1 of the
TBT Agreement.24 Furthermore, the Appellate Body found that the panel had erred in concluding
that the original Tuna Measure was more trade restrictive than necessary to fulfil the United States'
legitimate objectives, taking into account the risks non -fulfilment would create, and therefore
reversed the finding of inconsistency under Article 2.2 of the TBT Agreement.25 The Appellate Body
also reversed the original panel's finding that the AIDCP dolphin -safe definition and certification
constituted a relevant international standard, but left undisturbed the panel's finding that the original
Tuna Measure was not inconsistent with Article 2.4 of the TBT Agreement.26 Finally, the
Appellate Body found that the original panel acted inconsistently with Article 11 of the DSU in
deciding to exercise judicial economy with respect to Mexico's claims under Articles I:1 and III:4 of
the GATT 1994.27 In conclusion, the Appellate Body recommended that the DSB request the
United States to bring its measure into conformity with its obligations under the TBT Agreement.28
1.6. On 13 June 2012, the DSB ad opted the original panel and Appellate Body reports.29
On 17 September 2012, Mexico and the United States informed the DSB that they had agreed on a
reasonable period of time – 13 months from 13 June 2012 – to comply with the recommendations
and rulings of the DSB. The reasonable period of time expired on 13 July 2013.30
1.7. On 9 July 2013, the United States published amendments to Sections 216.91 and 216.93 of
CFR Title 5031 (2013 Rule).32 According to the United States, the 2013 Rule constituted the measure
taken to comply with the recommendations and rulings of the DSB pursuant to Article 21.5 of the
DSU.33
1.8. Mexico considered that the United States had not brought its labelling regime into compliance
with the recommendations and rulings of the DSB, and that the re gime remained inconsistent with
its obligations under the covered agreements. 34 On 2 August 2013, Mexico and the United States

23 Original Panel Report, paras. 7.748 and 8.2.
24 Appellate Body Report, US – Tuna II (Mexico), paras. 298-299 and 407(b).
25 Appellate Body Report, US – Tuna II (Mexico), paras. 331 and 407(c).
26 Appellate Body Report, US – Tuna II (Mexico), paras. 401 and 407(f).
27 Appellate Body Report, US – Tuna II (Mexico), paras. 405 and 407(g).
28 Appellate Body Report, US – Tuna II (Mexico), para. 408.
29 On 2 August 2012, Mexico and the United States informed the DSB that additional time was required
to discuss a mutually agreed reasonable period of time for the United States to implement the
recommendations and rulings of the DSB. (First Compliance Panel Report, para. 1.12 (referring to
Communication from Mexico and the United States concerning Article 21.3(c) of the DSU, WT/DS381/16))
30 First Compliance Panel Report, para. 1.12 (referring to Agreement under Article 21.3(b) of the DSU,
WT/DS381/17).
31 United States Department of Commerce (USDOC), National Oceanic and Atmospheric Administration
(NOAA), Enhanced Document Requirements to Support Use of the Dolphin Safe Label on Tuna Products,
United States Federal Register, Vol. 78, No. 131 (9 July 2013), pp. 40997-41004 (First Compliance Panel
Exhibit MEX-7). Section 216.92 of the original implementing regulations, the DPCIA, and the Hogarth ruling
remained unchanged. (First Compliance Panel Report, paras. 3.32 and 3.39)
32 First Compliance Panel Report, para. 1.13 (referring to United States' first written submission to the
first compliance panel, para. 10). We note that the first compliance panel referred to these amendments as the
"2013 Final Rule", whereas the Panels referred to them as the "2013 Rule". (First Compliance Panel Report,
paras. 1.13 and 2.1; Panel Reports, para. 2.1) For the purpose of this Report, we refer to them as the
"2013 Rule".
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

informed the DSB of their Agreed Procedures under Articles 21 and 22 of the DSU .35
On 14 November 2013, Mexico requested the establishment of a panel under Articles 6 and 21.5 of
the DSU, Article 14 of the TBT Agreement, and Article XXIII of the GATT 1994.36 In its panel request,
Mexico indicated that the measure taken to comply with the recommendations and rulings of the
DSB (2013 Tuna Measure) comprised: (i) the DPCIA; (ii) Subpart H of Part 216 of CFR Title 50 as
amended by the 2013 Rule (2013 implementing regulations) 37; (iii) the Hogarth ruling38; and
(iv) any implementing guidance, directives, policy announcements, or any other document issued in
relation to instruments (i) through (iii), including any modifications or amendments in relation to
those instruments.39 Mexico claimed that the 2013 Tuna Measure was inconsistent with Article 2.1
of the TBT Agreement, Article I:1 of the GATT 1994, and Article III of the GATT 1994.40
1.9. The first compliance panel considered that the question before it was whether the 2013 Tuna
Measure brought the United States into compliance with the covered agreements .41 The first
compliance panel found that : (i) the eligibility criteria were consistent with Article 2.1 of the
TBT Agreement42, but inconsistent with Articles I:1 and III:4 of the GATT 199443; (ii) the certification
requirements and the tracking and verification requirements were inconsistent with Article 2.1 of the
TBT Agreement and Articles I:1 and III:4 of the GATT 199444; (iii) the eligibility criteria, certification
requirements, and tracking and verification requirements under the 2013 Tuna Measure were
provisionally justified under Article XX(g) of the GATT 199445; and (iv) the eligibility criteria met the
requirements of the chapeau of Article XX, whereas the certification requirements and the tracking
and verification requirements constituted arbitrary or unjustifiable discrimination, and accordingly
did not satisfy the requirements of the chapeau of Article XX of the GATT 1994.46
1.10. On appeal, the Appellate Body reversed the first compliance panel's findings under Article 2.1
of the TBT Agreement, Articles I:1 and III:4 of the GATT 1994, and the chapeau of Article XX of the
GATT 1994.47 In particular, the Appellate Body considered that the first co mpliance panel had
conducted isolated analyses of, and reached separate findings with respect to, each of the three
components of the 2013 Tuna Measure, without accounting for the manner in which these elements
were interrelated.48 The Appellate Body also found that the first compliance panel erred by failing to
consider whether the differences in the relevant labelling conditions under the measure were

35 First Compliance Panel Report, para. 1.15 (referring to WT/DS381/19). The parties agreed that, in the
event that the DSB, following a proceeding under Article 21.5 of the DSU, ruled that a measure taken to
comply does not exist or is inconsistent with a WTO covered agreement, Mexico may request authorization to
suspend the application of concessions or other obligations under the covered agreements to the United States
pursuant to Article 22 of the DSU and that the United States would not assert that Mexico is precluded from
obtaining such authorization on the grounds that the request was made outside the 30-day time period
specified in Article 22.6 of the DSU. (WT/DS381/19, para. 5)
36 First Compliance Panel Report, para. 1.1 (referring to WT/DS381/20). See also Appellate Body
Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 1.8.
37 USDOC, National Marine Fisheries Service (NMFS)/NOAA, Dolphin Safe Tuna Labeling, 2013
implementing regulations, Sections 216.90-216.95. (First Compliance Panel Exhibit US-2)
38 See para. 5.10 below and fn 104 thereto.
40 First Compliance Panel Report, para. 2.2. Mexico also claimed that the 2013 Tuna Measure nullifies or
impairs benefits that accrue to Mexico under the GATT 1994 within the meaning of Article XXIII:1(b) of the
GATT 1994.
41 First Compliance Panel Report, para. 7.24. The first compliance panel agreed with both parties that
the 2013 Tuna Measure was a "technical regulation" for the purpose of the TBT Agreement, and that the
relevant tuna products were "like". (Ibid., para. 7.71) The first compliance panel disagreed with the
United States that the [2013 Rule] is "separable from the rest of the tuna measure". The first compliance panel
instead expressed the view that the 2013 Final Rule was "an integral component" of the 2013 Tuna Measure
and "the fact that it add[ed] new requirements rather than changing pre-existing requirements … d[id] not
have the effect of removing the rest of the tuna measure, which was the object of the DSB's rulings and
recommendations, from [the first compliance panel's] jurisdiction." (Ibid., para. 7.41 (fn omitted))
42 First Compliance Panel Report, paras. 7.135 and 8.2.a.
43 First Compliance Panel Report, paras. 7.451, 7.499, and 8.3.a.
44 First Compliance Panel Report, paras. 7.233, 7.263, 7.400, 7.456, 7.465, 7.501, 7.503, 8.2.b-c,
and 8.3.b-c.
45 First Compliance Panel Report, paras. 7.541 and 8.4.
46 First Compliance Panel Report, paras. 7.585, 7.605, 7.611, and 8.5.
47 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.230, 7.282, 7.335,
and 8.1.
48 See Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.14-7.21,
7.169, 7.229, and 7.335.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

calibrated to, or explained by, differences in the relative risks of harm to dolphins from different
fishing methods in different areas of the ocean.49
1.11. Having reversed the first compliance panel's findings, the Appellate Body completed the
analysis and found that: (i) the 2013 Tuna Measure modified the conditions of competition to the
detriment of Mexican tuna products in the US market; (ii) such detrimental impact did not stem
exclusively from a legitimate regulatory distinction; and, thus, (iii) the 2013 Tuna Measure accorded
less favourable treatment to Mexican tuna products compared to like tuna products from the
United States and other countries. 50 Therefore, the Appellate Body found that the 2013 Tuna
Measure was inconsistent with Article 2.1 of the TBT Agreement. The Appellate Body also found that
the 2013 Tuna Measure was inconsistent with Articles I:1 and III:4 of the GATT 1994, and that the
United States had not demonstrated that the measure was applied in a manner that did not
constitute arbitrary or unjustifiable discrimination as required by the chapeau of Article XX of the
GATT 1994.51 The Appellate Body thus recommended that the DSB request the United States to
bring its measure into conformity with its obligations under the TBT Agreement and the
GATT 1994.52
1.12. The DSB adopted the first compliance panel report and the Appellate Body report
on 3 December 2015.53 On 22 March 2016, the United States published a new rule modifying the
2013 Tuna Measure54 (2016 Rule) with the aim of bringing the 2013 Tuna Measure into compliance
with the recommendations and rulings of the DSB .55 Following the issuance of the 2016 Rule, the
United States and Mexico each requested the establishment of a compliance panel under Article 21.5
of the DSU.56 On 29 July 2016, the Panels in the proceedings brought by the United States and the
proceedings brought by Mexico adopted a harmonized timetable for these compliance proceedings
and thereafter held a consolidated substantive meeting with the parties on 24 and
25 January 2017.57
1.13. In these compliance proceedings, the United States requested the Panels to find that the
United States has brought itself into compliance with the recommendations and rulings of the DSB
and that the measure taken to comply with the recommendations and rulings of the DSB is consistent
with Article 2.1 of the TBT Agreement and justified under Article XX of the GATT 1994.58 Mexico
requested the Panels to reject the United States' claims in their entirety and to find that the measure
taken to comply with the recommendations and rulings of the DSB is inconsistent with Article 2.1 of

49 See Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.169, 7.229,
and 7.334.
50 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.238, 7.266, 7.340,
7.360, and 8.1.
51 Panel Reports, para. 7.2 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 8.1).
52 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 8.2.
53 On 10 March 2016, Mexico requested authorization from the DSB to suspend concessions to the
United States in the amount of US$472.3 million annually (WT/DS381/29). On 25 April 2017, while the
compliance proceedings were pending before the Panels, the Arbitrator circulated its decision to WTO Members.
The Arbitrator determined that the level of nullification or impairment suffered by Mexico as a result of the
2013 Tuna Measure is US$163.23 million annually. The Arbitrator concluded that, in accordance with
Article 22.4 of the DSU, Mexico may request authorization from the DSB to suspend concessions or other
obligations up to a level not exceeding US$163.23 million annually. (Decision by the Arbitrator, US – Tuna II
(Mexico) (Article 22.6 – US), para. 7.1) On 11 May 2017, Mexico requested authorization from the DSB to
suspend the application of certain tariff concessions and related obligations to the United States under the
GATT 1994 in the amount of US$163.23 million. (WT/DS381/44) At its meeting on 22 May 2017, the DSB
authorized Mexico to suspend the application to the United States of concessions or other obligations.
(WT/DSB/M/397)
54 Panel Reports, para. 2.3. See also Enhanced Document Requirements and Captain Training
Requirements to Support Use of the Dolphin Safe Label on Tuna Products, United States Federal Register,
Vol. 81, No. 56 (23 March 2016) (Panel Exhibit MEX-47).
55 Panel Reports, para. 7.3.
56 WT/DS381/32; WT/DS381/38. In addition to Article 21.5 of the DSU, Mexico's request was also made
pursuant to Article 6 of the DSU, Article 14 of the TBT Agreement, and Article XXIII of the GATT 1994. (See
WT/DS381/38. See also Panel Reports, para. 1.7)
57 Panel Reports, paras. 1.11-1.13.
58 Panel Reports, para. 3.1.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the TBT Agreement and Articles I:1 and III:4 of the GATT 1994, and cannot be justified under
Article XX of the GATT 1994.59
1.14. During the P anel proc eedings, the United States and certain third parties 60 requested the
Panels to lift the confidentiality of their statements at the Panels' consolidated substantive meeting
with the parties and at the third-party session.61 Mexico objected to such request, arguing that the
Panels could open their substantive meeting with the parties to public viewing only with the consent
of both parties. 62 The Panels, after consulting with the parties, adopted Additional Working
Procedures on Partially Open Meetings.63 Pursuant to their Additional Working Procedures, the Panels
permitted the partial public observation of the Panels' consolidated substantive meeting with the
parties and session with the third parties through delayed viewing, to ensure that the confidentiality
of Mexico's statements and the statements of non-disclosing third parties was not breached.64
1.15. The Panel Reports were circulated to Members of the World Trade Organization ( WTO) on
26 October 2017. The Panels identified the measure at issue in these compliance proceedings
(2016 Tuna Measure), as consisting of the following instruments: ( i) the DPCIA; ( ii) Subpart H of
Part 216 of CFR Title 50 as amended by the 2013 Rule and the 20 16 Rule (collectively, the
2016 implementing regulations); and ( iii) the Hogarth ruling.65 The Panels noted the parties'
agreement that: (i) the 2016 Tuna Measure is a technical regulation within the meaning of Annex 1.1
to the TBT Agreement; (ii) Mexican tuna products are "like" tuna products produced by the
United States and other count ries; (iii) the 2016 Tuna Measure modifies the conditions of
competition to the detriment of Mexican tuna products in the US market under Article 2.1 of the
TBT Agreement; (iv) the 2016 Tuna Measure is inconsistent with both Article I:1 and Article III:4 of
the GATT 1994; and (v) the 2016 Tuna Measure is provisionally justified under Article XX(g) of the
GATT 1994.66
1.16. The Panels considered that the parties' disagreement centred on the question whether the
detrimental impact accords "treatment no less favourable" within the meaning of Article 2.1 of the
TBT Agreement because such detrimental impact stems exclusively from a legitimate regulatory
distinction.67 The Panels found that, to address this question, the applicable legal standard under
Article 2.1 of the TBT Agreement required them to assess whether the relevant regulatory
distinctions under the measure at issue are calibrated to the risks to dolphins arising from the use
of different fishing methods in different areas of the ocean.68 On the basis of their findings regarding
the risks to dolphins69, the Panels found that each of the elements of the 2016 Tuna Measure70 and
the 2016 Tuna Measure as a whole are calibrated in accordance with the applicable legal standard.71
Relying on their analysis under Article 2.1 of the TBT Agreement, the Panels found that the

59 Panel Reports, para. 3.2.
60 Australia, Canada, the European Union, Japan, New Zealand, and Norway supported the
United States' request, while Brazil, China, Ecuador, Guatemala, India, and Korea opposed it. (Panel Reports,
paras. 7.14-7.15)
61 Panel Reports, para. 1.14.
62 Panel Reports, paras. 7.10-7.13.
63 Panel Reports, para. 1.19. See also Annex A-4 to the Panel Reports (Panels' Additional Working
Procedures).
64 Panel Reports, paras. 1.20 and 7.5-7.34. In addition, upon request by both parties, the Panels
adopted Additional Working Procedures of the Panels Concerning Business Confidential Information. (See Panel
Reports, paras. 1.22-1.23; Annex A-3 to the Panel Reports)
65 Panel Reports, paras. 2.1 and 7.47. In addition to the three items referred to above, the Panels noted
that Mexico, in its panel request in these compliance proceedings, also referred to "[a]ny implementing
guidance, directives, policy announcements or any other document issued in relation to instruments [(i)]
through [(iii)] above, including any modifications or amendments in relation to those instruments". (Ibid.,
para. 7.43 (quoting Mexico's panel request, p. 2)) Having reviewed all of Mexico's submissions and evidence in
these compliance proceedings, the Panels observed that Mexico's description had referred to this additional
element "in the abstract, without arguing that in fact there exists such an element which is subsumed within
the definition of the measure taken to comply subject to these proceedings". (Ibid., para. 7.44) Furthermore,
the Panels considered that "the claims and arguments that Mexico has presented in these proceedings [did] not
in any way pertain to this alleged additional element of the 2016 Tuna Measure." (Ibid.)
66 Panel Reports, paras. 7.74-7.75 and 7.729-7.730.
67 Panel Reports, para. 7.79.
68 Panel Reports, para. 7.103.
69 Panel Reports, section 7.7.
70 These elements of the 2016 Tuna Measure are explained in section 5.2 below.
71 Panel Reports, paras. 7.547, 7.611, 7.676, and 7.717.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

2016 Tuna Measure is not applied in a manner that constitutes a means of arbitrary or unjustifiable
discrimination within the meaning of the chapeau of Article XX of the GATT 1994.72
1.17. On this basis:
a. with respect to the United States' and Mexico's claims under Article 2.1 of the
TBT Agreement, the Panels concluded that the 2016 Tuna Measure is not inconsistent with
Article 2.1 of the TBT Agreement73; and
b. with respect to Mexico's claims under the GATT 1994, and the United States' defence
under Article XX of the GATT 1994, the Panels concluded that the 2016 Tuna Measure is
inconsistent with Articles I:1 and III:4 of the GATT 199474, but is justified under
Article XX(g), and meets the requirements of the chapeau of Article XX.75
1.18. The Panels therefore considered that the United States has implemented the
recommendations and ruli ngs of the DSB in the original and first compliance proceedings of this
dispute to bring its measure into conformity with its obligations under the Marrakesh Agreement
Establishing the World Trade Organization ( WTO Agreement). Th us, th e Panels did not find it
necessary to make any recommendations under Article 19.1 of the DSU.76
1.19. On 1 December 2017, Mexico notified the DSB, pursuant to Articles 16.4 and 17 of the DSU,
of its intention to appeal certain issues of law covered in the Panel Reports, and certain l egal
interpretations developed by the Panels, and filed a Notice of Appeal and an appellant's submission.77
On 19 December 2017, the United States filed an appellee's submission. 78 On 4 January 2018,
Australia, Brazil, the European Union, and Japan each filed a third participant's submission. 79
On 3-4 January 2018, Canada, China, Ecuador, Guatemala, India, New Zealand, and Norway each
notified its intention to appear at the oral hearing as a third participant.80 Subsequently, Korea also
notified its intention to appear at the oral hearing as a third participant.81
1.20. By letter dated 29 January 2018, the Chair of the Appellate Body notified the Chair of the DSB
that the Appellate Body would not be able to circulate its Report within the 60-day period pursuant
to Article 17.5 of the DSU, or within the 90 -day period pursuant to the same provision, for the
reasons mentioned therein. 82 For the reasons explained in the letter, work on this appeal could
gather pace only in May 2018. On 20 November 2018, the Chair of the Appellate Body notified the
Chair of the DSB that the Appellate Body Report in these proceed ings would be circulated to
WTO Members no later than 14 December 2018.
1.21. The oral hearing in this appeal was held on 30-31 July 2018. The participants and five of the
third participants (Brazil, Canada, the European Union, Japan, and Norway) made opening oral

72 Panel Reports, para. 7.740.
73 Panel Reports, paras. 8.2 and 8.6.
74 Panel Reports, para. 8.7.
75 Panel Reports, paras. 8.3 and 8.7.
76 Panel Reports, paras. 8.4-8.5 and 8.8-8.9.
77 Pursuant to Rules 20 and 21, respectively, of the Working Procedures for Appellate Review,
WT/AB/WP/6, 16 August 2010 (Working Procedures).
78 Pursuant to Rule 22 of the Working Procedures.
79 Pursuant to Rule 24(1) of the Working Procedures. According to the Working Schedule drawn up by
the Division hearing this appeal, the third participants' submissions and executive summaries were due on
3 January 2018. On 20 December 2017, the Appellate Body Division issued a procedural ruling extending the
deadline to 4 January 2018 for all third participants following a request by Japan dated 19 December 2017 to
extend the deadline. The Procedural Ruling is contained in Annex D of the Addendum to this Report,
WT/DS381/AB/RW/USA/Add.1; WT/DS381/AB/RW2/Add.1.
80 Pursuant to Rule 24(2) of the Working Procedures. Canada, New Zealand, and Norway each notified
its intention on 3 January 2018, and the other third participants did so on 4 January 2018.
81 On 27 July 2018, Korea submitted its delegation list for the oral hearing to the Appellate Body
Secretariat and the participants and third participants in this dispute. For the purpose of this appeal, we have
interpreted this action as a notification expressing Korea's intention to attend the oral hearing pursuant to
Rule 24(4) of the Working Procedures.
82 WT/DS381/46. The letter is contained in Annex E of the Addendum to this Report,
WT/DS381/AB/RW/USA/Add.1; WT/DS381/AB/RW2/Add.1.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

statements. The participants and third participants responded to questions posed by the Members
of the Appellate Body Division hearing the appeal.
2 ARGUMENTS OF THE PARTICIPANTS
2.1. The claims and arguments of the participants are reflected in the executive summaries of their
written submissions provided to the Appellate Body.83 The Notice of Appeal and the executive
summaries of the participants' claims and arguments are contained in Annexes A and B of the
Addendum to this Report, WT/DS381/AB/RW/USA/Add.1, WT/DS381/AB/RW2/Add.1.
3 ARGUMENTS OF THE THIRD PARTICIPANTS
3.1. The arguments of the third participants that filed a written submission (Australia, Brazil, the
European Union, and Japan) are reflected in the executive summaries of their written submissions
provided to the Appellate Body84 and are contained in Annex C of the Addendum to th is Report,
WT/DS381/AB/RW/USA/Add.1, WT/DS381/AB/RW2/Add.1.
4 ISSUES RAISED IN THIS APPEAL
4.1. The following issues are raised in this appeal:
a. whether the Panels erred in finding that the 2016 Tuna Measure accords to Mexican tuna
products treatment no less favourable than that accorded to like products originating in
the United States and other countries and is therefore consistent with Article 2.1 of the
TBT Agreement. Specifically, in determining whether the detrimental impact caused by the
2016 Tuna Measure stems exclusively from a legitimate regulatory distinction , whether
the Panels erred:
i. by failing to include risks relating to inaccurate labelling in their calibratio n analysis,
and thereby failing to assess whether the regulatory distinctions under the 2016 Tuna
Measure are rationally related to its objectives;
ii. by failing to properly assess the risk profiles of different fishing methods and ocean
areas for the purpose of their calibration analysis; and
iii. by finding that the individual components of the 2016 Tuna Measure (i.e. the eligibility
criteria; the certification requirements; and the tracking and verification
requirements), as well as the 2016 Tuna Measure as a w hole, are calibrated to the
risks to dolphins arising from the use of different fishing methods in different ocean
areas;
b. whether the Panels erred in finding that the 2016 Tuna Measure is not applied in a manner
that constitutes "a means of arbitrary or un justifiable discrimination between countries
where the same conditions prevail" and is therefore justified under Article XX of the
GATT 1994; and
c. whether the Panels erred in finding that they had the authority to conduct a partially open
meeting of the parties without the consent of both parties.
5 BACKGROUND AND MEASURE AT ISSUE
5.1. These compliance proceedings represent the third time that the dispute between Mexico and
the United States over the WTO-consistency of the United States' labelling regime for dolphin -safe
tuna products is before us. As the Appellate Body in the first compliance proceedings described,

83 Pursuant to the Appellate Body's communication on "Executive Summaries of Written Submissions in
Appellate Proceedings" and "Guidelines in Respect of Executive Summaries of Written Submissions in
Appellate Proceedings" (WT/AB/23, 11 March 2015).
84 Pursuant to the Appellate Body's communication on "Executive Summaries of Written Submissions in
Appellate Proceedings" and "Guidelines in Respect of Executive Summaries of Written Submissions in
Appellate Proceedings" (WT/AB/23, 11 March 2015).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

commercial tuna fishing can have harmful effects on marine mammals, including dolphins, and these
effects may vary depending on factors such as the method of fishing used, the size of the fishing
vessel, and the area of the ocean in which the vessel engages in tuna fishing. 85 As we describe
below, the United States has undertaken ce rtain domestic measures, and participated in certain
multilateral initiatives, aimed at reducing the adverse effects on dolphins associated with commercial
fishing operations.
5.1 US participation in multilateral initiatives
5.2. The United States and Mexico are pa rties to the A IDCP, which entered into force in
February 1999.86 The AIDCP, administered by the Inter -American Tropical Tuna Commission
(IATTC), addresses a particular tuna -fishing method (purse seine fishing) in a specific area of the
ocean, namely the Eastern Tropical Pacific (ETP).87
5.3. As the original panel described, there is a regular association between tuna and dolphins in the
ETP, meaning that schools of tuna tend to aggregate and swim beneath certain species of dolphins.88
Certain vessels operating in this area employ a fishing method known as setting on dolphins, which
takes advantage of this association. This fishing method involves chasing and encircling the dolphins
with a purse seine net in order to catch the tuna swimming beneath them.89 The ETP is a "traditional
fishing ground" for Mexico, and its tuna fleet operates almost exclusively therein using the method
of setting on dolphins.90
5.4. As the original panel noted, the AIDCP was negotiated in response to evidence that many
dolphins were dying in the ETP each year91 and is recognized to have made an important contribution
to dolphin protection and to the dramatic reduction of observed dolphin mortality in the ETP. 92 The
AIDCP regulates the fishing methods of purse seine vessels in the ETP according to the size of the
vessel, by prohibiting small purse seine vessels from setting on dolphins and permitting large purse
seine vessels to set on dolphins only within specified dolphin mortality limits (DMLs), and subject to
a number of requirements.93
5.5. The AIDCP establishes a dolphin-safe scheme for the ETP that is separate from the US domestic
scheme.94 Under the AIDCP, "dolphin-safe tuna" is a term that is used to describe "tuna captured in
sets in which there is no mortality or serious injury of dolphins".95

85 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.2.
86 Belize, Colombia, Costa Rica, Ecuador, El Salvador, the European Union, Guatemala, Honduras,
Mexico, Nicaragua, Panama, Peru, the United States, and Venezuela are parties to the AIDCP. Bolivia and
Vanuatu apply the AIDCP provisionally. (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
fn 106 to para. 6.4)
87 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.4.
88 Original Panel Report, para. 7.306; Appellate Body Report, US – Tuna II (Mexico), fn 355 to
para. 172.
89 Appellate Body Report, US – Tuna II (Mexico), fn 355 to para. 172. See also ibid., para. 248; Original
Panel Report, para. 7.306.
90 Appellate Body Report, US – Tuna II (Mexico), para. 234. See also Original Panel Report, para. 7.308;
Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.5.
91 Original Panel Report, para. 2.35.
92 Original Panel Report, paras. 2.39 and 7.609.
93 Large purse seine vessels are defined as vessels with a carrying capacity greater than 363 metric
tons. The AIDCP does not apply to other fishing vessels in the ETP, such as longline vessels and pole and line
vessels. According to the United States, this is because such vessels are not capable of setting on dolphins.
(Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.6 and fn 116 thereto (referring
to United States' appellant's submission in the first compliance proceedings, fn 61 to para. 65; AIDCP,
Annexes I, IV(I)(3)(c), and VII(6) (Original Panel Exhibit MEX-11); AIDCP, as amended October 2009,
Article I:8 and Annex II, paras. 1-3 (First Compliance Panel Exhibit MEX-30)))
94 Original Panel Report, para. 2.34.
95 Original Panel Report, para. 2.40 (quoting AIDCP, Resolution to Adopt the Modified System for
Tracking and Verification of Tuna (20 June 2001) (Original Panel Exhibit MEX-55)). (emphasis original)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

5.2 US domestic dolphin-safe labelling regime: the measure at issue and its evolution
over the course of the Tuna II dispute
5.6. As indicated in para. 1.15 above, the Panels described the 2016 Tuna Measure (the measure
at issue in these compliance proceedings) as con sisting of the following three elements "on which
both parties agree, and to which both parties' claims and arguments pertain"96:
a. the DPCIA;
b. Subpart H of Part 216 of CFR Title 50 (Dolphin Safe Tuna Labeling), as amended by the
Enhanced Document Requirements to Support Use of the Dolphin Safe Label on Tuna
Products, 78 Fed. Reg. 40,997 (9 July 2013) (2013 Rule) and the Enhanced Document
Requirements and Captain Training Requirements to Support Use of the Dolphin Safe Label
on Tuna Products, 81 Fed. Reg. 15,44 4 (23 March 2016) (2016 Rule) (collectively, the
2016 implementing regulations); and
c. the Hogarth ruling.97
5.7. On appeal, Mexico does not challenge the Panels' definition of the 2016 Tuna Measure.
Consequently, for the purpose of these appellate proceedings, w e too understand the 2016 Tuna
Measure to comprise the above instruments.
5.8. The Panels found that, like the original and 2013 Tuna Measures, the 2016 Tuna Measure
pursues two objectives: (i) to ensure that consumers are not misled or deceived about whether tuna
products contain tuna caught in a manner that adversely affects dolphins; and (ii) to contribute 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 dolph ins.98 Similarly, like its predecessors, the
2016 Tuna Measure provides that the use of the term "dolphin-safe", or any other term that claims
or suggests that the tuna contained in a tuna product was harvested using a method of fishing that
is not harmful to dolphins, is prohibited if the tuna was not harvested and processed in compliance
with the applicable labelling conditions. 99 Thus, like its predecessors, t he 2016 Tuna Measure
prohibits the use of the dolphin -safe label on a tuna product sold in the US market unless the
conditions specified in the measure are met.
5.9. The 2016 Tuna Measure broadly places three types of conditions on the use of the dolphin-safe
label for tuna products exported from or offered for sale in the United States: (i) conditions relating
to the automatic disqualification of certain tuna products (eligibility criteria); (ii) conditions relating
to certifications (certification requirements); and (iii) conditions relating to record keeping and the
segregation of dolphin-safe and non-dolphin-safe tuna (tracking and verification requirements). 100
Additionally, the certification requirements and tracking and verification requirements, applicable to
fisheries other than the ETP large purse seine fishery, may become stricter in certain circumstances,
owing to an element of the 2016 Tuna Measure referred to as the "determination provisions".101
5.10. As regards the eligibility criteria, the DPCIA excludes from bearing the "dolphin-safe" label
tuna products "exported from or offered for sale in the United States" containing either: (i) tuna
harvested on the high seas by a vessel engaged in driftnet fishing; or (ii) tuna harvested by vessels
using purse seine nets to encircle, or "set on", dolphins anywhere in the world. 102 The DPCIA's
disqualification of tun a products containing tuna caught by setting on dolphins was briefly
suspended, in 2002 and 2003, following administrative action by the U nited States Secretary of

96 Panel Reports, para. 7.47 and supra, fn 65.
97 Panel Reports, para. 2.1.
98 Panel Reports, paras. 7.49, 7.186, and 7.705. See also Appellate Body Report, US – Tuna II (Mexico),
para. 302; Original Panel Report, paras. 7.401 and 7.425.
99 Panel Reports, para. 2.4 (referring to DPCIA (Panel Exhibits MEX-1 and USA-1), Section 1385(d);
2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Section 216.91(a)). See also ibid.,
para. 7.49.
101 Panel Reports, paras. 7.67-7.69 (referring to 2016 implementing regulations (Panel Exhibits MEX-2
and USA-2), Section 216.91(a)(3)(v)). As further explained in paragraph 5.15 below, the 2013 Tuna Measure
also contained certain determination provisions, elements of which were modified under the 2016 Tuna
Measure.
102 DPCIA (Original Panel Exhibit US-5), Section 1385(b)-(d).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Commerce.103 However, the Hogarth ruling overturned that action and restored thi s condition of
access to the US dolphin-safe labelling regime.104
5.11. The 2016 Tuna Measure makes no changes to the eligibility criteria set out in the DPCIA and
the Hogarth ruling. Thus, under the 2016 Tuna Measure , the following tuna products are
automatically ineligible for the dolphin -safe label: (i) tuna harvested using large -scale driftnets on
the high seas; and (ii) tuna products containing tuna harvested by setting on dolphins anywhere in
the world.105 All other tuna products may be labelled dolphin-safe only if no dolphins were killed or
seriously injured in the gear deployments in which the tuna was caught. To this end, these tuna
products must satisfy the certification and tracking and verification requirements of the 2016 Tuna
Measure.106
5.12. Apart from large-scale driftnet fishing on the high seas107, the certification requirements under
the 2016 Tuna Measure make a distinction between the ETP large purse seine 108 fishery109, on the
one hand, and all other fisheries, on the other hand.110 For tuna caught in the ETP large purse seine
fishery, the 2016 Tuna Measure, like the 2013 Tuna Measure, mandates that certification must be

103 In 1997, the US Congress adopted the International Dolphin Conservation Program Act (IDCPA),
which attempted to amend the DPCIA and change the criterion of accessing the US dolphin-safe label from
"no encirclement of dolphins" (i.e. no setting on dolphins) to "no dolphin mortality or serious injury", akin to
the standard under the AIDCP as described in paragraph 5.5 above. However, the US Congress made this
amendment of the DPCIA contingent upon the outcome of scientific studies on the effects of setting on
dolphins, to be undertaken by US agencies in cooperation with the IATTC. On 31 December 2002, the
US Secretary of Commerce determined that there was insufficient evidence to conclude that intentional
encirclement of dolphins with purse seine nets was having a significant adverse effect on "depleted dolphin
stock in the ETP". (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.9 and fn 127
thereto)
104 The determination by the US Secretary of Commerce was challenged in the US District Court for the
Northern District of California by the Earth Island Institute and a number of other organizations. The court
ruled in Earth Island Institute v. Evans that the Secretary's finding was "arbitrary, capricious, an abuse of
discretion, or otherwise not in accordance with the law". The court also clarified that "dolphin-safe" shall
continue to mean that: (i) no tuna was caught on the trip in which such tuna was harvested using a purse
seine net intentionally deployed on or used to encircle dolphins; and (ii) no dolphins were killed or seriously
injured during the sets in which the tuna was caught. (Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 6.9 and fn 128 thereto (referring to Earth Island Institute v. Evans, 34 ELR
20069 (N.D. Cal. 2004) (Original Panel Exhibit MEX-29), pp. 23-24)) On 13 July 2007, the ruling in Earth
Island Institute v. Evans was affirmed on appeal in United States Court of Appeals for the Ninth Circuit, Earth
Island Institute et al. v. William T. Hogarth, 484 F.3d 1123 (9th Cir. 2007) and United States Court of Appeals
for the Ninth Circuit, Earth Island Institute et al. v. William T. Hogarth, 494 F.3d 757 (9th Cir. 2007) (Panel
Exhibit MEX-3) (Hogarth ruling).
105 Panel Reports, para. 7.50 (referring to DPCIA (Panel Exhibits MEX-1 and USA-1), Section 1385(d);
2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Section 216.91(a)).
106 Panel Reports, para. 7.50.
107 Panel Reports, para. 7.51 and fn 88 thereto (referring to 2016 implementing regulations (Panel
Exhibits MEX-2 and USA-2), Section 216.91(a)(3)).
108 Large purse seine vessels are defined as vessels with a carrying capacity greater than 363 metric
tons. See supra, fn 93.
109 As the Appellate Body in the first compliance proceedings noted, for the purpose of this dispute, the
term "fishery" may be defined by the geographic region in which the fishing occurs, the vessel and fishing
method used, and the target species. (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
fn 130 to para. 6.10)
110 Panel Reports, paras. 7.51 and 7.54 (referring to 2016 implementing regulations,
Section 216.91(a)(1) and (3) (Panel Exhibits MEX-2 and USA-2)). This differs from the 2013 Tuna Measure,
which distinguished between three general categories of fisheries: (i) large purse seine vessels in the ETP (the
ETP large purse seine fishery); (ii) purse seine vessels outside the ETP (the non-ETP purse seine fishery); and
(iii) other fisheries, which include non-purse seine vessels in any ocean area and small purse seine vessels in
the ETP. (See Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 6.10-6.11
(referring to DPCIA (First Compliance Panel Exhibit MEX-8), Section 1385(d)(1)(B)-(D) and
Section 1385(d)(2); 2013 implementing regulations (First Compliance Panel Exhibit US-2),
Section 216.91(a)(1)-(2) and (4)))
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

provided by the captain of the vessel and an International Dolphin Conservation Program 111
(IDCP)-approved observer, indicating that: (i) none of the tuna was caught on a trip using a purse
seine net intentionally deployed on or used to encircle (i.e. set on) dolphins; and (ii) no dolphins
were killed or seriously injured during the sets in which the tuna was caught.112
5.13. As for all fisheries other than the ETP large purse seine fishery, for fishing trips that began on
or after 21 May 2016, captains of all vessels must certify that: (i) no purse seine net or other fishing
gear was intentionally deployed on or used to encircle (i.e. set on) dolphins during the fishing trip in
which the tuna was caught; and (ii) no dolphins were killed or seriously injured in the sets or other
gear deployments in which the tuna was caught.113 Additionally, under the 2016 Tuna Measure, the
captains of the vessels in all fisheries other than the ETP large purse seine fishery must certify that
they have completed the National Marine Fisheries Service (NMFS) Tuna Tracking and Verification
Program dolphin -safe training course (Captain Training Course). 114 In additio n to the captain's
certification, in certain circumstances, certifications from an observer participating in a national or
international programme acceptable to the Assistant Administrator 115 will be required pursuant to
the following two elements of the 2016 Tuna Measure.
5.14. The first element concerns seven US domestic fisheries for which the Assistant Administrator
has determined that observers are qualified and authorized to make the relevant certifications. 116
In these fisheries, certification by such an observer is required when the observer is already on
board the fishing vessel for other reasons (i.e. reasons unrelated to the dolphin -safe labelling
regime).117
5.15. The second element concerns what the first compliance panel described as the "determination
provisions" under the 2013 Tuna Measure .118 The 2013 Tuna Measure provided that the Assistant
Administrator could make a determination: (i) within a non-ETP purse seine fishery, that there is a
regular and significant association between dolphins and tuna, simi lar to the association between
dolphins and tuna in the ETP; or (ii) with respect to non-purse seine vessels in any ocean area and
small purse seine vessels in the ETP, that there is a regular and significant mortality or serious injury
of dolphins.119 In those situations, not only the captain of the vessel but also an observer had to

111 The United States explained in the first compliance proceedings that the IDCP was established by the
AIDCP. According to the United States, one of the tools of enforcing the IDCP is the on-board observer
program that is described in Annex II to the AIDCP. Pursuant to Annex II, an observer must be on board a
large purse seine vessel in the ETP during each fishing trip. The observer must: (i) have completed the specific
training required by the guidelines established under the AIDCP; (ii) be a national of one of the IATTC parties;
and (iii) be included in the list of observers maintained by the IATTC or, if part of a national observer program,
by the party maintaining such a program. (United States' appellant's submission in the first compliance
proceedings, paras. 65-66; AIDCP, as amended October 2009, Article I:8 and Annex II, paras. 1-3 (First
Compliance Panel Exhibit MEX-30))
112 Panel Reports, para. 7.54 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(1) and (b)(2)(iii)). See also 2016 implementing regulations (Panel Exhibits MEX-2
and USA-2), Section 216.92.
113 Panel Reports, paras. 7.51 and 7.53 (referring to 2016 implementing regulations (Panel Exhibits
MEX-2 and USA-2), Section 216.91(a)(3)).
114 Panel Reports, para. 7.53 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)(iii)(B)).
115 United States Assistant Administrator for Fisheries, NMFS, NOAA, or his/her designee. (United States
Code of Federal Regulations, Title 50, Section 216.3 (First Compliance Panel Exhibit MEX-20))
116 In the first compliance panel proceedings, the United States identified the seven domestic fisheries
where tuna is regularly harvested as: (i) American Samoa Pelagic Longline Fishery; (ii) Atlantic Bluefin Tuna
Purse Seine Fishery; (iii) Atlantic Highly Migratory Species Pelagic Longline Fishery; (iv) California Deep-set
Pelagic Longline Fishery; (v) California Large-mesh Drift Gillnet Fishery; (vi) Hawaii Deep-set Longline Fishery;
and (vii) Hawaii Shallow-set Longline Fishery. (United States' second written submission to the first compliance
panel, para. 128 and fn 244 thereto (referring to Determination of Observer Programs as Qualified and
Authorized by the Assistant Administrator for Fisheries, United States Federal Register, Vol. 79, No. 134
(14 July 2014) (First Compliance Panel Exhibit US-113), p. 40720). See also United States' appellee's
submission, fn 679 to para. 624)
117 Thus, tuna caught on a trip where no observer is already on board may still be labelled dolphin-safe
with only a captain's certification. (See First Compliance Panel Report, para. 3.46; Appellate Body Report,
US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.23 and fn 171 thereto. See also para. 6.173 and fn 613
below)
118 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.11 (referring to First
Compliance Panel Report, paras. 7.249 and 7.256).
119 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.11 (referring to First
Compliance Panel Report, paras. 7.249 and 7.256).
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certify that: (i) no fishing gear was intentionally deployed on or used to encircle dolphins during the
trip on which the tuna was caught; and (ii) no dolphins were killed or seriously injured in the sets or
other gear deployments in which the tuna was caught.120
5.16. The determination provisions have been modified under the 2016 Tuna Measure. Pursuant to
the 2016 Tuna Measure, tuna caught in all fisheries other than the ETP large purse seine fishery121
may require an observer certification, in addition to the captain certification described in
paragraph 5.13 above, where the Assistant Administrator has determined that in such a fishery:
(i) there is a regular and significant association between dolphins and tuna (similar to the association
between dolphins and tuna in the ETP); or (ii) a regular and significant mortality or serious injury of
dolphins is occurring. In those situations, both the captain and the observer must certify that:
(i) no purse seine net or other fishing gear was intentionally deployed on or used to encircle (i.e. set
on) dolphins during the tr ip on which the tuna was caught; and (ii) no dolphins were killed or
seriously injured in the sets or other gear deployments in which the tuna was caught.122
5.17. As was the case with the 2013 Tuna Measure, the tracking and verification requirements
under the 201 6 Tuna Measure concern the physical segregation of dolphin -safe tuna from
non-dolphin-safe tuna, from the moment of harvest and throughout the processing chain. 123
Specifically, like its predecessor, the 2016 Tuna Measure prescribes the documentation requirements
for recording and verifying segregation and the corresponding regulatory oversight. These
requirements distinguish between: (i) the ETP large purse seine fishery, which must comply with the
AIDCP Tracking and Verification System124; and (ii) all other fisheries, which must comply with the
requirements prescribed in the 2016 implementing regulations that the United States refers to as
the "NOAA regime".125 Thus, the ETP large purse seine fishery is subject to the AIDCP regime, while
all other fisheries are subject to the NOAA regime.
5.18. The AIDCP Tracking and Verification System is based on the use of Tuna Tracking Forms
(TTFs). Every TTF has a unique number. On every fishing trip, ETP large purse seine vessels must
maintain two TTFs, one to record tuna harvested in dolphin -safe sets, and one to record tuna
harvested in non-dolphin-safe sets.126 At the end of each fishing trip, the IDCP -approved observer
and the captain of the fishing vessel initial both TTFs to certify that the information on the forms is
accurate.127
5.19. At the time of unloading, the relevant TTF must be transmitted to the competent authority of
an AIDCP party.128 The relevant TTF number must then accompany the tuna through sales of portions

120 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 6.10-6.11. The
Appellate Body upheld the first compliance panel's findings that the determination provisions in the 2013 Tuna
Measure were not even-handed. The first compliance panel found that the design of the determination
provisions meant that, in some cases, fisheries other than the ETP large purse seine fishery may be treated
differently, and less stringently, under the amended 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 serious
injury, on the one hand, or the degree of tuna-dolphin association, on the other hand. (Appellate Body Report,
US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.182, 7.188, and 8.1.a.v; First Compliance Panel
Report, para. 7.263)
121 We recall that, under the 2013 Tuna Measure, these fisheries were further subdivided into: (i) the
non-ETP purse seine fishery; and (ii) non-purse seine vessels in any ocean area and small purse seine vessels
in the ETP. (See para. 5.15 above and supra, fn 110. See also Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), paras. 6.10-6.11)
122 Panel Reports, paras. 7.51 and 7.68 (referring to 2016 implementing regulations (Panel Exhibits
MEX-2 and USA-2), Section 216.91(a)(3)(v)).
123 Panel Reports, paras. 7.55-7.66.
124 Panel Reports, paras. 7.56-7.61. See also 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(a)-(c)(1).
125 Panel Reports, para. 7.62 (quoting United States' first written submission to the Panels, para. 143).
See also ibid., paras. 7.63-7.67; 2016 implementing regulations (Panel Exhibits MEX-2 and USA-2),
Section 216.91(4)-(5) and Section 216.93(c)(2)-(4).
126 Panel Reports, para. 7.57 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 3(2); Appellate Body Report,
US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.19).
127 Panel Reports, para. 7.57 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 6.19).
128 Panel Reports, para. 7.59 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 5(2)-(5)).
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of the catch and through every processing step of those portions. 129 A tuna product exported as
AIDCP dolphin-safe must be accompanied by a certificate of its dolphin -safe status issued by a
competent authority, which must also include a reference to the relevant TTF number.130 The AIDCP
Tracking and Verification System also provides that the national programs established by the parties
to the AIDCP should include periodic audits and spot checks for tuna products, as well as mechanisms
for cooperation among national authorities.131
5.20. In addition, all tuna products imported into the United States, regardless of where the tuna
was caught and whether the dolphin -safe label is used, must be accompanied by NOAA Form 370,
which designates, inter alia, whether the tuna is dolphin-safe.132 This means that, for imported tuna
caught in the ETP large purse seine fishery, both TTFs and Form 370 are required. By contrast, for
imported tuna caught in all other fisheries, only Form 370 is required.
5.21. Moreover, as regards all other fisheries, the NOAA regime requires US tuna processors to
submit monthly reports to the US Tuna Tracking and Verification Program for all tuna received at
their processing facilities. These reports contain the same information contained in NOAA Form 370,
as well as additional information, such as unloading dates and the condition of the tuna products.133
Furthermore, under the NOAA regime, the NMFS is empowered to undertake verification activities,
including dockside inspections of vessels, monitoring of Form 370s, monitoring of cannery reports,
audits of US canneries, and retail market spot checks. 134 Other US agencies may also conduct
on-board inspections on the high seas and in US waters.135
5.22. Furthermore, while the 2016 Tuna Measure has made no changes to the tracking and
verification requirements applicable to the ETP large purse seine fishery, it has introduced some
additional requirements under the NOAA regime , which governs all other fisheries. As the Panels
observed, the 2016 Tuna Measure establishes new chain of custody record -keeping requirements
for tuna products harvested from all other fisheries. Specifically, the US processors and importers
of such tuna products must collect and retain, for two years, information on each point in the chain
of custody of the tuna or tuna products, including information on all storage facilities, trans-shippers,
processors, and wholesalers or distributors. Th is information must be provided to the NMFS upon
request, and must be sufficient for the NMFS to conduct a trace-back of any tuna product marketed
as dolphin-safe to verify that the tuna product in fact meets the dolphin-safe labelling requirements.
These new requirements apply to all tuna products labelled dolphin -safe if those prod ucts contain
tuna harvested on a fishing trip beginning on or after 21 May 2016.136
5.23. Importantly, the breach of these new chain of custody record-keeping requirements may lead
to the imposition of sanctions under US law. Sanctions for offering for sale or exp ort tuna products
falsely labelled dolphin-safe may be assessed against any producer, importer, exporter, distributor,
or seller that is subject to the jurisdiction of the United States.137 They may be prosecuted under

