United States Court of Appeals

For the First Circuit

No. 16-2089

UNITED STATES OF AMERICA,

Appellee,

v.

JEFFRI DÁVILA-REYES,

Defendant, Appellant.

No. 16-2143

UNITED STATES OF AMERICA,

Appellee,

v.

JOSÉ D. REYES-VALDIVIA,

Defendant, Appellant.

APPEALS FROM THE UNITED STATES DISTRICT COURT

FOR THE DISTRICT OF PUERTO RICO

[Hon. Francisco A. Besosa, U.S. District Judge]

Before

Howard, Chief Judge,

Lipez and Thompson, Circuit Judges.
Franco L. Pérez-Redondo, Research and Writing Specialist, 

with whom Eric Alexander Vos, Federal Public Defender, Vivianne M. 

Marrero, Assistant Federal Public Defender, and Liza L. RosadoRodríguez, Research and Writing Specialist, were on brief, for 

appellant José D. Reyes-Valdivia.

Raymond L. Sánchez-Maceira on brief for appellant Jeffri 

Dávila-Reyes.

Thomas F. Klumper, Assistant United States Attorney, with 

whom Rosa Emilia Rodríguez-Vélez, United States Attorney, Mariana 

E. Bauzá-Almonte, Assistant United States Attorney, Chief, 

Appellate Division, John A. Mathews II, Assistant United States 

Attorney, and David C. Bornstein, Assistant United States 

Attorney, were on brief, for appellee.

January 20, 2022
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LIPEZ, Circuit Judge. These consolidated appeals arise 

from the U.S. Coast Guard's interdiction of a small speed boat in 

the western Caribbean Sea and the subsequent arrest and indictment 

of the three men on board for drug trafficking under the Maritime 

Drug Law Enforcement Act ("MDLEA"), 46 U.S.C. §§ 70501-08. In a 

motion to dismiss the indictment, appellants José Reyes-Valdivia 

and Jeffri Dávila-Reyes challenged the constitutionality of the 

MDLEA in multiple respects. Most relevant here, they argued that

the statute, which in certain circumstances allows U.S. law 

enforcement to arrest and prosecute foreign nationals for drug 

crimes committed in international waters, exceeds Congress's 

authority under Article I of the Constitution. The district court 

denied the motion to dismiss. Both appellants then pleaded guilty 

pursuant to plea agreements in which each waived his right to 

appeal if sentenced in accordance with his agreement's sentencing 

recommendation provision.

On appeal, appellants renew their constitutional 

objections to their prosecution. In our original decision, we did 

not reach appellants' "primary argument" -- that their prosecution

was unlawful because their vessel was not properly deemed stateless 

-- on the ground that "our governing precedent concerning the 

protective principle of international law . . . permit[ted] 

prosecution under the MDLEA even of foreigners on foreign vessels." 

United States v. Dávila-Reyes, 937 F.3d 57, 59 (1st Cir. 2019)
- 4 -

(withdrawn).1 That precedent, we concluded, required that we 

affirm appellants' convictions.

Appellants then petitioned for panel rehearing and en 

banc review. We held their requests in abeyance pending the en 

banc decision in another drug-trafficking case involving a 

constitutional challenge to the MDLEA. See United States v. AybarUlloa, 987 F.3d 1 (1st Cir. 2021) (en banc). Subsequently, based 

on our view that the decision in Aybar-Ulloa "diminished the force 

of this circuit's precedent on the protective principle," we 

concluded that it would no longer be appropriate to rely on that 

principle to uphold appellants' convictions. Order, Nos. 16-2089, 

2143 (Mar. 17, 2021). We therefore granted panel rehearing to 

address appellants' constitutional challenge to their prosecution 

under the MDLEA.

We now hold that Congress exceeded its authority under 

Article I of the Constitution in enacting § 70502(d)(1)(C) of the 

MDLEA. That provision expands the definition of a "vessel without 

nationality" beyond the bounds of international law and thus 

unconstitutionally extends U.S. jurisdiction to foreigners on 

foreign vessels. Hence, appellants' convictions must be vacated. 

1 The protective principle of international law "permits a 

nation 'to assert jurisdiction over a person whose conduct outside 

the nation's territory threatens the nation's security.'" DávilaReyes, 937 F.3d at 62 (quoting United States v. Cardales, 168 F.3d 

548, 553 (1st Cir. 1999)).
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I.

We draw the following facts primarily from appellants'

change of plea colloquies and the uncontested portions of their

Presentence Investigation Reports. See United States v. VélezLuciano, 814 F.3d 553, 556 (1st Cir. 2016).2 In October 2015, 

while patrolling waters approximately 30 nautical miles southeast 

of San Andrés Island, Colombia,3 U.S. Coast Guard officers observed 

a small vessel4 moving at a high rate of speed. When the occupants 

of the vessel became aware of the Coast Guard boat nearby, they 

began throwing packages and fuel barrels overboard. The Coast 

Guard officers approached the boat and began to question its 

occupants, the two appellants and a third co-defendant. ReyesValdivia, as the "master"5 of the vessel, claimed Costa Rican 

2 We also draw some facts from statements by Coast Guard 

officials that were submitted to the district court as attachments 

to the government's Motion in Limine and Memorandum of Law in 

Support of Jurisdiction. See United States v. Reyes-Valdivia, No. 