129 Panel Reports, para. 7.59 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 5(7)).
130 Panel Reports, para. 7.59 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 6(d)).
131 Panel Reports, para. 7.60 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 7).
132 Panel Reports, para. 7.63 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 6.13; Taking and Related Acts Incidental to Commercial Fishing Operations by
Tuna Purse Seine Vessels in the Eastern Tropical Pacific Ocean, United States Code of Federal Regulations,
Title 50, Section 216.24 (2016) (Panel Exhibit USA-3), Section 216.24(f)(2)(i)-(ii); 2016 implementing
regulations (Panel Exhibits MEX-2 and USA-2), Section 216.93(f); NOAA Form 370 (Panel Exhibit USA-4)).
regulations (Panel Exhibits MEX-2 and USA-2), Section 216.93(d)-(e)).
134 Panel Reports, para. 7.64 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(d)(1)-(3), (f), and (g)(3)).
135 Panel Reports, para. 7.64.
136 Panel Reports, para. 7.65 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(5)).
137 Panel Reports, para. 7.66 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(g)(3); NOAA Form 370 (Panel Exhibit USA-4); United States' response to Panel
question No. 29, paras. 148-149).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the DPCIA provisions, the federal provi sions prohibiting false statements and smuggling, or the
federal labelling standards.138
5.24. Additionally, in fisheries where the Assistant Administrator has made a determination under
the determination provisions described in paragraph 5.16 above, the following conditions apply. Any
imported tuna or tuna product made from tuna caught on a trip, in those fisheries, beginning on or
more than 60 days after the publication of a notice of the determination in the Federal Register, and
which is intended to be labelled as dolphin-safe, must be accompanied by valid documentation signed
by a representative of the vessel flag nation or the processing nation (if processed in another nation)
certifying that: (i) the catch documentation recorded on NOAA Form 370 is correct; (ii) the tuna or
tuna products meet the US dolphin -safe labelling standards; and (iii) the chain of custody
information is correct.139
5.25. In sum, we observe that the eligibility criteria, the certification requirements, and the tracking
and verification requirements all form part of a single measure, the 2016 Tuna Measure, and thus
work together in pursuing the same objectives. Hence, following the Appellate Body's findings in the
first compliance proceedings, in our review of the Panels' evaluation of the 2016 Tuna Measure, we
"take account of the fact that its various elements – the eligibility criteria, the certification
requirements, and the tracking and verification requirements – establish a series of conditions of
access to the dolphin-safe label that are cumulative and highly interrelated".140
6 ANALYSIS OF THE APPELLATE BODY
6.1 Article 2.1 of the TBT Agreement
6.1.1 Introduction
6.1. As noted above, in the present compliance proceedings, the United States requested the Panels
to find that the 2016 Tuna Measure is consistent with Article 2.1 of the TBT Agreement. Mexico
asked the Panels to find that the 2016 Tuna Measure is inconsistent with the same provision. The
Panels recalled that a finding of inconsistency with Article 2.1 must be based on the following three
elements: (i) the measure at issue is a technical regulation within the meaning of Annex 1.1 to the
TBT Agreement; (ii) the relevant products are "like" products; and (iii) the measure at issue accords
less favourable treatment to imported products than to the relevant group of like products.141 Noting
the similarity in the factual circumstances underlying the first two elements in the first compliance
proceedings, the Panels in these compliance proceedings agreed with the parties that the 2016 Tuna
Measure is a technical regulation and that the relevant products are like.142
6.2. Regarding the third element, the Panels recalled the Appellate Body's finding that assessing
whether the measure accords less favourable treatment under Article 2.1 requires two distinct steps:
(i) determining whether the challenged measure modifies the conditions of competition to the
detriment of the relevant imported products vis-à-vis like products of domestic origin and/or like
products originating in any other country; and, if the panel makes such a finding, (ii) determining
whether the detrimental impact on imports stems exclusively from a legitimate regulatory distinction
rather than reflecting discrimination against the grou p of imported products. 143 The Panels noted
that the 2016 Tuna Measure maintains the overall architecture and structure of the original and

138 Panel Reports, para. 7.66 (referring to NOAA Form 370 (Panel Exhibit USA-4); United States Code,
Title 18, Section 545 (Panel Exhibit USA-166); United States Code, Title 18, Section 3571 (Panel Exhibit
USA-167); United States Code, Title 16, Section 3372 (Panel Exhibit USA-169), Section 3372(d); Civil
Monetary Penalty Adjustments for Inflation, United States Federal Register, Vol. 81, No. 109 (7 June 2016)
(Panel Exhibit USA-170); United States Code, Title 16, Section 3373 (Panel Exhibit USA-171),
Section 3373(d)(3); United States Code, Title 16, Section 3374 (Panel Exhibit USA-172), Section 3374(a)(1);
United States Code, Title 18, Section 1001 (Panel Exhibit USA-173), Section 1001(a); United States Code,
Title 16, Section 1375 (Panel Exhibit USA-174), Sections 1375(a)(1) and 1375(b))).
139 Panel Reports, para. 7.69 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(5)(ii)).
140 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166.
141 Panel Reports, para. 7.73 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.25).
142 Panel Reports, para. 7.74.
143 Panel Reports, para. 7.73 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.26).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

2013 Tuna Measures and that the parties agreed that the relevant factual situation has not changed
from the original o r the first compliance proceedings. 144 The Panels thus found that, by excluding
most Mexican tuna products from accessing the dolphin-safe label, while granting conditional access
to such label to like products from the United States and other countries, the 2016 Tuna Measure,
like the original and the 2013 Tuna Measures, modifies the conditions of competition to the detriment
of Mexican tuna products in the US market.145
6.3. The Panels therefore noted that the parties' disagreement on the consistency of the 2016 Tuna
Measure with Article 2.1 of the TBT Agreement centred on the question whether the detrimental
impact caused by the 2016 Tuna Measure stems exclusively from a legitimate regulatory distinction.
The Panels understood their task in these proceedings to be ascertaining "whether the relevant
regulatory distinctions are appropriately 'calibrated' and 'tailored' to, and commensurate with", the
different risks to dolphins arising from the use of different fishing methods in different areas of the
ocean.146
6.4. The Panels went on to establish "the risk profiles of the relevant fishing methods in different
areas of the ocean, taking into account data on both observable and unobser vable harms". 147
Thereafter, the Panels examined whether the 2016 Tuna Measure, including its relevant constituent
elements, is calibrated to different risks to dolphins . In this regard, the Panels examined,
sequentially, the eligibility criteria, the certif ication requirements, the tracking and verification
requirements, and the determination provisions 148, before providing an overall assessment of the
consistency of the 2016 Tuna Measure with Article 2.1.149
6.5. On appeal, Mexico claims that the Panels erred in th eir interpretation and application of
Article 2.1 of the TBT Agreement in finding that the 2016 Tuna Measure is not inconsistent with that
provision. Mexico raises four main grounds of appeal. First, Mexico contends that the Panels relied
on a legal standa rd that fails to take into account whether the regu latory distinctions of the
2016 Tuna Measure are rationally related to its objectives. In this regard, Mexico argues that the
Panels erred in their calibration analysis because they failed to consider the risks of inaccurate
labelling under the 2016 Tuna Measure. 150 Second, Mexico contends that the Panels erred in their
application of Article 2.1 by limiting aspects of their calibration analysis to a comparison of the risk
profiles of different fishing method s.151 Third, Mexico alleges that the Panels erred in their
assessment of the risks to dolphins arising from the use of different fishing methods in different
areas of the ocean by: (i) failing to adequately evaluate the risk profiles of different fisheries 152;
(ii) using setting on dolphins in the ETP as the benchmark 153; and (iii) ignoring relevant
measurements of risks. 154 Fourth, Mexico alleges that the Panels erred in the ir application of
Article 2.1 of the TBT Agreement in finding that the eligibility criteria, the certification requirements,
the tracking and verification requirements, as well as the 2016 Tuna Measure as a whole, are
calibrated to the risks to dolphins arising from the use of different fishing methods in different areas
of the ocean.155
6.6. The United States claims that the Panels correctly determined that the regulatory distinctions
of the 2016 Tuna Measure are properly calibrated to different risks to dolphins arising from the use
of different fishing methods in different areas of the oceans, based on the Appellate Body's guidance
in the first compliance proceedings. First, the United States contends that, in the first compliance
proceedings, the Appellate Body examined the interplay between the rational connection and
calibration analyses and made clear that, in this dispute, the concept of calibration "reflects the

144 Panel Reports, para. 7.77.
145 Panel Reports, para. 7.78 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.238).
146 Panel Reports, para. 7.103 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.252).
147 Panel Reports, para. 7.149.
148 In response to questioning at the hearing, Mexico and the United States agreed that the Panels acted
appropriately in undertaking this sequential analysis.
149 Panel Reports, para. 7.529.
150 Mexico's Notice of Appeal, para. 8.a; appellant's submission, paras. 99-142.
151 Mexico's Notice of Appeal, para. 8.b; appellant's submission, paras. 159-172, 181-185, and 230-234.
152 Mexico's Notice of Appeal, para. 8.c; appellant's submission, paras. 162-171 and 235-240.
153 Mexico's Notice of Appeal, para. 8.c; appellant's submission, paras. 175-191.
154 Mexico's Notice of Appeal, para. 8.c; appellant's submission, paras. 192-225 and 241-246.
155 Mexico's Notice of Appeal, para. 9; appellant's submission, paras. 226-307.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

nexus between the distinctions of the measure and the measure's objective [s]".156 Second, in the
United States' view, the Panels acted in accordance with the requirements of Article 2.1 in examining
the relevant regulatory distinctions under the 2016 Tuna Measure. 157 Third, the United States also
considers that the Panels appropriately examined the risk profiles of fishing methods and fisheries.158
Fourth, the United States submits that the Panels' "intermediate conclusions" concerning the
eligibility criteria, certification requirements, and tracking and verification requirements were
"correct and not in e rror".159 The United States adds that, contrary to Mexico's arguments, the
Panels' overall assessment of the 2016 Tuna Measure was not only based on their intermediate
analyses but also their examination as to how the different parts of the measure interact to address
the risks to dolphins arising from the use of different fishing methods in different ocean areas.160
6.7. We begin by briefly recalling the relevant legal standard under Article 2.1, before assessing
whether the Panels erred in their articulation thereof. Thereafter, we turn to the Panels' application
of that standard in the context of this dispute , by first addressing Mexico's two overarching
arguments regarding the Panels' analysis under Article 2.1, namely, that the Panels: (i) failed to
examine the nexus between the regulatory distinctions under the measure at issue and its
objectives; and (ii) erred by limiting aspects of their calibration analysis to a comparison of the risk
profiles of different fishing methods. Next, we address Mexico's arguments pertaining to specific
aspects of the Panels' assessment of risk profiles, including the allegations that the Panels did not
adequately assess the risks arising from tuna fishing in different fisheries, adopted a wrong
benchmark, and ignored relevant measurements of risks. Finally, we examine Mexico's arguments
that the Panels erred in concluding that the eligibility criteria, certification requirements, and tracking
and verification requirements, as well as the 2016 Tuna Measure as a whole, are calibrated to the
relevant risk profiles.
6.1.2 "Treatment no less favourable" under Article 2.1 of the TBT Agreement
6.1.2.1 Whether the Panels erred in their articulation of the legal standard
6.8. Article 2.1 of the TBT Agreement provides that:
Members shall ensure that in respect of technical 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.
6.9. The Appellate Body has identified a two -step analysis for examining whether the technical
regulation at issue accords less favourable treatment to imported products under Article 2.1 of the
TBT Agreement: (i) whether it modifies the conditions of competit ion to the detriment of such
imported products vis-à-vis like products of domestic origin and/or like products originating in any
other country; and (ii) whether the detrimental impact on imports stem s exclusively from a
legitimate regulatory distinction.161 Where the detrimental impact caused by a technical regulation
is found to stem exclusively from a legitimate regulatory distinction, "such a technical regulation
does not accord less favourable treatment to imported products and is therefore consistent wi th
Article 2.1 of the TBT Agreement."162
6.10. To determine whether the detrimental impact stems exclusively from a legitimate regulatory
distinction, "a panel must carefully scrutinize whether the techni cal regulation at issue is

156 United States' appellee's submission, para. 32 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), paras. 7.92, 7.98, and 7.101. See also ibid., paras. 35-85.
157 United States' appellee's submission, paras. 116-123.
158 United States' appellee's submission, paras. 96-203.
159 United States' appellee's submission, para. 353. See also ibid., paras. 204-353.
160 United States' appellee's submission, para. 354.
161 See Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.26 (referring to
Appellate Body Reports, US – Clove Cigarettes, paras. 180, 182, and 215; US – COOL, paras. 268 and 271;
162 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.96. In interpreting
Article 2.1 as such, the Appellate Body took into account the context provided by the definition of "technical
regulation" found in Annex 1.1 to the TBT Agreement, as well as Article 2.2 and the sixth recital of the
preamble of the TBT Agreement. (Ibid., para. 7.87. See also Appellate Body Reports, US – COOL, para. 271;
US – Clove Cigarettes, paras. 171-174; US – Tuna II (Mexico), paras. 212-213)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

even-handed in its design, archi tecture, revealing structure, operation, and application in the light
of the particular circumstances of the case." 163 The Appellate Body has found that there may be
different ways to demonstrate that a measure does not stem exclusively from a legitimate regulatory
distinction, including, "for example", by showing that the measure is applied in a manner that
constitutes arbitrary or unjustifiable discrimination. 164 At the same time, the Appellate Body has
emphasized that "an examination of whether a measure is designed or applied in a manner that
constitutes a means of arbitrary or unjustifiable discrimination is not the only way to assess whether
a measure lacks even-handedness".165
6.11. The Appellate Body has said that, in light o f the "important parallels" between the analyses
under Article 2.1 of the TBT Agreement and the chapeau of Article XX of the GATT 1994166, relevant
jurisprudence under the latter, particularly that relating to the concept of "arbitrary or unjustifiable
discrimination", may provide useful insight as to how the concept should be understood in the
context of the second step of the "treatment no less favourable" analysis under Article 2.1.167 In this
connection, "[o]ne of the most important factors in the assessment of arbitrary or unjustifiable
discrimination [under the chapeau of Article XX] 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."168 To the
Appellate Body, the "same considerations … are valid in the context of the second step of the analysis
of 'treatment no less favourable' under Article 2.1".169 Thus, for the purpose of Article 2.1 of the
TBT Agreement, in examining whether a technical regulation constitutes a means of arbitrary or
unjustifiable discrimination, "it is likely that this assessment [will] in volve[] consideration of the
nexus between the regulatory distinctions found in the measure and the measure's policy
objectives"170, although "consideration of other factors … may also be relevant to the analysis."171
6.12. In the original proceedings, the United States sought to demonstrate that the detrimental
impact under the original Tuna Measure stemmed exclusively from a legitimate regulatory distinction
by introducing the notion of calibration. More specifically, the United States contended that the
regulatory distinctions drawn under the original Tuna Measure "between different tuna fishing
methods and different areas of the oceans could be explained or justified by differences in the risks
associated with such fishing methods and areas of the oceans". 172 This led the Appellate Body to
examine the legitimacy of the original Tuna Measure 's regulatory di stinctions "through the lens
of … 'calibration'".173 The Appellate Body emphasized that its use of the terms "even -handed" and
"calibrated":
[D]id not constitute different legal tests, since the entire inquiry by the Appellate Body
revolved around whether the United States had properly substantiated its argument

163 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.31 (referring to
Appellate Body Report, US – Clove Cigarettes, para. 182). See also Appellate Body Reports, US – Clove
164 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.31. See also
Appellate Body Reports, US – COOL, para. 271; US – COOL (Article 21.5 – Canada and Mexico), para. 5.94.
165 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.94. (emphasis original)
See also ibid., para. 7.31.
166 Appellate Body Reports, EC – Seal Products, para. 5.310; US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.89. We recall that the chapeau of Article XX of the GATT 1994 provides that
WTO Members may resort to measures that fall within one of the discrete categories of general exceptions
contained in Article XX of the GATT 1994 "[s]ubject 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". Given that the sixth recital of the
preamble of the TBT Agreement "serves as relevant context for understanding Article 2.1, and the language of
that recital has important commonalities with the chapeau of Article XX of the GATT 1994", the jurisprudence
under the chapeau of Article XX is relevant to understanding the content of the second step of the "treatment
no less favourable" requirement under Article 2.1 of the TBT Agreement. (Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), para. 7.88)
167 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.91.
168 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.92 (quoting
Appellate Body Reports, EC – Seal Products, para. 5.306, in turn referring to Appellate Body Reports,
US – Shrimp, para. 165; Brazil – Retreaded Tyres, paras. 227-228 and 232).
169 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.92.
170 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.97.
171 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.95.
172 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.98.
173 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.98.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

that the original tuna measure was even -handed, and thus not inconsistent with
Article 2.1, because it was "calibrated" to the risks to dolphins arising from different
fishing methods in different areas of the oceans.174
6.13. Thus, rather than being a separate legal test, calibration is the means to assess whether the
detrimental impact of the measure at issue in this dispute stems exclusively from a legitimate
regulatory distinction, in the context of the second step of the "treatment no less favourable" analysis
under Article 2.1 . As we explai n in greater detail in section 6.1.3 below, if done properly, the
calibration analysis should encompass consideration of the rational relationship between the
regulatory distinctions and the objectives of the 2016 Tuna Measure. Thus, if calibrated properly,
these regulatory distinctions will not amount to arbitrary or unjustifiable discrimination and will thus
comply with the requirements of Article 2.1 of the TBT Agreement.
6.14. In articulating the applicable legal standard under Article 2.1 in these compliance proceedings,
the Panels recalled the Appellate Body's findings as set forth above. The Panels considered that,
"while there may in theory be a number of ways" to assess whether the measure satisfies the second
step of the analysis under Article 2.1175, in this dispute it was appropriate to assess whether the
detrimental impact caused by the 2016 Tuna Measure stems exclusively from a legitimate regulatory
distinction through the lens of calibration.176
6.15. On appeal, Mexico highlights the Appellate Body's statement that a rational relationship test
is "[o]ne of the most important factors" in assessing arbitrary and unjustifiable discrimination under
the chapeau of Article XX of the GATT 1994. 177 Thus, Mexico argues that, given the "close
relationship" between the notion of even -handedness under Article 2.1 and the chapeau of
Article XX, "an assessment of whether the detrimental impact can be reconciled with, or is rationally
related to, the policy objective pursued by the measure" is required in the analysis under
Article 2.1.178
6.16. As indicated above, the assessment of whether the detrimental impact of a measure amounts
to arbitrary or unjustifiable discrimination in the context of Article 2.1 will likely involve consideration
of the nexus between the regulatory distinctions of the measure and its objectives. This does not
mean that such consideration necessarily constitutes a step that is separate and distinct from a
proper calibration analysis, as Mexico appears to suggest. At the same time, we do not understand
Mexico's arguments on appeal to relate primarily to the Panels' ar ticulation of the legal standard
under Article 2.1. Rather, as further discussed in section 6.1.3 below, Mexico contends that the
Panels, in their calibration analysis, failed to include an examination of the nexus between the
regulatory distinctions giving rise to the detrimental impact, on the one hand, and the 2016 Tuna
Measure's objectives, on the other hand. Therefore, while Mexico indicates that its claims relate,
inter alia, to the Panels' interpretation of Article 2.1, we observe that its arguments mainly concern
the Panels' application of the legal standard under Article 2.1 in the context of the present dispute.
We address these arguments in section 6.1.3 below. However, before turning to the issue of what
constitutes a proper calibration analysis in this dispute, we address Mexico's argument that the
Panels should have taken into account the objective of sustainable development set out in the
preamble of the WTO Agreement when interpreting and applying Article 2.1 of the TBT Agreement
in this dispute.
6.1.2.2 Whether the Panels erred in rejecting Mexico's argument c oncerning the
relevance of the sustainability of tuna stock and the marine ecosystem
6.17. Before the Panels, Mexico argued that, "while the reference to sustainable development in the
preamble of the WTO Agreement does not itself create any obligations, nevertheless the text of all

174 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.98. (emphasis added)
175 Panel Reports, para. 7.102.
176 Panel Reports, para. 7.102. The Panels noted that the Appellate Body had, in the first compliance
proceedings, repeatedly emphasized that the appropriate way, in the context of this dispute, for a panel to
assess whether the detrimental impact caused by the Tuna Measure stems exclusively from a legitimate
regulatory distinction is to assess whether the Measure is properly "calibrated" to different risks to dolphins.
(See Panel Reports, para. 7.84 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.155))
177 Mexico's appellant's submission, para. 325 (quoting Appellate Body Report, US – Tuna II (Mexico)
178 Mexico's appellant's submission, para. 86.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

WTO obligations that in any way relate to the objective of sustainable development or environmental
protection must be interpreted and clarified within [the] … context" provided by the preamble. 179
Therefore, Mexico contended that, while WTO Members are free to choose their own objectives, the
Members would be acting inconsistently with their WTO obligations "if the means … to achieve" such
objectives "are inconsistent wit h the objectives of sustainable development". 180 Mexico submitted
that the principle of sustainable development has risen to the status of a principle of international
law applicable to all countries.181
6.18. The Panels rejected Mexico's argument, finding that this argument "appear[ed] to elevate the
preambular language to the level of substantive obligation, despite Mexico's assertion to the
contrary".182 Furthermore, the Panels emphasized that the 2016 Tuna Measure is not concerned with
sustainable development, but rather with the protection and well -being of dolphins, and that the
WTO Agreement does not obligate a Member to regulate only for the objective of "sustainable
development".183
6.19. On appeal, Mexico argues that, where the obligations at issue in a dispute relate to sustainable
development, they must be interpreted consistently with the objective of sustainable development.
For Mexico, this requirement arises under Article 2.1 in the determination of whether the 2016 Tuna
Measure stems exclusively from a legitim ate regulatory distinction.184 In Mexico's view, applying a
technical regulation that is inconsistent with or undermines the objective of sustainable development
results in "unjustifiable discrimination".185 Mexico highlights that, by encouraging the use of fish
aggregating devices (FADs) and other forms of tuna fishing outside the ETP as alternatives to the
fishing method of setting on dolphins, the 2016 Tuna Measure "does grievous harm to fisheries and
to the overall marine ecosystem" and "must therefore be seen as inconsistent with the objective of
sustainable development".186 Mexico contends that the application of the 2016 Tuna Measure results
in "unjustifiable discrimination", and therefore that the regula tory distinctions under the measure
"cannot be 'legitimate'" for the purpose of the second step of the analysis under Article 2.1.187
6.20. The United States responds that Mexico seek s to transform preambular language regarding
sustainable development into a substantive obligation.188 In addition, the United States argues that,
to make its argument, "Mexico is forced to substantially change the objectives of the 2016 measure"
and transform the dolphin-protection and consumer -information objectives of the measure int o
labelling requirements that relate to "the sustainability of tuna stocks and of the marine ecosystem
generally".189
6.21. We observe that the issue raised by Mexico is twofold. First, we must determine whether,
under the "treatme nt no less favourable " requiremen t in Article 2.1 of the TBT Agreement, the
means through which a technical regulation achieves its objectives must be compatible with the
principle of sustainable development in the preamble of the WTO Agreement. Second, if we find that
there is such a requirement under Article 2.1, we must determine whether, in the circumstances of
the present dispute, the 2016 Tuna Measure is incompatible with this requirement because it
encourages the use of FADs and other forms of fishing that are unsustainable for tuna stock.
6.22. The Appellate Body has said that , in assessing whether a technical regulation accords less
favourable treatment to imported products under Article 2.1, a panel's task lies , in part, in
ascertaining whether the detrimental impact caused by a technical regulation stems exclusively from

180 Panel Reports, para. 7.128.
181 Panel Reports, para. 7.128.
182 Panel Reports, para. 7.130.
183 Panel Reports, para. 7.131.
184 Mexico's appellant's submission, paras. 147-148.
185 Mexico's appellant's submission, para. 149.
186 Mexico's appellant's submission, para. 148. For instance, Mexico argues that the floating object/FAD
method "attracts and kills immature as well as mature tuna, as well as a wide variety of other bycatch,
including sea turtles, sharks, and other species". (Mexico's appellant's submission, para. 25 (referring to
Original Panel Report, para. 4.10))
187 Mexico's appellant's submission, para. 149.
188 United States' appellee's submission, para. 91.
189 United States' appellee's submission, para. 92 (referring to Mexico's appellant's submission,
para. 148). (emphasis omitted)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

a legitimate regulatory distinction.190 The Appellate Body has also indicated that the preamble of the
TBT Agreement informs "the ambit of the 'treatment no less favourable' requirement in Article 2.1,
by making clear that technical regulations may pursue the objectives listed therein".191
6.23. We consider that the preamble of the WTO Agreement may also inform interpretations of the
covered agreements in appropriate circumstances. In this regard, the Appellate Body has found that
the preamble of the WTO Agreement "add[s] colour, texture and shading" to the interpretation of
the covered agreements.192 Thus, while the preamble of the WTO Agreement does not itself create
substantive obligations, it can provide important context for the interpretation of the covered
agreements, for example, by shedding light on the kinds of policy objectives a Member may pursue.
6.24. We note that the legitimacy of the objectives of the 2016 Tuna Measure is not at issue before
us in this dispute. Indeed, in response to questioning at the hearing, Mexico indicated that it did not
challenge the right of the United States or other WTO Members to determine the objectives of their
measures.193 Mexico also acknowledged that "the reference to sustainable development in the
preamble of the WTO Agreement does not itself create any obligations."194 At the same time, Mexico
maintains that "[w]here … obligations [at issue in a dispute] relate to sustainable development, they
must be interpreted consistently with the objective of sustainable development."195 In Mexico's view,
"this interpretive requirement arises under Article 2.1 of the TBT Agreement" when determining
whether the detriment al impact under the Tuna Measure stems exclusively from a legitimate
regulatory distinction.196
6.25. Mexico's argument thus appears to be premised on its view that Article 2.1 is an obligation
that "relate[s] to sustainable development".197 However, Article 2.1 is concerned with ensuring that
technical regulations are designed and applied in a manner that affords "treatment no less
favourable" to like imported products. In our view, Mexico seems to conflate the nature of the
obligation in Article 2.1 with the natur e of the technical regulations that Members may choose to
adopt. For instance, Mexico indicates that "[n]ot all technical regulations will relate to sustainable
development, but, where they do, they will be inconsistent with [ Article 2.1] if their effects are
unsustainable."198 Thus, Mexico's argument appears to suggest that the relevance of the principle
of sustainable development to the interpretation of Article 2.1 may differ depending on whether a
measure "relates to", or has "effects" on, sustainable dev elopment. We fail to see why the
interpretation of Article 2.1 should vary depending on the kind of technical regulation that a Member
adopts. While a Member's technical regulation may, depending on the circumstances, relate to
sustainable development, the nature and scope of the obligation in Article 2.1 remain unchanged.
6.26. In any event, we recall that the objectives of the 2016 Tuna Measure are: (i) to ensure that
consumers are not misled or deceived about whether tuna products contain tuna caught in a manner
that adversely affects dolphins; and (ii) to contribute 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.199 Given that the legitimacy of the objectives of the 2016 Tuna Measure is not at
issue in these compliance proceedings, we consider that the question before the Panels was whether

190 See para. 6.9 above.
191 Appellate Body Report, US – Clove Cigarettes, para. 173.
192 Appellate Body Report, US – Shrimp, para. 153. We recall that, in US – Shrimp, the Appellate Body
relied on the objective of sustainable development contained in the preamble of the WTO Agreement to
determine whether a measure aimed at protecting sea turtles could fall within the ambit of the policy objective
of conservation of "exhaustible natural resources" within the meaning of Article XX(g) of the GATT 1994. The
Appellate Body indicated that the expression "exhaustible natural resources" contained in this provision should
be read in light of the objective of sustainable development contained in the preamble of the WTO Agreement,
and interpreted to refer not only to the conservation of exhaustible mineral or other non-living natural
resources but also to living natural resources including sea turtles, the protection of which was sought by the
measure at issue in that dispute. (Appellate Body Report, US – Shrimp, para. 131)
193 See also Panel Reports, para. 7.128 (quoting Mexico's second written submission to the Panels,
para. 32).
194 Panel Reports, para. 7.128 (referring to Mexico's response to Panel question No. 84, para. 130).
195 Mexico's appellant's submission, para. 147.
196 Mexico's appellant's submission, para. 148.
197 Mexico's appellant's submission, para. 147. In Mexico's view, "[a]s expressed in the preamble of the
WTO Agreement, the objective of every WTO Member is to act sustainably", and this objective must "inform
the interpretation of the Article 2.1 of the TBT Agreement". (Ibid., para. 149)
198 Mexico's appellant's submission, para. 149.
199 See para. 5.8 above.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the detrimental impact caused by the 2016 Tuna Measure stems exclusively from a legitimate
regulatory distinction in light of the objectives the United States chose to pursue through the
measure. On the basis of the above considerations, we do not need to examine whether, in the
circumstances o f the present dispute, the 2016 Tuna M easure is incompatible with Article 2.1
because it encourages the use of FADs and other forms of fishing that are unsustainable for tuna
stock.
6.27. We now turn to examine what the legal standard under Article 2.1 of the TBT Agreement, as
articulated above, entails in the context of the present dispute, and whether the Panels erred in their
articulation and application thereof.
6.1.3 What the legal standard under Article 2.1 of the TBT Agreement entails in this
dispute
6.28. As noted in paragraph 6.3 above, the Panels cons idered that, in light of the specific
circumstances of this dispute, their task in examining the parties' respective claims under Article 2.1
was to ascertain "whether the relevant regulatory distinctions are appropriately 'calibrated' and
'tailored' to, and commensurate with", the different risks to dolphins arising from the use of different
fishing methods in different areas of the ocean.200 After establishing "the risk profiles of the relevant
fishing methods in different areas of the ocean, taking into ac count data on both observable and
unobservable harms"201, the Panels examined the relevant constituent elements of the 2016 Tuna
Measure. They then synthesized their intermediate analyses "to reach an overall, holistic conclusion"
regarding whether the labelling conditions under the m easure are calibrated to the relevant risk
profiles.202 On this basis, the Panels ultimately found that the 2016 Tuna Measure is consistent with
Article 2.1.203
6.29. On appeal, Mexico claims that the Panels erred in their "legal interpretation" of the calibration
test under Article 2.1.204 We recall, however, that calibration is not a separate legal standard under
Article 2.1 but, rather, a case-specific analytical tool used to assess whether the 2016 Tuna Measure
is consistent with this provision. As explained above, we understand Mexico's arguments to concern
whether, in applying the calibration analysis, the Panels prope rly assessed the nexus between the
regulatory distinctions and the measure's objectives.205
6.30. Mexico argues in this regard that, in assessing the consistency of the 2016 Tuna Measure with
Article 2.1, the Panels erred in determining that the measure is calibrated to the risks to dolphins
arising from different fishing methods in different areas of the oceans, without at the same time
considering whether the regulatory distinctions that the measure draws are rationally related to its
objectives. In particular, Mexico contends that the Panels failed to consider risks relating to
inaccurate labelling in examining the risk profiles of relevant fishing methods and ocean areas for
the purpose of the calibration analysis. In Mexi co's view, because the 2016 Tuna Measure cannot
achieve its objectives without label accuracy, a proper calibration analysis should have included
considerations of such risks of inaccurate labelling.206
6.31. Mexico also alleges several errors in the Panels' "esta blishment and assessment of the risk
profiles of different fishing methods in different ocean areas", which, in Mexico's view, "resulted in
deficiencies that caused the Panels to subsequently err in conducting their assessment of whether
the relevant regulatory distinctions [under the 2016 Tuna Measure] are calibrated". 207 Specifically,
Mexico claims that the Panels erred in assessing and comparing the risk profiles of different fishing
methods without differentiating between different ocean areas.208 Mexico contends that, as a result,

200 Panel Reports, para. 7.103 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.252).
201 Panel Reports, paras. 7.149 and 7.525.
202 Panel Reports, paras. 7.529 and 7.704.
203 Panel Reports, para. 7.717.
204 Mexico's appellant's submission, para. 78.
205 See para. 6.16 above.
206 Mexico's appellant's submission, paras. 99 and 117-118.
207 Mexico's appellant's submission, para. 154.
208 Mexico's appellant's submission, paras. 159-172, 235-240, and 254-260.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the Panels' calibration analysis is deficient because it fails to examine whether the relevant
regulatory distinctions under the measure are calibrated on a fishery-by-fishery basis.209
6.32. Addressing Mexico's arguments calls for us to establish what a proper calibration analysis
entails for the purpose of this dispute, before assessing whether the Panels erred in their calibration
analysis. Specifically, we address: (i) how the objectives of the 2016 Tuna Measure, and the risk of
inaccuracy of the dolphin-safe label, should be taken into account in a proper calibration analysis;
and (ii) whether the Panels erred by limiting aspects of their calibration analysis to a comparison of
the risk profiles of different fishing methods.210
6.1.3.1 Whether the Panels erred in failing to consider the nexus between the regulatory
distinctions of the measure and its objectives
6.33. Mexico raises three interconnected arguments in support of its claim that the Panels failed to
assess the nexus between the regulatory distinctions of the measure and its objectives in their
calibration analysis. Mexico argues that: (i) the Panels' calibration analysis fail ed to recognize the
relevance of label accuracy in light of the objectives of the 2016 Tuna Measure; (ii) the Panels failed
to include risks of inaccuracy as part of the risk profiles of the different ocean areas to which the
2016 Tuna Measure should be calibrated; and (iii) by finding that the 2016 Tuna Measure
contemplates a margin of error, the Panels erroneously considered that the measure tolerates label
inaccuracy. We examine these arguments in turn.
6.1.3.1.1 Whether the Panels' calibration analysis t ook into account the accuracy of the
dolphin-safe label in light of the objectives of the 2016 Tuna Measure
6.34. Based on the App ellate Body's findings in the first compliance proceedings, Mexico submits
that a proper calibration analysis "must take into account the nexus between the regulatory
distinctions and the objectives of the measure". 211 In Mexico's view, "[c]onsideration of t he nexus
between the detrimental impact and the objectives of the measure as a part of the 'calibration' test
helps to ensure that a WTO Member 's regulatory space is respected without undermining the
disciplines set forth in the TBT Agreement and other WTO Agreements."212 Mexico argues that,
"[a]s a consumer labelling measure", the 2016 Tuna Measure "cannot achieve [its] objectives
without label accuracy".213 For Mexico, a claim that the regulatory distinctions of the measure are
"'calibrated' to the different risks posed to dolphins by different fishing methods in different ocean
areas … cannot justify the detrimental impact on Mexican tuna products if the measure fails to ensure
that the label provides accurate information to consumers" .214 Mexico thus alleges t hat the
Panels' calibration analysis was "narrow" 215 and "incomplete" 216 because the Panels failed to
recognize the relevance of label accuracy to the calibration analysis.

209 Mexico's appellant's submission, paras. 230-240, 252-260, and 273-274, and fn 207 to para. 166.
210 We address the other specific errors alleged by Mexico regarding the Panels' assessment of risk
profiles in section 6.1.4, and whether the 2016 Tuna Measure is properly calibrated in section 6.1.5, below.
211 Mexico's appellant's submission, para. 97 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.155). In its appellant's submission, Mexico argues that "both an examination of
the nexus between the regulatory distinctions and the objectives of the measure and an examination of
whether the measure is 'calibrated' are relevant factors for consideration in the assessment of whether the
2016 tuna measure is designed and applied in an even-handed manner." (Ibid., para. 98 (emphasis added))
This statement suggests that, in Mexico's view, consideration of the rational relationship may not be
encompassed in the calibration analysis, such that the Panels should have determined separately whether
there is, indeed, a rational relationship between the regulatory distinctions of the 2016 Tuna Measure and its
objectives. However, Mexico clarified at the hearing that, in order to be properly calibrated, the regulatory
distinctions of the 2016 Tuna Measure would have to be rationally related to its objectives.
212 Mexico's appellant's submission, para. 100. Mexico also indicated at the hearing that, for a measure
to be properly calibrated, it must not be designed or applied in a manner that constitutes a means of arbitrary
or unjustifiable discrimination, and the primary factor for examining whether the measure constitutes such
discrimination is to assess whether the detrimental impact can be reconciled with, or is rationally related to,
the objectives of the measure.
213 Mexico's appellant's submission, para. 99.
214 Mexico's appellant's submission, para. 99.
215 Mexico's appellant's submission, para. 116.
216 Mexico's appellant's submission, para. 117.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.35. The United States contends that Mexico is wrong in claiming that the Panels erred in following
the Appellate Body's guidance in the previous compliance proceedings.217 The United States argues
that the Appellate Body clearly set out what it considered to be the appropriate calibration analysis
by repeatedly referring to the risk profiles of different fishing methods in different areas of the ocean,
and by indicating that those risk profiles should reflect the relative risks of observed and unobserved
mortalities and injury. 218 In the United States' view, the Panels correctly assessed the
WTO-consistency of the 2016 Tuna Measure by considering whether its distinctions are calibrated to
different risks to dolphins.
6.36. We begin by recalling the Appellate Body's relevant findings in the original and first
compliance proceedings regarding the calibration analysis in this dispute . We recall that the
United States sought to demonstrate that the detrimental impact under the original Tuna Measure
stemmed exclusively from a legitimate regulatory distinction by i ntroducing the notion of
calibration.219 As a result, the Appellate Body used the notion of calibration as an analytical tool to
assess the consistency of the original Tuna Measure under the second step of the analysis of
"treatment no less favourable". However, the Appellate Body found that the United States had not
demonstrated that the original Tuna Measure was calibrated to the risks to dolphins.220 Rather, the
Appellate Body shared the original panel's view that, while the risks to dolphins arising fro m purse
seine fishing by setting on dolphins – a fishing method predominantly used by Mexican fleets – were
fully addressed in the original Tuna Measure 221, the risks to dolphins arising from the use of other
fishing methods – predominantly used by US and ot her fishing fleets – were not.222 In the original
proceedings, the Appellate Body thus accepted the premise that the original Tuna Measure would
not violate Article 2.1 if it was properly calibrated to the risks to dolphins arising from the use of
different fishing methods in different areas of the oceans.223
6.37. Referring to the original proceedings , the Appellate Body indicated in the first compliance
proceedings that it was therefore appropriate to conduct an analysis involving the following:
[F]irst, an identification of whether different tuna fishing methods in different areas of
the oceans pose different risks to dolphins; and, second, examination of whether, in the
light of these risks, the different treatment created by the relevant regulatory distinction
shows that, as between different groups, the treatment accorded to each group is
commensurate with the relevant risks, taking account of the objectives of the
measure.224
6.38. The Appellate Body further noted that "the reasoning set out in adopted Appellate Body and
panel reports" provides guidance for WTO Members to bring their inconsistent measures into
compliance with their obligations under the covered agreements. 225 In light of the fact that the
United States had defended its 2013 Tuna Measure under Article 2.1 in terms very similar to those
used in the original proceedings, the Appellate Body considered that the first compliance panel's
inquiry in those proceedings should have encompassed: (i) an assessment of the "overall relative
risks or levels of harm to dolphins" arising from different fishing methods in different ocean areas226;

217 United States' appellee's submission, para. 47.
218 United States' appellee's submission, para. 48. According to the United States, "at no time did the
Appellate Body ever suggest that the risk profiles reflect anything other than observed and unobserved
mortality or injury to dolphins." (Ibid. (referring to Panel Reports, para. 7.108))
219 See para. 6.12 above.
220 Appellate Body Report, US – Tuna II (Mexico), para. 297.
221 Appellate Body Report, US – Tuna II (Mexico), para. 287 (referring to Original Panel Report,
para. 7.505).
222 Appellate Body Report, US – Tuna II (Mexico), para. 292 (referring to Original Panel Report,
para. 7.534 and fn 767 thereto).
223 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.154-7.155 (referring
to Appellate Body Report, US – Tuna II (Mexico), para. 297).
224 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.155.
225 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.156.
226 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.252 and 7.353.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

and (ii) an assessment as to whether the differences in the dolphin -safe labelling conditions under
the measure are appropriately tailored to227, or commensurate with228, those respective risks.229
6.39. Thus, under the calibration analysis set out by the Appellate Body in the original and first
compliance proceedings, the risks to which the regulatory distinctions must be calibrated are risks
to dolphins from the use of different fishing methods in different areas of the ocean. In our view,
therefore, the Panels correctly considered that "the relevant inquiry is one that focuses on the risks
that dolphins face as a result of the use, in different areas of the ocean, of different fishing
methods."230
6.40. Moreover, as the Appellate Body found in the first compliance proceedings, the examination
of whether the regulatory distinctions are commensurate with different risks to dolphins must be
conducted "taking account of the objectives of the measure". 231 Indeed, aspects of the
Appellate Body's reasoning as to why the first compliance panel erred in its application of Article 2.1
illustrate how considerations of the 2013 Tuna Measure's objectives, and the related issue of label
accuracy, form part of the cal ibration analysis. Specifically, the Appellate Body noted that the first
compliance panel had dismissed the United States' argument that the different tracking and
verification requirements are justified or explained in light of the higher degree of risk to dolphins in
the ETP large purse seine fishery.232 According to the first compliance panel, the different risk profiles
of different fisheries do not explain regulatory distinctions in the tracking and verification
requirements because such distinctions are triggered after the tuna has been caught. 233 The
Appellate Body, however, disagreed with the first compliance panel's view that considerations of the
similarities and differences in risks to dolphins were irrelevant to evaluating the even -handedness
of the tracking and verification requirements. To the Appellate Body, the first compliance panel's
disregard of the "considerations of the similarities and differences in risks [to dolphins]" did not
comport with its own reasoning that "the accuracy of the US dolphin-safe label can be compromised
at any stage of the tuna production stage, in contradiction with the objectives of the amended tuna
measure".234
6.41. Thus, in the first compliance proceedings, th e Appellate Body found that the tracking and
verification requirements should have been calibrated to the risks to dolphins arising from the
different fishing methods in different areas of the ocean so as to avoid co mpromising the accuracy
of the dolphin-safe label and contradicting the measure's objectives.235 These findings confirm that
considerations regarding label accuracy should have informed the calibration analysis, precisely
because the accuracy of the dolphin-safe label was directly related to the objectives of the 2013 Tuna
Measure. Thus, considerations of the nexus between the regulatory distinctions and the measure's
objectives, rather than being a separate inquiry, are encompassed in a proper calibration analysis.

227 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.163 and 7.252-7.253.
228 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.155, 7.160,
and 7.252-7.253.
229 See e.g. Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.252.
230 Panel Reports, para. 7.109.
231 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.155.
232 We recall that the Appellate Body also found that the first compliance panel had not performed a
proper analysis under Article 2.1 of the TBT Agreement due to the following errors: (i) the panel's segmented
analysis of the 2013 Tuna Measure; (ii) its erroneous assumption that disqualifying the method of setting on
dolphins from the dolphin-safe label was found to be consistent with Article 2.1 of the TBT Agreement in the
original proceedings; (iii) its failure to take due account of the different risks associated with tuna fishing in
different fisheries by focusing solely on unobserved harms to dolphins; and (iv) its focus on the technique of
setting on dolphins in assessing the respective risk profiles of different fishing methods and areas of the ocean.
(Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.126, 7.159, 7.161, and 7.165)
233 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.142 (referring to
Original Panel Report, para. 7.398).
234 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166. (Ibid., fn 611 to
para. 7.166 (referring to First Compliance Panel Report, para. 7.233) (emphasis added)) The Appellate Body
also noted that the first compliance panel had indicated that the different tracking and verification
requirements that apply outside the ETP large purse seine fisheries are less burdensome, making it more likely
that tuna caught other than by ETP large purse seine vessels will be incorrectly labelled as dolphin-safe. (See
also Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.253)
235 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166 and fn 611
thereto, and para. 7.169.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.42. Turning to the Panels' findings in these proceedings, the Panels recalled that the
Appellate Body's findings in the first compliance proceedings made clear that:
[W]hile there may in theory be a number of ways in which a panel could assess the
'even-handedness' of a measure challenged under Article 2.1 of the TBT Agreement, in
the specific context of these proceedings, the appropriate legal standard for the Panels
to apply is one that focuses on the relationship between the risks posed to dolphins by
different fishing methods in different areas of the ocean, o n the one hand, and the
relevant regulatory distinctions, on the other hand.236
Thus, the Panels understood their task to be that of ascertaining "whether the relevant regulatory
distinctions are appropriately 'calibrated' and 'tailored' to, and commensurat e with, the different
risks to dolphins arising in different fisheries." 237 If the relevant regulatory distinctions are so
calibrated, the Panels considered that this would indicate that the 2016 Tuna Measure is not
inconsistent with Article 2.1.
6.43. The Panels found that, insofar as Mexico considered that they should assess the existence of
a rational relationship between the detrimental impact and the objectives of the 2016 Tuna Measure
as a separate or distinct step in their analysis, such an approach was not supported by the
Appellate Body's reports in the original or the first compliance proceedings. 238 In this regard, the
Panels did not read the Appellate Body's reports as requiring, beyond calibration, "any additional,
separate analysis" of the relationship between the objectives of the measure and the detrimental
impact.239 In our view, the Panels' statements comport with the Appellate Body's findings, as
reviewed in paragraphs 6.36-6.41 above, that considerations of the nexus between the regulatory
distinctions and the measure's objectives, rather than being a separate inquiry, are an integral part
of a proper calibration analysis.
6.44. To the Panels, the Appellate Body's statement that the calibration analysis must be conducted
"taking account of the measure's objectives" meant that those objectives must "inform the criteria
in respect of which calibration is to be assessed", and that the Panels had to "bear in mind" those
objectives in applying the calibration analysis to the facts of this dispute.240 The Panels recalled that
the objectives of the 2016 Tuna Measure are: (i) "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" ; and (ii) "ensuring that consumers are not misled or deceived about
whether tuna products contain tuna that was caught in a manner that adversely affects dolphins".241
Thus, the Panels considered that the 2016 Tuna Measure "aims to convey accurate information to
consumers in orde r to ensure that the US tuna market is not used to encourage fishing fleets to
catch tuna in a manner that adversely affects dolphins." 242 In the Panels' view, calibration to the
risks to dolphins arising from the use of different fishing methods in differen t areas of the ocean
would take into account the objectives of the 2016 Tuna Measure. 243 The Panels' findings correctly
suggest that the design, structure, and expected operation of the tuna measure reveal that the
measure seeks to achieve both its objectives in concert. We thus share the Panels' view that these
objectives are "mutually complementary and reinforcing, and work together to 'address [the adverse
effects of] fishing techniques on dolphins'".244
6.45. In this respect, we recall Mexico's argument that, "[ a]s a consumer labelling measure", the
2016 Tuna Measure "cannot achieve [its] objectives without label accuracy", and that a claim that
the regulatory distinctions of the measure are "'calibrated' to the different risks posed to dolphins
by different fish ing methods in different ocean areas … cannot justify the detrimental impact on
Mexican tuna products if the measure fails to ensure that the label provides accurate information to

236 Panel Reports, para. 7.102.
237 Panel Reports, para. 7.103 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.252).
238 Panel Reports, para. 7.115.
239 Panel Reports, para. 7.115.
240 Panel Reports, paras. 7.116-7.117.
241 Panel Reports, para. 7.117 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.16).
242 Panel Reports, para. 7.125 (referring to Original Panel Report, para. 7.427). (fn omitted)
243 Panel Reports, para. 7.117.
244 Panel Reports, para. 7.125 (quoting Original Panel Report, para. 7.550). Mexico agrees that the
objectives of the measure are "inseparable". (Mexico's appellant's submission, para. 144)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

consumers".245 As discussed above, the Appellate Body's findings in the first compliance proceedings
indicate that considerations regarding label accuracy are encompassed in a proper calibration
analysis. Accordingly, we disagree that a calibration analysis, on the basis of risks to dolphins, would
fail to ascertain whether the labels granted under the relevant labelling conditions are accurate and,
as a consequence, whether the regulatory distinctions in such conditions are rationally related to the
measure's objectives.
6.46. Instead, we consider that, where the calibration analysis is conducted properly, taking account
of the objectives pursued by the 2016 Tuna Measure, this exercise should also ascertain whether
the label granted under the measure at issue convey s the information regarding the dolphin -safe
nature of the tuna products to consumers.246 This is because, if the calibration analysis shows that
the strictness of the different labelling conditions is indeed commensurate with the risks of harms to
dolphins, it indicates that the labels granted under these conditions would allow consumers to obtain
information regarding whether the tuna in the tuna products is harvested in a manner that harms
dolphins. Therefore, we agree with the Panels that a proper calibration to the risks to dolphins arising
from the use of different fishing methods in different areas of the ocean would take into account the
objectives of the 2016 Tuna Measure 247, and would help to ascertain the nexus between such
objectives and the different labelling conditions under the measure. In the same vein, we also agree
with the Panels that the existence of a rational relationship between the regulatory distinctions and
the objectives of the 2016 Tuna Measure need not be assessed as a separate or distinct step in their
analysis.248
6.1.3.1.2 Whether the risks of label inaccuracy form part of the risks to which the 2016
Tuna Measure must be calibrated
6.47. Mexico contends that the Panels erred in finding that calibration under Article 2.1 "requires a
panel to simply 'bear in mind the objectives of the … Measure'". 249 Rather, Mexico emphasizes that
the objectives of the measure "must be reflected in the substantive criteria for assessing whether
the measure's regulatory distinctions are designed and applied in an even-handed manner, including
on the basis of ' calibration'".250 As the 2016 Tuna Measure can only achieve its objectives through
label accuracy251, such criteria must include factors relating to the risk of inaccurate labelling. 252
Thus, Mexico argues that the Panels erred in finding that, for the purpose of the calibration analysis,
risks relating to inaccurate labelling are not part of the risk profiles of the different fishing methods
and ocean areas. Mexico submits that, in doing so, the Panels' approach "preclude[d] an assessment
from taking full account of the particular circumstances of the case"253, and "did not give meaningful
relevance" to the nexus between the detrimental impact caused by the regulatory distinctions and
the objectives of the measure.254
6.48. The A ppellate Body's findings reviewed above suppo rt Mexico's view that considerations
regarding label accuracy are relevant to assessing the nexus between the regulatory distinctions
under the 2016 Tuna Measure and its policy objectives. 255 However, the Appellate Body did not
suggest that the risk of label inaccuracy constitutes a risk to which the relevant regulatory
distinctions must be calibrated. Rather, as noted above, the Appellate Body emphasized that the
risks to which the regulatory distinctions must be calibrated were risks to dolphins arising fro m
tuna fishing in different fisheries.256 Thus, while accuracy of the information conveyed to consumers
through the dolphin-safe label is a consideration that should inform the calibration analysis, we share
the Panels' view that this is "different from saying that the applicable legal standard … requires the

245 Mexico's appellant's submission, para. 99. (fn omitted)
246 As noted in para. 5.11 above, under the 2016 Tuna Measure, tuna products labelled as dolphin-safe
must not contain tuna harvested in a manner that adversely affects dolphins.
247 See para. 5.8 above.
248 Panel Reports, para. 7.115. In sections 6.1.4 and 6.1.5 below, we examine whether the Panels
conducted the calibration analysis properly in this dispute.
250 Mexico's appellant's submission, para. 138.
251 Mexico's appellant's submission, para. 99.
252 See Mexico's appellant's submission, paras. 99, 114, and 124.
253 Mexico's appellant's submission, para. 123.
254 Mexico's appellant's submission, para. 127.
255 See paras. 6.36-6.41 above. See also Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.166 and fn 611 thereto (referring to First Compliance Panel Report,
para. 7.398).
256 See e.g. Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.155.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Panels to determine whether the 2016 Tuna Measure is calibrated, inter alia, to the risk of inaccurate
dolphin-safe information being passed to consumers".257
6.49. Mexico additionally argues that, in finding that risk profiles of different fisheries do not
encompass risks of label inaccuracy258, the Panels failed to recognize that the risks to dolphins "are
inextricably linked to the characteristics of ocean areas and fisheries that impact the accuracy of the
dolphin-safe label". 259 Specifically, "[f]or a given fishing method capable of causing harms to
dolphins, dolphins will be at a greater relative risk of harms from that fishing method in ocean areas
that are unregulated or that have insufficient regulatory oversight, resulting in unreliable reporting,
significant [illegal, unreported, and unregulated] IUU fishing, and/or significant transshipment at
sea, than in ocean areas that have sufficient regulatory oversight and reliable reporting." 260
In Mexico's view, fo r tuna caught in such ocean areas, "stricter certification requirements and
tracking and verification requirements are justified (and required) on the basis that they are
calibrated to the higher relative risks of harms to dolphins". 261 Mexico therefore contends that the
Panels erroneously focused the calibration assessment solely on the impact of fishing methods in
terms of their harm to dolphins, and that such an approach is "incomplete " and "legally
erroneous".262
6.50. The United States contends that "Mexico makes a new factual allegation not made (or
supported) before the Panels", namely, that "'the reliability of applicable systems' is 'inextricably
linked' with actual, physical harm to dolphins" 263, and that dolphins will therefore be at a g reater
risk of harms in unregulated or insufficiently regulated ocean areas, resulting in unreliable reporting,
significant IUU fishing, and/or significant trans-shipment at sea, than in sufficiently regulated ocean
areas.264 The United States points out that Mexico never provided any evidence to the Panels of a
link between the risks of harm to dolphins, on the one hand, and the low reliability of applicable
systems, on the other hand. 265 The United States highlights that "Mexico never even argued this
point before the Panels – and the Panels made no such finding of fact."266
6.51. By arguing that "dolphins will be at a greater relative risk of harms from [a given] fishing
method in ocean areas that are unregulated or that have insufficient regulatory oversight, resulting
in unreliable reporting, significant IUU fishing, and/or significant transshipment at sea" 267, we
understand Mexico to suggest that tuna fishing in ocean areas with less reliable regulatory systems
is more likely to lead to "actual, physical harm to dolp hins".268 However, Mexico has not
substantiated such an assertion. In these circumstances, we see no reason to disagree with the
Panels' statement that "the risks of inaccurate certification, reporting, and/or record-keeping are not
risks that affect dolphins themselves", or "risks that arise from the use of different fishing methods
in different areas of the ocean".269
6.52. At the same time, we emphasize that issues regarding label inaccuracy are relevant to
assessing whether the labelling conditions under the measure are properly calibrated. As the Panels
also acknowledged, the risks of inaccurate certification, reporting, and/or record-keeping may "have
an indirect influence on the extent to which different fishing methods are used to catch tuna intended
for the US market".270 Furthermore, the Panels recognized that "fish caught in different areas of the
ocean through the use of different fishing methods may be associated with a greater or smaller risk

257 Panel Reports, para. 7.112.
258 Panel Reports, para. 7.112.
259 Mexico's appellant's submission, para. 124.
260 Mexico's appellant's submission, para. 109.
261 Mexico's appellant's submission, para. 110.
262 Mexico's appellant's submission, para. 124.
263 United States' appellee's submission, para. 45 (quoting Mexico's appellant's submission, para. 124).
264 United States' appellee's submission, para. 45 (quoting Mexico's appellant's submission, para. 109).
265 United States' appellee's submission, para. 53.
266 United States' appellee's submission, para. 53 (referring to Panel Reports, para. 7.110).
267 Mexico's appellant's submission, para. 109.
268 United States' appellee's submission, para. 45 (referring to Mexico's appellant's submission,
paras. 120 and 124).
270 Panel Reports, para. 7.110. This is because "one of the objectives of the label is to provide
consumers with information as to the dolphin-safe status of tuna products in order to ensure 'that the
US market is not used to encourage fishing fleets to catch tuna in a manner that adversely affects dolphins'."
(Panel Reports, fn 222 to para. 7.110 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 6.3))
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of inaccurate labelling depending on a range of interconnected factors, including the persons involved
in the catch, available technology, and applicable domestic and international regulatory
requirements."271 To the Panels, these risks were "relevant" 272, and even "central", to their
application of the calibration analysis, precisely because, in doing so, they were required to take the
objectives of the measure into account.273 We therefore consider that the Panels did not, as Mexico
contends, adopt an approach to calibration that is "narrow" and "incomplete".274
6.53. Furthermore, by noting that the risk of inaccuracy depends on a range of interconnected
factors, including "the persons involved in the catch, available technology, and applicable domestic
and international regulatory requirements" 275, the Panels expressly recognized tha t the risk of
inaccuracy encompasses the factors leading to such inaccuracy. Indeed, as the Panels explained,
the expression "risk of inaccuracy" means "the risk that an error in the recording and reporting of
information somewhere in the catch and processing chain could result in a batch of t una being
designated as dolphin -safe while in fact containing tuna that sho uld have been designated as
non-dolphin-safe."276 Our review of the Panels' findings therefore does not support Mexico's
argument that the Panels erred in defining the risk of inaccuracy "narrowly to relate to the symptom
or outcome (i.e. an inaccurate label) rather than the risk factors that cause such an outcome".277
6.1.3.1.3 Whether the Panels erred in referring to "margin of error" in their calibration
analysis
6.54. Mexico also takes issue with the Panels' discussion of the margin of error in the context of
their analysis regarding risks of inaccuracy. Mexico disagrees with the Panels that the existence of
margins of error in the certification and track ing and verification requirements is not necessarily
inconsistent with the objectives of the measure.278 Rather, Mexico contends that "the measure does
not contemplate a 'margin of error' or a tolerance threshold for inaccurate labelling, and it does not
incorporate a de minimis test for accuracy."279 Mexico also argues that the Panels erroneously "took
the position that fisheries that have lower risk profiles … will always have a lower risk of conveying
incorrect information to consumers", and that, by doing s o, "determined that allowing inaccurate
labels is consistent with the objectives of the measure".280
6.55. The United States contends that Mexico's argument is based on a fundamental
misunderstanding of the Panels' analysis to the extent that it suggests that the Panels' approach is
driven to tolerate less accurate labelling for tuna products from outside the ETP large purse seine
fisheries.281 In the United States' view, the Panels properly recognized that the risk of inaccurate
labelling is not a constant 282, and that "the U.S. measure need not 'be completely error -proof in
order to be calibrated' (and, thus consistent with Article 2.1)."283 Rather, the Panels correctly
indicated that "the more pertinent question is whether the possibility of error is tailored to, or
commensurate with, the different risks to dolphins arising from the use of different fishing methods
in different areas of the ocean."284 Therefore, the United States argues that the Panels did not err in
relying on the concept of margin of error in discussing the certification and tracking and verification
requirements, and that this concept is entirely consistent with the guidance provided by the
Appellate Body in both the original proceedings and the first compliance proceedings.285

271 Panel Reports, para. 7.110.
272 Panel Reports, para. 7.113.
273 Panel Reports, para. 7.118.
274 Mexico's appellant's submission, para. 124.
277 Mexico's appellant's submission, para. 139.
278 Mexico's appellant's submission, para. 133 (referring to Panel Reports, para. 7.122).
279 Mexico's appellant's submission, para. 140.
280 Mexico's appellant's submission, para. 135.
281 United States' appellee's submission, para. 66.
282 United States' appellee's submission, para. 68.
283 United States' appellee's submission, para. 74 and fn 168 thereto (quoting Panel Reports,
paras. 7.601 and 7.605).
284 United States' appellee's submission, para. 74 (quoting Panel Reports, para. 7.605). (emphasis
added)
285 United States' appellee's submission, para. 75.
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6.56. In our view, by equating "margin of error" with "a tolerance threshold of inaccurate
labelling"286, Mexico's above arguments are based on its understanding of the term "margin of error"
as being synonymous with the ultimate inaccuracy of a dolphin -safe label. However, the
Panels' discussion of "margin of error", when read in its totality, suggests that the Panels did not
equate the term with label inaccuracy. Rather, we understand the Panels' reference to the term
"margin of error" as relating to the different degrees of strictness of the certification and tracking
and verification requirements under the 2016 Tuna Measure. Pursuant to this understanding, the
ultimate accuracy of the label depends not only on the different degrees of the strictness of the
relevant requirements, but al so on the level of risks to dolphins in a given fishery to which these
requirements apply.
6.57. We recall that the Panels introduced the notion of margin of error in discussing the "risk of
inaccuracy".287 To this effect, the Panels indicated that "the existence of a margin of error in
certification, and tracking and verification requirements does not necessarily equate or give rise to
a risk that the information ultimately conveyed to a consumer by a dolphin -safe label will itself be
incorrect."288 Rather, to the Panels, "the risk of inaccurate information being passed to consumers
by the label will depend not only on the referred margin of error, but also, and importantly, on the
extent of events that require recording whether a dolphin mortality or serious injury was observed
in a given fishery."289 The Panels explained that the risk profile of relevant fisheries "is a good proxy
to measure the extent of [such] events that require recording". 290 Therefore, the Panels reasoned
that "in applying the calibration test, it is appropriate … to consider whether the certification, and
tracking and verification requirements applied in different fisheries are commensurate with, and
tailored to, the particular risk profiles of those fisheries."291 More specifically:
[I]n a fishery where the risks to dolphins are low, it may be calibrated to apply
certification, and tracking and verification requirements that tolerate a higher margin of
error than the certification, reporting, and/or record -keeping requirements that apply
in respect of fisheries with a high risk profile. This is be cause the risk that the
dolphin-safe label will communicate inaccurate information is a function of numerous
factors, including not only the regulations in place, but also the different levels of dolphin
interaction, mortality, and serious injury in different fisheries. Thus, in fisheries with
high dolphin interactions and harms, more sensitive certification , and tracking and
verification requirements may be needed to ensure the u ltimate accuracy of the
dolphin-safe label, whereas in fisheries with low dolphin interactions and harms, less
sensitive requirements may be sufficient.292
6.58. Thus, the Panels' findings as set forth above indicate that the term "margin of error" relate s
to the strictness of the releva nt certification and tracking and verification requirements, such that
the less sensitive they are, the more likely that adverse effects on dolphins might go undetected
and unreported. This, however, does not automatically translate into inaccuracy of the ultimate
dolphin-safe label. Rather, as the Panels' statements quoted above make clear, the accuracy of the
ultimate label depends not only on the sensitivity of the labelling conditions, but also on the level of
risks to dolphins in a fishery. Where such risks are higher, the corresponding labelling conditions
may need to be more "sensitive" 293, or strict, to ensure the accuracy of the label in conveying the

286 Mexico's appellant's submission, para. 140.
287 As noted above, the Panels defined the "risk of inaccuracy" as the risk that, due to "an error in the
recording and reporting of information", a batch of tuna containing tuna that should have been designated as
non-dolphin-safe is nonetheless designated as dolphin-safe. (Panel Reports, para. 7.119)
288 Panel Reports, para. 7.120.
289 Panel Reports, para. 7.120. (emphasis added) The Panels indicated that, for example, where the
margin of error is high but the occurrence of such events is low in a given fishery, the risk of inaccurate
information being conveyed to consumers would be low. Conversely, where the margin of error is low but
occurrence of such events is high, the resulting risk of inaccurate information would be high. (Ibid.,
para. 7.121) The Panels further explained that the "events that require recording" include "not only the events,
such as death or serious injury of dolphins, which make up the risk profile of the relevant fishery, but also
other events, such as the fact that dolphins were observed by the vessel captain or independent observer;
whether or not dolphin-safe and non-dolphin-safe tuna were segregated in the wells on board the vessel; and
whether that segregation was maintained during the trans-shipment and unloading of the tuna". (Ibid., fn 235
to para. 7.121)
291 Panel Reports, para. 7.123.
293 Panel Reports, para. 7.123.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

information regarding the dolphin -safe nature of the tuna products. Conversely, where such risks
are lower, less sensitive labelling conditions may be sufficient to ensure accuracy. Thus, we
understand the Panels to have meant that the sensitivity of the labelling conditions should
correspond, or be calibrated, to the risks to dolphins arising from the use of different fishing methods
in different areas of the ocean, so as to ensure accurate labelling.
6.59. We thus disagree with Mexico's contention that the Panels erroneously "took the position that
fisheries that have lower risk profiles … will always have a lower risk of conveying incorrect
information to consumers", and t hat, by doing so, "determined that allowing inaccurate labels is
consistent with the objectives of the measure" .294 In our view, Mexico's argument conflates the
strictness of the relevant labelling conditions with the inaccuracy of the ultimate dolphin-safe label.
While the term "margin of error", read in isolation, may be understood in the sense Mexico suggests,
our above analysis indicates that the Panels used this term to denote the possibil ity of error as a
result of different levels of strictness in the certification and tracking and verification requirements,
and did not equate it to the accuracy of the ultimate label. Rather, the latter depends not only on
the sensitivity of the labelling conditions but also, importantly, on the risks to dolphins arising from
the use of different fishing methods in different areas of the ocean.
6.60. This being said, we do not consider that a reference to the term "margin of error" was
necessary to the Panels' a ssessment of whether the 2016 Tuna Measure is properly calibrated.295
Indeed, the Panels highlighted that the question whether margins of error in the certification and
tracking and verification requirements are consistent with the objectives of the measure "cannot be
answered by looking at the regulations in isolation" but must be assessed "in the light of the relevant
risk profiles in different fisheries". 296 Read in its totality, the Panels' discussion rightly focused on
the question whether the relevant reg ulatory distinctions are properly calibrated to the risks to
dolphins.
6.1.3.2 Whether the Panels erred by limiting aspects of their calibration analysis to a
comparison of the risk profiles of different fishing methods
6.61. Mexico argues that the Panels erred in asses sing and comparing the risk profiles of different
fishing methods without distinguishing between different ocean areas. 297 Mexico considers that, in
order to assess whether the measure is properly calibrated to the risks to dolphins, the Panels were
required to examine whether the 2016 Tuna Measure makes all relevant regulatory distinctions on
the basis of both fishing methods and ocean areas.298 This is because, according to Mexico, risks to
dolphins depend not only on the fishing methods used but also on the relevant characteristics of the
ocean areas where those fishing methods are used. 299 Mexico considers this view to be supported

294 Mexico's appellant's submission, para. 135.
295 Indeed, we observe that certain statements by the Panels regarding the term "margin of error",
when read in isolation, could potentially give rise to the understanding Mexico suggests. Specifically, the Panels
stated that "a measure that tolerates a larger margin of error where a risk is low, but tolerates a lower margin
of error where the risk is high, may very well be calibrated." (Panel Reports, para. 7.606) To the extent "a
larger margin of error" in this statement could be read to suggest a higher degree of label inaccuracy, this
would be contradicted by other statements by the Panels and the totality of their calibration analysis.
296 Panel Reports, para. 7.123.
297 Mexico's appellant's submission, paras. 159-172.
298 Mexico's appellant's submission, para. 166 and fn 207 thereto. In Mexico's view, fisheries "with
relatively higher risk profiles" must be distinguished from fisheries with "relatively lower risk profiles", and
should be ineligible for the label. (Ibid., para. 167) Mexico refers to certain gillnet, longline, and trawl fisheries
that the Panels found to have particularly high-risk profiles, and argues that "[p]ermitting access to the label to
tuna caught by such methods in those ocean areas contradicts and undermines the objective of the tuna
measure to discourage fishing practices that adversely affect dolphins." (Ibid., para. 167)
299 Mexico's response to questioning at the hearing. The Appellate Body in the first compliance
proceedings explained that "[f]or purposes of this dispute, the term 'fishery' may be defined by the geographic
region in which the fishing occurs, the vessel and fishing method used, and the target species." (Appellate
Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), fn 130 to para. 6.10)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

by the Appellate Body's articulation of the calibration analysis in previous proceedings in this dispute,
as well as the "design, architecture, and revealing structure of the measure".300
6.62. The United States argues that the eligibility criteria relevant to this dispute draw distinctions
on a fishing -method-by-fishing-method basis, and that it has not been suggested in any of the
previous proceedings in this di spute, by panels, the Appellate Body, or Mexico, that addressing
eligibility on a fishing -method-by-fishing-method basis is inconsistent with Article 2.1 of the
TBT Agreement.301 The United States considers that Mexico has not explained why this type of
distinction is not permitted under Article 2.1 of the TBT Agreement.302 In particular, the
United States explains that, in the first compliance proceedings, the Appellate Body did not reverse
the panel's findings on the basis that the panel had failed to make findings on a fishery -by-fishery
basis with respect to the eligibility criteria. 303 The United States also highlights that Mexico's
approach would render the determination provisions redundant.304
6.63. We note at the outset that what Mexico considers is required of the 2016 Tuna Measure, in
order for it to be consistent with Article 2.1 is based at least in part on the Appellate Body's
statement that the dolphin -safe labelling regime "will not violate Article 2.1 if it is properly
'calibrated' to the risks to dolphins arising from different fishing methods in different areas of the
oceans".305 The Appellate Body also explained that applying the calibration analysis entails an
"identification of whether differ ent tuna fishing methods in different areas of the oceans pose
different risks to dolphins" and examining whether, in light of these risks, "the different treatment
created by the relevant regulatory distinction shows that, as between different groups, the treatment
accorded to each group is commensurate with the relevant risks."306 However, these statements do
not prescribe that the regulatory distinctions under the 2016 Tuna Measure must be drawn on the
basis of different ocean areas in order for the measure to be consistent with Article 2.1. Rather, the
foregoing guidance by the Appellate Body acknowledges that the risks to dolphins may differ across
different ocean areas and that, in conducting an assessment of risks to dolphins for the purpose of
assessing whether the regulatory distinctions under the measure are indeed calibrated to different
risks to dolphins, it is necessary to assess the risks across all relevant ocean areas in which a
particular fishing method is practised (i.e. individual fisheries).
6.64. The essential question before the Panels was whether the relevant regulatory distinctions
under the measure are calibrated to different risks to dolphins. The nature of this analysis (i.e. how
the Panels were required to apply the calibration analysis) is informed by the nature of the regulatory
distinctions made under the measure itself. In this respect, we recall that, in determining whether
detrimental impact stems exclusively from a legitimate regulatory distinction, "a panel must carefully
scrutinize whether the technical regulation at issue is even -handed in its design, architecture,
revealing structure, operation, and application in the light of the particular circumstances of the
case."307 It is therefore useful to briefly recall certain features of the measure for the purpose of
assessing Mexico's arguments.
6.65. The 2016 Tuna Measure makes several sets of distinctions between different tuna products.
In terms of the eligibility criteria, the measure distinguishes between: (i) tuna products containing

300 Mexico's appellant's submission, para. 166 and fn 207 thereto. Mexico highlights that tuna caught by
driftnet fishing on the high seas is ineligible for the dolphin-safe label and argues on this basis that the
measure, in setting out the eligibility criteria, makes distinctions involving both fishing methods and ocean
areas. In response to questioning at the hearing, Mexico stated that the design of the measure is subject to the
legal analysis; so even if the eligibility requirement was assessed under the measure on a fishing-method-by-
fishing-method basis, that would not shield it from challenge and it would not shield the measure from being
assessed for calibration on a fishery-by-fishery basis.
301 United States' appellee's submission, paras. 117-118.
302 United States' appellee's submission, para. 118.
303 United States' appellee's submission, paras. 122-123.
304 United States' appellee's submission, para. 119. The United States explains that, since the
determination provisions increase the certification and tracking and verification requirements in specific
high-risk fisheries, the determination provisions would be "meaningless" if such high-risk fisheries were in any
event ineligible for the label.
305 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.155. (emphasis added)
See also Mexico's appellant's submission, para. 159.
306 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.155. (emphasis added)
307 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.31 (referring to
Appellate Body Report, US – Clove Cigarettes, para. 182). See also Appellate Body Reports, US – Clove
Cigarettes, para. 215; US – COOL, para. 340; US – Tuna II (Mexico), paras. 216 and 225.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

tuna caught by setting on dolphins or caught by driftnet fis hing on the high seas; and
(ii) tuna products containing tuna caught by other fishing methods. 308 While the former are
automatically ineligible for the dolphin-safe label, the latter are eligible for the label subject to certain
certification and tracking and verification requirements. Such certification and tracking and
verification requirements distinguish between: (i) tuna products containing tuna caught in the ETP
large purse seine fishery; and (ii) tuna products containing tuna caught in all other fisheries.309 Thus,
at the level of the eligibility criteria, the 2016 Tuna Measure draws a distinction on the basis of
fishing methods insofar as the ineligibility of tuna caught by setting on dolphins is concerned. 310
Furthermore, at the level of the certification and tracking and veri fication requirements, the
2016 Tuna Measure makes a distinction on the basis of different fisheries (i.e. the use of a particular
fishing method in a particular ocean area). 311 Specifically, these requirements distinguish between
tuna products containing tuna caught in the ETP large purse seine fishery and tuna products
containing tuna caught in all other fisheries.312 In order for a tuna product to receive the dolphin-safe
label, it must satisfy all of these requirements (in other words, the tuna must have been caught
using an eligible fishing method, and it must have been certified, as well as tracked and verified, in
accordance with the relevant requirements applicable to the fishery in which the tuna was caught).
6.66. Turning to the relevant findings by the Panels, we recall that the parties do not contest on
appeal the Panels' finding that the 2016 Tuna Measure has a detrimental impact on Mexican tuna
products. In this regard, the Panels highlighted the Appellate Body's finding in the first compliance
proceedings 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 provisions', while 'most tuna caught by US vessels is potentially eligible for the label'". 313
The Panels noted that "the 2016 Tuna Measure maintains the overall architectu re and structure of
the original and 2013 Tuna Measures", including "the regulatory distinction between tuna products
derived from tuna caught by setting on dolphins and tuna products derived from tuna caught by
other fishing methods".314 The Panels considered that, in light of the unchanged factual situation,
"by excluding most Mexican tuna products from access to the dolphin -safe label, while granting
conditional access to such label to like products from the United States and other countries, the
2016 Tuna Measure, similar to the original and the 2013 Tuna Measure, modifies the conditions of
competition to the detriment of Mexican tuna products in the US market."315
6.67. The Panels proceeded to examine whether this detrimental impact stems exclusively from a
legitimate regulatory distinction. The Panels began by assessing the evidence before them
concerning the use of all relevant fishing methods in different areas of the ocean (i.e. fisheries) 316
before arriving at an overall conclusion regarding the risk profile o f each fishing method. Following
their examination of the relevant risk profiles, the Panels considered it appropriate to examine
"whether each of the elements of the measure is calibrated to the risks to dolphins arising from the
use of different fishing methods in different areas of the ocean, and then synthesizing [their]
intermediate analyses to reach an overall, holistic conclusion about the WTO -consistency of the
Measure".317 For the purpose of assessing whether the eligibility criteria are properly calibrated, the
Panels compared the risk profile of setting on dolphins with the risk profiles of other fishing
methods.318 By contrast, in examining the certification and tracking and verification requirements,
the Panels compared the risk profiles of the relevant fisheries (i.e. fishing methods and ocean areas)
with respect to which the 2016 Tuna Measure draws a distinction, namely, the ETP large purse seine

308 See paras. 5.10-5.11 above.
309 See paras. 5.12-5.13 and 5.17 above.
310 Panel Reports, para. 7.568.
311 See Panel Reports, para. 7.568. As explained above, for the purpose of this dispute, the term
"fishery" may be defined by the geographic region in which the fishing occurs, the vessel and fishing method
used, and the target species. See supra, fn 299.
312 See Panel Reports, para. 7.568. We also note that, since tuna products containing tuna caught by
driftnet fishing on the high seas are ineligible for the dolphin-safe label, any certification (or tracking and
verification) of tuna caught by driftnet fishing on the high seas would only have the effect that such tuna
products would not receive the dolphin-safe label.
313 Panel Reports, para. 7.76 (quoting Appellate Body Report, US – Tuna II (Mexico)
314 Panel Reports, para. 7.77.
315 Panel Reports, para. 7.78.
316 To the extent that Mexico argues that the Panels failed to take into account all the relevant evidence
in making this assessment, we address these arguments in section 6.1.4 below.
317 Panel Reports, para. 7.529.
318 See Panel Reports, paras. 7.539-7.546.
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fishery and all other fisheries.319 The Panels explained that, "unlike the eligibility requirements, the
certification requirements (and the tracking and verification requirements ) … draw distinctions on
the basis of different fisheries, rather than different fishing methods."320
6.68. As explained above, Mexico contends that the Panels erred by comparing the risk p rofiles of
different fishing methods, and not of individual fisheries.321 As indicated, in the context of assessing
the certification and tracking and verification requirements, the Panels compared the risk profiles of
different fisheries. Since that approac h appears consistent with Mexico's preferred approach, we
understand that this aspect of Mexico's arguments pertains specifically to the Panels' assessment of
the eligibility criteria, with respect to which the Panels compared the risk profiles of fishing methods,
but not of individual fisheries.322
6.69. In this regard, Mexico argues that the Panels' approach is "incorrect" because the eligibility
criteria under the measure "clearly distinguish based on method and area".323 Mexico considers that
this is illustrated by the fact that tuna caught by driftnet fishing on the high seas is also ineligible
for the dolphin-safe label.324
6.70. We note that the distinction under the eligibility criteria between driftnet fishing on the high
seas and other fisheries is indeed on the basis of both fishing method and ocean area.325 However,
we recall that the second step of the "less favourable treatme nt" analysis under Article 2.1
"focusses on the regulatory distinction(s) causing the detrimental impact on imported products".326
Our above review of the Panels' findings and the Appellate Body's findings in the first compliance
proceedings indicates that the relevant regulatory distinctions giving rise to the detrimental impact
in this dispute do not concern driftnet fishing on the high seas. Mexico has not demonstrated how
the treatment under the measure of driftnet fishing on the high seas is related to the Panels' findings
of detrimental impact. 327 Furthermore, one of the regulatory distinctions c ausing the detrimental
impact on Mexican tuna products is that tuna products containing tuna caught by setting on dolphins
are ineligible for the dolphin-safe label, while tuna products containing tuna caught by other fishing
methods are provisionally eligible for the label. 328 As noted above, the distinction underlying the
ineligibility of tuna caught by setting on dolphins is made on the basis of fishing method, wit hout
reference to any particular ocean area or fishery. In our view, therefore, the fact that the measure
at issue also disqualifies from the dolphin-safe label tuna products containing tuna caught by driftnet
fishing on the high seas does not, in itself, undermine the Panels' approach in assessing, inter alia,
whether the distinction between setting on dolphins and other fishing methods is calibrated to
different risks to dolphins.
6.71. Mexico nonetheless argues that, "[e]ven if the measure did not apply the eligibility criteria on
an ocean area basis, legally the calibration assessment must be undertaken on a fishing method and
ocean area basis and, in certain circumstances, requires that the measure apply the eligibility criteria

319 See Panel Reports, paras. 7.568-7.573, 7.578, 7.599-7.603, 7.613, 7.651-7.652, 7.671-7.673,
and 7.709-7.716.
320 Panel Reports, para. 7.568.
321 See para. 6.61 above.
322 We are aware of Mexico's view that the Panels unduly focused on fishing methods in conducting their
assessment of risk profiles, such that the Panels failed to adequately assess the risks in each individual fishery.
(See paras. 6.91 and 6.100 below) Since that aspect of Mexico's arguments relates more specifically to the
way in which the Panels conducted their assessment of risk profiles, we address it in section 6.1.4 below,
rather than this section, which concerns more broadly whether the Panels correctly framed the calibration
analysis.
323 Mexico's appellant's submission, fn 207 to para. 166.
324 Mexico's appellant's submission, fn 207 to para. 166.
325 See paras. 5.10-5.11 above.
326 Appellate Body Reports, US – COOL (Article 21.5 – Canada and Mexico), para. 5.93. See also
Appellate Body Report, US – Tuna II (Mexico), para. 286.
327 We note that, on appeal, Mexico only raises the measure's distinct treatment of driftnet fishing on
the high seas in support of its view that the Panels erred by making a fishing-method-by-fishing-method
analysis. Mexico does not argue in its appellant's submission that: (a) the distinction between driftnet fishing
on the high seas and other individual fisheries causes the detrimental impact on Mexican tuna products; or
(b) the Panels erred by failing to examine whether this particular distinction is calibrated to different risks to
dolphins.
328 Panel Reports, paras. 7.76-7.78; Appellate Body Report, US – Tuna II (Mexico)
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on an ocean area basis in orde r to be in compliance with Article 2.1."329 In Mexico's view, because
risks to dolphins depend not only on fishing methods but also on the characteristics of the ocean
areas in which those fishing methods are used, eligibility criteria that are based solely on a distinction
between different fishing methods (without identifying specific ocean areas in which those methods
are used) would undermine the measure's objective of protecting dolphins from the risks of tuna
fishing. As Mexico further explained at the hearing, in its view , the distinction between setting on
dolphins and other fishing methods is per se inconsistent with Article 2.1, in light of the objectives
of the measure, the manner in which the Appellate Body has previously articulated the calibration
analysis, and the fact that certain fisheries may have a risk profile equivalent to that of setting on
dolphins in the ETP.
6.72. We recall that, under the second step of the "less favourable treatment" analysis under
Article 2.1 of the TBT Agreement, the relevant question is whether the detrimental impact caused
by the measure at issue stems exclusively from a legitimate regulatory d istinction.330 In our view,
in order to answer this question , it is necessary to examine the distinction that gives rise to the
detrimental impact. As indicated above, the detrimental impact in this dispute results, in part, from
the distinction under the el igibility criteria between setting on dolphins and other fishing methods.
Consequently, the test of whether the measure is even -handed requires assessing, inter alia331,
whether this distinction is a legitimate regulatory distinction.
6.73. Furthermore, in this dispute, the Appellate Body has accepted the premise that the Tuna
Measure would not violate Article 2.1 if the relevant regulatory distinctions leading to detrimental
impact are properly "calibrated" to the risks to dolphins arising f rom different fishing methods in
different areas of the oceans. 332 Thus, to the extent that Mexico's argument suggests that the
distinction between setting on dolphins and other fishing methods is not even -handed simply
because it is drawn on the basis of fi shing methods, we do not consider Mexico's approach to be
consistent with the findings from the original and first compliance proceedings. To the contrary,
whether this distinction is legitimate for the purpose of Article 2.1 must be assessed through a
comparison of the risk profiles of these different fishing methods.
6.74. In response to questioning at the hearing, Mexico argued that a fishing-method-by-fishing-
method distinction for the purpose of the eligibility criteria would undermine the measure's objective
of protecting dolphins from the risks of tuna fishing.333 We recall, however, that the Appellate Body
has accepted that if it is shown that the regulatory distinctions under the measure are calibrated to
different risks to dolphins, then the detrimental im pact under the measure would stem exclusively
from a legitimate regulatory distinction. 334 This approach by the Appellate Body reflected the
understanding that, given the design and structure of the Tuna Measure (including the distinction
between setting on dolphins and other fishing methods), if it can be shown that the distinctions are
calibrated to different risks to dolphins, this would also indicate that such distinctions are rationally
related to, and hence capable of contributing to, the measure's obje ctives (including the objective
of protecting dolphins). Indeed, as discussed in section 6.1.3.1.1 above, we consider that the
calibration analysis as set out by the Appellate Body encompasses considerations of the nexus
between the regulatory distinctions under the measure and the measure's objective. However, under
Mexico's approach, the 2016 Tuna Measure would be per se inconsistent with Article 2.1, solely on
the basis that such a distinction would undermine the objective of protecting dolphins. In our view,
Mexico has not demonstrated why a distinction on the basis of fishing methods would undermine
the objective of protecting dolphins.

329 Mexico's appellant's submission, fn 207 to para. 166.
330 See para. 6.9 above.
331 As part of this assessment, the Panels were also required to examine whether the regulatory
distinctions underlying the certification and tracking and verification requirements are calibrated to the risk
profiles of the ETP large purse seine fishery and all other fisheries. As noted in paragraph 6.67 above, we
understand the Panels to have compared the risk profiles of the relevant fisheries for the purpose of this
analysis, and we examine in section 6.1.5 below whether the Panels properly concluded that the relevant
regulatory distinctions are calibrated to these risk profiles.
332 See para. 6.36 above. See also Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.155.
333 We note that Mexico does not contest that the objectives of the 2016 Tuna Measure include the
protection of dolphins. (Mexico's appellant's submission, para. 71)
334 See supra, fn 332. See also Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
para. 7.98.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.75. We also note Mexico's argument that, because the Panels "disregarded"335 the fact that certain
fisheries may have risk profiles equivalent to, or higher than, the risk profile of setting on dolphins
in the ETP , the Pan els also failed to recognize that permitting access to the dolphin -safe label to
tuna caught in such ocean areas undermines the measure's objectives.336 However, from our review
of the Panels' findings, it is clear that the 2016 Tuna Measure does not draw a regulatory distinction
between the ETP setting-on-dolphins-fishery and other fisheries. As explained above, the eligibility
criteria distinguish between setting on dolphins and other fishing methods, while the certification
requirements and tracking and ve rification requirements distinguish between the ETP large purse
seine fishery (whether by setting on dolphins or by other methods of purse seine fishing) and all
other fisheries.337 It is on the basis of these regulatory distinctions that the Panels were required to
compare the risk profiles of different fishing methods ( with respect to the eligibility criteria) and
fisheries ( with respect to the certification and tracking and verification requirements), having
established such risk profiles on the basis of t heir review of all relevant evidence of the risks to
dolphins from different fishing methods as used in different ocean areas.
6.76. In any event, to the extent that Mexico is asserting that the Panels' analysis of risk profiles
should have addressed all ocean areas because risks differ across different ocean areas, we have
already addressed this argument above. 338 As discussed, we agree that information pertaining to
the risks to dolphins in individual fisheries is relevant, and should be taken into account, in assessing
and comparing the overall relative risks of different fishing methods.339 On the basis of the evidence
concerning the use of different fishing methods in different ocean areas, the Panels would then be
able to compare the relative risks of specific fishing methods in order to examine whether the
eligibility criteria are calibrated to such risks. To the extent that Mexico is asserting that the Panels
failed to assess relevant evidence regarding the use of fishing methods in specific ocean areas, we
address this argument in the context of our discussion of the Panels' assessment of risk profiles
below.340
6.77. In sum, given that the eligibility criteria under the 2016 Tuna Measure distinguish between
setting on dolphins and other fishing methods, and Mexico h as not demonstrated how such a
distinction would undermine the objective of protecting dolphins, we consider that assessing whether
this distinction is calibrated to different risks to dolphins required the Panels to compare, inter alia,
the risk profiles of the relevant fishing methods. Based on the foregoing, we consider that Mexico
has not demonstrated that the Panels erred by comparing the risk profiles of different fishing
methods in applying the calibration analysis to the eligibil ity criteria. Specifically, we consider that
the Panels were correct to compare, in the context of the eligibility criteria, the risk profiles of
different fishing methods, given that the relevant regulatory distinction under the eligibility criteria
is indeed on the basis of fishing methods. We also consider that the Panels acted appropriately by
comparing the risk profiles of individual fisheries in the context of applying the calibration analysis
to the certification and tracking and verification require ments, since those requirements make a
distinction on the basis of fisheries (i.e. both fishing method and ocean area).
6.78. In setting out the foregoing analysis, we are mindful of the need to avoid assessing each
element of the measure at issue in isolation. We recall that, in the first compliance proceedings, the
Appellate Body recognized that it may be appropriate for a panel "to proceed by assessing different
elements of [a] measure in a sequential manner", provided that doing so does not "lead to the
isolated consideration of a particular element" where the elements of a measure are closely
interrelated.341 Thus, a segmented approach may raise concerns "when a panel fails to make an
overall assessment that synthesizes its reasoning or intermediate conclusion s concerning related
elements of a measure at issue so as to reach a proper finding of consistency or inconsistency in
respect of that measure".342 In our view, the Panels' approach as described above343, whereby they
compared the risks of fishing methods in the context of the eligibility criteria, and risks of fishing
methods as used in specific ocean areas in the context of the certification and tracking and
verification requirements, appears to comport with the Appellate Body's guidance in the original and

335 Mexico's appellant's submission, para. 167.
336 Mexico's appellant's submission, paras. 159-162 and 164-171.
337 See para. 6.65 above.
338 See para. 6.63 above.
339 See para. 6.63 above.
340 See section 6.1.4 below.
341 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.14-7.15.
342 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.15.
343 See para. 6.67 above.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

first compliance proceedings. 344 Such an approach adapted the calibration analyses to reflect the
specific distinctions made under the measure and allowed the Panels to evaluate the way in which
the different interconnected aspects of the measure work togethe r. We also recall that, having
examined sequentially, the eligibility criteria, the certification requirements, the tracking and
verification requirements, and the determination provisions, the Panels provided an overall
assessment of the consistency of the 2016 Tuna Measure with Article 2.1.345
6.1.3.3 Conclusion
6.79. Under Article 2.1 of the TBT Agreement, in order to determine whether the detrimental impact
stems exclusively from a legitimate regulatory distinction, a panel must carefully scrutinize whether
the technical regulation at issue is even-handed in light of the particular circumstances of the case.
In the present dispute, an examination of whether the 2016 Tuna Measure is consistent with
Article 2.1 of the TBT Agreement entails an assessment of whether the regulatory distinctions of the
measure are calibrated to the risks to dolphins arising from different fishing methods in different
areas of the ocean. Such assessment involves: (i) an assessment of the overall relative risks of harm
to dolphins arising from the use of different fishing methods in dif ferent ocean areas; and
(ii) an assessment as to whether the differences in the dolphin -safe labelling conditions under the
measure are appropriately tailored to, or commensurate with, those respective risks. If co nducted
properly, this calibration analysis would encompass consideration of the rational relationship
between the regulatory distinctions drawn by the 2016 Tuna Measure and its objectives. Thus, there
is no need to separately assess the rational relationship between the regulatory distinctions drawn
by the measure and its objectives. Furthermore, while risks of inaccurate labelling are relevant to
the calibration analysis, this does not mean that the applicable legal standard requires the Panels to
determine whether the 2016 Tuna Measure is calibrated, inter alia , to the risk of inaccurate
dolphin-safe information being passed to consumers.
6.80. In conducting the calibration analysis, it is necessary to examine the risks to dolphins across
all relevant ocean areas in which different fishing methods are practi sed. This does not mean that,
under Article 2.1 of the TBT Agreement, a measure that seeks to protect dolphins must make all
relevant regulatory distinctions on the basis of both fishing method and ocean area. Rather, the
nature of the calibration analysis to be conducted is informed by the nature of the regulatory
distinctions made under the measure itself, and it is the regulatory distinction s causing the
detrimental impact on imported products that must be calibrated to different risks to dolphins. The
relevant regulatory distinctions that need to be examined for the purpose of calibration in this dispute
include the distinction between setting on dolphins and other fishing methods (in the context of the
eligibility criteria) and the distinction between the ETP large purse seine fishery and all other fisheries
(in the context of the certification and the tracking and verification requirements).
6.81. For these reasons, we do not consider that Mexico has established that the Panels, in
considering that they were required to examine whether the 2016 Tuna Measure was calibrated to
the risks to dolphins arising from the use of different fishing methods in different areas of the ocean,
failed to include an inquiry into the nexus between the relevant regulatory distinctions and the
objectives of the measure. We also disagree with Mexico that the Panels erred by comparing the risk
profiles of different fishing methods in applying the calibration analysis to the eligibility criteria. In
our view, in the specific context of the 2016 Tuna Measure, in order to assess whether the
detrimental impact on Mexican tuna products stems exclusively from a legitimate regu latory
distinction, the Panels were required to assess whether the regulatory distinctions causing that
detrimental impact are calibrated to different risks to dolphins, in terms of the overall relative risks
to dolphins, taking into account the objectives of the measure.
6.1.4 The Panels' assessment of risk profiles
6.82. Mexico makes three sets of arguments with respect to the Panels' assessment of different risk
profiles, alleging that the Panels erred by: (i) failing to adequately evaluate the risk profiles of
different fisheries; (ii) using the risk profile of setting on dolphins in the ETP as the benchmark for
assessing the risk profiles of other fisheries; and (iii) relying predominantly on "per set" evidence
for measuring the level of risks to dolphins, and ignoring other relevant evidence in their evaluation

344 We address whether the Panels' analysis took into account the manner in which the discrete
elements of the 2016 Tuna Measure are cumulative and highly interrelated in section 6.1.5 below.
345 See Panel Reports, section 7.8.6. See also section 6.1.5.5 below.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

of the risk profiles.346 The United States submits that the Panels correctly assessed the risk profiles
of different fishing methods, as used in different areas of the ocean. 347 The United States argues
that certain aspects of Mexico's arguments appear to pertain to the Panels' appreciation of the facts
and therefore fall outside the scope of this appeal, since Mexico did not raise any claims of error
under Article 11 of the DSU.348 Furthermore, in the United States' view, the Panels acted correctly
in relying primarily on per set evidence, and not relying on evidence that would have been misleading
and inapposite for comparing the relative risk profiles of different fishing methods and fisheries. 349
We begin by recal ling the Panels' assessment of different risk profiles, before turning to address
each of the three sets of arguments put forward by Mexico.350
6.1.4.1 The Panels' findings
6.83. The Panels recalled that the Appellate Body criticized the first compliance panel for failing to
analyse "the overall levels of risks in different fisheries, and how these fisheries compared to each
other" despite "considerable evidence" before it in this regard, in particular because it had failed to
consider the relative risks arising from observed mortalities and serious injuries to dolphins.351 The
Panels therefore considered that it was necessary "to establish the risk profiles of the relevant fishing
methods in different areas of the ocean, taking into account data on both observable and
unobservable harms".352
6.84. In establishing the risk profiles of different fishing methods in different areas of the ocean,
the Panels considered it appropriate to "rely to the greatest extent possible on a quantitative
analysis, and recur to a qualitative assessment in cases where this seem[ed] to be the most
reasonable avenue to properly gauge and describe the risks at issue."353 The Panels also highlighted
the importance of a "standardized benchmark or metric when determining and comparing the
different risk profiles", emphasizing that "[b]ecause the different scientific evidence on the record
does not necessarily follow the same methodology or present its results in a homogeneous and
consistent manner, there is a need to use a standardized benchmark so that compariso ns across
studies are meaningful and adequate." 354 The Panels considered several differen t possible
standardized metrics and ultimately adopted a "per set" methodology that entailed averaging the
total number of a particular indicator of adverse effects to d olphins by the number of operations of

346 Mexico's appellant's submission, paras. 154-225. As further discussed below, per set evidence
involves averaging the total number of a particular indicator of adverse effects to dolphins, such as mortalities
and serious injuries, by the number of operations of a particular type of fishing gear used in a particular fishery
in a given time period. (See para. 6.84 below)
347 United States' appellee's submission, paras. 96-203.
348 See e.g. United States' appellee's submission, paras. 114, 138, 152, 172-173, and 192.
349 United States' appellee's submission, paras. 151-203.
350 We note that, in its appellant's submission, Mexico states that, although "the evaluation of the
risk profiles in certain respects required scientific expertise …, the Panels declined to consult with
experts … [and i]n Mexico's view, the Panels did not make an appropriate exercise of their discretion under
Article 13 of the DSU in declining to request technical advice from experts". (Mexico's appellant's submission,
paras. 155 and 157) The United States, in its appellee's submission, stated that "Mexico makes no appeal with
respect to the Panels' decision not to consult experts, and thus there is no reason, or basis, for the
Appellate Body to engage on this aspect of the Panel Reports." (United States' appellee's submission, para. 98
(fn omitted)) However, Mexico clarified at the hearing that it was not asserting any legal error by the Panels in
this respect, and that its comments regarding Article 13 of the DSU were not relevant to the specific issues
before the Appellate Body. We therefore do not address this aspect of Mexico's appellant's submission.
351 Panel Reports, para. 7.146 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.243).
352 Panel Reports, para. 7.149.
353 Panel Reports, para. 7.170.
354 Panel Reports, para. 7.171.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

a particular fishing gear used in a particular fishery in a given time period.355 The Panels found that
relevant indicators included observed mortalities, serious injuries, and tuna-dolphin interactions.356
6.85. The Panels als o made several distinctions between different types of harm occurring to
dolphins.357 The Panels first distinguished between observable harm (i.e. any type of harm that can
be detected and reported) and unobservable harm (i.e. the type of harm that occurs but cannot be
detected during the set itself). As regards observable harm, the Panels also distinguished between
observed harm (i.e. the harm that is observable and that has, as a matter of fact, been detected
and reported during the conduct of a set) and unobserved harm (i.e. the type of harm that is
observable but that has not been detected or reported during the conduct of a set). Given that, by
definition, there can be no observer -based evidence of such unobserved but observable harm, the
Panels looked at the level of association between dolphins and tuna as a proxy in order to determine
probable levels of unobserved but observable harm. 358 Finally, the Panels distinguished between
direct harm (caused by direct interaction with fishing gear) and indirect harm (consequent upon
other harm sustained as a result of direct interaction with fishing gear).
6.86. The Panels proceeded to conduct their analysis of risk profiles by distinguishing between seven
different fishing methods, namely: purse seine fishing by setting on dolphins; purse seine fishing
without setting on dolphins; gillnet fishing; longline fishing; trawl fishing; tuna handlining; and pole
and line fishing. The Panels found that purse seine fishing by setting on dolphins359 causes serious
injuries to dolphins.360 In particular, the Panels found that, in the ETP, while the evidence suggested
that setting on dolphins does not pose a very high risk of observable serious injury361, such serious
injury is less frequent than mortality362, and the likelihood of unobserved mortality or serious injury
is present in every set, as a consequence of the tuna-dolphin association in that ocean area.363 The
Panels also found that setting on dolphins causes unobservable harms as a result of the chase and
encirclement process itself364, including "cow-calf separation; potential muscle injury resulting from
the chase; immune and reproductive systems failures; and other adverse health consequences for
dolphins, such as continuous acute stress".365