3:15-cr-00721-FAB (D.P.R. Mar. 25, 2016), ECF No. 46.

We note that all citations to the district court's electronic 

docket in this case will hereafter be cited using the short-form 

"Reyes-Valdivia, ECF No. __ (filing date)."

3 Although part of Colombia, San Andrés Island is located off 

the coast of Nicaragua.

4 The government's Motion in Limine describes the vessel as a 

35-foot "low profile, open hull, 'go-fast-type' vessel." ReyesValdivia, ECF No. 46, at 3 (Mar. 25, 2016). 

5 The term "master" is synonymous with "captain." It is a 

legal term of art meaning the person "to whom are committed the 

government, care, and direction of the vessel and cargo." 

Kennerson v. Jane R., Inc., 274 F. Supp. 28, 30 (S.D. Tex. 1967). 

The statement of facts attached to Reyes-Valdivia's plea agreement 
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nationality for the vessel but did not provide any documentation

to support that claim.6

The Coast Guard officers boarded and searched the vessel 

pursuant to a provision of an agreement between the United States 

and Costa Rica "Concerning Cooperation to Suppress Illicit 

Traffic." See Reyes-Valdivia, ECF No. 46-2, at 1 (Mar. 25, 2016)

(Dep't of State Certification). The officers did not find any 

contraband, but a chemical test detected traces of cocaine. Based 

on that evidence, the Coast Guard detained the three men -- all 

citizens of Costa Rica -- and took them to the U.S. Naval Base at 

Guantánamo Bay, Cuba, and then eventually to Puerto Rico. At some 

point, the United States contacted the government of Costa Rica

requesting confirmation of the vessel's registry or nationality, 

and Costa Rica subsequently responded that it could not confirm 

does not identify him as the "master" of the vessel, see ReyesValdivia, ECF No. 68, at 11 (Apr. 4, 2016), but a statement from 

a Coast Guard officer reports that Reyes-Valdivia identified 

himself as such, see id., ECF No. 46-1, at 1 (Mar. 25, 2016) 

(Statement of Officer Luis Rosado).

6 The Coast Guard reported that Reyes-Valdivia initially 

stated that "there was no nationality for the vessel" before 

asserting Costa Rican nationality. Reyes-Valdivia, ECF No. 46-1, 

at 1 (Mar. 25, 2016) (Statement of Officer Luis Rosado). However, 

this statement was not cited in the U.S. Department of State 

Certification as a basis for identifying the vessel as stateless. 

The Certification reported only that "[t]he master made a claim of 

Costa Rican nationality for the go fast vessel." Id., ECF No. 46-

2, at 1 (Mar. 25, 2016). Nor was the statement included in the 

government's version of the facts in the appellants' plea 

agreements. See infra.
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the vessel's registry. The United States thus determined that, 

pursuant to § 70502(d)(1)(C) of the MDLEA, the boat was "without 

nationality" and subject to U.S. jurisdiction.7 

All three defendants were charged with two counts of 

trafficking cocaine in violation of the MDLEA. Reyes-Valdivia and 

Dávila-Reyes moved to dismiss the indictment for lack of 

jurisdiction,8 arguing that the MDLEA, particularly 

§ 70502(d)(1)(C), is unconstitutional. In their view, 

§ 70502(d)(1)(C) exceeds Congress's authority under Article I of 

the Constitution, and it violates the Due Process Clause of the 

Fifth Amendment because it is unconstitutionally vague, subject to 

arbitrary enforcement, and criminalizes conduct that has no nexus 

with the United States. The district court denied the motion. 

Reyes-Valdivia and Dávila-Reyes both subsequently agreed 

to plead guilty to one count of possession with intent to 

distribute five or more kilograms of cocaine in violation of the 

7 Section 70502(c)(1)(A) of the MDLEA provides that "a vessel 

without nationality" is "subject to the jurisdiction of the United 

States." 46 U.S.C. § 70502(c)(1)(A). As explained below, 

§ 70502(d)(1)(C) defines a "vessel without nationality" to include 

any vessel "aboard which the master or individual in charge makes 

a claim of registry and for which the claimed nation of registry 

does not affirmatively and unequivocally assert that the vessel is 

of its nationality." Id. § 70502(d)(1)(C).

8 Reyes-Valdivia filed the motion, and the district court 

granted Dávila-Reyes's motion to join. 
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MDLEA. See 46 U.S.C. § 70503(a)(1).9 Both men agreed to waive 

appellate review if sentenced in accordance with the sentencing 

recommendation provisions in their plea agreements. Ultimately, 

the district court sentenced Dávila-Reyes consistently with his 

agreement (a 120-month term), but sentenced Reyes-Valdivia to a 

term longer than proposed in his agreement (70 months instead of 

57) because it found that he should be given a two-level 

enhancement for being the "captain" of the vessel. See U.S.S.G. 