355 Panel Reports, para. 7.214. The Panels considered Mexico's proposed methodologies, consisting of:
(a) a Potential Biological Removal (PBR) methodology, measuring the maximum number of animals that may
be removed from an animal stock without affecting that stock's optimum sustainable population; and (b) either
as an alternative to a PBR methodology, or to be read in conjunction with PBR evidence, a comparison of the
absolute levels of dolphin mortalities and serious injury from different fishing methods and fishing areas. The
Panels rejected the PBR methodology and relied on evidence of absolute levels of adverse effects to dolphins in
situations where the Panels considered the per set evidence to be insufficient. (Ibid., paras. 7.175-7.195. See
also Mexico's first written submission to the Panels, para. 247) As discussed in section 6.1.4.4 below, Mexico
appeals the Panels' rejection of such benchmarks.
356 Panel Reports, para. 7.204.
357 Panel Reports, paras. 7.245-7.251.
358 Panel Reports, para. 7.253. The Panels explained that "the magnitude of interactions does not
indicate the number of dolphins that actually do suffer unobserved harms, but rather, the upper bound of
dolphins that could suffer such harms. The lower the interaction the less likely it is for the relevant fishing
method to cause harms to dolphins." (Ibid.)
359 Purse seine fishing by setting on dolphins consists of "chasing and encircling the dolphins with a
purse-seine net in order to catch the tuna swimming beneath the dolphins" in areas where there is an
association between tuna and dolphins. (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
para. 6.5) According to the Panel Reports, "[s]peedboats are used to chase down the dolphins and herd them
into a tight group; then the net is set around them. The tuna-dolphin bond is so strong that the tuna stay with
the dolphins during this process, and tuna and dolphins are captured together in the net. … If all goes well, the
dolphins are released alive, but … things can go wrong, and when they do, dolphins may be killed." (Panel
Reports, para. 7.258 (quoting T. Gerrodette, "The Tuna-Dolphin Issue", in Perrin, Wursig, and Thewissen
(eds.), Encyclopedia of Marine Mammals, 2nd edn (Elsevier, 2009) (Panel Exhibit USA-12), p. 1192))
360 Panel Reports, para. 7.281.
361 Panel Reports, para. 7.282.
362 The Panels found that the mortality rate per 1,000 sets associated with setting on dolphins in the ETP
ranged between 69.42 in 2015 and 113.38 in 2009, with an average of 91.15 mortalities. (Panel Reports,
para. 7.280)
363 Panel Reports, para. 7.285.
364 Panel Reports, para. 7.308.
365 Panel Reports, para. 7.309 (quoting Appellate Body Report, US – Tuna II (Mexico), fn 663 to
para. 330, in turn referring to Original Panel Report, paras. 7.491-7.506).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.87. Regarding purse seine fishing without setting on dolphins366, the Panels looked at evidence of
mortalities and serious injuries to dolphins in the ETP, Western and Central Pacific Ocean (WCPO),
Indian Ocean, and Eastern Tropic Atlantic Ocean (ETAO) .367 The Panels concluded that while purse
seine fishing without setting on dolphins has killed and seriously injured dolphins in the past and has
the potential of doing so in the future, the risk profile of this fishing method is generally low as it
does not require interaction with dolphins in order to spot tuna. 368 The Panels considered that this
fishing method has a "relatively low risk profile in terms of both observed and unobserved mortality
and serious injury".369 The Panels further concluded that the extent of unobserved harm in the ETP
may be low, but that without direct evidence on the record they were unable to base their finding
on a precise quantification. 370 The Panels also found that the likelihood of unobserved harm to
dolphins in the WCPO, the Indian Ocean, and the ETAO is low because interactions with dolphins are
infrequent.371 Additionally, the Panels found that purse seine fishing without setting on dolphins in
the ETP, the WCPO, the Indian Ocean, and the ETAO does not cause the kinds of unobservable harms
caused by purse seine fishing by setting on dolphins in the ETP, since purse seine fishing without
setting on dolphins does not require interaction with dolphins.372
6.88. With respect to gillnet fishing373, the Panels found that this fishing method poses high levels
of observable harm to dolphins in certain areas of the ocean, but does not pose the same level of
harm in other areas. 374 The Panels further noted that the evidence presented in relation to
"ghost fishing"375 indicated that ghost fishing does give rise to unobse rved harms, but that such
harms were at least observable, and not like the kinds of unobservable harm that are caused by
setting on dolphins.376
6.89. As regards longline377 and handline378 fishing, the Panels found that the risk profiles of these
methods were low in terms of observable harms, and that they do not cause the kinds of
unobservable harm caused by setting on dolphins.379 With regard to trawl fishing380, the Panels found
that this me thod is a low -to-moderate-risk fishing method in terms of observed mortalities and
observable harm, as it entails very little, if any, interaction with dolphins. 381 The Panels also found
that trawl fishing does not cause the kinds of unobservable harm caused by setting on dolphins.382
Regarding the pole and line fishing method, the Panels found no reports of any dolphins being killed

366 In addition to setting on dolphins, purse seine fishing is also conducted by setting on: (i) seamounts
(a category of oceanic ridges); (ii) floating objects; or (iii) schools of tuna (i.e. where the set is not based on
the tuna's association with any other marine feature/object/animal). (Panel Reports, paras. 7.313-7.316
(referring to Food and Agricultural Organization of the United Nations (FAO), FAO Fisheries and Aquaculture
Technical Paper 568, Bycatch and Non-Tuna Catch in the Tropical Purse Seine Fisheries of the World (Rome,
2013) (Panel Exhibit USA-60), pp. 17-24))
367 Panel Reports, paras. 7.326-7.399.
368 Panel Reports, para. 7.400.
369 Panel Reports, para. 7.401.
370 Panel Reports, para. 7.334.
371 Panel Reports, paras. 7.334, 7.367, 7.385, and 7.398.
372 Panel Reports, para. 7.401.
373 Gillnets are nets "set on the seafloor … or floated vertically" using buoys (i.e. driftnets or drift
gillnets). (Panel Reports, paras. 7.404-7.405 (referring to Natural Resources Defense Council, Net Loss: The
Killing of Marine Mammals in Foreign Fisheries (New York, January 2014) (Panel Exhibit MEX-18), p. 13; FAO,
"Tuna Drifting Gillnet" (Panel Exhibit MEX-15)))
374 Panel Reports, para. 7.444.
375 Ghost fishing occurs when fishing gear (such as gillnets) continue to cause harm to marine life (such
as dolphins) after being lost or discarded. (Panel Reports, paras. 7.410 and 7.447 (referring to NOAA, 2015
NOAA Marine Debris Program Report, Impact of "Ghost Fishing" via Derelict Fishing Gear (Charleston, March
2015) (Panel Exhibit MEX-104), p. 6))
376 Panel Reports, paras. 7.450-7.457.
377 Tuna longlining is "'a passive type of fishing technique making use of lines with baited hooks as
fishing gear'", with a typical set consisting of "'200 or more units or "baskets" connected together, with a buoy
at each connection, and a total of about 3,000 hooks'". (Panel Reports, para. 7.458 (quoting FAO, "Industrial
Tuna Longlining" (Panel Exhibit MEX-26), pp. 2-3))
378 A tuna handline is a "'single vertical line with one barbed hook at the distal point'", or several barbed
hooks connected to branchlines along the mainline at regular intervals. (Panel Reports, para. 7.495 (quoting
FAO, "Tuna Handlining" (Panel Exhibit MEX-38)))
379 Panel Reports, paras. 7.481 and 7.511.
380 Trawl fishing consists of "'towing a net … either with bottom contact or in midwater'", catching fish
and shellfish by filtering the water. (Panel Reports, para. 7.482 (quoting FAO, "Trawl Nets" (Panel Exhibit
MEX-37)))
381 Panel Reports, paras. 7.493-7.494.
382 Panel Reports, para. 7.494.
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or seriously injured as a result of pole and line fishing, and no evidence that any unobservable harm
is caused to dolphins.383 The Panels concluded that the risk profile is very low.384
6.90. Having set forth their analysis of the seven fishing methods, the Panels conducted an overall
relative assessment, in which they "provide[d] a comparative assessment of method -specific
findings".385 The Panels concluded that, given the differences between setting on dolphins and each
of the other six methods with respect to observable harm to dolphins, and taking into account that
none of the other methods causes the kinds of unobservable harms caused by setting on dolphins,
"overall, the risk profile of setting on dolphins is much higher than that of each of the other six fishing
methods used to catch tuna."386
6.1.4.2 Whether the Panels erred by failing to assess the risk profiles of individual
fisheries
6.91. We first turn to Mexico's argument that the Panels did not properly determine the risk profiles
of different fishing methods as used in different areas of the oceans, but erroneously limited their
assessment of risk profiles to the seven tuna-fishing methods, without assessing the risk profiles for
individual ocean areas.387 Mexico acknowledges that the Panels did address evidence with respect
to ocean areas for certain of the fishing methods they assessed388, but argues that the Panels erred
by forming conclusions on t he fishing methods as a whole, and thereby "effectively averaged or
sampled the overall relative risks or levels of harm over all of the fisheries that use the method".389
In particular, Mexico submits that the Panels effectively "disregarded that there are very high risks
to dolphins" from gillnet fishing, longline fishing, and trawl fishing, in certain ocean areas.390 Mexico
also argues that the Panels erred by failing to address the risk profile of purse seine fishing by setting
on dolphins in ocean areas other than the ETP.391
6.92. The United States submits that the Panels did assess the risks to dolphins in individual
fisheries.392 The United States indicates that, with respect to observable harms, the Panels assessed
"each fishery for which there was probative evi dence on the record" , and, on th is basis, "drew
conclusions about the risk of observable harms posed by the different fishing methods" .393 With
respect to unobservable harms, the United States asserts that the Panels concluded that "none of
the other fishing methods is capable of causing the sort of unobservable harms caused by dolphin
sets", and that this conclusion is applicable "to each and all of the fisheries where these fishing
methods are employed".394 The United States indicates that it was on the basis of these findings
that the Panels "drew conclusions about the risk profile of each tuna fishing method 'as used in

383 Panel Reports, para. 7.515.
384 Panel Reports, para. 7.516.
385 Panel Reports, para. 7.517. The Panels explained that the reason for conducting this comparative
assessment was that "the issue before [them was] whether the 2016 Tuna Measure, under which tuna
products obtained from tuna caught by setting on dolphins are ineligible for the dolphin-safe label whereas
tuna products obtained from tuna caught by the other six methods cited above are conditionally eligible for
that label, is calibrated to different levels of risks posed to dolphins by different fishing methods in different
areas of the ocean." (Ibid.)
386 Panel Reports, para. 7.525.
387 Mexico's appellant's submission, para. 161.
388 Specifically, purse seine fishing without setting on dolphins, gillnet fishing, longlining, trawl fishing,
and handlining. (See Mexico's appellant's submission, para. 162)
389 Mexico's appellant's submission, para. 164 (referring to Panel Reports, para. 7.517).
390 Mexico's appellant's submission, para. 167. See also Mexico's appellant's submission, paras. 168-170
(referring to Panel Reports, paras. 7.438, 7.440-7.443, 7.466-7.467, 7.473-7.474, 7.489-7.490,
and 7.493-7.494).
391 Mexico's appellant's submission, para. 162. We note that Mexico's appellant's submission additionally
states that "[t]he Panels did not address ocean areas in the context of the risk profile for pole-and-line fishing."
(Ibid.) However, Mexico also indicated in its appellant's submission that "the parties agreed during the first
compliance proceeding that this method is not known to harm dolphins." (Ibid., fn 21 to para. 22) Mexico
clarified at the hearing that pole and line fishing was included in paragraph 162 to be complete in describing
what the Panels said, and that Mexico does not take issue with the Panels' findings on pole and line fishing.
392 United States' appellee's submission, paras. 125-126.
393 United States' appellee's submission, para. 125 (referring to Panel Reports, paras. 7.401 (purse
seine fishing other than by setting on dolphins), 7.475 (longline fishing), 7.494 (trawl fishing), 7.511
(handlining), 7.514-7.515, and 7.520 (gillnet fishing)).
394 United States' appellee's submission, para. 125 (referring to Panel Reports, paras. 7.332-7.334,
7.365-7.367, 7.383-7.385, 7.396-7.398, 7.440-7.444, 7.466-7.471, 7.475, 7.488-7.494, 7.511, 7.514-7.515,
and 7.521).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

different areas of the ocean'".395 The United States further argues that Mexico's assertion that certain
fisheries are "high risk" is based on Mexico's own definitions of "high risk", as well as certain
misstatements of the Panels' analysis of the evidence, and reflects arguments that the Panels
rejected.396
6.93. We recall that, in order to properly assess whether the relevant regulatory distinctions under
the 2016 Tuna Measure are properly calibrated to the risks to dolphins, the Panels were, inter alia,
required to compare the risk profile of "setting on dolphins" with the risk profiles of other individual
fishing methods. In order to make such a comparison, the Panels were necessarily required to
establish the risk profiles of different fishing methods. We therefore consider it appropriate for the
Panels to have formed a conclusion for each individual fishing method, for the purposes of conducting
the calibration analysis.
6.94. We note, however, that , in forming a conclusion on each fishing method, the Panels were
required to take into account all evidence provided to them with respect to each ocean area in which
each fishing method is used. Furthermore, it is uncontested that, in the context of assessing whether
the certification and tracking and verification requirements are calibrated to the risks to dolphins,
the Panels were required to compare the risk profiles of the ETP large purse seine fishery and other
individual fisheries.397 It was therefore incumbent on the Panels to not only draw conclusions on
each fishing method as a whole, but also examine the risks to dolphins in each individual fishery.
6.95. In this respect, Mexico has not raised any claims under Article 11 of the DSU alleging that the
Panels failed to assess any individual fishery for which evidence was placed before them. We also
note that the Panels explicitly referred to eviden ce regarding individual fisheries for the purpose of
examining the relevant fishing methods. 398 Furthermore, certain of the evidence provided to the
Panels was of a general nature, such that it pertained to every fishery in which that fishing method
was practised.399 We therefore consider that Mexico has not demonstrated that the Panels failed to
examine each individual fishery for which evidence was provided.
6.96. Mexico additionally argues that, in drawing an overall conclusion on the risk profile for each
fishing method examined, the Panels effectively averaged or sampled the overall relative risks or
levels of harm over all of the fisheries that use that method, and, in doing so, disregarded that there
are very high risks to dolphins in certain ocean areas .400 For example, Mexico contrasts the Panels'
finding that "gillnet fisheries, and driftnet fisheries in particular, have caused, in some circumstances
and in certain regions, levels of observable harms greater than those caused by setting on dolphins
in the ETP" with the Panels' conclusion that "while gillnet fishing may be harmful to dolphins, it does
not necessarily cause such harms in every area of the ocean".401
6.97. We do not see a contradiction between a finding that a particular fishing method poses high
risks in some fisheries, but not others, and a conclusion that the fishing method as a whole has a
lower risk profile than the method of setting on dolphins. We recall that, according to the Panels,
setting on dolphins poses a high risk to dolphins in all fisheries for which evidence was provided to
the Panels402, whereas, for gillnet fishing, the Panels found that "gillnet fishing causes considerable

395 United States' appellee's submission, para. 125 (quoting Panel Reports, para. 7.517; referring to
Panel Reports, paras. 7.402, 7.457, 7.480, 7.493-7.494, 7.511, 7.516-7.518, 7.520-7.523, and 7.525).
396 United States' appellee's submission, para. 126 (referring to Mexico's appellant's submission,
paras. 168-170). The United States elaborates that Mexico specifically refers to the Panels' findings on Indian
Ocean gillnet fisheries, absolute levels of mortalities caused by longline fishing in the Pacific Ocean, PBR
evidence concerning an additional longline fishery, and per set evidence of mortalities in a North Atlantic trawl
fishery. The United States recalls that the Panels "rejected" the exhibits that Mexico relied on in defining the
Pacific Ocean longline fishery and North Atlantic trawl fisheries as "high risk", and explained why they chose
not to rely on PBR evidence. Furthermore, with respect to the Indian Ocean gillnet fisheries, the Panels
explained that the 2016 Tuna Measure "appropriately addresses the risks to dolphins in that fishery". (See
ibid., fn 285 to para. 126)
397 Mexico's and the United States' responses to questioning at the hearing.
398 For example, with respect to purse seine fishing without setting on dolphins, the Panels assessed the
risks to dolphins in the ETP, the WCPO, the Indian Ocean, and the ETAO. (Panel Reports, paras. 7.326-7.399)
399 For example, with respect to pole and line fishing, the Panels examined evidence pertaining to the
fishing method in general, without specifying any particular fisheries. (Panel Reports, paras. 7.514-7.516)
400 Mexico's appellant's submission, paras. 164 and 167.
401 Mexico's appellant's submission, para. 168 (quoting Panel Reports, paras. 7.441-7.442 (emphasis
original)).
402 Panel Reports, paras. 7.256-7.311.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

observable harms to dolphins in different areas of the ocean"403 but also that "there are other areas
where this particular method does not cause such harms."404 Furthermore, we do not consider that,
merely by forming conclusions on each fishing method as a whole, the Panels necessarily conflated
the risk profiles of individual fishing methods with the risk profiles of individual fisheries. In light of
the different sets of distinctions drawn under the measure, the Panels were required to compare the
risk profiles of fishing methods in the context of assessing the eligibility criteria, and to compare the
risk profiles of indi vidual fisheries when assessing the certification and tracking and verification
requirements. The Panels were therefore obliged to form conclusions on the risk profiles of different
fishing methods, in the process of which the Panels were also required to look at the evidence of
risks to dolphins in individual ocean areas. In our view, the fact that the Panels made conclusions
on fishing methods in assessing the eligibility criteria does not indicate that they inappropriately
applied the calibration analysis to the certification and tracking and verification requirements.
6.98. In any event, to the extent that Mexico considers that the Panels' conclusions on each
individual fishing method were flawed, because the Panels incorrectly weighed and balanced the risk
profiles of each individual fishery in drawing generalized conclusions on each fishing method as a
whole, we consider that such a question relates to the Panels' appreciation of the evidence and the
facts, rather than the Panels' application of the legal st andard under Article 2.1 of the
TBT Agreement. However, Mexico has not challenged the Panels' appreciation of the evidence under
Article 11 of the DSU. Consequently, we do not consider it necessary or appropriate to review
whether the Panels' conclusions on each fishing method were justified on the basis of the evidence
placed before them.405
6.99. It therefore suffices for our purposes to note that the Panels assessed each individual fishery
for which evidence was given to them, and, on the basis of these assessments, drew conclusions on
the risk profile of different fishing methods. 406 We therefore do not consider that Mexico has
demonstrated that the Panels failed to assess the risk profiles of individual fisheries or that the
Panels erred in drawing conclusions o n the risk profile of each fishing method on the basis of their
examination of the evidence before them (including evidence pertaining to each individual fishery).
6.1.4.3 Whether the Panels erred by using the risk profile of setting on dolphins in the
ETP as a benchmark
6.100. We turn now to Mexico's argument that the Panels erred by using the risk profile of setting
on dolphins in the ETP as a benchmark – referred to by Mexico as the "ETP benchmark"407 – for
assessing the risk profiles of other fisheries. Mexico asserts that a "benchmark cannot be used to
objectively assess the circumstances that constitute the benchmark itself".408 Rather, Mexico asserts
that the Panels should have relied on an "independent and objective standard or point of reference
against which the overall relative risks or levels of harm arising from each" fishery could be
assessed.409 Mexico also argues that the Panels erred by distinguishing setting on dolphins in the
ETP from other fisheries, because the "mere fact that the risk profiles of other [fisheries] … may be
different from or comparatively lower than the risk profile of [setting on dolphins] in the ETP does
not mean that the regulatory distinctions are 'calibrated' to the different overall relative risks or
levels of harm arising from different [fisheries]".410 Mexico further submits that the Panels' reliance
on the "ETP benchmark" for comparing the risk profiles of other fisheries resulted in the Panels
focusing their analysis on "qualitative attributes that are unique" to the ETP setting -on-dolphins
fishery.411 Mexico refers to the Panels' findings on unobservable harms with respect to "alleged stress
effects on dolphins in the ETP" 412, and considers that the Panels' emphasis on this kind of

403 Panel Reports, para. 7.440.
404 Panel Reports, para. 7.442.
405 Appellate Body Report, US – Large Civil Aircraft (2nd complaint), paras. 955-958. See also
Appellate Body Report, Mexico – Anti-Dumping Measures on Rice, para. 274.
406 We note that the only evidence adduced to the Panels with respect to any individual fishery where
setting on dolphins is practised was evidence related to the ETP. (See Panel Reports, paras. 7.270-7.311)
407 Mexico's appellant's submission, paras. 173 and 178.
408 Mexico's appellant's submission, para. 176.
409 Mexico's appellant's submission, para. 179.
410 Mexico's appellant's submission, para. 181.
411 Mexico's appellant's submission, para. 186.
412 Mexico's appellant's submission, para. 187 (referring to Panel Reports, para. 7.310).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

unobservable harm caused the Panels "to disregard the Appellate Body's direction to take into
account the overall effects of each fishing method".413
6.101. The United States argues that the Panels' approach was fully in line with the calibration
analysis as set forth by the Appellate Body in previous proceedings.414 The United States notes that
Mexico itself has consistently argued that "the ETP large purse [seine] fishery is a proper comparator
to determine whether the regulatory distinctions are even-handed, both in the previous compliance
proceeding and before the Panels."415 As for Mexico's arguments regarding different types of harm,
the United States considers that the Panels did take into account all evidence related to any kinds
of unobservable harms, including those identified by Mexico.416 According to the United States, "the
Panels found that, while some evidence suggested that 'ghost fishing linked to gillnets poses some
risks to dolphins, … its extent is unclear' … [and] 'the absolute numbers of marine mammals involved
are relatively small'."417
6.102. As discussed in paragraphs 6.72-6.73 above, in order to be consistent with Article 2.1 of the
TBT Agreement, it is the regulatory distinctions causing the detrimental impact under the 2016 Tuna
Measure that must be calibrated to different risks to dolphins. Thus, a proper calibration analysis in
this dispute does not mean that the Panels were requi red to examine whether the 2016 Tuna
Measure makes all relevant regulatory distinctions on a fishery -by-fishery basis.418 We have also
noted that, in light of the relevant distinctions made under the measure at issue, the Panels were
correct to have compared the risk profile of purse seine fish ing by setting on dolphins with the risk
profiles of other fishing methods for the purpose of examining the eligibility criteria, and to have
compared the risk profile of the ETP large purse seine fishery with the risk profiles of all other
fisheries for the purpose of examining the certification and tracking and verification requirements.419
6.103. We further note that the Panels did not, as Mexico contends, use setting on dolphins in the
ETP as a "benchmark". Indeed, the Panels did not use the expression "ETP ben chmark" in their
analysis of risk profiles. Rather, the Panels referred to this expression solely in the context of
describing the United States' explanation regarding the determin ation provisions under the
2016 Tuna Measure. 420 In contrast, in their analysi s of risk profiles, the Panels used the word
"benchmark" to describe a "standardized benchmark or metric" when assessing and comparing
different risk profiles.421 In this respect, the Panels were referring to the use of an appropriate metric,
or methodology, for comparing the risks to dolphins in different fisheries. As explained above, the
Panels relied primarily on data reflecting the numbers of observed mortalities, serious injuries, and
tuna-dolphin interactions on a per set basis, in different fisheries, to compare the risks to dolphins
from different fishing methods and in different fisheries. 422 Where such data were unavailable, the

413 Mexico's appellant's submission, para. 189 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), paras. 7.152 and 7.155-7.156).
414 United States' appellee's submission, paras. 139-143.
415 United States' appellee's submission, para. 142 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), para. 7.112; First Compliance Panel Report, paras. 7.111-7.112; Mexico's
first written submission to the Panels, para. 256; Mexico's second written submission to the Panels, paras. 248,
256, and 263). (fns omitted)
416 United States' appellee's submission, para. 147.
418 See paras. 6.64-6.77 above.
419 See paras. 6.65-6.77 above.
420 Panel Reports, paras. 7.417 and 7.685. The Panels noted the United States' explanation that NOAA
compared the bycatch rates (i.e. number of dolphins killed per ton of tuna landed) of the Indian Ocean gillnet
fishery to those caused by setting on dolphins in the ETP (the "ETP benchmark" to which Mexico refers). NOAA
concluded, on this basis, that there was a "regular and significant" dolphin mortality rate in the Indian Ocean
gillnet fishery. Under the structure of the 2016 Tuna Measure, this formal determination resulted in tuna from
the Indian Ocean gillnet fishery being subject to stricter certification and tracking and verification requirements
than would otherwise have been required to gain access to the dolphin-safe label. (See also ibid.,
paras. 7.67-7.69)
421 Panel Reports, para. 7.171.
422 See para. 6.84 above. Furthermore, Mexico clarified at the hearing that the Panels' reliance on
per set evidence constitutes an independent and objective standard or point of reference on which the Panels
should have relied. Mexico nonetheless argued that, in addition to relying on per set evidence, the Panels
should have also taken into account evidence related to the sustainability of different dolphin populations, as
well as absolute levels of adverse effects in different areas. We address these aspects of Mexico's arguments in
section 6.1.4.4 below.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Panels relied on other sources of information, including general information that relates to all
fisheries in which a particular fishing method is practised.423
6.104. Once the Panels had assessed the risk profiles of different fishing methods and fisheries on
the basis of per set data and other relevant evidence, the Panels did compare the risk profile of
setting on dolphins with the risk profile s of other fishing methods in the context of both their
assessment of risk profiles and their examination of whether the eligibility criteria are calibrated to
different risks to dolphins. 424 As we have discussed above, such a comparison of fishing methods
was, inter alia , required in light of the applicable legal standard and the circumstances of this
dispute.425 As to Mexico's contention that the Panels' assessment of the eligibility criteria was based
on a comparison of the risk profile of setting on dolphins in the ETP with the risk profiles of other
fishing methods426, we note that certain aspects of the Panels' assessment of the risk profile of
setting on dolphins were indeed limited to the use of this fishing method in the ETP.427 This, however,
was due to the fact that the only fishery-specific evidence provided to the Panels concerning the use
of setting on dolphins pertained to the use of this method in the ETP.428 Furthermore, other aspects
of the Panels' examination of the risks associated with setting on dolphins were not limited to the
ETP, but more broadly pertained to setting on dolphins anywhere in the world.429
6.105. We note Mexico's argument that, by "distinguishing Mexico's fishing method [i.e. setting on
dolphins] in the ETP from all other fishing methods in all other areas of the oceans … the Panels did
not assess whether tuna caught by other fishing methods in other ocean areas should also be
excluded from access to the label".430 In Mexico's view, the "mere fact that the risk profiles of other
fishing methods in other ocean areas may be different from or comparatively lower than the risk
profile of [setting on dolphins] in the ETP does not mean that the regulatory distinctions are
'calibrated' to the different overall relative risks or levels of harm arising from different fishing
methods in different ocean areas". 431 Mexico refers to the Appel late Body's statement that
even-handedness depends not only on the level of risk associated with the fishing method suffering
from a denial of access, but "also on whether the risks associated with other fishing methods in
other fisheries are addressed, commensurately with their respective risk profiles, in the labelling
conditions that apply in respect of tuna caught in such other fisheries". 432 In Mexico's view, the
Panels did not assess "whether the risks or levels of harm associated with other fishing methods in
other fisheries are addressed, commensurately with their respective risk profiles, in the label ling
conditions that apply in respect of tuna caught in such other fisheries".433
6.106. In the United States' view, Mexico's approach "directly conflicts not only with the design,
architecture, and revealing structure of the [Tuna Measure], but also with the Appel late Body's
analysis in the first compliance proceeding".434 The United States argues that the relevant question
under Article 2.1 is whether the differences arising under the relevant regulatory distinctions are
commensurate with different risks to dolphins . According to the United States, perfection is not an

423 See e.g. Panel Reports, paras. 7.212, 7.434, 7.446-7.456, 7.476-7.481, and 7.514.
424 See paras. 6.67 and 6.90 below.
425 See para. 6.77 above.
426 Mexico's appellant's submission, paras. 175 and 186.
427 Specifically, the Panels' assessment of observed mortality and serious injury, observable serious
injury, and unobserved mortality and serious injury appears to be based on evidence that is specific to the ETP.
(See Panel Reports, paras. 7.279-7.285) By contrast, we note that the Panels' conclusion that "setting on
dolphins causes unobservable harms" is not specific to the ETP and, consequently, applies to the fishing
method as a whole. (See ibid., para. 7.309)
428 See supra, fn 406.
429 For instance, with respect to unobservable harms, the Panels referred to the first compliance panel's
findings that certain unobservable harms "occur as a result of the 'chase itself'". (Panel Reports, para. 7.286
(referring to Original Panel Report, para. 7.504)) Further, on examining the evidence submitted by the parties,
the Panels concluded that "because chasing and encirclement are essential elements of the process of setting
on dolphins, setting on dolphins cannot be used without putting dolphins at risk, even though that risk may not
eventuate in every set." (Ibid., para. 7.310)
430 Mexico's appellant's submission, para. 182.
431 Mexico's appellant's submission, para. 181.
432 Mexico's appellant's submission, para. 182 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.126). Mexico argues that "[p]ermitting access to the label to tuna caught by
such methods in [high-risk] ocean areas contradicts and undermines the objective of the tuna measure to
discourage fishing practices that adversely affect dolphins." (Ibid., para. 167)
433 Mexico's appellant's submission, para. 183.
434 United States' appellee's submission, para. 145.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

appropriate benchmark under the covered agreements. Furthermore, in the United States' view, the
question whether there is a measure that would better contribute to a particular objective is more
pertinent to an analysis under Article 2.2 of the TBT Agreement, rather than under Article 2.1.435
6.107. We highlight that Mexico raises this argument in support of its view that the Panels erred in
their evaluation of risk profiles, by relying on "setting on dolphins in the ETP" as a "benchmark" by
which to compare the risk profiles of different fisheries. However, as explained above, the Panels
did not refer to the "ETP benchmark" in their analysis. 436 Furthermore, based on our review of the
Panels' findings, the Panels did not compare, or "distinguish", the risk profile of "setting on dolphins
in the ETP" with the risk profiles of all other individual fisheries. To the contrary, the Panels compared
the risk profile of setting on dolphins as a fishing method (used anywhere in the world) with the risk
profiles of other fishing methods (also used anywhere in the world), in the context of examining the
eligibility criteria437, and compared the risk profile of the ETP large purse seine fishery with other
individual fisheries i n the context of examining the certification and tracking and verification
requirements.438 Thus, the Panels did not compare the risk profile of the ETP setting-on-dolphins
fishery with the risk profile of other fisheries. Since Mexico's argument is incorrec tly premised on
the assertion that the Panels compared "setting on dolphins in the ETP" with other fisheries, we
consider Mexico's argument to be moot.
6.108. In any event, we also note that Mexico's argument suggests that the Panels erred by failing
to assess w hether certain individual fisheries should be ineligible for the dolphin -safe label. This
argument appears to rely on Mexico's understanding that, in order to be properly calibrated, the
eligibility criteria under the 2016 Tuna Measure must make distinctions on a fishery-by-fishery basis.
We have addressed, and rejected, this argument above.439 As explained, the nature of the calibration
analysis is defined by the nature of the regulatory distinctions under the measure itself.440 Since the
eligibility criteria distinguish between different fishing methods, it would have been inappropriate for
the Panels to compare the risk profiles of individual fisheries for the purpose of assessing whether
the eligibility criteria under the measure are properly calibrated. We therefore do not consider that
this aspect of Mexico's arguments demonstrates that the Panels erred by comparing the risk profile
of setting on dolphins with the risk profiles of other fishing methods in the context of examining the
eligibility criteria. W e also reiterate that, in examining whether the certification and tracking and
verification requirements are properly calibrated, the Panels were indeed required to compare the
risk profiles of different fisheries.441 We examine whether the Panels properly conducted this analysis
in section 6.1.5 below.
6.109. Turning to Mexico's argument that the Panels erred by focusing their analysis on qualitative
attributes that are unique to setting on dolphins in the ETP, thereby "further ingraining" their mistake
in adopting the single "ETP benchmark" for the purpose of the calibration analysis442, we note that
this argument relates to the Panels' findings on unobservable harms with respect to "alleged stress
effects on dolphins in the ETP".443 Specifically, Mexico considers that the Panels emphasized different
"kinds" of unobservable harms, which "caused them to disregard the Appellate Body's direction to
take into account the overall effects of each fishing method".444 Mexico highlights that, although the
Panels referred to the harms caused by "ghost fishing" (whereby lost or discarded gillnets continue

435 United States' response to questioning at the hearing.
436 See para. 6.103 above.
437 See para. 6.67 above. In the context of determining the risk profile of setting on dolphins (anywhere
in the world), the Panels relied to a significant extent on evidence related to the use of this fishing method in
the ETP in particular. (See supra, fn 406) Nevertheless, the Panels did not compare setting on dolphins in the
ETP – as a distinct fishery – with other fisheries. Rather, the Panels took into account the evidence regarding
the ETP setting-on-dolphins fishery in assessing the overall risk profile of setting on dolphins that the Panels
proceeded to compare with the overall risk profiles of other fishing methods.
438 See para. 6.67 above. The ETP large purse seine fishery refers to all purse seine fishing in the ETP by
large purse seine vessels, including by setting on dolphins and by other means.
439 See section 6.1.3.2 above.
440 See para. 6.64 above.
441 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.165.
442 Mexico's appellant's submission, paras. 173 and 186.
443 Mexico's appellant's submission, para. 187 (referring to Panel Reports, para. 7.310).
444 Mexico's appellant's submission, para. 189 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), paras. 7.152 and 7.155-7.156).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

to cause harm to marine life, including dolphins445), the Panels concluded that such harms "are not
the kind of unobservable harms caused by setting on dolphins".446
6.110. As explained above , in conducting their assessment of risk profiles for the purpose of the
calibration analysis, the Panels distinguished between, inter alia, observable harm (any type of harm
that can be detected and reported) and unobservable harm (the type of harm with respect to which
no evidence of its occurrence is produced during the set). 447 In our view, drawing distinctions
between different types of harm is not per se inconsistent with an assessment of overall relative
harm to dolphins for the purpose of the calibration analysis. Indeed, the Appellate Body in the first
compliance proceedings also distinguished between observed harms and unobserved harms (the
Panels referred to the latter as "unobservable" harms 448) in setting forth the parties' disagreement
over the risks associated with different fishing practices.449
6.111. Furthermore, the evidence examined by the Panels differed depending on the specific type
of harm being examined. With respect to "observed" mortalities and significant injuries, the Panels
tended to look a t quantitative evidence, primarily in the form of per set data, but also relying on
other data when per set data were lacking.450 This included quantitative data in the form of absolute
levels of mortalities and serious injuries as well as qualitative eviden ce where no quantitative
information was available.451 By contrast, as indicated above, in assessing "unobserved but
observable" harm (in other words, harm that could be detected during a fishing set, but was not
detected), the Panels focused on the level of association between dolphins and tuna as a proxy for
evidence of such unobserved harm.452 Finally, in assessing "unobservable" harms, the Panels looked
at evidence revealing the extent to which dolphins are harmed during a particular fishing operation
even though no evidence of that harm is actually produced during the fishing operation itself.453
6.112. Given that the Panels were examining different types of evidence for each "type" of harm
that they examined, we do not consider that the Panels erred merely by drawing distinctions between
different types of harm to dolphins. At the same time, we recall that the Appellate Body in the first
compliance proceedings faulted the first compliance panel, and found itself unable to complete the
analysis, because the first co mpliance panel had focused its analysis exclusively on differences in
unobserved harms, without comparing the overall relative harms. 454 Thus, in the present
proceedings, if the Panels had focused exclusively on a particular "kind" of harm in assessing the
overall relative harms of different fishing methods and fisheries, such an approach would not have
comported with the nature of the required calibration analysis as articulated by the Appellate Body.
In this respect, we note that Mexico highlights the evidence reviewed by the Panels regarding harms
caused by "ghost fishing" in the context of gillnet and longline fishing, and contends that the Panels
"omit[ted] a comparative assessment" of such harms because the Panels considered that such harms
are not the "kinds" of unobservable harms caused by setting on dolphins.455
6.113. In addressing this issue, we recall that the Panels found that "setting on dolphins" causes
unobservable harms such as cow-calf separation, potential muscle injury resulting from the chase,
immune and reproductive system failures, and other adverse health consequences for dolphins, such
as continuous acute stress. 456 The Panels found that no other fishing method poses similar
unobservable harms. 457 We further note that the Panels discussed the impact of ghost fishing
specifically.458 The Panels ultimately considered that the harms posed to dolphins by ghost fishing
were indeed relevant to their assessment of the risk profile of gillnet fishing, but that such harms
were observable in nature in that they result from interaction with the fishing gear. The Panels
explained that, although the harms from ghost fishing may not be observed, this "does not change

445 See supra, fn 375.
446 Mexico's appellant's submission, para. 188 (quoting Panel Reports, para. 7.450 (emphasis original)).
447 See para. 6.85 above (referring to Panel Reports, paras. 7.245-7.251).
448 Panel Reports, para. 7.251.
449 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.248.
450 See e.g. Panel Reports, paras. 7.327-7.332 and 7.434.
451 See e.g. Panel Reports, paras. 7.170, 7.310, and 7.514.
452 See e.g. Panel Reports, paras. 7.333 and 7.385. See also para. 6.85 above.
453 See e.g. Panel Reports, paras. 7.289-7.310.
454 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.246-7.251.
455 Mexico's appellant's submission, para. 188.
456 Panel Reports, para. 7.309.
457 See e.g. Panel Reports, para. 7.525.
458 Panel Reports, paras. 7.447-7.450.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the observable nature of such harms", and that harms posed by ghost fishing "are not the kind of
unobservable harms caused by setting on dolphins", because the latter "'may be inflicted even in
cases where no dolphin is caught in the net, or where any caught dolphin is released without
apparent injury'". 459 The Panels nevertheless considered, with respect t o "observable harms to
dolphins", that "gillnet fishing poses high levels of observable harms to dolphins in certain areas of
the ocean, but does not pose the same harms in other areas." 460 The Panels considered that the
same considerations applied with respect to ghost fishing in the context of longline fishing 461, and
concluded, with respect to observable harms caused by longline fishing, that "dolphins may suffer
some observable mortality and serious injury as a result of [longline fishing] in some fisheries ."462
Subsequently, when assessing whether the regulatory distinctions under the 2016 Tuna Measure are
calibrated to different risks to dolphins, the Panels took into account all relevant types of harm in
assessing and comparing different risk profiles.
6.114. In our view, the Panels' analysis is consistent with the requirement that they assess the
"overall relative risks" to dolphins from different fishing methods as used in different ocean areas.
Specifically, the Panels took into account ghost fishing in the context of gillnet and longline fishing,
and highlighted that certain gillnet fisheries pose a particularly high risk to dolphins, and that certain
longline fisheries do cause observable mortalities and serious injuries to dolphins. The Panels also
looked at similar observable harm to dolphins caused by setting on dolphins, as well as unobservable
harms. The Panels relied on all such information when comparing the risk profiles of setting on
dolphins with other fishing methods. We therefore consider that the Pa nels took into account all
relevant types of harm in conducting an assessment of the overall relative risks from different fishing
methods, as used in different fisheries, before reaching an overall conclusion regarding the risk
profile of each fishing method.
6.115. We briefly note that aspects of Mexico's arguments relate solely to the Panels' appreciation
of the evidence in their role as factfinder. Specifically, to the extent that Mexico considers that
"the Panels relied [on] speculative hypotheses" and that "there is no conclusive evidence that dolphin
sets … cause a material level of stress to dolphins" 463, we consider that these aspects of Mexico's
arguments pertain to the Panels' appreciation of the evidence.464 In the absence of any claim under
Article 11 of the DSU, we consider that such arguments pertain to issues outside the scope of this
appeal.
6.116. On the basis of the foregoing, we do not consider that Mexico has demonstrated that the
Panels relied on the risk profile of setting on dolphins in the ETP as a benchmark by which to assess
different fishing methods. Additionally, we do not consider that Mexico has demonstrated that the
Panels erred by distinguishing between different types of harm to dolphins.
6.1.4.4 Whether the Panels erred by relying primarily on per set data and excluding other
relevant factors
6.117. We now turn to Mexico's arguments regarding the factors or methodology on which the
Panels relied in assessing the risks of harm to dolphins. Mexico argues that, although the Panels
were correct to rely on per s et data to assess the overall relative risks to dolphins, the
Panels' analysis was incomplete. 465 In Mexico's view, "[a]ll factors that have a bearing on the
measure achieving its objectives must be included" in order to properly measure the risks to
dolphins.466 Mexico asserts that the Panels incorrectly omitted from their assessment: (i) the impact
of tuna-fishing methods on the sustainability of dolphin stocks through Potential Biological Removal
(PBR) data; (ii) data with respect to absolute dolphin mortalities and serious injuries in ocean areas;
and (iii) data concerning the risks created in certain ocean areas through insufficient regulatory
oversight, unreliable reporting, IUU fishing, and/or trans-shipment at sea.467

459 Panel Reports, para. 7.450 (quoting First Compliance Panel Report, para. 7.134). (emphasis original)
460 Panel Reports, para. 7.444.
461 Panel Reports, para. 7.480.
462 Panel Reports, para. 7.475.
463 Mexico's appellant's submission, fn 231 to para. 187.
464 See supra, fn 405.
465 Mexico's responses to questioning at the hearing.
466 Mexico's appellant's submission, para. 193. See also ibid., paras. 192 and 194.
467 Mexico's appellant's submission, para. 194.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.118. The United States argues that the Panels were correct not to rely on the data to which Mexico
refers.468 In the United States' view, Mexico's arguments concerning per set data are unsupported
by any evidence and, in any event, relate to the Panels' appreciation of the eviden ce and are
therefore outside the scope of this appeal in the absence of a claim under Article 11 of the DSU.469
The United States also submits that the Panels' approach to PBR evidence, as well as to absolute
levels of mortalities and serious injuries, was i n accordance with the approach taken by the
Appellate Body in prior proceedings in this dispute.470 The United States also considers that Mexico
has not demonstrated that the Panels erred by failing to take into account a lack of regulatory
oversight, or the risks of inaccurate certification or tracking, in assessing the risks to dolphins.471
6.119. As an initial matter, we note that Mexico's arguments concern ing the Panels' reliance on
per set data have evolved during these appellate proceedings. In its appellant's submission, Mexico
argued that the Panels' reliance on per set data was inconsistent, because the Panels disregarded
such data for gillnet fisheries and trawl fishing, and relied on a "very small sample as the basis for
[their] analysis of the risk profile of gillnet fishing".472 Mexico also stated that "[s]imilarly, although
acknowledging that trawl fishing has resulted in significant dolphin mortalities, and the Panels
identified a trawl fishery with a much higher per 1,000 set number than the ETP, they reli ed on
anecdotal information to conclude that trawl fishing has a 'low -to-medium' risk profile." 473 At the
hearing, Mexico clarified that, in its view, the Panels did not err by including per set data in their
assessment and did examine all evidence relating to per set data. Rather, Mexico argued, the Panels
erred in excluding other relevant factors, and that, in order to properly apply the calibration analysis,
an assessment of risks to dolphins should take into account all relevant factors, in order to captu re
all aspects of adverse effects on dolphins.474
6.120. In our view, Mexico's clarifications at the hearing indicate that it is not challenging the
Panels' reliance on per set evidence per se. We therefore do not consider it necessary to address
Mexico's arguments concerning alleged errors in the Panels' reliance on per set evidence. In any
event, to the extent that Mexico continues to assert that the Panels "disregarded" certain evidence,
or that the Panels' "sample size" was too small with respect to one particular fishing method, we
consider that such arguments concern the Panels' appreciation of the evidence. Mexico has not
claimed that the Panels' evaluation of per set data was inconsistent with their obligation under
Article 11 of the DSU to make an objective assessment of the matter before them. Consequently,
we consider that arguments relating to such a claim fall outside the scope of this appeal.
6.121. We therefore address, in turn, Mexico's arguments that, in addition to looking at per set
evidence, the Panels al so should have taken into account: (i) evidence pertaining to the risks to
dolphin populations in certain ocean areas; (ii) evidence of absolute levels of harm to dolphins in
certain ocean areas; and (iii) evidence concerning lack of sufficient regulatory oversight in certain
ocean areas.475 We note in this regard that Mexico does not argue on appeal that the Panels acted
inconsistently with Article 11 of the DSU in making their assessment of different risk profiles. 476 In
the absence of such a claim, we limit our analysis below to the question whether Mexico has
demonstrated that the Panels erred in applying Article 2.1 of the TBT Agreement, in making their
assessment of different risk profiles.

468 United States' appellee's submission, paras. 151-203.
469 United States' appellee's submission, paras. 162-174.
470 United States' appellee's submission, paras. 177-194 and 197-198.
471 United States' appellee's submission, para. 202.
472 Mexico's appellant's submission, para. 200.
473 Mexico's appellant's submission, para. 200. The United States argues that these aspects of Mexico's
arguments pertain to the Panels' appreciation of the facts, and that, in any event, the Panels did examine
per set data for trawl fishing, and, with respect to gillnet fishing, the Panels relied on per set data as far as
possible and relied on other evidence when per set data were not available. (United States' appellee's
submission, paras. 167-173 (referring to Panel Reports, paras. 7.433-7.434, 7.441-7.443, and 7.489-7.494))
474 Mexico's response to questioning at the hearing.
475 At the hearing, Mexico clarified that it is arguing that PBR evidence should have been taken into
account in addition to per set evidence, and that all relevant factors should have been taken into account.
476 Mexico does raise a claim under Article 11 of the DSU pertaining to the Panels' assessment of
whether the 2016 Tuna Measure is adequately calibrated to different risks to dolphins. We address this claim in
section 6.1.5.4 below.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.1.4.4.1 Risks to dolphin populations
6.122. Mexico argues that, in addition to looking at per set evidence, the Panels also should have
taken into account evidence pertaining to dolphin sustainability in certain ocean areas, specifically
evidence reflecting PBR levels. Mexico notes that PBR levels indicate the "maximum number of
animals, not including natural mortalities, that may be removed from an animal stock (such as
dolphins) while allowing that stock to reach or maintain its optimum sustainable population". 477 In
Mexico's view, the Panels erred by failing to take into account PBR evidence that shows high risks
to dolphin populations in certain ocean areas, because, in Mexico's view, such risks to dolphin
populations are relevant to an assessment of the overall relative risk profiles of certain fisheries. 478
Mexico considers that this view is supported by the findings of the original panel concerning adverse
effects to dolphins 479, findings by the first compliance panel concerning the objective of the
measure480, and the design and structure of the 2016 Tuna Measure.481
6.123. In the United States' view, the Panels' decision to disregard PBR evidence was in accordance
with both the design and structure of the measure, as well as relevant prior findings by previous
panels and the Appellate Body in this dispute.482 The United States highlights, and agrees with, the
Panels' finding that the objective of the measure is primarily to protect individual dolphins, and that
a PBR methodology is focused on the effect that dolphin mortalities have on a dolphin stock, rather
than the a ctual likelihood of dolphins being adversely affected. 483 To the extent that dolphin
sustainability may be an objective of the measure, the United States maintains that it is indirect
(i.e. "due to a relationship between reducing 'adverse effects' on individual dolphins and conserving
dolphin populations").484 The United States submits that the Panels fully explained their decision not
to rely on a PBR methodology485, and argues that Mexico has not challenged under Article 11 of the
DSU the Panels' factual findin g that the measure at issue is concerned more with the risks to
individual dolphins than the risks to dolphin populations.486
6.124. The Panels found that PBR evidence reveals "the maximum possible number of animals, in
this case dolphins, which can be removed from an animal stock without affecting the population or
its sustainability".487 The Panels considered that a PBR methodology is "suitable in the context of
policies that concern the sustainability of marine mammal stocks and where a certain level of
mortalities or serious injury is tolerated". 488 The Panels considered that "there is no part icular
indication that the Tuna Measure is directly concerned with the protection of the population levels of
dolphins" and that, while "mortality or serious injury suffered by individual dolphins may also have
population-level consequences[,] … [t]hat, however, is not directly relevant to the findings that [they
would] make about the overall levels of relative risks posed to dolphins by different fishing methods

477 Mexico's appellant's submission, para. 202 (referring to Panel Reports, para. 7.184 and fn 328
thereto).
478 Mexico's appellant's submission, paras. 202 and 211.
479 Mexico's appellant's submission, paras. 207 and 209 (referring to Original Panel Report,
paras. 7.419-7.420, 7.433, 7.485-7.486, 7.490, 7.550-7.552, 7.562, 7.574, 7.600, 7.621, 7.718, and 7.726).
480 Mexico's appellant's submission, para. 210 (quoting First Compliance Panel Report, para. 7.528, in
turn referring to Original Panel Report, paras. 7.485-7.486).
481 Mexico's appellant's submission, paras. 212-213.
482 United States' appellee's submission, paras. 177-184.
483 United States' appellee's submission, para. 178 (referring to Panel Reports, paras. 7.186-7.190
and 7.473). The United States notes that, under a PBR methodology, "huge numbers of dolphin mortalities in
one fishery may be tolerated while de minimis levels in another are deemed unacceptable." (Ibid.) The
United States highlights findings by the Appellate Body in the first compliance proceedings that the calibration
analysis relates to the "likelihood that dolphins would be adversely affected in the course of tuna fishing
operations in different fisheries". (Ibid., para. 179 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.157; referring to paras. 7.101, 7.110, 7.122, 7.157, 7.162, 7.239,
7.245-7.251, 7.288, 7.325, and 7.330)) In the United States' view, the original panel's reference to "dolphin
populations" should be read as referring to "risks to groups of dolphins in different areas" rather than risks to
dolphin stocks, and this is "confirmed" by relevant findings of the Appellate Body in the original proceedings.
(Ibid., paras. 181-182)
484 United States' appellee's submission, para. 183 (referring to Original Panel Report,
paras. 7.419-7.420, 7.485-7.486, 7.490, 7.550-7.551, and 7.528).
485 United States' appellee's submission, paras. 185-189 (referring to Panel Reports, paras. 7.186,
7.188-7.189, 7.469, and 7.473).
486 United States' appellee's submission, paras. 191-192 (referring to Panel Reports,
paras. 7.186-7.187).
487 Panel Reports, para. 7.184.
488 Panel Reports, para. 7.184.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

in different areas of the ocean."489 The Panels highlighted that, "[b]y allowing the existence of some
dolphin mortalities and focusing primarily on the population levels, the PBR methodology prioritizes
the sustainability of the population rather than the well -being of individual dolphins", which would
be "difficult to reconcile with the objectives of the Tuna Measure".490 The Panels also noted that "the
architecture of the measure … by its own terms is concerned with the mortality and serious injury
of individual dolphins, o n a per set basis, rather than with the overall sustainability of dolphin
stocks."491
6.125. We observe that Mexico has not made any claims under Article 11 of the DSU regarding the
Panels' appreciation of the facts, and that Mexico has clarified that its argument with respect to
PBR evidence relates to the Panels' omission of a relevant "factor" 492 or "methodology"493 in their
assessment of risk profiles. The legal issue before us is therefore whether the Panels erred in their
application of Article 2.1 of the TBT Agreement by declining to take into account PBR evidence in
assessing and comparing the risk profiles of different fishing methods and fisheries for the purpose
of the calibration analysis.
6.126. We recall that, in order to properly conduct the calibration analysis, the Panels were required
to assess the overall relative risks of different fishing methods and fisheries. 494 Furthermore, the
purpose of this analysis was to assess whether the detrimental impact from the 2016 Tuna Measure
stems exclusively from a legitimate regulatory distinction. As our analysis above reveals, the nature
of the calibration analysis, including the relevant risks to be assessed, is informed by the nature of
the relevant regulatory distinctions causing the detrimental impact.495
6.127. Under the 2016 Tuna Measure, a tuna product is ineligible for the label if it contains tuna
"caught in a set or gear deployment in which dolphins were killed or seriously injured". 496
Furthermore, the 2016 Tuna Measure "is generally applied on a per gear deployment basis in respect
of how often captains have to make non -dolphin safe certifications , or how frequently
non-dolphin safe tuna must be segregated from dolphin-safe tuna."497 Thus, the relevant regulatory
distinctions made by the measure itself apply on a per set basis. Based on the design and structure
of the measure, we agree with the Panels that the dolphin-safe label is concerned with the well-being
of individual dolphins, and that the design and structure of the relevant regulatory distinctions reveal
that the relevant risks to dolphins, for the purpose of the calibration analysis, are the risks of
individual dolphins being killed or seriously injured in the fishing process.498
6.128. We note Mexico's argument that the Panels' characterization of the Tuna Measure as "'mainly
concerned with the risks facing dolphins at an individual level, rather than at a population level', is
flatly contradicted by the measure itself".499 In Mexico's view, this is because the 2016 Tuna Measure
expressly contemplated that the prohib ition on the use of the dolphin -safe label for tuna derived
from setting on dolphins could be removed following "an evaluation of the potential impact of dolphin
sets on the populations of the dolphin stocks in the ETP". 500 In our view, however, the
Panels' understanding of the measure as "mainly concerned with the risks facing dolphins at an

489 Panel Reports, para. 7.186.
490 Panel Reports, para. 7.188.
491 Panel Reports, para. 7.190.
492 Mexico's appellant's submission, para. 202.
493 Mexico's appellant's submission, para. 204.
496 Panel Reports, para. 7.190.
497 Panel Reports, para. 7.213.
498 Panel Reports, para. 7.190. The Panels also explained that the 2016 Tuna Measure is concerned with
"the protection of the well-being of dolphins, and with informing consumers whether the tuna used in the
production of particular tuna products was caught in a set that harmed dolphins". (Ibid., para. 7.186)
499 Mexico's appellant's submission, para. 214 (quoting Panel Reports, para. 7.473). (emphasis omitted)
500 Mexico's appellant's submission, para. 214 (referring to Original Panel Report, para. 2.16).
Section 1385(g) of the DPCIA requires the Secretary of Commerce to make a finding regarding whether setting
on dolphins "is having a significant adverse impact on any depleted dolphin stock in the [ETP]".
Section 1385(h)(2) further requires that the certification requirements regarding tuna caught by large purse
seine vessels in the ETP are inapplicable if the Secretary of Commerce determines that setting on dolphins is
not having a significant adverse impact on depleted dolphin stock in the ETP. (See Original Panel Report,
para. 2.16; Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), fn 127 to para. 6.9. See also
DPCIA (Panel Exhibits MEX-1 and USA-1)) As noted in paragraph 5.10 above, although the Secretary of
Commerce made such a determination, it was overturned by the Hogarth ruling.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

individual level"501 does not suggest that the risks to dolphin populations are irrelevant, or that the
2016 Tuna Measure is not at least indirectly concerned with protecting dolphin populations. We see
no reason to disagree with the Panels' finding that "mortality or serious injury suffered by individual
dolphins may also have population -level consequences."502 We recall the original panel's findings
that "the adverse effect s on dolphins targeted by the US dolphin-safe provisions, as described by
the United States, relate to observed and unobserved mortalities and serious injuries to individual
dolphins in the course of tuna fishing operations" and that "the US objectives also incorporate, at
least indirectly, considerations regarding the conservation of dolphin stocks ."503 On this basis, we
also disagree with Mexico's argument that, because the dolphin -safe labels are granted under
conditions that primarily take into account the risks to individual dolphins, consumers are misled
and deceived about whether or not the tuna that they are purchasing was caught in a manner that
threatens or endangers dolphin populations.504
6.129. We recall Mexico's argument that, if the measure is truly concerned with the protection of
individual dolphins, any "fishing method that is capable of harming a dolphin should be ineligible"
for the dolphin-safe label.505 As explained above, we consider that the 2016 Tuna Measure will not
violate Article 2.1 if the relevant regulatory distinctions leading to detrimental impact are properly
"calibrated" to the risks to dolphins arising from different fishing methods in different areas of the
oceans.506 Furthermore, if it can be shown that the distinctions are calibrated to different risks to
dolphins, this would also indicate that such distinctions are rationally related to, and hence capable
of contributing to, the measure's objectives. 507 In our view, the fact that the 2016 Tuna Measure
grants a dolphin-safe label to certain fishing methods that may be capable of harming a dolphin does
not imply that the 2016 Tuna Meas ure is not concerned with informing consumers of the risks to
individual dolphins.
6.130. Thus, we agree with the Panels that the essential question for the purpose of assessing the
calibration of the 2016 Tuna Measure is whether the relevant regulatory distinct ions are calibrated
to different risks that dolphins will be killed or seriously injured in the process of harvesting tuna.508
It is uncontested that PBR evidence does not reveal the likelihood of dolphins being killed or seriously
injured in a particular fi shing operation.509 Rather, it indicates the number of dolphins that can be
safely removed without jeopardizing the sustainability of the dolphin population as a whole.
6.131. We recall that, before the Panels, Mexico contended that the Panels should have adopted
the PBR methodology, rather than the per set methodology, in assessing the risks to dolphins.510 On
appeal, Mexico acknowledges the utility of per set evidence where dolphin mortalities per set are
high, but challenges the Panels' reliance on per set evidence in circumstances in which PBR evidence
indicates that even a low level of mortalities per set would endanger the dolphin population of a
fishery.511 However, Mexico has not explained how reliance on PBR evidence in these circumstances
relates to, or reveal s, the actual risks that dolphins were killed or seriously injured in the fishing
process. Thus, as noted by the Panels, relying on PBR evidence would have resulted in an assessment
of a different kind of risk to dolphins than the risks of which the measur e seeks to inform
consumers.512 We therefore agree with the Panels' assessment that the PBR methodology prioritizes
the sustainability of the population in a way that would have prevented the Panels from adequately
assessing whether the measure is calibrated to different risks that a dolphin was harmed or killed in

502 Panel Reports, para. 7.186.
503 Original Panel Report, para. 7.486. The first compliance panel also found that "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." (First Compliance Panel Report, para. 7.527 (quoting Appellate Body
504 Mexico's response to questioning at the hearing.
505 Mexico's appellant's submission, para. 216.
506 See para. 6.36 above.
507 See para. 6.74 above.
508 Panel Reports, para. 7.186.
509 In contrast, per set evidence, revealing the risk of a dolphin being injured in any individual set, is
indeed a relevant and useful measure of the risk that dolphins are killed or seriously injured in the fishing
process. (Panel Reports, para. 7.204)
510 Panel Reports, para. 7.175 (stating that "[f]or Mexico, the use of the PBR methodology would
capture all of the relevant factors that need to be taken into account by the Panels").
511 Mexico's appellant's submission, para. 215; responses to questioning at the hearing.
512 Panel Reports, paras. 7.186-7.190.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the fishing process, and that "the PBR methodology … sits uncomfortably with the design and
structure of the 2016 Tuna Measure."513
6.132. Mexico further maintains that its position comports with the Appel late Body's statement in
the first compliance proceedings that it did "not exclude that reference to … objective indicators
[such as PBR evidence] might assist in an assessment of whether regulatory differences in the
treatment of different fisheries can b e explained on the basis that such treatment is calibrated to,
or commensurate with, the relative risks to dolphins arising from different fishing methods in
different areas of the oceans".514 This statement by the Appellate Body acknowledging the possible
relevance of PBR evidence does not state that a panel is necessarily required to rely on such evidence
as an objective indicator or means of assessing whether the measure is properly calibrated. To the
contrary, the Appellate Body avoided taking a position on that issue and explained that a panel
should rely on evidence reflecting appropriate objective indicators in assessing the risks to dolphins.
In our view, the Panels adequately explained their decision to rely primarily on per set evidence,
and not PBR evidence, in accordance with the Appellate Body's guidance to rely on objective
indicators.
6.133. Additionally, we recall Mexico's assertion that the Panels arbitrarily included, within their
analysis, "unobservable harms 'whose realization cannot be definitely established'" and excluded
"measured and realized harms that threaten the sustainability of entire dolphin populations in areas
of the oceans".515 We consider that the appropriate "measured and realized harms" that the Panels
were obliged to take into accou nt were the risks of harm to individual dolphins (e.g. mortality and
serious injury), which the Panels did take into account in their reliance on per set evidence.516 In the
same vein, we also disagree with Mexico's assertion that the Panels did not explain how the use of
a fishing method that causes or threatens dolphin population collapse could not be considered as
"adversely affecting dolphins".517 Rather, the Panels explicitly recognized "that mortality or serious
injury suffered by individual dolphins may also have population -level consequences ."518
Furthermore, as indicated above, we agree with the Panels that the protection of individual dolphins
can indeed contribute to the conservation of dolphin populations.
6.134. For these reasons, we consider that Mexico has not demonstrated that the Panels erred in
applying Article 2.1 by not taking into account PBR evidence when assessing the overall relative
risks to dolphins of di fferent fishing methods in different ocean areas. This is not meant to imply
that the Panels failed to take into consideration risks to dolphin populations. Rather, we understand
the Panels to have considered that the 2016 Tuna Measure seeks to protect dol phin populations by
protecting individual dolphins and , consequently, their analysis focused on evidence revealing the
risks that individual dolphins are harmed or killed in the fishing process. In our view, this approach
is consistent with the nature of the calibration analysis the Panels were required to undertake.
6.1.4.4.2 Absolute levels of adverse effects
6.135. Mexico argues that the Panels erred by failing to compare the absolute levels of mortalities
and serious injuries to dolphins in different fisheries. Mexico explains that, in fisheries with many
sets, the "overall" adverse effects will be "masked" by the per set data, such that "tuna caught in
an ocean area where tuna fishing is causing tens of thousands of deaths per year could be found
eligible for the dolphin-safe label."519 To Mexico, these absolute levels of adverse effects constitute
"'overall adverse effects on dolphins' for the fishing method/area". 520 Mexico argues that "fishing
practices in such ocean areas should be discouraged" 521, and that "the omission of these overall
adverse effects contradicts the two objectives of the measure."522
6.136. In the United States' view, a comparison of absolute levels of adverse effects fails to take
into account unobservable harms, and does not "'contextualize' the adverse effec ts on dolphins in

513 Panel Reports, para. 7.190.
514 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), fn 827 to para. 7.251.
516 Panel Reports, paras. 7.186-7.191, 7.204-7.214, and 7.251.
517 Mexico's appellant's submission, para. 213.
518 Panel Reports, para. 7.186.
519 Mexico's appellant's submission, para. 218.
520 Mexico's appellant's submission, para. 218.
521 Mexico's appellant's submission, para. 218.
522 Mexico's appellant's submission, para. 219.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

different fisheries", given the different sizes and effort levels of fisheries. 523 The United States
explains that "a fishery with a few vessels would be compared directly with a fishery comprising
thousands of vessels" and the "'absolute' numbers of dolphin mortalities might be greater in the
second fishery, even if dolphins were hardly ever killed or even seen in the fishery, simply due to its
far greater size."524 The United States also points out that Mexico has "never defined or explained
the 'ocean regions' or 'fisheries' that should be assessed", but has "consistently compared the
dolphin mortalities caused by the 80-90 vessels setting on dolphins with those caused by thousands
of other vessels around the world", which "perversely" disto rts the comparison, since setting on
dolphins "has been banned almost everywhere in the world".525
6.137. We note as an initial matter that the Panels did not completely exclude evidence of absolute
levels of dolphin mortalities and serious injuries. Rather, the Pa nels opted to rely on such evidence
in assessing certain fishing methods and fisheries where they considered that the available per set
evidence was lacking. 526 Furthermore, Mexico has not identified any specific evidence of absolute
levels of mortalities or serious injuries that the Panels disregarded. We also note that calculating
levels of harm on a per set basis necessarily takes into account absolute levels of harm as part of
the calculation. 527 We therefore understand that Mexico's argument pertains not t o the Panels'
"rejection" of such "absolute" evidence, but to the Panels' decision to rely on per set evidence, rather
than absolute evidence, as their primary methodology by which to assess and compare the risks to
dolphins.528
6.138. The Panels opted not to rely primarily on evidence of absolute levels of dolphin mortalities
and significant injuries, on the basis that:
[S]uch a methodology would not necessarily deal with the issue of how to compare the
levels of adverse effects on dolphins arising from different fishing methods in different
areas of the ocean, or contextualize them in the light of the relative extent and
intensity to which different fishing methods are use d, in such a way as to allow
an apples-to-apples assessment of the relative harmfulness of different fishing methods
as used in different areas of the oceans.529
6.139. As explained above530, an assessment as to whether the 2016 Tuna Measure is consistent
with Article 2.1 of the TBT Agreement calls for an analysis of the overall relative risks to dolphins.531
The Panels were therefore required to use a metric, or methodology, that allowed for a proper
comparison of risks to dolphins across fisheries. In light of the relative nature of the comparison to
be undertaken, we agree with the Panels that any comparison of risks to dolphins in different tuna
fisheries should, in principle, be an "apples -to-apples" comparison, such that relevant differences
between the fisheries are appropriately taken into account.532 We also note the Panels' findings that
the "extent and intensity to which different fishing methods are used" varies from fishery to
fishery.533
6.140. The Panels considered that data reflecting the number of absolute dolphin mortalities or
serious injuries in a particular fishery do not account for such differences. In the Panels' view,
absolute levels of mortalities or serious injuries present a number that is independent of the specific

524 United States' appellee's submission, para. 198.
525 United States' appellee's submission, para. 199. (fn omitted)
526 See e.g. Panel Reports, paras. 7.434, 7.438, 7.441, and 7.467.
527 As the Panels explained, "a per set or per gear deployment comparison entails averaging some of the
relevant indicators identified in paragraph 7.169 [of the Panel Reports], including observed mortalities, serious
injuries, and interactions, by the number of operations of the fishing gear used in a particular fishery in a given
528 Mexico has not argued that the Panels' appreciation of the evidence was inconsistent with Article 11
of the DSU, and we therefore proceed by assessing only whether the Panels' primary reliance on per set
evidence was inconsistent with the legal standard under Article 2.1 of the TBT Agreement.
531 See also Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.169, 7.229,
and 7.248. The Appellate Body emphasized in the first compliance proceedings the "relational and comparative
nature of the analysis of whether the amended measure is calibrated and even-handed" under Article 2.1 of
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

features of the fishery (for instance, the number of fishing operations conducted per year in that
fishery).534 The Panels stated that "such a methodology would not necessarily … allow an
apples-to-apples assessment of the relative harmfulness of different fishing methods as used in
different areas of the oceans."535 In contrast, the Panels found that the per set methodology, which
entailed "averaging" the total number of a particular indicator of adverse effects 536 to dolphins by
the number of operations of a particular type of fishing gear used in a particular fishery in a given
time period, would "control for the intensity of a given fishing operation in a given area of the
ocean".537
6.141. Furthermore, it is uncontested, as the Panels found, that the 2016 Tun a Measure
"is generally applied on a per gear deployment basis in respect of how often captains have to make
non-dolphin safe certifications, or how frequently non -dolphin safe tuna must be segregated from
dolphin-safe tuna".538 As we have explained above, we understand that the regulatory distinctions
drawn under the measure are intended to addre ss the risks that dolphins were killed or seriously
injured in the fishing process.539 In our view, a proper examination as to whether such distinctions
are calibrated to the relevant risks to dolphins should take into account the relevant differences
across fisheries. The Panels' reasoning as set forth above indicates tha t a per set methodology is
well suited to the kind of comparative analysis that Article 2.1 required the Panels to perform in this
dispute. The Panels' factual findings also demonstrate that a comparison of absolute levels of
mortalities or serious injuries would be less likely to reveal the relative likelihood of a dolphin being
killed or injured in the fishing process than a comparison of per set data.540
6.142. We recall Mexico's argument that "ov erall" adverse effects will be "masked" by the per set
data, and that the absolute levels of adverse effects constitute "'overall adverse effects on dolphins'
for the fishing method/area".541 In the first compliance proceedings, the Appellate Body faulted the
panel for not examining all relevant relative risks of harm to dolphins, including both observed and
unobserved harms.542 Thus, an assessment of the overall relative risks to dolphins requires a panel
to assess all relevant risks of harm to dolphins. We do not discount that, depending on the particular
evidence provided to the Panels, evidence of absolute levels of adverse effects might indeed be
useful in this regard. However, as explained above, the Panels were not only required to assess the
overall risks, but the overall relative risks to dolphins. 543 As indicated above, comparing absolute
levels of mortalities or serious injuries across different fisheries would not take into account
important differences between those fisheries. By contrast, a comparison of per set data does indeed
take into account such differences.544
6.143. For these reasons, we consider that Mexico has not demonstrated that, in deciding to rely
primarily on a per set methodology rather than comparing absolute levels of harm, the Panels acted
inconsistently with the requirement to assess the overall relative risks to dolphins from different
fishing methods and fisheries.

534 Panel Reports, paras. 7.195 and 7.204.
536 These include observed mortalities, serious injuries, and interactions with dolphins of the fishing
method in a given area of the ocean. (Panel Reports, paras. 7.169 and 7.204)
537 Panel Reports, para. 7.204. We note that this tension between per set evidence and "absolute"
evidence was demonstrated in the Panels' assessment of longline fishing, with respect to which Mexico
presented evidence of high levels of absolute annual mortalities in the Pacific Ocean. (Ibid., para. 7.467) The
Panels declined to accord much weight to this data, on the basis that the data reflected many different longline
fisheries, and relevant per set data for certain individual longline fisheries covered by the absolute data
revealed a low rate of dolphin interactions. (Ibid., para. 7.468)
538 Panel Reports, para. 7.213.
539 See para. 6.127 above.
540 Panel Reports, para. 7.195.
541 Mexico's appellant's submission, para. 218.
542 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.161.
543 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.169, 7.229,
and 7.248.
544 See Panel Reports, para. 7.204. Notwithstanding that such absolute levels of harm are less helpful in
comparing the risks to dolphins for the purpose of the calibration analysis, we see no reason for the Panels not
to rely on such evidence in assessing the risks to dolphins in situations where the relevant per set evidence
was lacking.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.1.4.4.3 Insufficient regulatory oversight
6.144. Mexico argues that the Panels erred by omitting evidence of insufficient regulatory oversight
in certain ocean areas, because "dolphins will be at a greater relative risk of harms from … fishing
method[s used] in ocean areas that have insufficient regulatory oversight including unreliable
reporting, significant IUU fishing and/or significant transhipment at sea than in ocean areas that do
not."545 In Mexico's view, the omission of the "reliability of reporting as a criterion in the risk profiles
of the fishing areas contradicts the objectives of the measure". 546 Mexico explains that, in
"unreliable" fisheries there is a "greater risk that adverse effects on dolphins will be
unreported … and, therefore, that actions that adversely affect dolphins in unreliable fisheries will
not be discouraged by the measure".547
6.145. The United States considers that Mexico ma kes two distinct arguments: (i) insufficient
regulatory oversight causes greater risk of harm to dolphins; and (ii) insufficient regulatory oversight
should be included in the risk profiles of fisheries "because it can affect the reliability of reporting of
harms to dolphins".548 The United States considers that it fully addressed Mexico's first argument in
the context of Mexico's claim that the Panels erred in their interpretation of Article 2.1 of the
TBT Agreement.549 As to Mexico's second argument, the United States highlights that this argument
was "fully considered and rejected by the Panels", and argues that the Panels correctly explained
that the risks of inaccuracy are not themselves risks of harm to dolphins. 550 In the
United States' view, such risks of inaccuracy rather "may be relevant to assessing whether the
distinctions of the 2016 measure are calibrated to the risk profiles of different fisheries".551
6.146. As explained above552, the question whether the relevant regulatory distinctions under the
2016 Tuna Measure are properly calibrated to different risks to dolphins does not require assessing
whether the 2016 Tuna Measure is also calibrated to the "risk of inaccuracy". As discussed in
paragraph 6.51 above, Mexico has not su bstantiated its assertion that tuna fishing in ocean areas
with less reliable regulatory systems is more likely to lead to harm to dolphins.553 We therefore see
no reason to disagree with the Panels' statement that "the risks of inaccurate certification, reporting,
and/or record-keeping are not risks that affect dolphins themselves."554
6.147. As noted, the Panels did not exclude the possibility that factors such as a lack of regulatory
oversight may affect the accuracy of the label. 555 We have explained above that suc h risks of
inaccuracy are relevant to the assessment of whether the measure is calibrated to the risks to
dolphins.556 It was, however, incumbent upon Mexico to provide relevant evidence in support of its
argument that a lack of regulatory oversight in a fishery will increase the risk that labelling of tuna

545 Mexico's appellant's submission, para. 220.
546 Mexico's appellant's submission, para. 223 (referring to Panel Reports, paras. 7.186 and 7.705).
547 Mexico's appellant's submission, para. 223.
548 United States' appellee's submission, para. 202.
549 United States' appellee's submission, para. 202. See also paras. 6.47-6.50 above. The United States
argued in that context that, contrary to Mexico's preferred approach, the Panels' approach was consistent with
the Appellate Body's guidance in the first compliance proceedings. (Ibid., paras. 47-50) The United States also
argued that Mexico's approach implies that the Panels should have applied a different type of calibration
analysis to the certification and tracking and verification requirements than to the eligibility criteria, and that
Mexico has never argued as a factual matter that dolphins are at a greater risk of harm in areas where the
reliability of applicable systems is low. (Ibid., paras. 51-53)
550 United States' appellee's submission, para. 202 (referring to Panel Reports, paras. 7.109-7.113
and 7.119-7.124).
551 United States' appellee's submission, para. 202 (referring to Panel Reports, paras. 7.119-7.124).
553 We further note that Mexico has not argued that the Panels erred under Article 11 of the DSU by
omitting specific evidence of a heightened risk to dolphins in any particular fishery in their examination of risks
to dolphins in different fisheries.
554 Panel Reports, para. 7.110. Although Mexico has described its arguments on appeal as relating to
"insufficient regulatory oversight", we note that Mexico specifically takes issue with the Panels' findings with
respect to "inaccurate certification, reporting, and/or record-keeping". (Mexico's appellant's submission,
paras. 220-222) We therefore see no distinction between Mexico's references to "regulatory oversight" and the
Panels' discussion of "inaccurate certification, reporting, and/or record-keeping".
555 See para. 6.52 above.
556 See para. 6.52 above.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

products containing tuna caught in such a fishery will not accurately reflect the dolphin-safe nature
of the tuna. We address this issue in section 6.1.5 below.
6.1.4.5 Conclusion
6.148. In conducting their examination of the risk profiles of different fishing methods as used in
different ocean areas, the Panels reviewed all relevant evidence of risks to dolphins as provided to
them by the parties, including all evidence pertaining to individual fisheries. Additionally, the Panels
appropriately took into account all relevant types of harm to dolphins in assessing the risk profiles
of different fishing methods and fisheries. Moreover, the Panels did not err in relying on per set data
as the primary measurement of the risks to dolphins, despite three additional measurements
proposed by Mexico. First, because the relevant risks to be assessed for the purpose of calibration
are the risks of individual dolphins being harmed or killed in the fishing process, the Panels were
correct not to rely on PBR evidence to assess the risks to dolphins. Second, given the comparative
nature of the calibration analysis, the Panels did not err by relying primarily on a per set methodology
instead of a comparison of absolute levels of harm. Finally, Mexico did not substantiate its assertion
that tuna fishing in ocean areas with less reliable regulatory systems is more likely to lead to harm
to dolphins, and therefore the Panels did not err by excluding evidence pertaining to regulatory
oversight from their assessment of the overall relative risks to dolphins from the use of different
fishing methods as used in different areas of the ocean. We therefore find no error in the
Panels' assessment of the risks to dolphins arising from the use of differe nt fishing methods in
different ocean areas or in their conclusions regarding the risk profiles of relevant fishing methods
on the basis of that assessment.
6.1.5 The Panels' assessment of whether the 2016 Tuna Measure is calibrated to the risks
to dolphins
6.1.5.1 Introduction
6.149. As noted above, in assessing whether the detrimental impact caused by the 2016 Tuna
Measure stems exclusively from a legitimate regulatory distincti on, the Panels examined whether
(i) the eligibility criteria; (ii) the certif ication requirements; (iii) the tracking and verification
requirements; and (iv) the determination provisions of the 2016 Tuna Measure are calibrated to the
difference in the overall risks to dolphins arising from the use of different fishing methods in different
areas of the ocean.557 After concluding their intermediate analyses of these component elements of
the 2016 Tuna Measure, the Panels "synthesize[d]" their analysis in order to reach their conclusion
as to the consistency of the 2016 Tuna Measure with the TBT Agreement.558 Following their analyses,
the Panels came to the "general conclusion" that:
[T]he 2016 Tuna Measure, as a whole, is calibrated to the risks to dolphins arising from
the use of different fishing methods in different areas of the ocean. Therefore, the Panels
find that the distinctions made by that Measure between setting on dolphins and the
other fishing methods (except, of course, high seas driftnet which is also disqualified
from the dolphin -safe label) stem exclusively from legitimate regulatory distincti ons.
Consequently, the Panels conclude that the 2016 Tuna Measure accords to Mexican tuna
products treatment no less favourable than that accorded to like products from the
United States and other countries, and therefore is consistent with Article 2.1 of the
TBT Agreement.559
6.150. On appeal, Mexico requests us to reverse several of the intermediate findings that led to the
above "general conclusion" by the Panels, which Mexico also contests. 560 Specifically, Mexico
challenges the Panels' assessment of the following aspects of the 2016 Tuna Measure:
(i) the eligibility criteria; (ii) the certif ication requirements; (iii) the tracking and verification

557 Panel Reports, para. 7.530. See also ibid., paras. 7.547, 7.611, 7.676, 7.702, and 7.704.
558 Panel Reports, para. 7.530 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.21). See also ibid., paras. 7.703-7.716.
559 Panel Reports, para. 7.717.
560 Mexico's Notice of Appeal, para. 9; appellant's submission, paras. 75, 76, and 307.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

requirements; and (iv) the 2016 Tuna Measure as a whole. In its Notice of Appeal, Mexico does not
separately challenge the Panels' findings regarding the determination provisions.561
6.151. We begin with a few preliminary observations. First, we recall that the Appellate Body
criticized the first compliance panel's analysis because, while the first compliance panel had initially
emphasized the interlinkages between elements of the 2013 Tuna Measure:
[I]t subsequently conducted a segmented analysis that isolated consideration of each
element of the measure without accounting for the manner in which the elements are
interrelated, and without aggregating or synthesizing its analyses or findings relating to
those elements before reaching its ultimate conclusions as to the consistency or
inconsistency of the [2013 Tuna Measure].562
6.152. In the first compliance proceedings, the Appellate Body re cognized that it may be
appropriate for a panel "to proceed by assessing different elements of [a] measure in a sequential
manner", provided that doing so does not "lead to the isolated consideration of a particular element"
where the elements of a measure are closely interrelated. 563 Similarly, an assessment of the
even-handedness of the 2016 Tuna Measure "must take account of the fact that its various
elements – the eligibility criteria, the certification requirements, and the tracking and verification
requirements – establish a series of conditions of access to the dolphin-safe label that are cumulative
and highly interrelated".564
6.153. In these compliance proceedings, as described in paragraph 6.149 above, the Panels first
examined the different elements of the 2016 Tuna Measure (i.e. the eligibility criteria, the
certification requirements, the tracking and verification requirements, and the determination
provisions) in a sequential manner before synthesizing their analysis in order to reach their
conclusion as to the consistency of the 2016 Tuna Measure with the WTO Agreement.565 As indicated
above, analysing the measure in a sequential manner does not, in itself, render the analysis
erroneous. Rather, in reviewing the Panels' analysis, we examine whether it resulted in an "isolated
consideration of a particular element" 566, or whether the Panels' analysis took into account the
manner in which the discrete elements of the 2016 Tuna Measure are "cumulative and highly
interrelated".567
6.154. Second, we take note that, in challenging the Panels' assessment of the component elements
of the 2016 Tuna Measure, Mexico contends, in several places, that the Panels' erroneous evaluation
of the relevant risk profiles resulted in an error in the Panels' assessment of the 2016 Tuna
Measure.568 In sections 6.1.3.2 and 6.1.4 above, we addressed Mexico's claim that the Panels erred
in their evaluation of the risk profiles. Thus, to the extent that Mexico's arguments in support of its
claim that the Panels erred in their assessment of the component elements of the 2016 Tuna Measure
mirror Mexico's arguments that we addressed and rejected above, we refer to our analysis in those
sections and do not revisit Mexico's arguments. Instead, we focus our review of the Panels' analysis
on Mexico's arguments that are not premised on the alleged errors in the Panels' evaluation of the
risk profiles.
6.155. We now turn to Mexico's challenges to the Panel's assessment of the following aspects of
the 2016 Tuna Measure: (i) the eligibility criteria; (ii) the certificat ion requirements; (iii) the
tracking and verification requirements; and (iv) the 2016 Tuna Measure as a whole.

561 These findings are contained in paragraphs 7.677-7.702 of the Panel Reports.
562 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.21. We note that the
Panels in these compliance proceedings took account of this reasoning by the Appellate Body in setting out
their approach to their assessment of the 2016 Tuna Measure. (Panel Reports, paras. 7.527-7.530)
563 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.14-7.15.
564 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166.
565 Panel Reports, para. 7.530 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.21). See also ibid., paras. 7.703-7.716.
566 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.15.
567 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166.
568 See e.g. Mexico's appellant's submission, paras. 233-237, 241-246, 252, 267, 273-274, and 306.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.1.5.2 Eligibility criteria
6.156. Mexico claims that the Panels erred in finding that the eligibility criteria embodied in the
2016 Tuna Measure are calibrate d to the risks to dolphins arising from the use of different fishing
methods in different areas of the ocean.569 Mexico contends that the Panels undertook an incomplete
calibration assessment that failed to assess the eligibility of all fishing methods and ocean areas, by
failing to assess and take into consideration the risk profiles of different ocean areas, and by omitting
relevant and important factors from the calibration assessment.570
6.157. The United States asserts that all of Mexico's arguments are without m erit and should be
rejected. In this regard, the United States argues that: (i) Mexico's a ttempt to undermine the
Panels' factual findings concerning the nature and content of the eligibility criteria is inappropriate
and incorrect; (ii) the Panels' analysis of the eligibility criteria encompassed both the ineligibility of
setting on dolphins and the potential eligibility of the other relevant fishing methods; (iii) the Panels
did not fail to conduct the necessary analysis of the risk profiles of the releva nt fishing methods,
including as used in different ocean areas; and (iv) the Panels' analysis did not omit critical factors.571
6.158. Under the 2016 Tuna Measure , the following tuna products are automatically ineligible for
the dolphin-safe label: (i) tuna harvested using large-scale driftnets on the high seas; and (ii) tuna
harvested by vessels using purse seine nets to encircle (i.e. set on) dolphins anywhere in the
world.572 All other tuna products are eligible and may be labelled dolphin -safe only if no dolphins
were killed or seriously injured in the gear deployments in which the tuna was caught. To this end,
these tuna products must satisfy the certification and tracking and verification requirements of the
2016 Tuna Measure.573
6.159. As part of the 2016 Tuna Measure, the relevant regulatory distinction under the eligibility
criteria is that tuna products containing tuna caught by setting on dolphins are ineligible for the
dolphin-safe label, while tuna products containing tuna caught b y other fishing methods are, in
principle, eligible for the label.574 Thus, to assess whether this distinction is properly calibrated, the
Panels were required to compare the risk profiles of relevant fishing methods. As discussed in
paragraphs 6.94-6.95 above, in assessing and comparing the over all relative risks of the
seven different fishing methods575, the Panels took account of relevant information pertaining to the
risks to dolphins in individual fisheries, to the extent that evidence with respect to such individual
fisheries was presented to the Panels. 576 In particular, the Panels found that setting on dolphins
poses a much higher risk of observed dolphin mortality and serious injury, on a per set basis, than
other fishing methods.577 Moreover, in terms of the magnitude of observed harms, the Panels found
that the greater risks caused by setting on dolphins appeared to justify the finding of the original
and first compliance panels that setting on dolphins is "particularly harmful" to dolphins. 578 The
Panels also determined that the method of setting on dolphins is more likely than other fishing
methods to cause unobserved mortality and serious injury.579 In addition, the Panels accepted, based
on their assessment of the evidence on the record, that setting on dolphins causes a unique kind of
unobservable harm that by its nature cannot be certified. The Panels noted that this contrasted with

569 Mexico's Notice of Appeal, para. 9.a (referring to Panel Reports, paras. 7.539-7.547).
570 Mexico's appellant's submission, para. 247 (referring to Panel Reports, paras. 7.538-7.547).
571 United States' appellee's submission, para. 206.
572 Panel Reports, para. 7.50 (referring to DPCIA (Panel Exhibits MEX-1 and USA-1), Section 1385(d);
2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Section 216.91(a)). See also ibid.,
para. 7.532.
573 Panel Reports, para. 7.50.
574 As noted in paragraph 6.158 above, the measure also automatically disqualifies tuna caught using
large-scale driftnets on the high seas from the dolphin-safe label. Before the Panels, the parties did not submit
"arguments concerning the disqualification of tuna caught by driftnet on the high seas". (Panel Reports, fn 936
to para. 7.532) For the reasons stated in paragraphs 6.69-6.70 above, this regulatory distinction is not
relevant for assessing whether the detrimental impact found in this dispute stems exclusively from a legitimate
regulatory distinction.
575 We recall that the seven fishing methods that the Panels discussed are: purse seine fishing by setting
on dolphins; purse seine fishing without setting on dolphins; gillnet fishing; longline fishing; trawl fishing; tuna
handlining; and pole and line fishing. (See para. 6.86 above)
576 See e.g. Panel Reports, para. 7.541.
577 Panel Reports, para. 7.541.
579 Panel Reports, para. 7.543.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

other fishing methods, which, based on the evidence before the Panels, do not cause the same kinds
of unobservable harms as setting on dolphins.580
6.160. For these reasons, the Panels concluded that "overall, the risk profile of setting on dolphins
is much higher than that of each of the other six fishing methods used to catch tuna."581 The Panels
relied on this conclusion582 in finding that, "[t]aking into account the relative risk profiles of setting
on dolphins, on the one hand, and other fishing methods on the other hand, … the eligibility criteria
are appropriately calibrated to the risks to dolphins arising from the use of different fishing methods
in different areas of the ocean."583
6.161. Mexico's arguments584 in support of its claim that the Panels erred in their assessment of
the eligibility criteria of the 2016 Tuna Measure largely repeat Mexico's arguments that we addressed
and rejected in our review of the Panels' evaluation of the relevant risk profiles. In particular, we
recall that, under Article 2.1 of the TBT Agreement, the relevant question is whether the detrimental
impact caused by the 2016 Tuna Measure stems exclusively from a legitimate regulatory distinction.
As described above, the detrimental impact in this dispute results, in part, from the distinction under
the eligibility criteria between setting on dolphins and other fishing methods. Consequently, the test
of whether the eligibility criteria are even-handed requires an assessment of whether the distinction
between setting on dolphins and other fishing methods in the eligibility criteria is explained by the
differences in the risk profiles of the fishing methods.
6.162. As we found above, for the purpose of this assessment, the Panels adopted the cor rect
approach by comparing the risk profiles of the different fishing methods, on the basis of their
examination of the evidence concerning the use of these fishing methods in different ocean areas.585
Moreover, following our review of the Panels' evaluation of the relevant risk profiles, we found that
Mexico has not demonstrated that the Panels erred by drawing conclusions on the risk profile of each
fishing method on the basis of their examination of the evidence before them (including evidence
pertaining to individual fisheries).586 Having found no legal error in the Panels' assessment of risk
profiles, we see no reason to vacate the Panels' conclusion, following that assessment, that "setting
on dolphins is significantly more dangerous to dolphins than are other fishing methods."587
6.163. We now turn to Mexico 's arguments that concern whether the eligibility criteria under the
measure are properly calibrated. Mexico points to evidence that it submitted to the Panels concerning
the dangers of other fishing methods, arguing that this evidence demonstrates that, for these fishing
methods and ocean areas, there are regular and substantial dolphin mortalities and serious injury.
Mexico asserts that the failure of the eligibility criteria to " designate such tuna as ineligib le"
demonstrates that the tuna measure is not calibrated to differences in the risk profiles of different
fishing methods in different ocean areas.588
6.164. These arguments by Mexico fail to take account of how t he various elements of the
2016 Tuna Measure work to gether. As the Appellate Body explained in the first compliance
proceedings, the eligibility criteria are the "substantive conditions for access to [a] dolphin -safe
label".589 However, the eligibility criteria are not the only conditions for access to a dolp hin-safe
label. The certification requirements and the tracking and verification requirements "work together"
with the eligibility criteria of the 2016 Tuna Measure "to limit access to the dolphin -safe label".590
This means that, with respect to the category of tuna products that are not automatically disqualified
by the eligibility criteria, these products must still satisfy the certification requirements and the
tracking and verification requirements before they can access the dolphin -safe label. For example,

580 Panel Reports, paras. 7.544-7.546.
581 Panel Reports, para. 7.525.
582 Panel Reports, para. 7.539.
583 Panel Reports, para. 7.540.
584 Mexico's appellant's submission, paras. 230-247.
585 See para. 6.77 above.
586 See para. 6.99 above.
587 Panel Reports, para. 7.539.
588 Mexico's appellant's submission, paras. 238-240. (emphasis added)
589 Panel Reports, para. 7.532 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.19).
590 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.159.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the certification requirements, which the Panels addressed in a later section of their Reports 591,
provide that tuna intended to be labelled as dolphin -safe in the US market must be accompanied
by, inter alia, a certificate attesting that: (i) no dolphins were killed or seriously injured during the
sets in which the tuna was caught; and (ii) no purse seine net or other fishing gear was intentionally
deployed on or used to set on dolphins during the fishing trip in which the tuna was caught.592 Thus,
contrary to Mexico's arguments, under the 2016 Tuna Measure, tuna caught with fishing methods
that, while provisionally eligible under the eligibility criteria, cause adverse effects to dolphins would
not have access to the dolphin-safe label if they do not fulfil the other labelling conditions under the
2016 Tuna Measure (i.e. the certification requirements and the tracking and verification
requirements).
6.165. Mexico also contends that the Panels erred by omitting from their assessment factors related
to the circumstances affecting the regulatory reliability of different ocean areas. According to Mexico,
"[d]olphins are at a greater overall risk in ocean areas with insufficient regulatory oversight,
unreliable reporting, IUU fishing and trans -shipment at sea than in oce an areas that do not have
these attributes."593 Thus, Mexico stresses that tuna caught in such ocean areas by any fishing
method that causes adverse effects to dolphins " should be ineligible for the label and therefore
discouraged".594
6.166. However, as discussed in section 6.1.3.1.2 above, we share the Panels' view that the risks
of inaccurate certification, reporting, and/or record-keeping are not:
[R]isks that arise from the use of different fishing methods in different areas of the
ocean, even though fish caught in different areas of the ocean through the use of
different fishing methods may be associated with a greater or smaller risk of inaccurate
labelling depending on a range of interconnected factors, including the persons involved
in the catch, available technology, and applicable domestic and international regulatory
requirements.595
6.167. Accordingly, we f ind that the Panels did not err in stating that "the risks of inaccurate
certification, reporting, and/or record -keeping are not risks that affect dolphins thems elves".596 In
any event, in response to questioning at the hearing, Mexico conceded that there was no evidence
on the record substantiating its assertion that "[d]olphins are at a greater overall risk in ocean areas
with insufficient regulatory oversight, un reliable reporting, IUU fishing and trans shipment at sea
than in ocean areas that do not have these attributes."597
6.168. We have found that the Panels did not err in finding that "setting on dolphins is significantly
more dangerous to dolphins than are other fish ing methods ."598 This finding implies that the

591 Panel Reports, section 7.8.3. We review the Panels' findings concerning the certification requirements
under the 2016 Tuna Measure in section 6.1.5.3 below.
592 Panel Reports, para. 7.549.
593 Mexico's appellant's submission, para. 246. In response to questioning at the hearing, Mexico
indicated that there was evidence on the Panel record illustrating the existence of risks arising from insufficient
regulatory oversight, IUU fishing, and trans-shipment at sea. However, Mexico conceded that there was no
evidence on the record to demonstrate that dolphins are at a greater overall risk in ocean areas where these
attributes exist than in ocean areas where the method of setting on dolphins is practised. Instead, Mexico
clarified that the assertion, in its appellant's submission, about "dolphins [being] at a greater overall risk in
ocean areas with insufficient regulatory oversight, unreliable reporting, IUU fishing and trans-shipment at sea"
was made merely as "a point of argument" in support of its view that the Panels should have turned their
attention to all of the factors that are relevant to the general objective of discouraging fishing practices that
harm dolphins.
594 Mexico's appellant's submission, para. 246. (emphasis added)
595 Panel Reports, para. 7.110 (referring to First Compliance Panel Report, paras. 7.169 and 7.372, and
597 Mexico's appellant's submission, para. 246. As discussed in section 6.1.3.1 above, factors that affect
the ultimate accuracy of the dolphin-safe label are relevant to assessing whether the labelling conditions under
the measure are properly calibrated. In this vein, we recall that the certification requirements and the tracking
and verification requirements, which, inter alia, address such factors, "work together" with the eligibility
criteria of the 2016 Tuna Measure "to limit access to the dolphin-safe label". (Appellate Body Report,
US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.159) We review the Panels' examination of the
certification requirements and the tracking and verification requirements in sections 6.1.5.3 and 6.1.5.4 below.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

distinction in the eligibility criteria between setting on dolphins, on the one hand, and other fishing
methods, on the other hand, is, as the Panels found, "appropriately calibrated to the risks to dolphins
arising from the use of different fishing methods in different areas of the ocean".599 Accordingly, we
find that Mexico has not demonstrated that the Panels erred in reaching the intermediate finding
that the eligibility criteria embodied in the 2016 Tuna Measure are calibrated to the risks to dolphins
arising from the use of different fishing methods in different areas of the ocean.600
6.1.5.3 Certification requirements
6.169. Mexico asserts that the Panels erred in finding that the different certification requirements
are calibrated to the risks to dolphins arising from the use of different fishing methods in different
areas of the ocean. 601 In addition to its arguments challenging the Panels' assessment of the risk
profiles602, Mexico also contends that the Panels erred: (i) by not ad dressing the fact that the
2016 Tuna Measure requires observer certifications in seven US domestic fisheries when the
observers are on board for other reasons 603; (ii) by finding that the measure can be considered
calibrated where it allows higher margins of error for certifications in all ocean areas other than the
ETP; and (iii) by finding that the determination provisions contribute to the calibration of the
measure, even though the determination provisions are only potentially applicable to a fi shery that
has a much higher risk profile than the one found by the Panels for the ETP large purse seine
fishery.604
6.170. The United States maintains that: (i) Mexico is wrong to argue that the Panels erred in not
addressing the observer certification requirement s on the seven US domestic fisheries 605; (ii) the
Panels' analysis and conclusions concerning margins of error did not constitute legal error 606; and
(iii) the Panels did not err in their analysis and conclusions concerning the determination
provisions.607
6.171. As described in section 5 above, with respect to the certification requirements, apart from
large-scale driftnet fishing on the high seas608, the 2016 Tuna Measure makes a distinction between
the ETP large purse seine fishery, on the one hand, and all other fisheries, on the other hand.609 For
tuna caught in the ETP large purse seine fishery, the 2016 Tuna Measure mandates that certification
must be provided by the captain of the vessel and an IDCP-approved observer that: (i) none of the
tuna was caught on a trip us ing a purse seine net intentionally deployed on or used to encircle
dolphins; and (ii) no dolphins were killed or seriously injured during the sets in which the tuna was
caught.610
6.172. As for all fisheries other than the ETP large purse seine fishery, for fishin g trips that began
on or after 21 May 2016, captains of all vessels must certify that: (i) no purse seine net or other
fishing gear was intentionally deployed on or used to encircle (i.e. set on) dolphins during the fishing
trip in which the tuna was caught; and (ii) no dolphins were killed or seriously injured in the sets or
other gear deployments in which the tuna was caught.611 Additionally, under the 2016 Tuna Measure,

599 Panel Reports, para. 7.540.
601 Mexico's Notice of Appeal, para. 9.b (referring to Panel Reports, paras. 7.571-7.573
and 7.600-7.611).
603 Mexico's appellant's submission, para. 258 (referring to First Compliance Report, para. 3.46;
United States' first written submission to the Panels, fn 225 to para. 116).
604 Mexico's appellant's submission, para. 267.
605 United States' appellee's submission, para. 264.
606 United States' appellee's submission, para. 244.
607 United States' appellee's submission, para. 244.
608 Panel Reports, para. 7.51 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)).
609 Panel Reports, paras. 7.51 and 7.54 (referring to 2016 implementing regulations (Panel Exhibits
MEX-2 and USA-2), Section 216.91(a)(1) and (3)).
610 Panel Reports, para. 7.54 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(1)). See also 2016 implementing regulations (Panel Exhibits MEX-2 and USA-2),
Section 216.92.
611 Panel Reports, para. 7.51 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)(iii)).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the captains of the vessels in all fisheries other than the ETP large purse seine fishery must certify
that they have completed the Captain Training Course.612
6.173. Moreover, in addition to the captain's certification described above, in certain circumstances,
certifications from an observer participating in a national or international programme ac ceptable to
the Assistant Administrator will also be required. First, certification by the observer is also required
in the seven US domestic fisheries for which the Assistant Administrator has determined that
observers are qualified and authorized to make the relevant certifications 613, and when such an
observer is already on board the fishing vessel for reasons unrelated to the dolphin -safe labelling
regime.614
6.174. Furthermore, pursuant to the 2016 Tuna Measure, tuna caught in all fisheries other than the
ETP large purse seine fishery may, under specified circumstances, require an observer615 certification
in addition to the captain certification. This is the case where the Assistant Administrator has
determined that in a fishery other than the ETP large purse seine fishery: (i) there is a regular and
significant association between dolphins and tuna (similar to the association between dolphins and
tuna in the ETP); or (ii) a regular and significant mortality or serious injury of dolphins is occurring.
The captain an d observer must certify that: (i) no purse seine net or other fishing gear was
intentionally deployed on or used to encircle (i.e. set on) dolphins during the trip on which the tuna
was caught; and (ii) no dolphins were killed or seriously injured in the sets or other gear deployments
in which the tuna was caught.616
6.175. In their analysis of the certification requirements, the Panels noted that, unlike the eligibility
requirements, the certification requirements (and the tracking and verification requirements) dr aw
distinctions based on both fishin g methods and ocean areas (i.e. fisheries), rather than solely on
different fishing methods. Specifically, the distinctions are made between the ETP large purse seine
fisheries and all other fisheries. Thus, the certification requirements that apply in the ETP large purse
seine fishery apply to all large purse seine vessels fishing in the ETP, regardless of whether those
vessels actually set on dolphins. Therefore, the Panels considered the question before them to be
whether the distinction that the 2016 Tuna Measure makes between the ETP large purse seine
fishery and all other fisheries is calibrated.617
6.176. In this regard, the Panels considered that the finding, from the original and first compliance
proceedings, that setting on dolphins is practised routinely and systematically only in the ETP
continued to be relevant to these compliance proceedings. 618 The Panels also found relevant the
finding of the original panel that "the association between schools of tunas and dolphins does not
occur outside the ETP as frequently as it does within the ETP ."619 In addition, the Panels recalled
their conclusion that setting on dolphins is a particularly dangerous fishing method that is liable to

612 Panel Reports, para. 7.53 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)(iii)(B)).
613 In the first compliance panel proceedings, the United States identified the seven domestic fisheries
where tuna is regularly harvested as: (i) American Samoa Pelagic Longline Fishery; (ii) Atlantic Bluefin Tuna
Purse Seine Fishery; (iii) Atlantic Highly Migratory Species Pelagic Longline Fishery; (iv) California Deep-set
Pelagic Longline Fishery; (v) California Large-mesh Drift Gillnet Fishery; (vi) Hawaii Deep-set Longline Fishery;
and (vii) Hawaii Shallow-set Longline Fishery. (United States' second written submission to the first compliance
panel, para. 128 and fn 244 thereto (referring to Determination of Observer Programs as Qualified and
Authorized by the Assistant Administrator for Fisheries, United States Federal Register, Vol. 79, No. 134
(14 July 2014) (First Compliance Panel Exhibit US-113), p. 40720))
614 Thus, in these fisheries, tuna caught on a trip where no observer is already on board may still be
labelled dolphin-safe with only a captain's certification. (See First Compliance Panel Report, para. 3.46;
Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 6.23 and fn 171 thereto)
615 This observer is described as one "participating in a national or international program acceptable to
the Assistant Administrator". (2016 implementing regulations (Panel Exhibits MEX-2 and USA-2),
Section 216.91(a)(3)(v). See also Panel Reports, para. 7.68)
616 Panel Reports, para. 7.68 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)(v)).
617 Panel Reports, para. 7.568.
618 Panel Reports, para. 7.570.
619 Panel Reports, para. 7.569 (quoting Original Panel Report, para. 7.520 (fn omitted; emphasis
original)). We also take note of the Panels' observation, in the context of their assessment of the risk profiles,
that "due to the significant and regular association between tuna and dolphins in the ETP, even purse seine
fishing without setting on dolphins might end up, inadvertently, interacting with dolphins, perhaps even at a
higher rate than purse seine fishing by setting on dolphins or other fishing methods in other areas of the
ocean." (Ibid., para. 7.333)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

cause observable and unobservable harms to dolphins at rates significantly in excess of those caused
by other fishing methods.620 The Panels observed that, in the ETP, unlike in other areas of the ocean,
large purse seine vessels are permitted to and actually can set on dolphins in a consistent and
systematic manner. The Panels highlighted that one of the purposes of the certification requirements
in the ETP is precisely to certify that dolphins were not set on, even though the fishing vessels could,
both technically and legally, have set on dolphins. Thus, in the Panels' view, it is both the technical
and legal possibilities of setting on dolphins and the fact that dolphin sets occur in a consistent and
systematic manner in the ETP large purse seine fishery that give this fishery its special risk profile.621
6.177. On appeal, Mexico challenges the Panels' finding that the ETP large purse seine fishery has
a "special risk profile", arguing that the Panels failed to compare individual fisheries.622 We first note
that Mexico's arguments concerning the Panels' alleged failure to assess individual fisheries repeat
Mexico's arguments addressed in section 6.1.4 above.623 In particular, we recall that, in assessing
whether there is "treatment no less favourable" under Article 2.1 of the TBT Agreement for the
purpose of this dispute, the analysis should "focus[] on the regulatory distinction(s) causing the
detrimental impact on imported products". 624 With respect to the certification requirements, the
2016 Tuna Measure makes a distinction between the ETP large purse seine fishery and all other
fisheries.625 We also recall our finding that, with respect to the certification requirements (and the
tracking and verification requirements), the Panels adopted the correct approach in comparing the
risk profiles of individual fisheries, because these requirements make a distinction on the basis of
both fishing method and ocean area. 626 Moreover, as discussed in section 6.1.4 above, the Panels
examined all available evidence before them regarding the risks to dolphins in individual fisheries,
and Mexico has not substantiated its claim that the Panels erred in assessing such risks. On the basis
of their assessment of risks to dolphins in individual fisheries, the Panels established that "in the
ETP, unlike in other areas of the ocean, large purse seine vessels are permitted to and actually can
set on dolphins in a consistent and systematic manner." 627 Thus, we understand that, having
assessed the risk profiles of individual fisheries, the Panels established that, when compared to the
ETP large purse seine fishery, which has a "special risk profile", all the other fisheries are similar in
their risk pro files insofar as in none of them is setting on dolphins practised consistently or
systematically.
6.178. In this regard, we take note of Mexico's allegation that the Panels did not address the fact
that only certain large purse seine vessels in the ETP, i.e. those that have been assigned an individual
DML, "are permitted to and actually can set on dolphins in a consistent and systematic manner".628
As a preliminary matter, we observe that Mexico's argument that vessels either set on dolphins or
do not, and that the ETP fishery can be divided into vessels with and without DMLs, was not made
before the Panels and finds no support on the Panel record.629
6.179. More importantly, in their evaluation of the certification requirements, the Panels expressly
addressed the issue of why the ETP large purse seine fisheries have a special risk profile, regardless
of whether setting on dolphins is actually practised. In particular, the Panels noted that:
[T]he crucial point is that in the ETP, unlike in other areas of the ocean, large purs e
seine vessels are permitted to and actually can set on dolphins in a consistent and

620 Panel Reports, para. 7.571.
621 Panel Reports, para. 7.572.
623 Mexico's appellant's submission, para. 252.
624 Appellate Body Reports, US – COOL (Article 21.5 – Canada and Mexico), para. 5.93. See also
Appellate Body Report, US – Tuna II (Mexico), para. 286.
625 See para. 6.65 above. See also Panel Reports, paras. 7.51-7.54; 2016 implementing regulations
(Panel Exhibits MEX-2 and USA-2), Section 216.91(a)(1) and (3).
626 See para. 6.77 above.
628 Mexico's appellant's submission, para. 256.
629 To the contrary, the United States, in its appellee's submission, points us to evidence on the Panel
record that indicates that vessels with DMLs may not set on dolphins during particular trips either because they
choose not to or because they have reached their DML for the year. Further, DMLs can be transferred or
changed mid-year, so the fact that a vessel was not given a DML does not mean that it can never legally set on
dolphins that year. (United States' appellee's submission, para. 262 (referring to AIDCP, Report on the
International Dolphin Conservation Program, Doc. MOP-28-05, 18 October 2013 (Panel Exhibit MEX-8),
pp. 2-3; AIDCP, Report on the International Dolphin Conservation Program, Doc. MOP-32-05, 20 October 2015
(Panel Exhibit USA-15), pp. 2-3))
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

systematic manner. … Thus, it is not simply the fact that dolphins are set on in the ETP
large purse seine fishery that gives it its "special risk profile", but the fact that only in
the ETP are large purse vessels actually able and permitted to set on dolphins. Thus, in
our view, it is both the technical and legal possibility of setting on dolphins and the fact
that dolphin sets occur in a consistent and systematic manner in the ETP large purse
seine fishery that gives this fishery its special risk profile.630
6.180. Beyond its argument concerning DMLs, which we have addressed above, Mexico does not
offer additional reasons why the above-quoted statements from the Panels are erroneous. Moreover,
as we found in section 6.1.4.2 above, Mexico has not demonstrated that the Panels failed to assess
the risk profiles of individual fisheries. 631 Having found no legal error in the Panels' assessment of
risk profiles, we see no reason to void t he Panels' finding that "it is both the technical and legal
possibility of setting on dolphins and the fact that dolphin sets occur in a consistent and systematic
manner in the ETP large purse seine fishery that gives this fishery its special risk profile."632
6.181. Mexico also alleges that the Panels failed to address the fact that the 2016 Tuna Measure
requires observer certifications in seven US domestic fisheries when the observers are on board for
other reasons.633 For Mexico, this raises questions such as wheth er those seven fisheries are "high
risk", or whether the enhanced certification requirements are imposed for reasons other than those
identified by the Panels. 634 The United States points out that, before the Panels, Mexico never put
forward any argument tha t the additional observer requirement i mposed on some US vessels in
US fisheries renders the 2016 Tuna Measure not even-handed. The United States adds that Mexico
has not suggested a reason for claiming that the Panels' failure to refer to this observer certification
requirement renders their analysis "legally in error". 635 In response to questioning at the hearing,
Mexico clarified that its argument was not that the observer certification requirement, in and of
itself, renders the measure not even-handed. Rather, Mexico was referring to the Panels' failure, in
their analysis, to address this requirement as yet another illustration of the incoherence of the
Panels' calibration analysis and of their failure to take account of all relevant factors.
6.182. We observe that Mexico's argument concerns an aspect of the certification requirements on
which the Panels made no finding . Before the Panels in these compliance proceedings, Mexico
referred to the observer certifications reflected in the first compliance panel report in describing the
certification requirements under the 2016 Tuna Measure. 636 However, Mexico did not raise specific
concerns regarding these observer certifications, either during the first compliance proceedings or
before the Panels in these compliance proceedings.
6.183. We recall that, in the first compliance proceedings, the United States identified seven
domestic fisheries where tuna is regularly harvested. 637 These seven US fisheries have a certain
level of observer coverage, meaning that observers may be on board the fishing vessels in these
fisheries for reasons unrelated to the dolphin -safe labelling regime. 638 As noted by the first
compliance panel and th e Appellate Body, the Assistant Administrator has determined that, in
addition to the captain's certification, the observers in these fisheries are qualified and authorized

630 Panel Reports, para. 7.572. (emphasis original; fns omitted)
631 See para. 6.99 above.
632 Panel Reports, para. 7.572.
634 Mexico's appellant's submission, para. 258 (referring to First Compliance Panel Report, para. 3.46;
United States' first written submission to the Panels, fn 225 to para. 116, in turn referring to 2016
implementing regulations (Panel Exhibits MEX-2 and USA-2), Section 216.91(a)(3)(iv); First Compliance Panel
Report, para. 3.45).
635 United States' appellee's submission, para. 264.
636 Mexico's first written submission to the Panels, para. 128 (referring to First Compliance Panel Report,
para. 3.46).
637 See supra, fn 613.
638 United States' second written submission to the first compliance panel, para. 128 and fn 245 thereto
(referring to NMFS, National Observer Program FY 2012 Annual Report (2013) (First Compliance Panel Exhibit
US-114), pp. 29-38).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

to make the certifications required for the dolphin -safe label. 639 Thus, with respect to these
seven US fisheries, the 2016 Tuna Measure, similar to the 2013 Tuna Measure, conditions access to
the dolphin-safe label on the provision of both captain and observer certifications, but only when an
observer is already on board the vessel. It is unclear to us why the presence of observers on board
fishing vessels in the seven US fisheries, for reasons unrelated to the dolphin-safe labelling regime,
"raises questions such as whether those seven fisheries are 'high-risk'".640
6.184. In any event, regardless of the reasons for which such an observer may already be on board
the vessel under the 2016 Tuna Measure, we note that the observer is required to prepare a written
statement certifying that: (i) no dolphins were killed or seriously injured in the sets or other gear
deployments in which the tuna was caught; and (ii) in purse seine fisheries, no purse seine net was
intentionally deployed on or used to encircle dolphins during the trip on which the tuna was caught.641
We recall that the aim of the Panels' calibration analysis was to establish whether "the distinctions
drawn between different tuna fishing methods and different areas of the oceans could be explained
or justified by the differences in risk associated with such fishing methods and areas of the
oceans."642 On its face, this requirement appears to reduce the differences in the requirements
applicable to the ETP large purse seine fishery and those applicable to all other fisheries, by making
use of an already available observer resource on board the vessel to complement the efforts of the
captain of the vessel in meeting the certification requirem ents. In our view, therefore, Mexico has
not demonstrated how this observer requirement renders the treatment accorded un der the
2016 Tuna Measure to the different fisheries not even-handed.
6.185. We now turn to Mexico's contention that the Panels did not approa ch the calibration test
from the perspective of accuracy, taking account of the objectives of the measure, but rather from
the perspective of how much inaccuracy should be tolerated, notwithstanding the objectives. Mexico
points to the Panels' statement th at "[w]e … do not believe that, by tolerating a higher or lower
margin of error, the certification requirements conflict with the objectives of the
2016 Tuna Measure."643 Mexico contends that the Panels did not explain how tolerating error can be
reconciled with, or rationally connected to, the consumer -information and dolphin -protection
objectives of the measure. Mexico posits that, if the Panels had done so, they may have found that
the detrimental impact caused by the 2016 Tuna Measure cannot be justified on the basis of
regulatory distinctions that tolerate different margins of error.
6.186. The United States argues that the Panels' statements concernin g margins of error in th ese
compliance proceedings do not suggest that there are differences in label accuracy for tuna produced
from the ETP large purse seine fishery and other fisheries. For the United States, a more sensitive
mechanism does not necessarily mean a more accurate label. Rather, the risk profile of a fishery
must also be taken into account.644
6.187. As described in section 6.1.3.1.3 above, the Panels first introduced the term "margin of
error" when examining, as a general matter, the relevance of the risk of inaccurate labelling to their
calibration analysis. As analysed in that section, the Panels used this term to refer to the sensitivity
of the relevant labelling conditions. In that context, we find that the Panels correctly recognized that
the accuracy of the ultimate label depends not only on the sensitivity of the labelling conditions, but

639 First Compliance Panel Report, para. 3.46; Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), fn 171 to para. 6.23. See also 2016 implementing regulations (Panel Exhibits MEX-2
and USA-2), Section 216.91(a)(3)(iv). The United States pointed to evidence on the record of the first
compliance panel indicating that the NMFS relies on fishery observers to collect data from US commercial
fishing and processing vessels, as well as from some shore-side processing plants. In response to questioning
at the hearing in these compliance proceedings, the United States indicated that the information collected by
fisheries observers is used for a wide range of assessment and monitoring purposes, and supports the
management and conservation of fisheries, protected resources, and ecosystems throughout the United States.
(NMFS, National Observer Program FY 2012 Annual Report (2013) (First Compliance Panel Exhibit US-114),
pp. vi-vii and 1-4)
640 Mexico's appellant's submission, para. 258.
641 2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Section 216.91(a)(3)(iv).
642 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.108 (referring to
Appellate Body Report, US – Tuna II (Mexico), paras. 282-284).
644 United States' appellee's submission, para. 269 (referring to Panel Reports, paras. 7.599,
7.603-7.604, and 7.607).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

also on the level of risks to dolphins in a fishery. In our view, the Panels used the term "margin of
error" in the same sense in their evaluation of the certification requirements.
6.188. Mexico takes issue with the Panels' statement that, "[i]n the context of the certification
requirements, … it is calibrated for the United States to tolerate a higher margin of error in respect
of fisheries other than the ETP large purse seine fishery and to tolerate a lower margin of error inside
the ETP large purse seine fishery." 645 The Panels' statement that Mexico refers to should be
understood in its proper context. Specifically, the Panels were addressing Mexico's argument that
the use of a less sensit ive mechanism outside the ETP large pur se seine fishery cannot be
even-handed if it would result in the label becoming less accurate. 646 In the Panels' view, Mexico's
argument appeared to be premised on the notion that certification can guarantee accurate labelling
in every case. However, the Panels considered the more pertinent question to be whether the
possibility of error is commensurate with the different risks to dolphins arising from the use of
different fishing methods in different areas of the ocean. Accordingly, the Panels considered that "it
is calibrated"647 for the United States to require a more sensitive mechanism in the ETP large purse
seine fishery, while "tolerating" a less sensitive mechanism in other fisheries, which have relatively
lower risk profiles. For the Panels, this distinction addresses the relative risks posed to dolphins in
the ETP large purse seine fishery, on the one hand, and other fisheries, on the other hand, in a way
that is calibrated to the risk profiles of those fisheries.648
6.189. The Panels' statements above, read in their proper context, confirm our view that the Panels
correctly focused on the question whether the sensitivity of the labelling conditions under the
measure is calibrated to the level of risks to dolphins so as to e nsure the accuracy of the ultimate
label. Indeed, as the Panels noted, the mere fact that a vessel has an observer on board does not
necessarily, or by itself, mean that that vessel will produce a more accurate certification.649 Rather,
accuracy is a function of potentially many variables, including not only the reporting requirements
in place, but also the different levels of dolphin interaction, mortality, and serious injury in different
fisheries.650 Thus, while an observer may strengthen the certification, such additional strength may
not always be needed, for example, in fisheries where the risk profile is relatively low.651
6.190. Still with regard to the potential risk of inaccuracy of the dolphin -safe label, we take note
of Mexico's assertion that the panel in the first compliance proceedings found that "it may be easier
or more likely for dolphin -safe certifications made only by captai ns to be inaccurate", with
"the consequence" that "it may be more likely that tuna caught by vessels other than large purse
seine vessels in the ETP will be inaccu rately labelled as dolphin -safe."652 However, the first
compliance panel did not make a definitive finding on this issue. Rather, the first compliance panel,
in making the statements to which Mexico refers , also explained th at, although the United States
seemed to have made the "concession that observer certification heightens or increases the accuracy
and reliability of the label", such a concession "does not entail the conclusion that, without observers,
captains' certifications are always and necessarily 'inherently unreliable'". 653 The first compliance
panel added that, in its view, it was "not necessary to make a definitive finding on this point".654
6.191. In any event, the first compliance panel was addressing the 2013 Tuna Measure. The Panels
in these compliance proceedings noted that, under the architecture of the 2016 Tuna Measure, the
private tuna companies that supply the US tuna market are subject to the requirements of the
2016 Tuna Measure, and it is they that must ensure that the products they sell meet the conditions
of US law, "including that the captain certifications are accurate". 655 The Panels considered that,
unlike the situation under the 2013 Tuna Measure, the training course incorporated in the
2016 Tuna Measure contains meaningful information concerning key aspects of the certification

645 Panel Reports, para. 7.602.
646 Panel Reports, para. 7.604 (referring to Mexico's response to Panel question No. 86, para. 147).
647 Panel Reports, paras. 7.602 and 7.606.
648 Panel Reports, para. 7.606 (referring to Appellate Body Reports, US – Tuna II (Mexico)
649 Panel Reports, para. 7.608.
650 Panel Reports, paras. 7.123 and 7.608.
651 Panel Reports, para. 7.608.
652 Mexico's appellant's submission, para. 263 (quoting First Compliance Panel Report, para. 7.168
(emphasis original)).
653 First Compliance Panel Report, para. 7.168. See also United States' appellee's submission, para. 268.
655 Panel Reports, para. 7.591.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

process that would assist captains to understand and properly carry out their responsibility to certify
the dolphin-safe status of a set or other gear deployment. The Panels also considered that the
training requirement is embedded within a sufficiently enforceable regulatory framework and is
therefore not meaningless or unenforceable, as Mexico contended. In addition, the Panels took note
that the Captain Training Course is now available online in nine languages, including the languages
of all of the largest suppliers of tuna and tuna products, such as the Philippines, Chinese Taipei, and
Thailand, which Mexico argues are significantly deficient in the control and monitoring of fishing
activities.656 As the Panels explained, the training course was being actively disseminat ed by the
United States itself to facilitate the effective implementation of the training re quirement.657 In our
view, the above findings illustrate the ways in which the Panels took account of the potential risks
of inaccuracy when undertaking their calibration analysis.
6.192. Finally, we address Mexico's allegation that the Panels erred in finding that the determination
provisions "help to ensure that the 2016 Tuna Measure treats similar situations similarly" and "help
to establish a mechanism for enforcing the eligibility criteria that are properly calibrated to the
different risk profiles in different fisheries".658 Mexico argues that the Panels failed to take fully into
account Mexico's assertion that the determination provisions do not allow calibration of the
certification requirement to the extreme danger to dolphins in fisheries where stock sustainability is
being threatened and a small number of dolphin mortalities can have disastrous consequences. For
Mexico, the Panels' approach also ignored the high number of dolphin mortalities and serious injury
when measured on an absolute basis.659
6.193. We recall that, pursuant to the 2016 Tuna Measure, tuna caught in all fisheries other than
the ETP large purse seine fishery may require an observer660 certification in addition to the captain
certification where the Assistant Administrator has determined that in a fish ery other than the
ETP large purse seine fishery: (i) there is a regular and significant association between dolphins and
tuna (similar to the association between dolphins and tuna in the ETP); or (ii) a regular and
significant mortality or serious injury of dolphins is occurring. The captain and observer must certify
that: (i) no fishing gear was intentionally deployed on or used to encircle dolphins during the trip on
which the tuna was caught; and (ii) no dolphins were killed or seriously injured in the sets or other
gear deployments in which the tuna was caught.661
6.194. We note that Mexico 's arguments concerning dolphin -stock sustainability and the
Panels' reliance on the per set methodology (as opposed to absolute levels of mortalities and serious
injuries) mirror its arguments relating to the Panels' evaluation of the risk profiles. These arguments
have already been addressed and rejected in section 6.1.4.4 above.662
6.195. In addition, Mexico contends that the Panels failed to fully take into account the fact that, in
applying the determination provisions, the Uni ted States relies on "a 20-year average of direct
dolphin mortalities caused by dolphin sets in the ETP" between 1997-2017 for determining whether
there is a regular and significant mortality or serious in jury of dolphi ns in a particular fishery. 663

656 Panel Reports, paras. 7.594 and 7.675.
657 Panel Reports, paras. 7.594-7.595.
659 Mexico's appellant's submission, para. 266 (referring to Panel Reports, para. 7.683).
660 An observer is described as one "participating in a national or international program acceptable to
the Assistant Administrator". (2016 implementing regulations (Panel Exhibits MEX-2 and USA-2),
Section 216.91(a)(3)(v). See also Panel Reports, para. 7.68)
661 Panel Reports, para. 7.68 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.91(a)(3)(v)). We take note of the Panels' explanation that the determination provisions
under the 2016 Tuna Measure have been applied on at least one occasion. On 28 September 2016, the
Assistant Administrator issued a determination, based on the best information available, that a regular and
significant mortality of dolphins was occurring in the Indian Ocean gillnet fisheries. The determination provided
that, for any tuna product produced from these fisheries to be marketed as dolphin-safe in the United States,
the product would have to be accompanied by a certification by an observer from a qualified and authorized
observer program and a certification attesting to the catch documentation, the substance of the dolphin-safe
labelling standards, and the chain of custody information. (See Panel Reports, paras. 7.685-7.686)
662 See also paras. 6.122-6.143 above.
663 Mexico's appellant's submission, para. 266 (referring to Panel Reports, para. 7.683). The 20-year
average encompasses a period that starts two years before the entry into force of the AIDCP regime when
mortalities were higher. The 20-year period also covers the years when there was dramatic reduction of
observed dolphin mortality in the ETP, following the entry into force of the AIDCP regime. (See para. 5.2
above; Original Panel Report, paras. 2.39 and 7.609)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Mexico contends that, because the 20-year average encompasses a period when dolphin mortalities
were higher in the ETP, the US benchmark under the determination provisions is materially higher
than the average mortalities between 2009 and 2015, on which the Panels relied "elsewhere". 664
According to Mexico, the Panels did not address this inconsistency in the data on which they relied.
Mexico further contends that the Panels' finding suggests an approach under which, if a fishery is
found to have a lower per set mortality rate t han the ETP (based on a 20 -year average), it is
automatically assumed that there are no, or de minimis, risks to dolphins. Mexico considers this to
be "an erroneous application of the test for calibration".665
6.196. We recall that, in its Notice of Appeal, Mexico expressly challenges the Panels' evaluation of:
(i) the eligibility criteria; (ii) the certification requirements; (iii) the tracking and verification
requirements; and (iv) the 2016 Tuna Measure as a whole. 666 Mexico's Notice of Appeal does not
include a claim challenging the Panels' discrete findings with respect to the determination
provisions.667 Yet, in its appellant's submission, Mexico appears to challenge these very findings.
Moreover, we no te that this allegation by Mexico does not directly concern the heightened
certification requirements, which follow once the Assistant Administrator has made the
determination: (i) that a fishery other than the ETP large purse seine fishery has either a re gular
and significant association between dolphins and tuna (similar to the association between dolphins
and tuna in the ETP); or (ii) that a regular and significant mortality or serious injury of dolphins is
occurring in a given fishery.668 Rather, Mexico's allegation concerns the methodology adopted by the
United States to allow the Assistant Administrator to make such determinations, which the Panels
did not address in their evaluation of the certification requirements, and which Mexico does not
separately challenge on appeal. Furthermore, in response to questioning at the hearing, Mexico
explicitly stated that it was not challenging the Panels' discrete findings on the determination
provisions. Instead, Mexico explained that its reference to the Panels' findings was merely aimed at
pointing out that the determination provisions do not remedy the lack of even-handedness of the
2016 Tuna Measure.
6.197. An assessment of the even -handedness of the 2016 Tuna Measure "must take account of
the fact that its various elements … establish a series of conditions of access to the dolphin -safe
label that are cumulative and highly interrelated". 669 Thus, to the extent that Mexico's arguments
concerning the US methodology for applying the determination provisions impact the
even-handedness of the 2016 Tuna Measure, owing to the "cumulative and highly interrelated"
aspects of the various conditions of access to the dolphin-safe label, we consider Mexico's arguments
to be properly before us.
6.198. Mexico's arguments on appeal suggest t hat there is an inconsistency between the Panels'
reliance on 2009 -2015 data from the ETP in arriving at one finding and the Panels' review of the
data drawn from a 20 -year average covering 1997 and 2017 in their evaluation of the
US methodology for applying the determination provisions.670 Mexico's arguments appear to conflate
two different aspects of the Panels' analyses. First, we recall that, in assessing whether the
2016 Tuna Measure is consistent with Article 2.1 of the TBT Agreement, the Panels first e xamined
the risk profiles of the different fishing methods, as used in different areas of the ocean. In this
regard, the Panels found that setting on dolphins caused both observable and unobservable harms
to dolphins.671 Specifically, the Panels found that, "[w]ith regard to observable harms, … setting on
dolphins in the ETP has caused on average 91.15 dolphin mortalities between 2009 and 2015." 672
For the purpose of reviewing the eligibility criteria under the 2016 Tuna Measure, the Panels relied
on, inter alia, this finding to conclude that "overall, the risk profile of setting on dolphins is much
higher than that of each of the other six fishing methods used to catch tuna."673

664 Mexico's appellant's submission, para. 266.
665 Mexico's appellant's submission, para. 266.
666 Mexico's Notice of Appeal, para. 9.a-d.
667 Panel Reports, paras. 7.677-7.702.
668 Panel Reports, para. 7.677.
669 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.166.
670 Mexico's appellant's submission, para. 266. In challenging these findings of the Panels, we note that
Mexico does not question the objectivity of the Panels' assessment of the facts, as required by Article 11 of the
DSU.
671 Panel Reports, para. 7.518.
672 Panel Reports, para. 7.519.
673 Panel Reports, para. 7.525.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.199. Second, in assessing the determination provisions under the 2016 Tuna Measure, the Panels
examined, inter alia, the methodology that the United States uses under the determination
provisions to assess the levels of mortality and serious injury to dolphins. In this regard, the Panels
observed that the United States uses an "average of per set data" collected in the ETP between 1997
and 2017 (which the United States calculated as 0.1265 dolphin mortalities per set).674 Thus, in the
context of the determination provisions, the Panels did not choose the data to rely on and were
instead tasked with examining whether the methodology relied on by the United States in applying
their determination provisions was arbitrary, as had been alleged by Mexico.
6.200. Therefore, unlike what Mexico's arguments suggest, there is no inconsistency between the
Panels' reliance on 2009-2015 data to examine the risk profiles of different fishing methods (based
on the evidence on the record of their use in different areas of the ocean), on the one hand, and the
Panels' assessment of the US methodology for applying the determination provisions based on data
drawn from a 20-year average covering 1997-2017, on the other hand.675
6.201. Mexico also contends that the Panels' finding, in connection with the determination
provisions, suggests an approach pursuant to which, if a fishery is dee med to have a lower per set
mortality rate than the ETP (based on a 20 -year average), and therefore not designated under the
determination provisions as requiring heightened certification requirements, "it is automatically
assumed that there are no or de minimis risks to dolphins."676 We consider that Mexico's argument
fails to recognize that, even absent a designation under the determination provisions, pursuant to
the 2016 Tuna Measure, all tuna products exported from, or offered for sale in, the United States
are subject to certification and tracking and verification requirements, regardless of the fishery from
which they originate. Likewise, Mexi co's argument finds no support o n the Panel record or in the
Reports of the Panels. The Panels, having reviewed the evidence on the record of risks to dolphins
arising from the use of different fishing methods in different areas of the ocean, concluded that, at
present, while some of the other fisheries manifested some risks to dolphins677, the vast majority of
the world's fisheries have a lower risk profile than the ETP large purse seine fishery.678
6.202. Moreover, the question before the Panels was not whether th e fisheries, other than the
ETP large purse seine fishery, manifested any risk to dolphins. Rather the question before the Panels
was whether the determination provisions, by imposing stricter certification and tracking and
verification requirements in specific circumstances, allow the 2016 Tuna Measure to address similar
risks in a similar manner, therefore ensuring that the 2016 Tuna Measure is properly calibrated to
the risks to dolphins. The Panels answered this question and found that the determination provisions
create flexibility "that helps to ensure that the 2016 Tuna Measure is calibrated to the different risks
to dolphins arising from the use of different fishing methods in different areas of the ocean". 679
In light of the above analysis, we see no reason to disagree with this finding by the Panels.

674 Panel Reports, para. 7.698 (referring to Dolphin Mortalities Per Set Due to ETP Dolphin Sets and in
Other Fisheries (Panel Exhibit USA-111)).
675 We understand that Mexico's main argument on appeal repeats its argument before the Panels that
the 20-year average (between 1997-2017) artificially inflates the benchmark that the United States relies on in
applying its determination provisions. At the same time, as indicated in paragraph 6.196 above, Mexico
explicitly stated that it was not challenging the Panels' discrete findings on the determination provisions where
the Panels addressed the US methodology. In any event, given the Panels' uncontested finding that the
additional requirements imposed by the AIDCP had significantly reduced the extent of mortality and serious
injury in the ETP large purse seine fishery, we see no reason to disagree with the Panels' explanation that, for
the purpose of the determination provisions, it would be misleading to compare, as Mexico suggests, the risk
profile of the ETP in 2015, following the adoption of heightened certification and tracking and verification
requirements pursuant to the AIDCP, with the risk profile of other fisheries that are not subject to similar
requirements. (See Panel Reports, para. 7.699) Moreover, even under the 2009-2015 data, with the exception
of the Indian Ocean gillnet fishery, the Panels explained that, based on their review of the available evidence
on the record, the other fisheries have a lower risk profile than the ETP large purse seine fishery. (Panel
Reports, paras. 7.441, 7.572, 7.685, and 7.699)
676 Mexico's appellant's submission, para. 266. (emphasis original) In response to questioning at the
hearing, Mexico acknowledged that the use of "de minimis" in its argument may have overstated the issue.
However, Mexico insisted that the point that it was making was that the determination provisions were
deficient because they did not take into account certain relevant factors, such as the mortality rates in a given
fishery.
677 Panel Reports, para. 7.541.
678 Panel Reports, para. 7.700.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.203. In sum, we have found that the Panels adopted the correct approach in comparing the risk
profiles of individual fisheries, because the certification requirements make a distinction on the basis
of both fishing method and ocean area. Having found no legal error in the Panels' assessment of risk
profiles, we consider that the Panels did not err in finding that the ETP large purse seine fishery has
a special risk profile that distinguishes it from other fisheries. We have also addressed and rejected
all of Mex ico's arguments challenging the Panels' assessment of the certification requirements ,
including the allegation that the Panels did not take into account the risks of inaccuracy in their
calibration analysis.
6.204. For all of these reasons, we find that Mexico has not demonstrated that the Panels erred in
arriving at the intermediate finding that the different certification requirements are calibrated to the
risks to dolphins arising from the use of different fishing methods in different areas of the ocean.680
6.1.5.4 Tracking and verification requirements
6.205. Mexico claims that the Panels erred in finding that, although there remain differences
between the NOAA and AIDCP regimes with respect to tracking and verification, such differences
have been considerably narrowed in the 2016 Tuna Measure, and that the remaining differences are
calibrated to the differences in the risk profile of the ETP large purse seine fishery compared to other
fisheries.681
6.206. As described in section 5 above, the tracking and verificat ion requirements under the
2016 Tuna Measure concern the physical segre gation of dolphin -safe from non-dolphin-safe tuna,
from the moment of harvest and throughout the entire processing chain. 682 Specifically, the
2016 Tuna Measure prescribes the documentation requirements for re cording and verifying
segregation and the corresponding regulatory oversight. Like the certification requirements, the
tracking and verification requirements distinguish between the ETP large purse seine fishery 683 and
all the other fisheries.684
6.207. We observe that Mexico's arguments on appeal, as well as the Panels' analysis of the tracking
and verification requirements, make extensive reference to the evolution of the tracking and
verification requirements under the 2016 Tuna Measure from those that were under the 2013 Tuna
Measure, in light of the first compliance panel and Appellate Body findings thereon. Accordingly,
in order to situate the issue on appeal in its proper context, we provide a brief background of the
tracking and verification requirements under the 2013 Tuna Measure and the first compliance panel
and Appellate Body's findings thereon. Next, we briefly describe the tracking and verification
requirements under the 2016 Tuna Measure before summarizing the Panels' findings. Thereafter,
we address M exico's claims that the Panels erred in making their findings on the tracking and
verification requirements under the 2016 Tuna Measure.
6.1.5.4.1 Summary of the findings from the first compliance proceedings regarding
tracking and verification requirements under the 2013 Tuna Measure
6.208. Under the 2013 Tuna Measure, the tracking and verification requirements primarily
concerned the physical segregation of dolphin -safe from non-dolphin-safe tuna, from the moment
of harvest and throughout the entire processing chain. Like the 2016 Tuna Measure, the 2013 Tuna
Measure prescribed the documentation requirements for recording and verifying segregation and the
corresponding regulatory oversight. The first compliance panel observed that there were differences
between the tracking and verification requirements that applied to the ETP large purse seine fishery,
on the one hand, which was governed by the AIDCP Tracking and Verification System, and all other
fisheries, on the other hand. The first compliance panel considered that thes e differences related

680 Panel Reports, para. 7.611.
681 Mexico's Notice of Appeal, para. 9.c (referring to Panel Reports, paras. 7.650, 7.652,
and 7.671-7.676).
682 Panel Reports, para. 7.613 (referring to 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(c)(1)-(3); Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
para. 6.12).
683 Panel Reports, paras. 7.56-7.61. See also 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(a)-(c)(1).
684 Panel Reports, para. 7.62 (quoting United States' first written submission to the Panels, para. 143).
See also 2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Sections 216.91(4)-(5)
and 216.93(c)(2)-(3) and (d)(4).
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

"broadly to the depth, accuracy, and degree of government oversight of the tracking and verification
systems".685
6.209. The first compliance panel used the word "depth" to refer to the point to which tuna can be
traced back. According to the first compliance panel, pursuant to the record -keeping requirements
applicable to the ETP large purse seine fishery, tuna could be traced all the way back to the particular
set in which the tuna was caught and the particular well in which it was stored.686 By contrast, in all
other fisheries, tuna could only be traced back to the vessel and trip on which it was caught.687
6.210. The first compliance panel used the word "accuracy" to describe the degree to which a
captain's (or, where applicable, observer's) statement properly describes the lot of tuna to which it
is assigned. The first compliance panel found that the accuracy attributable to the records required
under the ETP large purse seine fishery was much more robust than that of the records required
with respect to all other fisheries.688
6.211. Finally, the first compliance panel used the term "government oversight" to refer to the
extent to which a national, regional, or international authority was involved in the tracking and
verification process. The first compliance panel found that, unlike in the other fisheries, in the
ETP large purse seine fishery, information concerning every stage of the tuna catch and canning
process was made available to national and regional authorities. Thus, these authorities were, in
principle, able to verify at any stage of the catch and canning process whether a particular batch of
tuna harvested in the ETP large purse seine fishery was dolphin-safe.689
6.212. Hence, the first compliance panel found that the differences in depth, accuracy, and
government oversight showed that the tracking and verification system in place outside the
ETP large purse seine fishery is less burdensome than that inside the ETP. Therefore, the first
compliance panel found that the different tracking and verification requi rements modify the
conditions of competition in the US tuna market to the detriment of like Mexican tuna and tuna
products.690 The first compliance panel further concluded that the 2013 Tuna Measure was
inconsistent with Article 2.1 of the TBT Agreement because, inter alia, the United States had failed
to show that the detrimental impact caused by the tracking and verification requirements stems
exclusively from a legitimate regulatory distinction.691
6.213. On appeal, the Appellate Body found certain flaws in the first compliance panel's reasoning
underpinning its findings of inconsistency. With particular respect to the tracking and verification
requirements, the Appellate Body found, inter alia, that the first compliance panel's analysis had
failed to encompass cons ideration of: (i) the relative risks to dolphins from different fishing
techniques in different areas of the oceans; and (ii) whether the distinctions that the 2013 Tuna
Measure drew in terms of the different conditions of access to the dolphin-safe label were explained
in light of the relative profiles. In addition, the Appellate Body found that the first compliance panel
had failed to take full account of the particular circumstances of this case. The Appellate Body
considered these circumstances to include the "design, architecture, revealing structure, operation,
and application" of the 2013 Tuna Measure , as well as of the manner in which similar issues
pertaining to the original Tuna Measure had been assessed in the original proceedings.692 In making
these findings, the Appellate Body did not specifically review the first compliance panel's findings
regarding the depth, accuracy, and government oversight of the tracking and verification
requirements under the 2013 Tuna Measure.
6.214. However, following its review, the Appellate Body still found that: (i) the 2013 Tuna Measure
modified the conditions of competition to the detriment of Mexican tuna products in the US market;
(ii) such detrimental impact did not stem exclusive ly from a legitimate regulatory distinction; and

685 First Compliance Panel Report, para. 7.354. (emphasis omitted)
686 First Compliance Panel Report, para. 7.355 (referring to AIDCP, Resolution to Adopt the Modified
System for Tracking and Verification of Tuna (20 June 2001) (First Compliance Panel Exhibit MEX-36)).
688 First Compliance Panel Report, paras. 7.360-7.363.
689 First Compliance Panel Report, paras. 7.364-7.369.
690 First Compliance Panel Report, paras. 7.370 and 7.382.
691 First Compliance Panel Report, paras. 7.400 and 8.2.
692 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.169.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

thus (iii) the 2013 Tuna Measure accorded less favourable treatment to Mexican tuna products as
compared to like tuna products from the United States and other countries.693
6.1.5.4.2 Summary of the Panels' findings reg arding tracking and verification
requirements under the 2016 Tuna Measure
6.215. As described in section 5 above, the tracking and verificatio n requirements under the
2016 Tuna Measure prescribe the documentation requirements for recording and verifying
segregation and the corresponding regulatory oversight. These requir ements distinguish between:
(i) the ETP large purse seine fishery, which must comply with the AIDCP Tracking and Verification
System694; and (ii) all other fisheries, which must comply with the requirements prescribed in the
2016 implementing regulations, referred to as the "NOAA regime".695 Thus, the ETP large purse seine
fishery is subject to the AIDCP regime, while all other fisheries are subject to the NOAA regime.
6.216. The Panels considered tha t the question before them was whether the distinctions with
respect to tracking and verification made by the 20 16 Tuna Measure between the ETP large purse
seine fishery and all other fisheries are calibrated to the different risk profiles of the relevant
fisheries.696 Regarding the difference in the risk profiles that the Panels took into account in their
analysis, the Panels recalled their finding that "the ETP large purse seine fishery has a special risk
profile that sets it apart from other fisheries around the world."697
6.217. The Panels recognized that the Appellate Body had found fault with the first compliance
panel's "segmented approach" to its analysis of the tracking and verification requirements under the
2013 Tuna Measure. However, the Panels highlighted that the Appellate Body had not found fault
with the first compliance panel's conceptual approach to assessing the 2013 Tuna Measure's tracking
and verification requirements. In particular, the Panels noted that the Appellate Body had not
criticized the first compliance panel for analysing the differences between the different regimes from
the perspective of depth, accuracy, and degree of government oversight . The Panels pointed out
that, during the course of these compliance proceedings, the parties had themselves presented their
arguments from the same perspective. Therefore, being mindful of the Appellate Body's criticism of
the fact that the first compliance panel had failed to take "full account … of the manner in which
similar circumstances pertaining to the original tuna measure had been assessed in the origina l
proceedings"698, the Panels found it appropriate to follow the conceptual framework devised by the
first compliance panel with respect to depth, accuracy, and degree of government oversight , in
assessing the 2016 Tuna Measure.699
6.218. Regarding depth, the Panels found that, like the 2013 Tuna Measure, the 2016 Tuna Measure
subjects the tuna caught in the ETP large purse seine fishery to the requirements of the AIDCP
regime, whereby such tuna can be potentially traced back all the way to the particular set in which
the tuna was caught and the particular well in which it was stored, or to a particular TTF, if the well
or wells in which the tuna subject to the TTF was stored contained tuna from several sets. The Panels
found that, under the NOAA regime, following the amendments introduced in the
2016 Tuna Measure regarding the new chain of custody record -keeping requirements, tuna can be
traced back to one or more storage wells or other storage locations for a particular fishing trip. Thus,
on the basis of the evidence on the record, it appeared to the Panels that , under both the AIDCP
and the NOAA regimes, it is possible to trace tuna back to one or more wells in which it was stored.
Accordingly, it seemed to the Panels that there is no longer any meaningful difference with respect
to the depth of the requirements between the AIDCP regime and the NOAA regime.700

693 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 8.1.a.viii. See also
para. 1.11 above.
694 Panel Reports, paras. 7.56-7.61. See also 2016 implementing regulations (Panel Exhibits MEX-2 and
USA-2), Section 216.93(a)-(c)(1).
695 Panel Reports, para. 7.62 (quoting United States' first written submission to the Panels, para. 143).
See also 2016 implementing regulations (Panel Exhibits MEX-2 and USA-2), Sections 216.91(4)-(5)
and 216.93(c)(2)-(3) and (d)(4).
696 Panel Reports, para. 7.651.
697 Panel Reports, para. 7.652.
698 Panel Reports, para. 7.622 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.169).
699 Panel Reports, paras. 7.622 and 7.653.
700 Panel Reports, paras. 7.654-7.656.
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6.219. As regards accuracy, the Panels noted that, under the 2016 Tuna Measure, and, in particular,
under the new NOAA regime chain of custody record -keeping requirement for tuna products
produced from "other fisheries", US processors and importers of tuna or tuna products are now
required to collect and retain, for two years, information on each point in the chain of custody of the
tuna or tuna product. This information must be provided to the NMFS upon request and must be
sufficient for the NMFS to conduct a trace -back of any product marketed as dolphin -safe to verify
that the tuna product in fact meets the dolphin -safe labelling requirements. For the Panels, these
modifications seem to directly address the first compliance panel's concern that, under the
2013 Tuna Measure, the accuracy attributable to the records required under the ETP large purse
seine fishery had appeared to be much more robust than that of the records required with respect
to all other fisheries.701
6.220. Concerning government oversight, the Panels recalled that the first compliance panel had
explained that, under the AIDCP regime, 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
TTFs and are thus able to verify at any stage of the catch and canning process whether a particular
batch of tuna is dolphin -safe. By contrast, the first comp liance panel had expressed concern with
respect to the inability of the US government under the NOAA regime to go "behind the documents"
in order to verify the movements of the tuna prior to its arrival at the cannery.702
6.221. The Panels noted that the 2016 Tuna Measure maintains the requirement, under the
2013 Tuna Measure, that US tuna processors submit monthly reports to the US Tuna Tracking and
Verification Program for all tuna received at their processing facilities. At the same time, the Panels
noted that t he new NOAA regime chain of custody record -keeping requirement for tuna products
harvested from "other fisheries", referred to in paragraph 6.219 above, addresses the previous
inability of the US government under the NOAA regime to go "behind the documents", because NMFS
now has the ability to check the information on the movement of the tuna, even before it arrives at
the cannery. For the Panels, this modification seems to bridge the previous existing difference
between the AIDCP regime and the NOAA regime.703
6.222. However, with particular respect to the delegation of responsibility for developing tracking
and verification systems, the Panels noted that differences remained between the two regimes. The
Panels observed that, under the AIDCP regime, the Secretariat704 brokers requests for the data and
documentation that would allow a party to obtain information from processors of another party
sufficient to trace back a tuna product through its chain of custody to the harvesting vessel and
trip.705 By contrast, the Panel s agreed with Mexico that the process of collecting and keeping the
information under the NOAA regime still seems to rely heavily on importers and processors.
Moreover, under the 2016 Tuna Measure, the degree of government oversight of the catch and
processing operations that take place outside the United States seemed to the Panels to be
somewhat limited.706
6.223. Thus, the Panels considered that , although the 2016 Tuna Measure had narrowed the
differences between the AIDCP and the NOAA regimes in several aspects of the tracking and
verification requirements, there were still differences between the two regimes regarding the extent
of government oversight. In assessing the legal significance of these differences, the Panels noted
that the measure may be calibrated to the risks to dolphins where it uses a more sensitive
mechanism in areas where risks are h igh but a less sensitive mechanism in areas where the risks
are low. The Panels considered that, owing to the special risk profile of the ETP large purse seine
fishery, "it is calibrated" for the 2016 Tuna Measure to apply less strict (i.e. less sensitive)
requirements with respect to fisheries other than the ETP large purse seine fishery and to pose
stricter (i.e. more sensitive) requirements inside the ETP large purse seine fishery.707 For the Panels,

701 Panel Reports, para. 7.657 (referring to First Compliance Panel Report, paras. 7.360-7.361).
702 Panel Reports, paras. 7.658-7.660 (referring to First Compliance Panel Report, paras. 7.364-7.368).
703 Panel Reports, paras. 7.661-7.663.
704 The word "Secretariat" refers to the staff of the IATTC. (International Dolphin Conservation Program,
System for Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 1.i.)
705 Panel Reports, para. 7.665 (referring to International Dolphin Conservation Program, System for
Tracking and Verifying Tuna, as amended (2015) (Panel Exhibit USA-90), Section 7).
706 Panel Reports, paras. 7.664-7.666.
707 Panel Reports, para. 7.671.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the differences in the requirements are commensurate wit h the difference in the risks to dolphins
arising from the use of different fishing methods in different areas of the ocean.708
6.224. Moreover, in the Panels' view, the determination provisions create flexibility that enables the
2016 Tuna Measure to treat similar situations similarly. According to the Panels, the determination
provisions work together with the tracking and verification requirements to ensure that the
2016 Tuna Measure is calibrated to the risks to dolphins arising from the use of different fishing
methods in different areas of the ocean.709
6.225. The Panels also took note of Mexico's contention that a number of the countries that are the
largest suppliers of tuna and tuna products, such as the Philippines, Chinese Taipei, and Thailand
are significantly deficient in the control and monitoring of fishing activities and have been identified
as extremely vulnerable to IUU fishing. However, the Panels recalled that the NOAA regime provides
that breaches of the tracking and verification requirements may lead to the imposition of sanctions.
In particular, sanctions for offering for sale or export tuna products falsely labelled as dolphin-safe
may be assessed against any producer, importer, exporter, distributor, or seller who is subject to
the jurisdiction of the United States. Thus, even in the absence of jurisdiction by the US Department
of Commerce to audit foreign fishing vessels, carrier vessels, and foreign processors, or vulnerability
to IUU fishing in some countries, the Panels considered that the United States, through the
2016 Tuna Measure, has the necessary tools to induce compliance of US processors and
importers.710
6.226. For these reasons, the Panels found that, although there remained differences between the
NOAA and AIDCP regimes with respect to tracking and verification, such differences had been
considerably narrowed in the 2016 Tuna Measure. The Panels also found that these remaining
differences are calibrated to the differences in the risk profile of the ETP large purse seine fishery
compared to other fisheries.711
6.1.5.4.3 Legal analysis
6.227. Mexico contends that the Panels erred in their calibration analysis of the tracking and
verification requirements: (i) by rejecting the reliability of reporting and fisheries management as
relevant to evaluating the calibration of t he tracking and verification requirements, and by finding
that the measure can be considered calibrated where it allows higher margins of error for
certifications in all ocean areas other than the ETP 712; (ii) by finding that the determination
provisions contribute to the calibration of the measure713; and (iii) by applying an incorrect analysis
to conclude that differences between the requirements for the ETP large purse seine fishery and
other fisheries have been narrowed. 714 In addition, Mexico contends that the Panels acted
inconsistently with Article 11 of the DSU by refusing to give any consideration to evidence that,
according to Mexico, was directly relevant and material to the outcome of the Panels' legal
analysis.715
6.228. The United States posits that Mexico's challenge to the Panels' evaluation of the tracking
and verification requirements should be dismissed. The United States argues that: (i) the Panels did
not omit any relevant factors in their assessment of whether the 2016 Tuna Measure is calibrated
to the risk profiles of different fishing methods in different ocean areas716; (ii) Mexico's claim against
the Panels' reasoning concerning the determination provisions contributing to the calibration of the
tracking and verification requirements should be rejected717; and (iii) Mexico puts forward no reason
as to why the Panels' analysis of the differences between the AIDCP and NOAA tracking and

708 Panel Reports, paras. 7.671-7.673.
709 Panel Reports, para. 7.674.
710 Panel Reports, para. 7.675.
711 Panel Reports, para. 7.676.
712 Mexico's appellant's submission, paras. 275-277.
713 Mexico's appellant's submission, para. 280.
714 Mexico's appellant's submission, paras. 285-299. Mexico also argues that the Panels' calibration
analysis is flawed, owing to alleged errors in the Panels' assessment of risk profiles. (Mexico's appellant's
submission, paras. 273-274) We recall that these arguments were addressed in section 6.1.4 above.
715 Mexico's Notice of Appeal, para. 9.c (referring to Panel Reports, paras. 6.57 and 7.656); appellant's
submission, para. 306.
716 United States' appellee's submission, para. 281.
717 United States' appellee's submission, para. 300.
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verification regimes constitutes legal error.718 The United States further asserts that Mexico's claim
under Article 11 of the DSU should be rejected.719
6.229. We begin with Mexico's allegation that the Panels erred in their calibration analysis by failing
to take into account several relevant criteria including "the sufficiency of regulatory oversight, the
reliability of reporting, t he existence of IUU fishing and the existence of transshipment at sea". 720
Instead, according to Mexico, the Panels erroneously based their calibration analysis on "the
likelihood of AIDCP-compliant setting on dolphins in the ETP producing dolphin-safe and non-dolphin
safe tuna compared to the likelihood in all other fisheries … and the perceived 'margin of error' in
the label associated with such likelihood".721
6.230. As a preliminary observation, we note that, by referring to "AIDCP -compliant setting on
dolphins in the ETP", Mexico's argument seems to suggest that the Panels examined the tracking
and verification requirements through the lens of the AIDCP regime. We recall that the AIDCP applies
only to the ETP. While the 2016 Tuna Measure applies the AIDCP Tracking and Verification System
to the ETP large purse seine fishery, the 2016 Tuna Measure does not apply the AIDCP system to
the other fisheries in the ETP. Instead, the other fisheries are subject to the NOAA regime. Thus,
the Panels were not focused on what distinctions manifested between AIDCP-compliant methods and
non-AIDCP-compliant methods. Rather, in our view, the Panels rightly focused their analysis on the
distinctions in the tracking and verification requirements under the 2016 Tuna Measure, taking
account of the differences in the risk profiles of the different fisheries. We recall that, having assessed
the risk profiles of the individual fisheries, the Panels established that, when compared to the
ETP large purse seine fishery, which has a "special risk profile", all the other fisheries are similar in
their risk profiles insofar as in none of them is setting on dolphins practised consistently or
systematically.722
6.231. Turning to Mexico's assertion that "[t]he Panels' reasoning regarding the margin of error
suffered from the same errors identified above in respect of the risks of inaccurate information and
the certification requirements", we recall that we addressed these arguments in section 6.1.5.3
above. Thus, our discussion in paragraphs 6.187-6.189 above applies equally to our review of the
Panels' reasoning in their evaluation of the tracking and verification requirements.
6.232. Moreover, specifically in their evaluation of the tracking and verification requirements, the
Panels explained that:
In our view, the difference in the risk profile of the ETP large purse seine fishery
compared to other fisheries indicates that there is a greater likelihood that a vessel in
the ETP large purse seine fishery will produce both dolphin -safe and non-dolphin-safe
tuna on any fishing trip, and that the two groups of tuna will have to be segregated and
tracked. Conversely, there would be a lower likelihood that a set produces
non-dolphin-safe tuna in other fisheries that would need to be segregated as a
consequence of this. This justifies, in our view, the need for a stricter regime of tracking
and verification in the ETP large purse seine fishery. … We thus consider that it is
reasonable for the United States to apply a more sensitive tracking and verification
mechanism in respect of high-risk fisheries. Doing so is "commensurate with" the risks
to dolphins arising from the use of different fishing methods i n different areas of the
ocean.723
6.233. We share the Panels' view as quoted above. The key question before the Panels was whether
the differences in the sensitivity of the labelling conditions are properly calibrated to the differences
in risk profiles of the fisheries. If the sensitivity of the labelling conditions is calibrated to the risks
to dolphins arising from the use of different fishing methods in different areas of the ocean, then the
2016 Tuna Measure addresses these different levels of risks to dolphins in such a way as to ensure

718 United States' appellee's submission, para. 281.
719 United States' appellee's submission, para. 281.
720 Mexico's appellant's submission, para. 278.
721 Mexico's appellant's submission, para. 278. See also ibid., paras. 275-277.
722 See para. 6.177 above.
723 Panel Reports, para. 7.672.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

accurate labelling (i.e. less sensitive requirements in fisheries with lower risks, and more s ensitive
requirements in fisheries with higher risks).
6.234. This leads us to Mexico's contention that the Panels erred by completely omitting the
sufficiency of regulatory oversight, the reliability of reporting, the existence of IUU fishing, and the
existence of trans-shipment at sea as criteria for their calibration assessment. 724 As we explain
below, Mexico's contention fails to take into account the Panels' explanations regarding these factors.
6.235. First, concerning government oversight, the Panels noted that the new NOAA regime chain
of custody record-keeping requirement for tuna products harvested from other fisheries, referred to
in paragraph 6.219 above, addresses the previous inability of t he US government under the
NOAA regime to go "behind the documents", be cause NMFS now has the ability to check the
information of the movement of the tuna, even before it arrives at the cannery. For the Panels, this
modification seemed to bridge the previous existing difference between the AIDCP regime and the
NOAA regime. 725 In response to questioning at the hearing, Mexico accepted that the new
custody-keeping requirements under the 2016 Tuna Measure appeared to have narrowed the
differences between the AIDCP regime and the NOAA regime. However, Mexico stressed that the
differences had not been eliminated.
6.236. We recall that the calibration analysis is not intended to test for uniformity in the
requirements applicable to the different fisheries. Rather, the sensitivity of the labelling conditions
under the 2016 Tuna Measure should be calibrated to the risks to dolphins arising from the use of
different fishing methods in different areas of the ocean. Thus, requiring the 2016 Tuna Measure to
be calibrated to the risks to dolphins does not mean that the differences between the AIDCP regime
and the NOAA regime must be eliminated under the 2016 Tuna Measure, given that the ETP large
purse seine fishery has a special risk profile that distinguishes it from other fisheries.
6.237. Second, the Panels took note of Mexico's contention that a number of the countries that are
the largest suppliers of tuna and tuna products, such as the Philippines, Chinese Taipei, and Thailand
are significantly deficient in the control and monitoring of fishing activities, and have been identified
as extremely vulnerab le to IUU fishing. Mexico had also argued that the US Department of
Commerce lacks jurisdiction to audit foreign fishing vessels, carrier vessels, and foreign processors.
However, as indicated in paragraph 6.225 above, the Panels recalled that the NOAA regime provides
that breaches of the tracking and verification requirements may lead to the imposition of sanctions.
Thus, even in the absence of jurisdiction by the US Department of Commerce to audit foreign fishing
vessels, carrier vessels, and foreign proc essors, or vulnerability to IUU fishing in some countries,
the Panels considered that the United States, through the 2016 Tuna Measure, has the necessary
tools to induce compliance of US processors and importers.726
6.238. Thus, contrary to Mexico's arguments, in t heir calibration analysis , the Panels did not
"completely omit[] the sufficiency of regulatory oversight, the reliability of reporting, the existence
of IUU fishing and the existence of transshipment at sea".727 Still in this regard, and as discussed in
paragraph 6.147 above, we do not exclude the possibility that the above-mentioned factors
highlighted by Mexico may affect the ultimate accuracy of the dolphin -safe label. Such risks of
inaccuracy are relevant to the assessment of whether the measure is ca librated to the risks to
dolphins. However, as the United States suggests 728, it was incumbent upon Mexico to provide
relevant evidence in support of its assertion that , in fisheries where factors affecting regulatory
reliability persist, there is an increas ed risk that the labels for tuna products would not accurately
reflect the dolphin-safe nature of those products. Mexico has pointed to no evidence on the Panel
record that pertains specifically to the risk of inaccurate labelling under the 2016 Tuna Measu re,
owing to "the sufficiency of regulatory oversight, the reliability of reporting, the existence of
IUU fishing and the existence of transshipment at sea". 729 Nor has Mexico identified any evidence
on the Panel record that would suggest that these fa ctors undermine the ability "of the

724 Mexico's appellant's submission, para. 278.
725 Panel Reports, paras. 7.661-7.663.
726 Panel Reports, para. 7.675.
727 Mexico's appellant's submission, para. 278.
728 United States' appellee's submission, para. 53 and fn 122 thereto.
729 Mexico's appellant's submission, para. 278.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

US government under the NOAA regime to go 'behind the documents' in order to verify the
movements of the tuna prior to the arrival to the cannery".730
6.239. With respect to the determination provisions, Mexico contends that the Panels erred in
finding that the determination provisions create flexibility that enables the 2016 Tuna Measure to
treat similar situations similarly. In support of its contention, Mexico relies on the arguments that it
made in connection with the Panels' calibr ation analysis of the certification requirements. 731
We recall that we addressed these arguments in section 6.1.5.3 above. Thus, our discussion in
paragraphs 6.192-6.202 above applies equally to our review of the Panels' reasoning in their
evaluation of the tracking and verification requirements. In particular, we note that Mexico relies on
its argument regarding the relevance of PBR evidence, which we have rejected above. Furthermore,
we do not share Mexico's view that the Panels relied on inconsistent sets of data in assessing the
eligibility criteria, on the one hand, and the application of the determination provisions, on the other
hand.
6.240. We now turn to Mexico's argument that the Panels applied a faulty analysis to conclude that
the 2016 Tuna Measure had narrowed the differences between the requirements for the ETP large
purse seine fishery and the other fisheries. 732 Mexico relies heavily on the findings of the first
compliance panel to argue that the different approach taken by the Panels in these compliance
proceedings is faulty.733 However, we note that the first compliance panel was addressing a different
measure that did not incorporate: (i) the new custody record-keeping requirements that introduce
a legal requirement that can be enforced through the sanctions existing in the measure; (ii) the new
Captain Training Course available online in nine languages; and (iii) the amended determination
provisions.
6.241. Specifically, Mexico highlights that the first compliance panel, in addressing the "accuracy"
of the NOAA regime, found that the United States had "submitted no evidence showing that
canneries actually do ensure that the tuna they receive matches a particular captain's statement".734
The first compliance panel also considered that the United States had "not provided any evidence
explaining how canneries are able to ensure that captains' certifications remain with the tuna batches
they identify throughout this process". 735 Moreover, the first compliance panel considered that,
under the 2013 Tuna Measure, "there [did] 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."736 Contrary to Mexico's suggestion that the Panels did not pay
attention to the first compliance panel's findings, the Panels in these compliance proceedings
explicitly took into account these findings identified by Mexico 737 and explained why the
2016 Tuna Measure addressed the first compliance panel's concerns. The Panels stated:
We note, however, that under the 2016 Tuna Measure, and in particular, under the new
chain of custody record-keeping requirements for tuna products pro duced from "other
fisheries", this situation has changed. Specifically, US processors and importers of tuna
or tuna products are now required to collect and retain, for two years, information on
each point in the chain of custody of the tuna or tuna product and this information must
be provided to the NMFS upon request and must be sufficient for the N MFS to conduct
a trace-back of any product marketed as dolphin-safe to verify that the tuna product in
fact meets the dolphin-safe labelling requirements. Thus, these modifications seem to
directly address the first compliance panel's concerns with the 201 3 Tuna Measure, in
particular, because they require US processors and importers of tuna or tuna products
to collect and retain information on each point in the chain of custody of the tuna or
tuna product.738

730 Panel Reports, para. 7.660. See also ibid., paras. 7.659-7.663.
731 Mexico's appellant's submission, paras. 279-280.
732 Mexico's appellant's submission, paras. 285 and 299.
733 We note that the findings of the first compliance panel that Mexico seeks to rely on were not the
subject of appeal in the first compliance proceedings.
734 Mexico's appellant's submission, para. 288 (quoting First Compliance Panel Report, para. 7.361).
735 Mexico's appellant's submission, para. 289 (quoting First Compliance Panel Report, para. 7.362).
736 Mexico's appellant's submission, para. 290 (referring to First Compliance Panel Report, para. 7.363).
737 Panel Reports, para. 7.657.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.242. In addition , we note that Mexico refers to the first compliance panel's "government
oversight" findings.739 Mexico points to the first compliance panel's statement that , under the
2013 Tuna Measure, the United States had to rely on the canneries for information about the
movement of the tuna prior to its arrival at the cannery and was not ab le to go "behind the
documents" to verify that a particular dolphin -safe certification describes t he batch of tuna with
which it is associated.740 However, the first compliance panel explained that it had seen "no evidence
suggesting that canneries and other importers in fact do this, and, as [it understood] the measure,
canneries and other importers are not legally required to conduct such checks".741
6.243. We observe that the Panels in these compliance proceedings expressly took account of the
first compliance panel's findings in this regard.742 The Panels identified the main concern of the first
compliance panel with respect to government oversight as the inability of the US government under
the NOAA regime to go "behind the documents" in order to verify the movements of the tuna prior
to its arrival at the cannery.743 The Panels then explained how, in their view, the modifications under
the 2016 Tuna Measure addressed these concerns. Specifically, the Panels stated:
Under the modifications in 50 CFR 216.91(a)(5), US processors and importers of tuna
or tuna products from such "other fisheries" are now required to co llect and retain, for
two years, information on each point in the chain of custody of the tuna or tuna product
... This information must be provided to the NMFS upon request and must be sufficient
for the NMFS to conduct a trace-back of any product marketed as dolphin-safe to verify
that the tuna product in fact meets the dolphin-safe labelling requirements. To us, this
addresses the previous inability of the US government under the NOAA regime to go
"behind the documents", as NMFS will have the ability to check the information of the
movement of the tuna, even before it arrives at the cannery. Indeed, these
modifications require US processors and importers to have information relating to the
storage facilities, trans-shippers, processors, and wholesalers/distributors of tuna, and
such information must be sufficient for the NMFS to trace any non -dolphin-safe tuna
loaded onto the harvesting vessel back to one or more storage wells or other storage
locations. Therefore, the US government may now go behind the documents and check
the movements of the tuna along the various steps of the catch and processing of
tuna.744
6.244. Thus, contrary to Mexico's arguments, we consider that the Panels in these compliance
proceedings followed the Appellate Body's guidance by taking fu ll account of the "particular
circumstances" of this case, including "the manner in which similar circumstances" pertaining to the
2013 Tuna Measure had been assessed in the first compliance proceedings. 745 Moreover, on the
basis of our above review of the P anels' reasoning, we share their view that the amendments
incorporated in the 2016 Tuna Measure – including (i) the new custody record-keeping requirements
that introduce a legal requirement that can be enforced through the sanctions existing in the
measure; (ii) the new Captain Training Course available online i n nine languages; and
(iii) the amended determination provisions – have narrowed the differences between the AIDCP and
NOAA regimes.746
6.245. Finally, Mexico considers that the Panels' finding that the differences between the AIDCP and
NOAA regimes have been "narrowed" in the 2016 Tuna Measure is faulty because the Panels did not
comply with their duty under Article 11 of the DSU by failing to take into account the evidence
contained in Panel Exhibit MEX -127.747 Specifically, Mexico challenges the following finding of the
Panels, contained in the interim review section of their Reports:
Mexico requests that a sentence be added … to better describe Mexico's argument
regarding the complex supply chain for tuna by referring to evidence submitted by

739 Mexico's appellant's submission, para. 292.
740 Mexico's appellant's submission, para. 293 (quoting First Compliance Panel Report, para. 7.365).
741 Mexico's appellant's submission, para. 294 (quoting First Compliance Panel Report, para. 7.368
(emphasis original)).
742 Panel Reports, paras. 7.658-7.664.
743 Panel Reports, para. 7.659.
745 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.169.
746 Panel Reports, paras. 7.670 and 7.676.
747 Mexico's appellant's submission, para. 305. See also ibid., paras. 300-304.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

Mexico on this point, namely, a recent report of the International Seafood Sustainability
Foundation. … We note that the argument that Mexico r equests the Panels to
reflect … pertains to the issue of whether tuna companies are able to track a particular
catch to the individual vessel that caught it and to other points in the supply chain. The
present proceedings, however, concern whether the 2016 Tuna Measure is calibrated to
different levels of risks posed to dolphins by different fishing methods in different parts
of the ocean, among others, in terms of its tracking and verification requirements.
Therefore, the argument that Mexico requests us to reflect in the paragraph at issue is
not directly relevant to our inquiry. We therefore deny Mexico's request.748
6.246. Article 11 of the DSU provides, in relevant part, that "a panel should make an objective
assessment of the matter before it, including an objective assessment of the facts of the case ."
As the Appellate Body has explained, in accordance with Article 11, a panel is required to "consider
all the evidence presented to it, assess its credibility, determine its weight, and ensure that its factual

findings have a proper basis in that evidence".749 Within these parameters, "it is generally within the
discretion of the [p]anel to decide which evidence it chooses to utilize in making findings" 750, and
the mere fact that a panel did not explicitly refer to each and every piece of evidence in its reasoning
is insufficient to establish that the panel applied an improper standard of review.751
6.247. Turning to the claim before us, we note that, on appeal, Mexico refers to the content of Panel
Exhibit MEX -127752 to argue that , if market participants sourcing tu na from the Western and
Central Pacific and the Indian Oceans are unable to track tuna to the vessel from which it was caught,
the differences between the requirements for tuna sourced from large purse seine vessels in the ETP
and tuna from those other ocean areas cannot, as the Panels found, have been "narrowed".753
6.248. We note that Panel Exhibit MEX -127 is a document produced by the International Seafood
Sustainability Foundation (ISSF) entitled Regional Fishery Management Organization (RFMO) Catch
Documentation Schemes: A Summary. This document defines catch documentation schemes (CDSs)
as:
[G]lobal traceability systems that certify a unit of legal catch, providing a catch
certificate (CC) to the legal owner of the fish (at the point of capture) and then trace
the movement of this unit o f catch from unloading through international trade (export
and re-export), into the end market (the first point of sale/import).754
6.249. The document explicitly states that it "provides an overview of the current activities
regarding the development, implementati on, review and amendm ent of CDS by RFMOs and the
FAO Technical Consultation on the Development of Voluntary Guidelines for CDS". 755 Indeed, in
opting not to rely on this exhibit, the Panels explained that Mexico's argument in connection with
Panel Exhibit MEX-127 pertained to the "complex supply chain for tuna" and "to the issue of whether
tuna companies are able to track a particular catch to the individual vessel that caught it and to
other points in the supply chain". 756 However, the Panels highlighted that these compliance

748 Panel Reports, para. 6.57.
749 Appellate Body Reports, China – Rare Earths, para. 5.178; Brazil – Retreaded Tyres, para. 185
(referring to Appellate Body Report, EC – Hormones, paras. 132-133). See also Appellate Body Reports,
Australia – Salmon, para. 266; EC – Asbestos, para. 161; EC – Bed Linen (Article 21.5 – India), paras. 170,
Japan – Agricultural Products II, paras. 141-142; Korea – Alcoholic Beverages, paras. 161-162; Korea – Dairy,
750 Appellate Body Reports, EU – Fatty Alcohols (Indonesia), para. 5.87; China – Rare Earths,
para. 5.178; EC – Hormones, para. 135.
751 Appellate Body Reports, EU – Fatty Alcohols (Indonesia), para. 5.87; EC – Fasteners (China),
752 Mexico's appellant's submission, para. 300 (referring to ISSF, RFMO Catch Documentation Schemes:
A Summary (Washington, DC, 14 September 2016) (Panel Exhibit MEX-127), paras. 1 and 9).
753 Mexico's appellant's submission, para. 305.
754 ISSF, RFMO Catch Documentation Schemes: A Summary (Washington, DC, 14 September 2016)
(Panel Exhibit MEX-127), para. 1. See also United States' appellee's submission, para. 335.
755 ISSF, RFMO Catch Documentation Schemes: A Summary (Washington, DC, 14 September 2016)
(Panel Exhibit MEX-127), para. 3.
756 Panel Reports, para. 6.57.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

proceedings concern whether the 2016 Tuna Measure, including the tracking and verification
requirements, is calibrated to different levels of risks posed to dolphins by different fishing methods
in different parts of the ocean. Therefore, the Panels considered that the information that Mexico
sought to rely on in Panel Exhibit MEX-127 was not directly relevant to their inquiry.757
6.250. Mexico appears to draw a correlation between the experiences of CDSs recorded in Panel
Exhibit MEX-127 and the potential operation of the 2016 tracking and verification requirements. 758
However, Mexico has provided no reasons for such a correlation, especially given that the data point
for certification under a CDS, by "unit of legal catch", is not applicable to either the AIDCP or NOAA
regimes.759 Rather, as the Panels in these compliance proceedings found, unlike a CDS, both the
AIDCP and NOAA regimes under the 2016 Tuna Measure require that the records that accompany
the tuna from harvest through processing must be sufficient to allow the verification or "trace-back"
of the tuna products to the storage wells of a particular vessel for each fishing trip. 760 Moreover, to
the extent that the 2016 Tuna Measure applies the AIDCP Tracking and Verification System with
respect to the ETP large purse seine fishery, we note that Panel Exhibit MEX -127 contains a
discussion of the AIDCP. The document states that the AIDCP "does not track all yellowfin catch
from all gears nor all parties fishing for yellowfin tuna in the eastern Pacif ic Ocean and as such is
not a true CDS". 761 Thus, our review of the content of Panel Exhibit MEX -127 suppor ts the
Panels' view that Mexico's arguments regarding CDSs, contained in this exhibit, was not relevant to
the Panels' calibration analysis of the 2016 Tuna Measure.
6.251. For these reasons, we find that Mexico has not demonstrated that the Panels failed to make
an objective assessment of the facts of the case as required under Article 11 of the DSU by omitting
Panel Exhibit MEX-127 from their analysis of the tracking and verification requirements.
6.1.5.4.4 Conclusion for tracking and verification requirements
6.252. As with the certification requirements, we have found that, with respect to the tracking and
verification requirements, the Panels adopted the correct approach in comparing the risk profiles of
individual fisheries, because these requirements make a distinction on the basis of both fishing
method and ocean area. Having found no legal error in the Panels' assessment of risk profiles, we
consider that the Panels did not err in finding that it is both the technical and legal possibilit ies of
setting on dolphins and the fact that dolphin sets occur in a consistent and systematic manner in
the ETP large purse seine fishery that give this fishery its special risk profile. Moreover, we have
rejected Mexico's claims that: (i) the Panels erred in their evaluation of the tracking and verification
requirements, including the allegation that the Panels did not take into account the risks of
inaccuracy; and (ii) the Panels failed to make an objective assessment of the facts of the case as
required under Article 11 of the DSU. Consequently, we find that Mexico has not demonstrated that
the Panels erred in arriving at the intermediate finding that:
[A]lthough there remain differences between the NOAA and AIDCP regimes with respect
to tracking and verification, the Panels are of the view that such differences have been
considerably narrowed in the 2016 Tuna Measure and the Panels find that the remaining
differences are calibrated to the differences in the risk profile of the ETP large purse
seine fishery compared to other fisheries.762
6.1.5.5 The 2016 Tuna Measure "as a whole"
6.253. Mexico argues that, because the Panels' reasoning of the 2016 Tuna Measure as a whole
was based entirely on their findings and conclusions with respect to the calibration of the eligibility
criteria, the certification requirements, and the tracking and verification requirements, respectively,
all of the erroneous findings made in those assessments flowed through and were the exclusive basis
for the Panels' assessment of the measure as a whole. Accordingly, Mexico contends that the Panels

757 Panel Reports, para. 6.57.
758 Mexico's appellant's submission, para. 305.
759 United States' appellee's submission, paras. 335-337.
760 Panel Reports, paras. 7.57-7.59 and 7.63-7.66. See also United States' appellee's submission,
para. 336.
761 ISSF, RFMO Catch Documentation Schemes: A Summary (Washington, DC, 14 September 2016)
(Panel Exhibit MEX-127), para. 22.
762 Panel Reports, para. 7.676.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

incorrectly assessed the calibration and consistency with Article 2.1 of the TBT Agreement of the
2016 Tuna Measure as a whole.763
6.254. The United States posits that the Panels' intermediate conclusions concerning the eligibility
criteria, certification requirements, and tracking and verification requirements were correct and not
in error. In addition, the United States submits that, contrary to Mexico's arguments, the
Panels' intermediate conclusions were not the excl usive basis for the Panels' overall assessment of
the measure as a whole. The United States indicates that the Panels also considered how the
different parts of the measure interact to address the risks to dolphins arising from different fishing
methods in different ocean areas, and explained how the components of the measure
"work together" to "achieve the objectives of the 2016 Tuna Measure".764
6.255. We have found above that Mexico has failed to demonstrate that the Panels erred in their
evaluation leading to th eir intermediate findings regarding the calibration of the eligibility criteria,
certification requirements, and tracking and verification requirements. We recall that analysing the
measure in a sequential manner does not, in itself, render the analysis er roneous, provided that
such sequential analysis does not "lead to the isolated consideration of a particular element" where
the elements of a measure are closely interrelated.765
6.256. Based on a review of the Panels' examination of the 2016 Tuna Measure, we consider that
the Panels took into account the "cumulative and highly interrelated" nature of the different aspects
of the 2016 Tuna Measure. For instance, the Panels repeatedly noted that the determination
provisions work together with and reinforce the certif ication and tracking and verification
requirements. Therefore, the Panels' consideration of the certification and tracking and verification
requirements included a consideration of the determination provisions.766 As a second example, the
Panels found that t he certification requirements, including the newly introduced Captain Training
Course, are "embedded within a sufficiently enforceable regulatory framework", referring to the
tracking and verification requirements.767 Furthermore, the Panels synthesized their findings about
the various elements of the measure, "taking into account the important interlinkages among such
elements".768 In this regard, the Panels explained that:
Without the certification, and tracking and verification requirements, as well as the
determination provisions, however, the distinction made through the eligibility criteria
would not have achieved the Measure's objective of dolphin protection. In our view, the
interlinkage among these four elements of the Measure is so crucial that without one of
them the 2016 Tuna Measure, as we know it, could not function. We see the
certification, and the tracking and verification requirements, as well as the
determination provisions, as tools that enforce the eligibility criteria with a view to
achieving the objective of protecting dolphins from harmful fishing methods.769
6.257. We thus consider that the Panels' analyses of e ach of the elements of the 2016 Tuna
Measure, as well as their examination of the measure as a whole , were properly informed by the
interlinkages between these elements and the fact that they operate together to regulate access to
the dolphin-safe label. Furthermore, we recall that Mexico's appeal in this regard is consequential
upon its challenge of the Panels' assessment of the eligibility criteria, certification requirements, and
tracking and verification requirements. Having reviewed and rejected Mexico's arguments against
the Panels' assessment of each of these elements of the 2016 Tuna Measure, we fi nd that Mexico
has not demonstrated that the Panels erred in their assessment of the 2016 Tuna Measure, as a
whole, or in finding that the 2016 Tuna Measure, as a whole, is calibrated to the risks to dolphins
arising from the use of different fishing methods in different areas of the ocean.770

763 Mexico's appellant's submission, para. 307 (referring to Panel Reports, paras. 7.703-7.717).
764 United States' appellee's submission, para. 353 (quoting Panel Reports, paras. 7.711 and 7.713;
referring to ibid., paras. 7.709 and 7.712).
765 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.15.
766 Panel Reports, paras. 7.530, 7.609-7.610, and 7.674.
767 Panel Reports, para. 7.593.
768 Panel Reports, para. 7.704.
769 Panel Reports, para. 7.707.
770 Panel Reports, para. 7.717.
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6.1.6 Conclusion under Article 2.1 of the TBT Agreement
6.258. Based on our analyses and findings in sections 6.1.1 to 6.1.5 above, we uphold the
Panels' conclusion that the 2016 Tuna Measure accords to Mexican tuna products treatment no less
favourable than that accorded to like products from the United States and other countries and
therefore is consistent with Article 2.1 of the TBT Agreement.771
6.2 Article XX of the GATT 1994
6.259. At the outset of their analysis, and noting the parties' agreement in this regard, the Panels
found that the 2016 Tuna Measure is inconsistent with Articles I:1 and III:4 of the GATT 1994772,
but is provisionally justified under subparagraph (g) of Article XX of the GATT 1994.773 The Panels
hence focused their analysis on the disagreement between the parties as to whether the
2016 Tuna Measure meets the requirement of the chapeau of Article XX, and concluded:
[H]aving found, in our analysis under Article 2.1 of the TBT Agreement, that the
Measure is calibrated to different levels of risks posed to dolphins by different fishing
methods in different areas of the ocean, we also find that the Measure is not applied in
a manner that constitutes a means of arbitrary or unjustifiable disc rimination, and is
therefore justified under Article XX of the GATT 1994.774
6.260. Mexico appeals the above conclusion, arguing that the Panels erred in relying on their
reasoning developed under Article 2.1 of the TBT Agreement, and thereby failed to consider whether
the discrimination caused by the measure is rationally related to its objectives as required by the
applicable legal standard under the chapeau of Article XX of the GATT 1994.775 We begin by recalling
the relevant findings by the Panels, before analysing the issues raised by Mexico's appeal.
6.2.1 The Panels' findings
6.261. The Panels recalled that three analytical elements must be demonstrated with respect to
arbitrary or unjustifiable discrimination under the chapeau of Article XX, namely: (i) the application
of the measure results in discrimination; (ii) the conditions prevailing between countries are the
same; and (iii) the discrimination is arbitrary or unjustifiable. 776 With respect to the existence of
discrimination, the Panels noted the Appellate Body's finding in the first compliance proceedings
that, by excluding most Mexican tuna products from access to the "dolphin-safe" label while granting
conditional access to such label to like products from the United States and other countries, the
2013 Tuna Measure, similar to the original Tuna Measure, modified the conditions of competition to
the detriment of Mexican tuna products in the US market.777 Since the 2016 Tuna Measure maintains
the overall architecture and structure of the original and 2013 Tuna Measures, the Panels found that
"the 2016 Tuna Measure continues to cause the same detrimental impact resulting from the
discriminatory treatment between tuna products containing tuna caught in the ETP large purse seine
fishery and those containing tuna caught in other fisheries."778
6.262. With respect to the second element, the Panels recalled that , in the first compliance
proceedings, the Appellate Body found that , in this dispute, the conditions pre vailing between
countries are the same for the purpose of the chapeau of Article XX, namely, "the risks of adverse

771 Panel Reports, paras. 7.717, 8.2, and 8.6.
772 Panel Reports, para. 7.729 (referring to First Compliance Panel Report, paras. 7.404-7.416, 7.434,
7.469-7.481, and 7.494-7.495; Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
para. 8.1(d)(ii)).
773 Panel Reports, para. 7.730 (referring to First Compliance Panel Report, para. 7.541; Appellate Body
Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.341).
774 Panel Reports, para. 7.740.
775 Mexico's Notice of Appeal, para. 10; appellant's submission, paras. 308-309.
776 Panel Reports, para. 7.731.
777 Panel Reports, para. 7.732 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.238).
778 Panel Reports, para. 7.732.
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effects on dolphins arising from tuna fishing practices".779 The Panels noted that, with regard to the
first two elements, neither of the parties had argued otherwise before them.780
6.263. With respect to the third element, that is, whether the measure is applied in a manner that
constitutes a means of "arbitrary or unjus tifiable discrimination", the Panels found that, based on
the guidance provided by the Appellate Body in the first compliance proceedings, "so long as the
similarities and differences between Article 2.1 of the TBT Agreement and Article XX of the
GATT 1994 are taken into account, it may be permissible to rely on reasoning developed in the
context of one agreement for purposes of conducting an analysis under the other". 781 The Panels
then recalled that, following the guidance provided by the Appellate Body in the first compliance
proceedings, they had conducted their analysis under Article 2.1 "on the basis of the concept of
calibration, and found that the 2016 Tuna Measure is calibrated to different risks to dolphins arising
from the use of different fishing methods in different areas of the ocean".782 On this basis, the Panels
recalled that they had concluded that the detrimental impact caused by the 2016 Tuna Measure
"stems exclusively from legitimate regulatory distinctions, and that, therefore, the Measure is
consistent with Article 2.1 of the TBT Agreement".783
6.264. The Panels found that, in the circumstances of the present compliance proceedings, and in
light of the Appellate Body's guidance in the first compliance proceedings, it was appropriate to use
their fact ual and legal findings under Article 2.1 in their assessment of whether the 2016 Tuna
Measure is applied in a manner that constitutes arbitrary or unjustifiable discrimination within the
meaning of the chapeau of Article XX.784 In this regard, the Panels did not consider that the
2016 Tuna Measure, "which is tailored to and commensurate with the relevant risks, can be said to
applied in a manner that constitutes a means of 'arbitrary or unjustifiable discrimination'" within the
meaning of Article XX of the GATT 1994.785 Therefore, in light of their finding under Article 2.1, the
Panels concluded that the 2016 Tuna Measure is not applied in a manner that constitutes a means
of arbitrary or unjustifiable discrimination within the meaning of the chapeau and is ther efore
justified under Article XX of the GATT 1994.786
6.2.2 Whether the Panels erred in finding that the 2016 Tuna Measure complies with the
requirements of the chapeau of Article XX of the GATT 1994
6.265. Mexico claims on appeal that the Panels erred in relying on their analysis under Article 2.1
to conclude that the 2016 Tuna Measure is not inconsistent with the requirements of the chapeau of
Article XX. Mexico submits that, to examine whether a measure is applied in a manner that
constitutes arbitrary or unjustifiable discrimination under the chapeau, a panel must consider
"whether the detrimental impact caused by the measure can be reconciled with, or rationally
connected to, the policy objective … that was provisionally found to justify the measure" under one
of the subparagraphs of Article XX.787 Mexico contends that the Panels made no substantive findings,
under Article 2.1, with respect to arbitrary or unjustifiable discrimination. Thus, according to Mexico,
by relying on their analysis under Article 2.1 for the purpose of the chapeau of Article XX, the Panels
did not properly take into account the differences between the legal analyses required under these
provisions.788
6.266. Mexico recalls the Appellate Body's finding in the first compliance proceedings that, if the
similarities and differences between Article 2.1 and Article XX are taken into account, it may be

779 Panel Reports, para. 7.733 (referring to Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.308).
780 Panel Reports, paras. 7.732-7.733 (referring to Mexico's first written submission to the Panels,
para. 204; response to Panel question No. 110; United States' first written submission to the Panels, para. 69;
response to Panel question No. 110).
781 Panel Reports, paras. 7.727 and 7.734 (quoting Appellate Body Report, US – Tuna II (Mexico)
(Article 21.5 – Mexico), para. 7.347).
782 Panel Reports, para. 7.738. In the Panels' view, they did not repeat the first compliance panel's
errors found by the Appellate Body, namely, the first compliance panel's segmented analysis under Article 2.1
of the TBT Agreement and its erroneous assumption that disqualifying tuna products containing tuna caught by
setting on dolphins from accessing the label was consistent with that provision. (Ibid., paras. 7.735-7.736)
783 Panel Reports, para. 7.738.
784 Panel Reports, para. 7.739.
785 Panel Reports, para. 7.739.
786 Panel Reports, para. 7.740.
787 Mexico's appellant's submission, para. 309.
788 Mexico's appellant's submission, para. 315.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

permissible to rely on reasoning developed under one provision for the analysis under the other. 789
Mexico highlights that, in the first compliance proceedings, the panel conducted its analyses under
Article 2.1 and Article XX on the basis of the same legal test, that is, whether the measure at issue
was designed and applied in a manner that constitutes a rbitrary or unjustifiable discrimination .790
In Mexico's view, due to the Panels' failure to examine the rational relationship between the
regulatory distinctions of the 2016 Tuna Measure and its objectives under Article 2.1, the
Panels' findings under Article 2.1 could not be used to resolve the assessment of arbitrary or
unjustifiable discrimination under Article XX.791
6.267. The United States argues that the Panels did not err in relying on their findings under
Article 2.1 for their analysis under the chapeau of Article XX. The United States submits that, as the
Appellate Body indicated in the first compliance proceedings, the analysis of whether the
requirements under the 2016 Tuna M easure are calibrated to the risks to dolphins posed by tuna
fishing is "relevant for an analysis of arbitrary or unjustifiable discrimination under the chapeau of
Article XX".792 Moreover, the United States recalls that the Appellate Body reversed the first
compliance panel's analyse s under both Article 2.1 and Article XX for ident ical reasons, namely,
because the panel had conducted a segmented analysis that failed to assess whether the measure,
as a whole, was calibrated to the risk s to dolphins posed by different fishing methods in different
ocean areas.793 Given that the Panels conducted a proper calibration analysis under Article 2.1, the
United States contends that the differences between the Panels' assessment and the first compliance
panel's assessment only "confirm that the Panels did not err in relying on their analysis and
conclusions under Article 2.1".794
6.268. The United States further contends that, contrary to Mexico's arguments, the Panels'
analysis under Article 2.1 encompassed an assessment of whether the regulatory distinctions of the
2016 Tuna Measure were rationally relat ed to the objectives of the measure. This is because the
Panels explained that the objectives of the measure inform both the form and the content of the
calibration analysis, and thus the rational relation ship test does not exist as a separate legal step,
but rather is assessed through the calibration analysis itself. 795 The United States adds that the
Appellate Body's analysis in the two previous proceedings confirms that the calibration assessment,
"done correctly, … reflects the relationship between the distinctions of the measure and the
measure's objective that renders the measure not discriminatory".796
6.269. The participants' disagreement on appeal centres on whether it was permissible for the
Panels, in the circumstances of these compliance proceedings, to r ely on their calibration analysis
under Article 2.1 in reaching their conclusion that the 2016 Tuna Measure is not applied in a manner
that constitutes arbitrary or unjustifiable discrimination within the meaning of the chapeau of
Article XX. The chapeau of Article XX provides, in relevant part, that:
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

789 Mexico's appellant's submission, para. 317 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), paras. 7.345-7.347).
790 Mexico's appellant's submission, para. 318.
791 Mexico's appellant's submission, paras. 319-330 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), para. 7.320). Mexico also argued in its appellant's submission that the
2016 Tuna Measure results in "unjustifiable discrimination" because the United States did not seek a
multilateral solution before imposing a unilateral measure. Mexico referred in this regard to the Appellate Body
Report in US – Shrimp, and argued that of importance in the present proceedings is the fact that there is a
fully functioning and highly effective multilateral process already in place that the United States helped to
create in the form of the IATTC and its dolphin-protection program, which the United States chose to ignore.
(Ibid., paras. 333-334) However, during the hearing, Mexico indicated that it was not pursuing a decision by
the Appellate Body on this issue but merely included it in its appellant's submission as relevant background.
(Mexico's response to questioning at the hearing) Therefore, we do not address this claim.
792 United States' appellee's submission, para. 365 (quoting Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), para. 7.330).
793 United States' appellee's submission, para. 367 (referring to Appellate Body Report, US – Tuna II
(Mexico) (Article 21.5 – Mexico), paras. 7.229 and 7.334-7.335).
794 United States' appellee's submission, para. 367.
795 United States' appellee's submission, para. 368 (referring to Panel Reports, paras. 7.115-7.127).
796 United States' appellee's submission, para. 370.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the same conditions prevail … nothing in this Agreement shall be construed to prevent
the adoption or enforcement by any contracting party of measures.
6.270. By its terms, the chapeau of Article XX is concerned with the "manner" in which a measure
that falls under one of the subparagraphs of Article XX is "applied".797 The Appellate Body has noted
that the manner in which a measure is applied "can most often be discerned from [its]
design, … and … revealing structure". 798 The Appellate Body has explained that there are three
constitutive elements in a ssessing the requirements under the chapeau: (i) the application of the
measure must result in discrimination; (ii) the discrimination must occur between countries where
the same conditions prevail; and (iii) the discrimination must be arbitrary or unjusti fiable in
character.799
6.271. The Appellate Body has found that "the analysis of whether discrimination is arbitrary or
unjustifiable 'should focus on the cause of the discrimination, or the rationale put forward to explain
its existence'." 800 Such analysis "'shoul d be made in the light of the objective of the measure',
and … discrimination will be arbitrary or unjustifiable when the reasons given for the discrimination
'bear no rational connection to the objective' or 'would go against that objective'" .801 Thus, "'[o]ne
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 m easure has been provisionally justified under one of the
subparagraphs of Article XX."802
6.272. The Appellate Body has further found that there are important parallels between the
analyses under the chapeau of Article XX and Article 2.1. In particular, the Appellate Body has noted
that the concept of "arbitrary or unjustifiable discrimination between countries where the same
conditions prevail" is found both in the chapeau of Article XX and in the sixth recital of the preamble
of the TBT Agreement, which the Appel late Body has found to provide relevant context for the
interpretation of Article 2.1.803 At the same time, the Appellate Body has cautioned that there are
also differences between these provisions, inter alia, in terms of their legal standards804, as well as
their main function and scope. In particular, the Appellate Body has noted that, while the analysis
under Article 2.1 concerns the regulatory distinction that accounts for the detrimental impact on
imported products, the discrimination examined under the chapeau of Article XX is not necessarily
the same as the discrimination found to be inconsistent with the relevant provisions of the
GATT 1994, "such as Articles I and III".805
6.273. In the first compliance proceedings, the Appellate Body stated that, "so long as t he
similarities and differences between Article 2.1 of the TBT Agreement and Article XX of the
GATT 1994 are taken into account, it may be permissible to rely on reasoning developed in the
context of one agreement for purposes of conducting an analysis und er the other." 806 The
Appellate Body noted that the first compliance panel had conducted its analyses under both
Article 2.1 and Article XX "on the basis of a legal test developed in the context of assessing arbitrary
or unjustifiable discrimination, namely , whether the discrimination can be reconciled with, or is

797 See also Appellate Body Reports, US – Gasoline, p. 22, DSR 1996:I, p. 20; US – Shrimp, para. 115;
Brazil – Retreaded Tyres, para. 215.
798 Appellate Body Report, Japan – Alcoholic Beverages II, p. 29, DSR 1996:I, p. 120.
799 Appellate Body Report, US – Shrimp, para. 150.
800 Appellate Body Report, Brazil – Retreaded Tyres, para. 226.
801 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.316 (quoting
Appellate Body Report, Brazil – Retreaded Tyres, para. 227).
802 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.316 (quoting
Appellate Body Reports, EC – Seal Products, para. 5.306). The Appellate Body has also explained that this is
not the sole test, and that, depending on the nature of the measure at issue and the circumstances of the case
at hand, additional factors may also be relevant to the overall assessment. (Ibid. (referring to Appellate Body
803 Appellate Body Reports, US – Clove Cigarettes, para. 173; US – Tuna II (Mexico), para. 213;
EC – Seal Products, para. 5.310.
804 Specifically, Article 2.1 of the TBT Agreement requires panels to consider whether the detrimental
impact on imported products caused by a measure stems from a legitimate regulatory distinction. Under the
chapeau of Article XX, by contrast, the question is whether a measure is applied in a manner that would
constitute a means of arbitrary or unjustifiable discrimination between countries where the same conditions
prevail. (See Appellate Body Reports, EC – Seal Products, para. 5.311)
805 Appellate Body Reports, EC – Seal Products, para. 5.312.
806 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.347.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

rationally related to, the policy objective with respect to which the measure has been provisionally
justified".807 In these circumstances, the Appellate Body considered that it was appropriate for th e
first compliance panel, "in principle, to have referred to and relied on" the reasoning it had developed
in the context of Article 2.1 in its analysis under the chapeau of Article XX.808
6.274. The Appellate Body emphasized that, in the circumstances of this disp ute, "an assessment
of whether the requirements of the amended tuna measure are calibrated to the likelihood that
dolphins would be adversely affected in the course of tuna fishing operations in the respective
conditions" was " relevant for an analysis of a rbitrary or unjustifiable discrimination under the
chapeau of Article XX".809 This was because the first compliance panel was required to examine the
United States' claim that "any differences in the regulatory requirements of the [2013 Tuna Measure]
are justified by reference to the objective of dolphin protection because such differences reflect the
differences in risks" to dolphins arising from the use of different fishing methods in different ocean
areas.810 However, the Appellate Body recalled its criticism of the first compliance panel's findings
under Article 2.1, including that the first compliance panel had failed to conduct a proper calibration
analysis, and that the first compliance panel's "decision to adopt a segmented analytical approach
prevented it from properly applying the legal standard that it had articulated"811, namely, "whether
the detrimental treatment can be reconciled with, or is rationally related to, the policy pursued by
the measure at issue".812 In the Appellate Body's view, "these criticisms concern aspects of the [first
compliance panel's] reasoning and findings that it also relied upon in the context of its analysis under
the chapeau of Article XX" of the GATT 1994.813 In light of these errors 814, the Appellate Body
reversed the first compliance panel's findings under the chapeau of Article XX.815
6.275. The above findings indicate that, in the circumstances of this dispute, it was appropriate for
the first compliance panel to "rel[y] on a similar analytica l process under" both Article 2.1 and the
chapeau of Article XX.816 This process should have involved ascertaining the existence of arbitrary
or unjustifiable discrimination through an examination of whether such discrimination can be
reconciled with, or is rationally related to, the measure's policy objective .817 Furthermore, for this
analytical process, it was relevant to examine whether the regulatory distinctions under the measure
at issue were calibrated to different risks to dolphins arising from the use of different fishing methods
in different areas of the ocean.818 However, because the first compliance panel had failed to conduct
a proper calibration analysis under Article 2.1, and had adopted a segmented approach to analysing
the requirements under the m easure, the panel had also failed to examine properly the rational
relationship between the measure's objectives and the regulatory distinctions giving rise to the
discrimination. As a result, the first compliance panel's findings under Article 2.1 had not in fact
ascertained the existence of arbitrary or unjustifiable discrimination. Thus, by relying on the same
reasoning and analysis developed under Article 2.1, the errors committed by the first compliance

807 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.347.
808 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.320.
809 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.330. (emphasis added)
810 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.330.
811 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.332.
812 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.229 (quoting First
Compliance Panel Report, para. 7.91).
813 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.332.
814 In addition to the above-mentioned errors, the Appellate Body also considered that the first
compliance panel had failed to properly analyse whether the existing discrimination is between countries where
the same conditions prevail. (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
para. 7.333) As noted above, this issue is not in dispute in the present proceedings. (See paras. 6.261-6.262
above)
815 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.333-7.335. At the
same time, the Appellate Body recalled that, in completing the analysis in the context of its findings under
Article 2.1 of the TBT Agreement, it had examined other features of the Tuna Measure that were not dependent
on the first compliance panel's calibration analysis. In this regard, the Appellate Body agreed with the panel
that the determination provisions left a "gap" in that fisheries other than the ETP large purse seine fishery may
be treated differently, and less stringently, even where the conditions in that fishery mirror those in the
ETP large purse seine fishery. (Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico),
paras. 7.354-7.359) Therefore, the Appellate Body found that, with respect to the determination provisions,
the United States had not demonstrated that the 2013 Tuna Measure was applied in a manner that did not
constitute arbitrary or unjustifiable discrimination. Consequently, the Appellate Body found that the 2013 Tuna
Measure was not justified under Article XX of the GATT 1994. (Ibid., para. 7.359)
816 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.320.
817 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), paras. 7.320 and 7.347.
818 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.330.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

panel therein also undermined its finding regardi ng arbitrary or unjustifiable discrimination under
the chapeau of Article XX.
6.276. Turning to Mexico's appeal in these compliance proceedings, we recall that its claim under
the chapeau of Article XX is premised on its view that the calibration analysis conduct ed by the
Panels under Article 2.1 of the TBT Agreement did not encompass consideration of the rational
relationship between the regulatory distinctions of the 2016 Tuna Measure and its objectives. 819
According to Mexico, because an assessment of such a relationship is required for examining
arbitrary or unjustifiable discrimination under the chapeau of Article XX, the Panels erred by relying
on their findings, made under Article 2.1, for their analysis under the chapeau of Article XX.820
6.277. We recall that , in this dispute, the "discrimination between countries where the same
conditions prevail" for the purpose of the chapeau of Article XX ar ises from the fact that "the
2016 Tuna Measure continues to cause the same detrimental impact resulting from the
discriminatory treatment between tuna products containing tuna caught in the ETP large purse-seine
fishery and those containing tuna caught in other fisheries ."821 Thus, while the discrimination
examined under the chapeau of Article XX may not be the same as the disc rimination found to be
inconsistent with the relevant provisions of the GATT 1994, in the present dispute, the relevant
discrimination for the analysis under the chapeau of Article XX is the same as the detrimental impact
caused by the relevant regulatory distinctions examined by the Panels in the context of Article 2.1.
Furthermore, we recall that two elements of the legal test under the chapeau – namely, the existence
of discrimination between countries , and whether the same conditions prevail in those
countries – are not at issue between the parti es.822 This means that the issue before us concerns ,
exclusively, whether the 2016 Tuna M easure is applied in a manner that constitute s a means of
arbitrary or unjustifiable discrimination.
6.278. In this regard, we recall that "'[o]ne 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."823 As discussed in
section 6.1.3.1 above, considerations of the rational relationship between the regulatory distinctions
causing such detrimental impact and the objectives of the 2016 Tuna Measure, rather than being a
separate inquiry, are encompassed in a proper calibration analysis under Article 2.1. This is because,
where the calibration analysis is conducted properly , it would also ascertain whether the label
granted under the measure at issue convey s the information regarding the dolphin -safe nature of
the tuna products to consumers. Thus, as explained, we consider that a proper assessment of
whether the measure is calibrated to the risks to dolphins arising from the use of different fishing
methods in different areas of the ocean would take into account the objectives of the 2016 Tuna
Measure regarding dolphin protection and consumer information.824 Such an assessment would also
help to ascertain the nexus between such objectives and the regulatory distinctions drawn under the
measure.
6.279. Furthermore, in sections 6.1.4 and 6.1.5 above, we have found that the Panels conducted a
proper calibration analysis of the 2016 Tuna Measur e by assessing whether the regulatory
distinctions of the 2016 Tuna Measure are calibrated to different risks to dolphins arising from the
use of different fishing methods in different areas of the ocean. We consider that the
Panels' sequential analyses of each of the elements of the 2016 Tuna Measure, as well as their
examination of the measure as a whole, were properly informed by the interlinkages between these
elements and the fact that they operate together to regulate access to the dolphin -safe label.825
We thus agree with the Panels that they were "mindful" of the Appellate Body's guidance in the
previous compliance proceedings, and that they conducted their calibration analysis accordingly. 826
In our view, unlike the first compliance panel's assessment o f the 2013 Tuna Measure, the
Panels' calibration analysis under Article 2.1 encompassed consideration of the rational relationship

819 Mexico's appellant's submission, para. 319.
820 Mexico's appellant's submission, para. 315.
821 Panel Reports, para. 7.732.
822 See paras. 6.261-6.262 above.
823 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.316 (quoting
Appellate Body Reports, EC – Seal Products, para. 5.306).
824 Panel Reports, para. 7.125.
825 See paras. 6.256-6.257 above.
826 Panel Reports, paras. 7.736-7.737.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

between the regulatory distinctions of the 2016 Tuna Measure and its objectives. Th us, the
Panels' analysis under Article 2.1 also demonstrates that the 2016 Tuna Measure is not designed or
applied in a manner that constitutes arbitrary or unjustifiable discrimination within the meaning of
the chapeau of Article XX.
6.280. In sum, the calibration analysis is the tool in the circumstan ces of this dispute to assess
whether the 2016 Tuna Measure is consistent with Article 2.1. It follows that, if the
2016 Tuna Measure is properly calibrated and hence not inconsistent with Article 2.1, it will also not
be found to be applied in a manner th at constitutes arbitrary or unjustifiable discrimination.
Furthermore, given the "important parallel s" between the analyses under Article 2.1 and the
chapeau of Article XX discussed above, the 2016 Tuna Measure, which is not applied in a manner
that amounts to arbitrary or unjustifiable discrimination under the former , would also be found not
to amount to such discrimination under the latter. Hence, in the circumstances of this dispute, a
proper calibration analysis is a tool that also serves to determine whether the measure is applied in
a manner that does not constitute arbitrary or unjustifiable discrimination for the purpose of the
chapeau of Article XX.
6.281. In light of the above considerations, we share the Panels' view that, because "the 2016 Tuna
Measure is 'tailored to', and 'commensurate with', the different risks to dolphins caused by different
fishing methods in different parts of the ocean", this also demonstrates that the discrimination under
the measure "can[not] be said to be applied in a manner t hat constitutes a means of 'arbitrary or
unjustifiable discrimination' within the meaning of Article XX".827 Therefore, we disagree with Mexico
that the Panels "declin[ed] to conduct, either under Article 2.1 or the chapeau of Article XX, a full
assessment of whether the [2016 Tuna Measure] is designed or applied in a manner that constitutes
arbitrary or unjustifiable discrimination".828
6.282. Mexico additionally contends that there is "an apparent conflict" in the Panels' reasoning.829
This is because, on the one ha nd, the 2016 Tuna Measure is provisionally justified as relating to
"conservation of exhaustible natural resources" under Article XX(g).830 On the other hand, according
to Mexico, the Panels "refus[ed] to consider", in their calibration analysis under Article 2.1, "PBR data
and evidence demonstrating that certain fishing methods in certain areas of the oceans are causing
adverse effects that threaten the collapse of dolphin populations". 831 Mexico argues
that t he Panels' calibration analysis focuses on the ris ks to indiv idual dolphins and
"overlook[s] … mortalities that do endanger the population of dolphins in [three longline]
fisheries".832 Thus, to Mexico, by relying on their erroneous calibration analysis for the purpose of
the chapeau of Article XX, the Panels failed to properly examine whether the discrimination under
the 2016 Tuna M easure can be reconciled with, or is rationally related to, the policy objective of
conserving exhaustible natural resources, with respect to which the measure has been provisionally
justified under Article XX(g).833 In Mexico's view, this conflict in the Panels' reasoning shows that
their refusal to consider "PBR data and evidence demonstrating that certain fishing methods in
certain areas of the oceans are causing adve rse effects that threaten the collapse of dolphin
populations is not objective and is legally incorrect".834
6.283. We recall that, in the first compliance proceedings, the Appellate Body rejected Mexico's
argument that the panel erred in articulating the legal standard under the chapeau of Article XX as
consisting of a focus on whether there is a rational connection with the objectives of the 2013 Tuna
Measure, rather than the objective reflected in Article XX(g).835 The Appellate Body considered such
a distinction t o be "somewhat artificial" given that, "by virtue of an examination of whether a
measure is provisionally justified under one of the subparagraphs, the objective of the measure will

827 Panel Reports, para. 7.739.
828 Mexico's appellant's submission, para. 315.
829 Mexico's appellant's submission, para. 316.
830 Mexico's appellant's submission, para. 316.
831 Mexico's appellant's submission, para. 316.
832 Mexico's appellant's submission, para. 215. (emphasis omitted) We recall that PBR evidence
calculates the "maximum possible number of animals … which can be removed from an animal stock without
affecting the population or its sustainability". (Panel Reports, para. 7.184) These three fisheries are the Main
Hawaii Island Insular Stock Longline fishery, the West North Atlantic Longline fishery, and the Pelagic Hawaii
Longline fishery. (Mexico's appellant's submission, para. 215. See also Panel Reports, para. 7.473)
833 Mexico's responses to questioning during the hearing.
834 Mexico's appellant's submission, para. 316.
835 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.318.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

already have been tested against, and will have been found to be aligned with, one of the objectives
set out in Article XX."836 The Appellate Body did not understand how, in the circumstances of th is
dispute, where the first compliance panel found that the objective of dolphin protection relates to
the conservation of exhaustible natural resources, "reliance on the objective of Article XX(g), rather
than that of the measure, would yield a different analytical result".837
6.284. We consider that Mexico's argument in the present compliance proceedings introduces a
similar artificial distinction between the objective of the 2016 Tuna Measure of protecting individual
dolphins and the objective of "conservation of exhaustible natural resources" within the meaning of
Article XX(g). In section 6.1.4.4 above, we reviewed Mexico's argument that the Panels erred in not
relying on PBR evidence for assessing the risks to dolphins arising from the use of different fishing
methods in different ocean areas. We agreed with the Panels' assessment that the PBR methodology
prioritizes the sustainability of the population in a way that would have prevented the Panels from
adequately assessing whether the measure is calibrated to different risks that a dolphin was killed
or seriously injured in the fishing process.838 That said, the fact that the Panels sought to examine
whether the measure is calibrated to risks to individual dolphins does not mean that their calibration
analysis failed to take into account the rational connection between the regulatory distinctions giving
rise to the discrimination and the goal of conserving exhaustible natural resources.
6.285. We also recall that the Panels noted the original and first compliance panel's findings that
the Tuna Measure is "more concerned with the 'well -being of individual dolphins'" 839, and the
dolphin-protection objective thereof is not to "be understood exclusively, or even primarily, in terms
of dolphin population recovery ".840 The Panels further noted that addressing adverse effects to
individual dolphins "might also be considered as seeking to conserve dolphin populations" and that,
consequently, the objectives of the measure "also incorporate" considerations regarding
conservation.841 The Panels highlighted that "mortality or serious injury suffered by individual
dolphins may also have population -level consequences."842 We further recall that, as the first
compliance panel found, "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", and that "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."843
6.286. We therefore disagree with Mexico's assertion that, because tuna harvested in three fisheries
with low PBR levels may be eligible to receive "dolphin-safe" labels under the 2016 Tuna Measure,
the measure is "not concerned" with the risks rel ated to fishing methods that threaten the
sustainability of dolphin populations. 844 As explained above, findings by the original and first
compliance panels, as well as the present Panels, indicate that, while the 2016 Tuna Measure may,
first and foremost, b e "concerned" with the protection of individual dolphins, the measure also
protects dolphin populations by ensuring that tuna producers who seek to have access to the
"dolphin-safe" label are deterred from harvesting tuna in a manner that harms dolphins. 845
Therefore, the fact that the 2016 Tuna Measure does not disqualify tuna caught in the three fisheries
concerned from accessing the dolphin -safe label does not mean that it fails to address the
conservation of dolphin populations. Rather, by seeking to ensu re that individual dolphins are not
being harmed in the fishing process, the 2016 Tuna Measure is also related to the conservation of
these populations.

836 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.318.
837 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.318.
838 See paras. 6.130-6.131 above.
839 Panel Reports, fn 331 to para. 7.187 (referring to Original Panel Report, para. 7.596; quoting
840 Panel Reports, para. 7.187 (quoting Original Panel Report, paras. 7.550 and 7.735).
841 Panel Reports, fn 331 to para. 7.187 (referring to Original Panel Report, para. 7.596;
842 Panel Reports, para. 7.186.
843 First Compliance Panel Report, para. 7.527. The first compliance panel also indicated that "the fact
that the [2013 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."
(Ibid.) Mexico did not appeal these findings in the first compliance proceedings.
844 Mexico's appellant's submission, para. 316.
845 Panel Reports, para. 7.186.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.287. In any event, by acknowledging that the 2016 Tuna Measure is provisionally justified under
Article XX(g) of the GATT 1994, Mexico accepted that the measure and its objectives, including the
protection of individual dolphins, are "designed" to address, and are "related to", the "conservation
of exhaustible natural resources". 846 Therefore, given that the regul atory distinctions causing the
discrimination under the 2016 Tuna Measure are rationally related to the protection of individual
dolphins, we do not consider that this discrimination "bears no rational connection to", or wou ld
"go against", the objective o f "conservation of exhaustible natural resources". 847 As the
Appellate Body found in the first compliance proceedings, once the measure at issue in this dispute
is found to be provisionally justified under Article XX(g), whether the rational relationship
requirement under the chapeau of Article XX is analysed through the lens of the objectives pursued
by the measure, or the policy objectives contained in Article XX(g), the analysis should not yield a
different result.848 In light of this finding, and the considerations set out above, we disagree with
Mexico's contention that, because of the Panels' rejection of the PBR evidence, their calibration
analysis cannot support a finding that the regulatory distinctions giving ri se to the discrimination
under the 2016 Tuna Measure are rationally related to the conservation of exhaustible natural
resources.
6.2.3 Conclusion
6.288. In sum, one of the most important factors in the assessment of arbitrary or unjustifiable
discrimination under the chapeau of Article XX of the GATT 1994 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.
As indicated above, the Appellate Body's guidance in the first compliance proceedings indicates that
the calibration analysis is the tool in the circumstances of this dispute to assess whether the
2016 Tuna Measure is consistent with Article 2.1 of the TBT Agreement. If done properly, th e
calibration analysis would encompass consideration of the rational relationship between the
regulatory distinction of the 2016 Tuna Measure and its objectives. As also indicated, it was
appropriate for the Panels, in the circumstances of these compliance proceedings, to rely on their
calibration analysis under Article 2.1 in their assessment of whether the 2016 Tuna Measure is
applied in a manner that constitutes arbitrary or unjustifiable discrimination wit hin the meaning of
the chapeau of Article XX. This is because, where the differences between Article 2.1 and Article XX
are taken into account, it may be permissible to rely on reasoning developed in the context of one
agreement for the purpose of conducting an analysis under the other.
6.289. We also indicated in section 6.1.5 above that the Panels did not err in finding that the
2016 Tuna Measure is calibrated to the risks to dolphins arising from the use of different fishing
methods in different areas of the ocean. Therefore, given that consideration of the rational
relationship between the regulatory distinctions and the objectives of the 2016 Tuna Measure was
encompassed in this analysis , w e find that the P anels did not err in relying on the reasoning
developed under Article 2.1 of the TBT Agreement in assessing the conformity of the 2016 Tuna
Measure with the chapeau of Article XX of the GATT 1994. We also reject Mexico's contention that,
due to the Panels' reliance on per set evidence, rather than PBR evidence, in assessing the risks to
dolphins, their calibration analysis cannot be relied on for assessing whether the 2016 Tuna Measure
is rationally related to the conservation of exhaustible natural resources.

846 The Appellate Body has found that the provisional justification of a measure under one of the
exceptions requires, first, that the measure be designed to "address the particular interest specified in that
paragraph" and, second, that "there be a sufficient nexus between the measure and the interest protected".
(Appellate Body Report, US – Gambling, para. 292. See also Appellate Body Reports, EC – Seal Products,
para. 5.169 and fn 1178 thereto) The required nexus is specified in the language of the paragraphs themselves
through the use of terms such as "necessary to", "essential to", or – as in the case of Article XX(g), which is
relevant to the present dispute – "relating to". (Appellate Body Report, Colombia – Textiles, para. 5.67
(referring to Appellate Body Report, US – Gambling, para. 292)) We also observe that the United States agree
with Mexico that the 2016 Tuna Measure is provisionally justified under Article XX(g). (Panel Reports,
para. 7.730) The issue of the provisional justification of the 2016 Tuna Measure is not on appeal before us.
847 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.316 (quoting
Appellate Body Report, Brazil – Retreaded Tyres, para. 227).
848 Appellate Body Report, US – Tuna II (Mexico) (Article 21.5 – Mexico), para. 7.318.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.290. For the foregoing reasons, we uphold the Panels' finding that the 2016 Tuna Measure is not
applied in a manner that constitutes a means of arbitrary or unjustifiable discrimination and is
therefore justified under Article XX of the GATT 1994.849
6.3 The Panels' decision to hold a partially open meeting
6.291. Mexico appeals " the findings and conclusion of the Panels that they had the authority to
conduct a partially open meeting of the parties without the consent of both Parties".850 In response,
the United States contends that Mexico's appeal is not properly raised due to deficiencies in Mexico's
Notice of Appeal in light of Article 17.6 of the DSU and Rule 20(2)(d) of the Working Procedures for
Appellate Review (Working Procedures).851
6.3.1 Procedural background
6.292. At the organizational meetings of the Panels in these proceedings, held on 10 June 2016 and
14 July 2016, respectively, the United States proposed a change to the Panels' working procedures
to allow the Panels' substantive meeting to be publicly observed. Alterna tively, if Mexico did not
agree to this, the United States requested the Panels to allow a party to request a partially open
meeting, whereby that party's statements during the Panel's meeting with the parties could be
viewed by the public, either simultan eously or through a delayed broadcast. The statements of a
party that wished to maintain the confidentiality of these statements could not be so viewed. 852
Mexico opposed the United States' request that the Panels conduct an open meeting either fully or
partially. Mexico argued that the Panels could only open their substantive meetings with the parties
to public viewing with the consent of both parties.853
6.293. On 4 July 2016, the Panel in the proceedings brought by the United States sought the views
of the third pa rties on this procedural issue. Nine third parties provided their views.
Six third parties854 opposed the United States' request, whereas three855 did not.856
6.294. On 29 July 2016, the Panels informed the parties that they considered themselves to have
the authority to authorize the United States to lift the confidentiality of its statements at the
substantive meeting with the parties. 857 Subsequently, in response to a formal request by the
United States, and following their consultation with the parties, the Panels adopted their Additional
Working Procedures on 22 December 2016.858
6.295. We understand Mexico's challenge, in its Notice of Appeal, to the Panels' conduct of a
"partially open meeting of the parties" to refer to the implementation of the Panels' Additional
Working Procedures. 859 Pursuant to these procedures, the Panels permitted the United States'
request to disclose, through public viewing, the statements of its own positions made during the
Panels' substantive meeting with the parties. The Panels also permitted an y third parties that so
requested to disclose, through public viewing, the statements of their own positions made during
the Panels' session with the third parties.860 The Panels granted these permissions on condition that

849 Panel Reports, para. 7.740.
850 Mexico's Notice of Appeal, para. 11. See also Mexico's appellant's submission, para. 353(g). While
previous panels and the Appellate Body have held meetings and hearings that were open to public observation,
this is the first time that a WTO adjudicator authorized such a meeting without the express consent of both
parties to the dispute. (See e.g. Panel Report, US – Tax Incentives, para. 1.20; Appellate Body Report, EC and
certain member States – Large Civil Aircraft (Article 21.5 – US), para. 1.30)
851 United States' appellee's submission, paras. 381-384.
852 Panel Reports, paras. 1.14 and 1.16.
853 Panel Reports, para. 1.18.
854 The six third parties were Brazil, China, Ecuador, Guatemala, India, and Korea. (Panel Reports,
para. 7.14)
855 The three third parties were Australia, Japan, and Norway. (Panel Reports, para. 7.15)
856 Panel Reports, para. 1.15.
857 The Panels informed the parties of their decision through a joint communication with the Arbitrator
acting under Article 22.6 of the DSU in the same dispute. (Panel Reports, para. 1.17)
858 Panel Reports, paras. 1.18-1.19. The Panels elaborated on their reasons for adopting these
procedures in section 7.7.2 of their Reports.
859 Panel Reports, Annex A-4.
860 Seven third parties sought and were given permission to disclose statements of their own positions
during the Panels' session with the third parties (Australia, Canada, the European Union, Japan, Korea,
New Zealand, and Norway). (Panel Reports, fn 54 to para. 7.34)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

the public viewing take the form of delayed (rather than simultaneous) viewing. The Panels also
required that any parts of the meeting, including the third -party session, opened for partial public
observation should not disclose statements of Mexico's positions or the po sitions of non-disclosing
third parties. To this end, these parts of the meeting that were eventually opened for partial public
observation were subjected to redaction prior to the public viewing.861
6.296. In explaining the ir reasons for the adoption of these Additional Working Proce dures, the
Panels stated that:
[I]t is … permissible for a WTO adjudicator to authorize a request for a partially open
meeting if the conduct of such a meeting does not imp air or interfere with
(a) a non-disclosing party's or non -disclosing third party's r ight to confidentiality
protection of statements of its own position, (b) due process, (c) the prompt settlement
of disputes, or (d) the careful and efficient discharge, or the integrity, of the adjudicative
function.862
6.297. According to the Panels, their Additional Working Procedures "fully protect[ed] Mexico's and
non-disclosing third parties' right to confidentiality protection, satisf[ied] the requirements of due
process, and [we]re sufficiently workable and efficient to safeguard the promptness of dispute
settlement and the proper discharge and integrity of [the Panels'] adjudicative function".863
6.3.2 Sufficiency of Mexico's Notice of Appeal
6.298. Mexico's Notice of Appeal identifies the alleged claim of error by the Panels as follows:
Mexico also seeks review by the Appellate Body of, and requests the Appellate Body to
reverse, the findings and conclusion of the Panels that they had the authority to conduct
a partially open meeting of the parties without the consent of both Parties.864
6.299. The United States challenges the sufficiency of Mexico's Notice of Appeal, arguing that it fails
to meet the requirements of Rule 20(2)(d) of the Working Procedures.865 The United States contends
that Mexico's Notice of Appeal fails to list any legal provision of any cov ered agreement that the
Panels are alleged to have erred in interpreting or applying. The United States adds that Mexico's
Notice of Appeal fails to indicate any paragraph of the Panel Reports containing the alleged errors.866
The United States also asserts that, "[m]ore fundamentally", Mexico's Notice of Appeal fails to
identify an alleged error in the issues of law covered in the Panel Reports or legal interpretation
developed by the Panels.867 For the United States, this means that Mexico "has failed to just ify its
appeal as being within the scope of Article 17.6 of the DSU". 868 At the hearing, the United States
added that an appellant cannot cure a defect in the notice of appeal by including something additional
in its appellant submission.
6.300. In response, at the hearing, Mexico acknowledged that the notice of appeal serves to provide
adequate notice to the appellee of the nature of the appeal and allegations of error, which in turn
enables the appellee to exercise fully its right of defence. At the same time, Mexico highlighted that
the Appellate Body has stated that an appellee will have a better understanding of the nature of the
appeal and the allegations of errors when a detailed written submission is filed on the same day.
Given that Mexico's Notice of Appeal and appellant's submission were filed on the same day, Mexico
argued that the references to the relevant Panels' findings and legal interpretation could be clearly
inferred from a review of both documents. In any event, Mexico contended that the perceived failures
of its Notice of Appeal had not prevented the United States from understanding the nature of
Mexico's appeal on this matter, nor had the failures impeded the United States' ability to exercise
its right of defence.

861 Panel Reports, para. 7.34.
862 Panel Reports, para. 7.31.
863 Panel Reports, para. 7.32.
864 Mexico's Notice of Appeal, para. 11.
865 United States' appellee's submission, paras. 381-384.
866 United States' appellee's submission, para. 385.
867 United States' appellee's submission, para. 387.
868 United States' appellee's submission, para. 389.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

6.301. Rule 20(2)(d) of the Working Procedures869 provides:
(2) A Notice of Appeal shall include the following information:
…
(d) a brief statement of the nature of the appeal, including:
(i) identification of the alleged errors in the issues of law covered in the panel report
and legal interpretations developed by the panel;
(ii) a list of the legal provision(s) of the covered agreements that the panel is alleged
to have erred in interpreting or applying; and
(iii) without prejudice to the ability of the appellant to refer to other paragraphs of
the panel report in the context of its appeal, an indicative list of the paragraphs of the
panel report containing the alleged errors.
6.302. The Appellate Body has referred to the notices of appeal and other appeal as the "documents
that define the scope of the appeal".870 In challenging the sufficiency of Mexico's Notice of Appeal,
apart fro m noting certain formal defects , the United States expressed concern "[m]ore
fundamentally" with the failure of Mexico's Notice of Appeal to identify "an alleged error in the issues
of law covered in the Panel Reports or legal interpretation developed by the Panels " within the
meaning of Rule 20(2)(d)(i) of the Working Procedures and Article 17.6 of the DSU.871
6.303. Article 17.6 of the DSU states that "[a]n appeal shall be limited to issues of law covered in
the panel report and legal interpretations developed by the panel". Rule 20(2)(d)(i) of the
Working Procedures is rooted in the language of Article 17.6 of the DSU by req uiring a notice of
appeal to include a "brief statement of the nature of the appeal, including identification of the alleged
errors in the issues of law covered in the panel report and legal interpretations developed by the
panel". Thus, Rule 20(2)(d)(i) reinforces the role of the notice of appeal as a document that defines
the scope of the appeal 872, within the boundaries delineated by Article 17.6 of the DS U.
A fundamental consideration in determining whether a notice of appeal is sufficient, therefore, is
whether the allegation of error identified in the notice of appeal is one that implicates "issues of law
covered in the panel report and legal interpretations developed by the panel" as required by
Article 17.6 of the DSU.
6.304. In the present dispute, Mexico ha s identified a decision made by the Panels regarding the
conduct of their proceedings. In its Notice of Appeal, Mexico challenges "the findings and conclusion
of the Panels that they had the authority to conduct a partially open meeting of the parties with out
the consent of both Parties".873 As described above, as early as the organizational meetings with the
Panels, Mexico objected to the public observation of the Panels' substantive meeting with the parties,
either fully or partially, without the consent of both parties. The Notice of Appeal again identifies the
same issue, that is, whether the Panels had the authority to conduct a meeting with the parties that
was partially open to public observation without the consent of both parties. Mexico's Notice of
Appeal, read in the context of the relevant procedural background leading to the Panels' findings,
set out in paragraphs 6.292-6.295 above, appears to identify the issue of law as whether the Panels
had the authority to conduct a meeting with the parties that was partially open to public observation
without the consent of both parties. Hence, the allegation of error identified in paragraph 11 of
Mexico's Notice of Appeal appears to be one that implicates an "issue[] of law covered in the panel
report" as required by Article 17.6 of the DSU.
6.305. Moreover, in assessing whether Mexico's Notice of Appeal sufficiently identifies, pursuant to
Rule 20(2)(d)(i) of the Working Procedures, "the alleged errors in the issues of law covered in the

869 Working Procedures for Appellate Review, WT/AB/WP/6, 16 August 2010 (Working Procedures).
870 Working Procedures for Appellate Review, Communication from the Appellate Body,
WT/AB/WP/W/11, 27 July 2010, p. 5.
871 United States' appellee's submission, para. 387.
872 Working Procedures for Appellate Review, Communication from the Appellate Body,
WT/AB/WP/W/11, 27 July 2010, p. 5.
873 Mexico's Notice of Appeal, para. 11.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

panel report and legal inter pretations developed by the panel", we recall that the Appellate Body
has stated that the notice of appeal is not expected to contain the reasons why the appellant regards
a panel's findings or interpretations as erroneous. Rather, the legal arguments in s upport of the
allegations of error are to be set out and developed in the appellant's submission. 874 We do not
consider that Mexico's Notice of Appeal was required to go beyond identifying the alleged erroneous
findings of the Panels and "contain the reasons why [Mexico] regards those findings or
interpretations as erroneous". 875 In our view, such reasons were to be provided in Mexico's
appellant's submission.
6.306. Furthermore, while we agree with the United States that a deficient notice of appeal cannot
be cured by including a new or additional issue in the appellant's submission 876, we consider that
the appellant's submission may be consulted in order to confirm the meaning of the words used in
the notice of appeal. 877 In its appellant's submission, Mexico points out the aspects of the
Panels' reasoning with which it takes issue and explains why it considers the Panels' reasoning to be
erroneous.878 For example, Mexico challenges the Panels' statement that "[i]f a WTO adjudicator has
the power to accede to a request to fully open a hearing or meeting with the parties, then a fortiori
it must in principle also have the power to go less far, including by opening only parts of a meeting
with the parties."879 Mexico contends that the Panels' statement is "incorrect" becaus e, in all prior
disputes to which the Panels referred in support of this statement, there was an agreement of both
disputing parties to open the meeting. 880 As we see it, these statements in Mexico's appellant's
submission confirm the Panels' decision with w hich Mexico takes issue in paragraph 11 of its
Notice of Appeal and provide the legal arguments in support of Mexico's claim of error.
6.307. We also take note of the United States' argument that Mexico has failed to justify its appeal
as being within the scope o f Article 17.6 of the DSU because, "[r]ather than relating to the matter
referred to the Panels by the DSB, Mexico's appeal relates to the procedures adopted by the Panels
to conduct their proceedings."881 We do not agree. In our view, the manner in which a panel adopts
procedures and conducts its proceedings when it addresses the matter referred to it by the DSB may
give rise to issues of law and legal interpretation, which would be subject to the scope of appellate
review within the meaning of Article 17.6.882
6.308. In addition to the United States' fundamental concern that Mexico's Notice of Appeal fails to
comply with Article 17.6 of the DSU and Rule 20(2)(d)(i) of the Working Procedures, the
United States argues that Mexico's Notice of Appeal fails to comply with the formal requirements set
out in Rule 20(2)(d)(ii) and (iii) of the Working Procedures. The United States contends that Mexico's
Notice of Appeal fails to refer to any legal provision of any covered agreement that the Panels are

874 Appellate Body Reports, US – Shrimp, para. 95; Indonesia – Iron or Steel Products, para. 5.6. It is
noted that the statements by the Appellate Body in US – Shrimp concern an earlier version of the Working
Procedures for Appellate Review. In those Working Procedures, Rule 20(2)(d) provided that a notice of appeal
shall include "a brief statement of the nature of the appeal, including the allegations of errors in the issues of
law covered in the panel report and legal interpretations developed by the panel". (Appellate Body Report,
US – Shrimp, para. 95 (quoting Working Procedures for Appellate Review, WT/AB/WP/2, 28 February 1997))
875 Appellate Body Report, US – Shrimp, para. 95. See also Appellate Body Report, Indonesia – Iron or
Steel Products, para. 5.6.
876 This is especially so because Rule 23bis of the Working Procedures provides the avenue through
which an appellant can amend its notice of appeal. Indeed, the Appellate Body has, in the past, considered
certain claims to fall outside the scope of the appeal where the appellant identified the claim of error in the
appellant's submission but not in the notice of appeal, as required by Rule 20(2)(d) of the Working Procedures.
(See e.g. Appellate Body Reports, US – Countervailing Measures on Certain EC Products, paras. 72-75;
Japan – Apples, paras. 126-128)
877 In this regard, we consider the statements by the Appellate Body regarding the sufficiency of a panel
request under Article 6.2 to be relevant, mutatis mutandis, to the discussion of the sufficiency of a notice of
appeal. In US – Carbon Steel, the Appellate Body found that a defect in the panel request cannot be cured by
including a claim in a panel submission. Nevertheless, in considering the sufficiency of a panel request,
submissions and statements made during the course of the panel proceedings may be consulted in order to
confirm the meaning of the words used in the panel request. (Appellate Body Report, US – Carbon Steel,
para. 127)
878 Mexico's appellant's submission, paras. 341 and 344 (quoting Panel Reports, paras. 7.16 and 7.20).
880 Mexico's appellant's submission, para. 342.
881 United States' appellee's submission, para. 389.
882 For example, in US – Shrimp, the Appellate Body considered a challenge of "the [p]anel's procedural
finding that [it] lacked discretion to accept materials received from non-governmental sources" to be properly
raised in the notice of appeal. (See Appellate Body Report, US – Shrimp, paras. 94 and 96)
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

alleged to have erred in interpreting or applying. The United States adds that Mexico's Notice of
Appeal fails to indicate any paragraph of the Panel Reports containing the alleged errors.883
6.309. A notice of appeal must provide a brief statement of the nature of the appeal.884 Pursuant to
Rule 20(2)(d)(ii) and (iii) of the Working Procedures, this brief statement should include a list of the
legal provisions of the covered agreements that the panel is alleged to have erred in interpreting or
applying and an indicative list of the paragrap hs of the panel report containing the alleged errors.
These two requirements facilitate the "identification of the alleged errors in the issues of law covered
in the panel report and legal interpretations developed by the panel" as required by Rule 20(2)(d)(i)
of the Working Procedures, read together with Article 17.6 of the DSU.
6.310. Mexico's Notice of Appeal does not include "an indicative list of the paragraphs" of the Panel
Reports containing the alleged errors, as required by Rule 20(2)(d)(iii). Nor does Mexico's Notice of
Appeal refer to "a list of the legal provision(s) of the covered agreements" that the Panels are alleged
to have erred in interpreting or applying, as required by Rule 20(2)(d)(ii). The Appellate Body has,
in the past, considered such omissions to constitute "formal defects in the Notice of Appeal".885
6.311. Nonetheless, as the Appellate Body highlighted in EC – Bananas III ( Article 21.5 –
Ecuador II) / EC – Bananas III ( Article 21.5 – US), Rule 20(2)(d) does not stipulate what
consequences flow from a failure to meet its formal requirements. 886 In assessing the potential
consequences of a failure of a notice of appeal to meet the formal requirements of Rule 20(2)(d)(ii)
and (iii), the Appellate Body has focused on due process considerations. 887 To this end, the
Appellate Body has taken into account the balance "that must be maintained between the right of
Members to exercise the right of appeal meaningfully and effectively, and the right of appellees to
receive notice through the notice of appeal of the findings under appeal, so that they may exercise
their right of defence effectively". Thus, the prospect of dismissal of an appeal because a notice of
appeal fails to meet the formal requirements of Rule 20(d)(ii) and (iii) should be weighed against
the possible denial of a party's right to appeal under Article 17.6 of the DSU. To the extent that an
appellee "was placed on notice of the issues raised" in the notice of appeal, the Appellate Body has
found that formal defects in the notice of appeal would not necessarily "give rise to procedural
detriment of the kind that would warrant the dismissal" of the appeal.888
6.312. In the present dispute, while the United States points to these formal defects in Mexico's
Notice of Appeal, the United States has not asserted that, owing to such formal defects, it did not
receive sufficient notice of Mexico's appeal regarding the Panels' decision to conduct a partially
opening meeting with the parties. Thus, despite Mexico's failure to comply with the requirements in
Rule 20(2)(d)(ii) and (iii), we consider that these formal defects do not, by themselves, warrant the
dismissal of Mexico's appeal.
6.313. Based on the foregoing, we find that paragraph 11 of Mexico's Notice of Appeal sufficiently
identifies an alleged error in the issues of law covered in the Panel Reports, as required by
Rule 20(2)(d)(i) of the Working Procedures and Article 17.6 of the DSU. In particular, Mexico's
Notice of Appeal identifies, as an issue of law, the question whether the Panels had the authority to
conduct a meeting with the parties that was partially open to public observation without the consent
of both parties. We also find that the formal defects in Mexico's Notice of Appeal, owing to Mexico's
failure to comply with the requirements in Rule 20(2)(d)(ii) and (iii) of the Working Procedures, do

883 United States' appellee's submission, para. 385.
884 Rule 20(2)(d) of the Working Procedures.
885 Appellate Body Reports, EC – Bananas III (Article 21.5 – Ecuador II) / EC – Bananas III
886 Appellate Body Reports, EC – Bananas III (Article 21.5 – Ecuador II) / EC – Bananas III
(Article 21.5 – US), para. 280.
887 Appellate Body Reports, US – Countervailing Measures on Certain EC Products, para. 62; US – Offset
Act (Byrd Amendment), para. 206. In this regard, the Appellate Body has also cautioned Members against
drafting their notices of appeal or other appeal at a level of vagueness and imprecision that would make it
"considerably difficult for the appellee, the third participants, and the Appellate Body to understand easily the
full scope of [an appellant's] claim". Understanding the full scope of an appellant's claim should not require
such effort. Drafting the notice of appeal or notice of other appeal with greater precision reduces the risk of
procedural objections and possible dismissal of a claim because it does not comply with the requirements of
Rule 20 or 23 of the Working Procedures. (Appellate Body Report, US – Large Civil Aircraft (2nd complaint),
para. 686)
888 Appellate Body Reports, EC – Bananas III (Article 21.5 – Ecuador II) / EC – Bananas III
(Article 21.5 – US), para. 283.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

not, by themselves, warrant the dismissal of Mexico's appeal. We therefore find that Mexico's claim
that the Panels erred in finding that they had the authority to conduct a p artially open meeting
without the consent of both parties is properly within the scope of this appeal.
6.3.3 Whether the Appellate Body should rule on this issue
6.314. Having found that Mexico's allegation of error, as identified in paragraph 11 of Mexico's
Notice of Appeal, is properly within the scope of this appeal, we take note of the suggestion by the
United States that, "it would be appropriate for the Appellate Body to exercise judicial economy"
with respect to this claim of error. In the United States' view, this is because Mexico's appeal of the
Panels' decision to conduct the partially open panel meeting does not concern "issues of law covered
in the panel report" or "legal interpretations developed by the panel".889
6.315. As a preliminary matter, we recall our finding above that paragraph 11 of Mexico's Notice of
Appeal sufficiently identifies, as an issue of law, the question whether the Panels had the authority
to conduct a meeting with the parties that was partially open to public observation without the
consent of both parties.890 We therefore disagree with the United States that Mexico's appeal does
not concern "issues of law covered in the panel report".
6.316. This, however, does not necessarily mean that a finding on this aspect of Mexico's appeal is
required. The following provisions of the DSU are relevant in this regard. Article 17.12 provides that
"[t]he Appellate Body shall address each of the issues raised in accordance with paragraph 6 during
the appellate proceeding."891 Article 3.2 states that:
The dispute settlement system of the WTO is a central element in providing security
and predictability to the multilateral trading system. The Members recognize th at it
serves to preserve the rights and obligations of Members under the covered
agreements, and to clarify the existing provisions of those agreements in accordance
with customary rules of interpretation of public international law. Recommendations and
rulings of the DSB cannot add to or diminish the rights and obligations provided in the
covered agreements.
6.317. Article 3.4 provides that "[r]ecommendations or rulings made by the DSB shall be aimed at
achieving a satisfactory settlement of the matter". Article 3.7 states that "[t]he aim of the dispute
settlement mechanism is to secure a positive solution to a dispute."
6.318. In the past, the Appellate Body has understood these overarching aims of the WTO dispute
settlement mechanism to mean that, while the Appellate Body is required to address each issue on
appeal, it has the discretion not to rule on an issue when doing so is not necessary to resolve the
dispute892, but the Appellate Body may rule on such an issue in light of the specific circumstances
of a given dispute.893
6.319. Turning to the specific circumstances of these proceedings, we note the following competing
considerations that are relevant to our decision on whether ruling on Mexico's claim of error is
necessary. First, the issue raised by Mexico's appeal does not directly relate to the "matter [at] issue

889 United States' appellee's submission, para. 390.
890 See para. 6.313 above.
891 Article 17.6 limits an appeal to "issues of law covered in the panel report and legal interpretations
developed by the panel".
892 Appellate Body Report, US – Upland Cotton, paras. 510-511. On many of the occasions where the
Appellate Body found that ruling on an issue would be unnecessary to resolve a dispute, this finding was made
after the Appellate Body had already found an error or inconsistency under a related substantive claim. (See
e.g. Appellate Body Reports, EU – Biodiesel (Argentina), para. 6.89; US – Zeroing (Japan), para. 140;
US – Gambling, para. 156; EC – Selected Customs Matters, para. 243) However, these examples are not
exhaustive in identifying the circumstances in which it would be appropriate for the Appellate Body to find that
ruling on an issue would be unnecessary to resolve a dispute. (See e.g. Appellate Body Reports, EU – Fatty
Alcohols (Indonesia), para. 5.252; US – Upland Cotton, paras. 510-511; US – Steel Safeguards,
paras. 483-484)
893 Appellate Body Report, China – HP-SSST (EU), paras. 5.310 and 5.317. See also Appellate Body
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

in the dispute" 894, that is, whether the 2016 Tuna Measure is consistent with the TBT Agreement
and the GATT 1994.895 At the same time, we recognize that the manner in which a panel adopts
procedures and conducts its proceedings when it addresses the matter referred to it by the DSB may
give rise to issues of law and legal interpretation, which would be subject to the scope of appellate
review within the meaning of Article 17.6 of the DSU.896 Second, Mexico considers that the Panels
were not authorized to partially open their meeting with the parties to public observation without
the consent of Mexico. Hence, in its appellant's submission, Mexico requests us to find that the
"Panels erred … in directing that the hearing be partially opened to the public when Mexico did not
agree to the opening" in this case. 897 However, Mexico's arguments on appeal do not elaborate on
the manner in which the Panels' decision is inconsistent with the DSU.898 Third, in addition to Mexico's
request above for a finding of error, Mexico requests "that the Appellate Body clarify that, in the
future, panels should not open a hearing even partially without the agreement of all disputing
parties".899 Mexico suggested that, by ruling on this issue, the Appe llate Body would be providing
clarification on a concern that impacts not only panels but also arbitrators under Article 22.6 of the
DSU.900 The fact that Mexico's request concerns the proceedings of other panels and arbitrators
casts doubt on whether ruling on this issue is necessary to resolve the present dispute.
6.320. In light of the specific circumstances of these proceedings as set out above, we find it
unnecessary to rule on whether the Panels erred in finding that they had the authority to conduct a
partially open meeting of the parties without the consent of both parties. Our finding should not be
construed as an endorsement of the Panels' decision to conduct a partially open meeting of the
parties without the consent of both parties.901
7 FINDINGS AND CONCLUSIONS
7.1. For the reasons set out in this Report, the Appellate Body makes the following findings and
conclusions:
7.1 Whether the Panels erred in their findings under Article 2.1 of the TBT Agreement
7.2. Under Article 2.1 of the TBT Agreement, in order to determine whether the detrimental impact
stems exclusively from a legitimate regulatory distinction, a panel must carefully scrutinize whether
the technical regulation at issue is even-handed in light of the particular circumstances of the case.
In the present dispute, an examination of whether the 2016 Tuna Measure is consistent with
Article 2.1 of the TBT Agreement entails an assessment of whether the regulatory distinctions of the
measure are calibrated to the risks to dolphins arising from different fishing methods in different
areas of the ocean. Such assessment involves: (i) an assessment of the overall relative risks of harm
to dolphins arising from the use of different fishing methods in different ocean ar eas; and
(ii) an assessment as to whether the differences in the dolphin -safe labelling conditions under the
measure are appropriately tailored to, or commensurate with, those respective risks. If conducted
properly, this calibration analysis would encompass consideration of the rational relationship
between the regulatory distinctions drawn by the 2016 Tuna Measure and its objectives. Thus, there
is no need to separately assess the rational relationship between the regulatory distinctions drawn
by the measure and its objectives. Furthermore, while risks of inaccurate labelling are relevant to
the calibration analysis, this does not mean that the applicable legal standard requires the Panels to

894 Appellate Body Report, US – Wool Shirts and Blouses, p. 19, DSR 1997:I, p. 340. See also
Appellate Body Reports, EU – PET (Pakistan), para. 5.28; India – Patents (US), para. 87; Brazil – Retreaded
Tyres, para. 257; Canada – Wheat Exports and Grain Imports, para. 133; US – Lead and Bismuth II, paras. 71
and 73; Argentina – Footwear (EC), para. 145; Australia – Salmon, para. 223; Japan – Agricultural Products II,
para. 111.
895 United States' panel request; Mexico's panel request.
896 See para. 6.307 above.
897 Mexico's appellant's submission, para. 353.
898 In this regard, we take note of the United States' assertion that "the DSU does not impose any
conditions on either opening the hearing or closing the hearing to the public." (United States' appellee's
submission, para. 396)
899 Mexico's appellant's submission, para. 352. (emphasis added)
900 Mexico's response to questioning at the hearing.
901 Paragraph 2 of Appendix 3 to the DSU states that "[t]he panel shall meet in closed session" and that
"[t]he parties to the dispute, and interested parties, shall be present at the meetings only when invited by the
panel to appear before it." Article 12.1 of the DSU states that "[p]anels shall follow the Working Procedures in
Appendix 3 unless the panel decides otherwise after consulting the parties to the dispute."
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

determine whether the 2016 Tuna Measure is calibrated, inter alia , to the risk of inaccurate
dolphin-safe information being passed to consumers.
7.3. In conducting the calibration analysis, it is necessary to examine the risks to dolphins across
all relevant ocean areas in which different fishing methods are practi sed. This does not mean that,
under Article 2.1 of the TBT Agreement, a measure that seeks to protect dolphins must make all
relevant regulatory distinctions on the basis of both fishing method and ocean area. Rather, the
nature of the calibration analysis to be conducted is informed by the nature of the regulatory
distinctions made under the measure itself, and it is the regulatory distinctions causing the
detrimental impact on imported products that must be calibrated to different risks to dolphins. The
relevant regulatory distinctions that need to be examined for the purpose of calibration in this dispute
include the distinction between setting on dolphins and other fishing methods (in the context of the
eligibility criteria) and the distinction between the ETP large purse seine fishery and all other fisheries
(in the context of the certification and the tracking and verification requirements).
7.4. For these reasons, we do not consider that Mexico has established that the Panels, in
considering that they were required to examine whether the 2016 Tuna Measure was calibrated to
the risks to dolphins arising from the use of different fishing methods in different areas of the ocean,
failed to include an inquiry into the nexus between the relevant regulatory distinc tions and the
objectives of the measure. We also disagree with Mexico that the Panels erred by comparing the risk
profiles of different fishing methods in applying the calibration analysis to the eligibility criteria. In
our view, in the specific context o f the 2016 Tuna Measure, in order to assess whether the
detrimental impact on Mexican tuna products stems exclusively from a legitimate regulatory
distinction, the Panels were required to assess whether the regulatory distinctions causing that
detrimental impact are calibrated to different risks to dolphins, in terms of the overall relative risks
to dolphins, taking into account the objectives of the measure.
7.5. In conducting their examination of the risk profiles of different fishing methods as used in
different ocean areas, the Panels reviewed all relevant evidence of risks to dolphins as provided to
them by the parties, including all evidence pertaining to individual fisheries. Additionally, the Panels
appropriately took into account all relevant types of ha rm to dolphins in assessing the risk profiles
of different fishing methods and fisheries. Moreover, the Panels did not err in relying on per set data
as the primary measurement of the risks to dolphins, despite three additional measurements
proposed by Mexico. First, because the relevant risks to be assessed for the purpose of calibration
are the risks of individual dolphins being harmed or killed in the fishing process, the Panels were
correct not to rely on PBR evidence to assess the risks to dolphins. Second, given the comparative
nature of the calibration analysis, the Panels did not err by relying primarily on a per set
methodology, instead of a comparison of absolute levels of harm. Finally, Mexico did not substantiate
its assertion that tuna fishing i n ocean areas with less reliable regulatory systems is more likely to
lead to harm to dolphins, and therefore the Panels did not err by excluding evidence pertaining to
regulatory oversight from their assessment of the overall relative risks to dolphins fr om the use of
different fishing methods as used in different areas of the ocean. We therefore find no error in the
Panels' assessment of the risks to dolphins arising from the use of different fishing methods in
different ocean areas or in their conclusions regarding the risk profiles of relevant fishing methods
on the basis of that assessment.
7.6. Regarding whether the 2016 Tuna Measure is calibrated to the risks to dolphins arising from
the use of different fishing methods in different ocean areas, we have addressed Mexico's challenges
to the Panels' assessment of the following aspects of the 2016 Tuna Measure: (i) the eligibility
criteria; (ii) the certification requirements; (i ii) the tracking and verification requirements; and
(iv) the 2016 Tuna Measure as a whole.
7.7. With respect to the eligibility criteria, we have found that the Panels did not err in finding, in
paragraph 7.539 of their Reports, that "setting on dolphins is significantly more dangerous to
dolphins than are other fishing methods ." This finding implies that the distinction in the eligibility
criteria between setting on dolphins, on the one hand, and other fishing methods, on the other hand,
is, as the Panels found in paragraph 7.540 of their Reports, "appropriately calibrated to the risks to
dolphins arising from the use of different fishing methods in different areas of the ocean".
Accordingly, we find that Mexico has not demonstrated that the Panels erred in re aching the
intermediate finding, in paragraph 7.547 of their Reports, that the eligibility criteria embodied in the
2016 Tuna Measure are calibrated to the risks to dolphins arising from the use of different fishing
methods in different areas of the ocean.
WT/DS381/AB/RW/USA • WT/DS381/AB/RW2

7.8. With respect to the certification requirements, we have found that the Panels adopted the
correct approach in comparing the risk profiles of individual fisheries, because the certification
requirements make a distinction on the basis of both fishing method and ocean area. Having found
no legal error in the Panels' assessment of risk profiles, we consider that the Panels did not err in
finding that the ETP large purse seine fishery has a special risk profile that distinguishes it from other
fisheries. We have also addressed and rejected all of Mexico's ar guments challenging th e
Panels' assessment of the certification requirements, including the allegation that the Panels did not
take into account the risks of inaccuracy in their calibration analysis . For all of these re asons,
we find that Mexico has not demonstrated that the Pa nels erred in arriving at the intermediate
finding, in paragraph 7.611 of their Reports, that the different certification requirements are
calibrated to the risks to dolphins arising from the use of different fishing methods in different areas
of the ocean.
7.9. As with the certification requirements, we have found that with respect to the tracking and
verification requirements, the Panels adopted the correct approach in comparing the risk profiles of
individual fisheries, because these requirements make a disti nction on the basis of both fishing
method and ocean area. Having found no legal error in the Panels' assessment of risk profiles, we
consider that the Panels did not err in finding that it is both the technical and legal possibilit ies of
setting on dolphi ns and the fact that dolphin sets occur in a consistent and systematic manner in
the ETP large purse seine fishery that give this fishery its special risk profile. Moreover, we have
rejected Mexico's claims that (i) the Panels erred in their evaluation of the tracking and verification
requirements, including the allegation that the Panels did not take into account the risks of
inaccuracy; and (ii) the Panels failed to make an objective assessment of the facts of the case as
required under Article 11 of the DSU. Consequently, we find that Mexico has not demonstrated that
the Panels erred in arriving at the intermediate finding, in paragraph 7.676 of their Reports, that:
[A]lthough there remain differences between the NOAA and AIDCP regimes with respect
to tracking and verification, the Panels are of the view that such differences have been
considerably narrowed in the 2016 Tuna Measure and the Panels find that the remaining
differences are calibrated to the differences in the risk profile of the ETP large p urse
seine fishery compared to other fisheries.
7.10. We further consider that the Panels' analyses of e ach of the elements of the 2016 Tuna
Measure, as well as their examination of the measure as a whole, were properly informed by the
interlinkages between these elements and the fact that they operate together to regulate access to
the dolphin-safe label. Furthermore, we recall that Mexico's appeal in this regard is consequential
upon its challenge of the Panels' assessment of the eligibility criteria, certification requirements, and
tracking and verification requirements. Having reviewed and rejected Mexico's arguments against
the Panels' assessment of each of these elements of the 2016 Tuna Measure, we find that Mexico
has not demonstrated that the Panels erred in their assessment of the 2016 Tuna Measure, as a
whole, or in finding, in paragraph 7.717 of their Reports, that the 2016 Tuna Measure, as a whole,
is calibrated to the risks to dolphins arising from the use of different fishing methods in different
areas of the ocean.
7.11. Based on our analyses and findings above , we uphold the Panels' conclusion , in
paragraphs 7.717, 8.2, and 8.6 of the Panel Reports, that the 2016 Tuna Measure accords to Mexican
tuna products treatment no less favourable than that accorded to like products from the
United States and other countries and therefore is consistent with Article 2.1 of the TBT Agreement.
7.2 Whether the Panels erred in their findings under Article XX of the GATT 1994
7.12. One of the most important factors in the assessment of arbitrary or unjustifiable
discrimination under the chapeau of Article XX of the GATT 1994 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. As
indicated above, the Appellate Body's guidance in the first compliance proceedings indicates that the
calibration analysis is the tool in the circumstances of this dispute to assess whether the 2016 Tuna
Measure is consistent with Article 2.1 of the TBT Agreement. If done properly, the calibration
analysis would encompass consideration of the rational relationship between the regulato ry
distinction of the 2016 Tuna Measure and its objectives. As also indicated, it was appropriate for the
Panels, in the circumstances of these compliance proceedings, to rely on their calibration analysis
under Article 2.1 in their assessment of whether the 2016 Tuna Measure is applied in a manner that