§ 2D1.1(b)(3)(C).

Reyes-Valdivia's motion for reconsideration was denied. 

Both Reyes-Valdivia and Dávila-Reyes then appealed. We affirmed 

their convictions on the basis that the protective principle 

permitted their prosecution.

II.

As noted, this court's en banc decision in United States

v. Aybar-Ulloa led us to withdraw our prior opinion and reconsider 

appellants' claims. In Aybar-Ulloa, the en banc court held that 

"international law accepts the criminal prosecution by the United 

States of persons . . . who [are] seized by the United States while 

trafficking cocaine on a stateless vessel on the high seas." 987 

9 The third defendant also pleaded guilty to this count and 

was sentenced to a 57-month term of imprisonment. He did not file 

an appeal.
- 9 -

F.3d at 3.10 In so holding, the court bypassed our circuit's 

precedent on the protective principle, which could have provided 

a straightforward basis for affirming the conviction, and instead 

addressed a more complex issue of international law. Notably, the

en banc court did not achieve unanimity on the legal basis for 

U.S. jurisdiction over foreign nationals apprehended on vessels 

conceded to be stateless. See infra. The choice of a nonunanimous analytical path over reliance on the protective 

principle is one basis for our conclusion that Aybar-Ulloa weakened 

our circuit's protective principle jurisprudence.

In addition, statements in both the majority and 

concurring opinions in Aybar-Ulloa more directly suggest 

skepticism about applying the protective principle to a foreign 

vessel whose occupants are foreign nationals allegedly involved in 

drug trafficking, at least absent acquiescence by the flag nation. 

The majority observed that one of our primary precedents on the 

protective principle -- United States v. Cardales, 168 F.3d 548 

(1st Cir. 1999) -- "can be read as applying only to the 

circumstance where a foreign flag nation consents to the 

application of United States law to persons found on that nation's 

flagged vessel." Aybar-Ulloa, 987 F.3d at 3. In our prior opinion 

10 Generally, there is a consensus that "high seas" denotes 

areas outside any country's territorial waters. See, e.g., United 

States v. Carvajal, 924 F. Supp. 2d 219, 234 (D.D.C. 2013), aff'd 

sub nom. United States v. Miranda, 780 F.3d 1185 (D.C. Cir. 2015).
- 10 -

in this case, we assumed that appellants' vessel was Costa Rican, 

as they had asserted, but we concluded that our precedent 

nonetheless required us to uphold their prosecution based on the 

protective principle. The Aybar-Ulloa majority's posited reading 

of Cardales, however, would foreclose reliance on the protective 

principle here because the record contains no consent from the 

Costa Rican government to the prosecution.

The Aybar-Ulloa concurring opinion aired an even broader 

uncertainty about the protective principle. In describing AybarUlloa's contentions, the concurrence noted the long-ago 

observation by then-Judge Breyer that there is a "'forceful 

argument' against application of [the] protective principle to 

encompass drug trafficking on the high seas." Id. at 15 (Barron, 

J., concurring) (quoting United States v. Robinson, 843 F.2d 1, 3 

(1st Cir. 1988) (Breyer, J.)); see also id. at 20 (referencing the 

same skepticism about the protective principle with a citation to 

Robinson). Both Aybar-Ulloa opinions, then, caused the panel to

doubt its reliance on the protective principle to uphold ReyesValdivia and Dávila-Reyes's prosecution under the MDLEA. See also

Aaron J. Casavant, In Defense of the U.S. Maritime Drug Law 

Enforcement Act: A Justification for the Law's Extraterritorial 

Reach, 8 Harv. Nat'l Sec. J. 191, 213 (2017) (noting that 

commentators have rejected the protective principle to support 

MDLEA prosecutions, "positing that 'the cases that see the MDLEA 
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as an exercise of protective jurisdiction fundamentally 

misconceive the principle'" (quoting Eugene Kontorovich, Beyond 

the Article I Horizon: Congress's Enumerated Powers and Universal 

Jurisdiction Over Drug Crimes, 93 Minn. L. Rev. 1191, 1231 (2009) 

(emphasis omitted))); but see id. at 222-23 (noting "a circuit 

split over whether the crime of maritime drug trafficking warrants 

the use of the protective principle"); id. at 225 (stating that 

"the protective principle of international law is broad enough to 

encompass maritime drug trafficking").

Apart from any reference to the protective principle, 

both Aybar-Ulloa opinions include statements indicating that the 

prosecution of a foreign national seized on the high seas under 

U.S. drug-trafficking laws would not be proper unless the targeted 

activity and seizure occurred on a stateless vessel. The majority, 

for example, concludes a passage on the reasonable expectations of 

"those who set out in stateless vessels" by noting: "Simply put, 

if a person intent on drug trafficking on the high seas wants to

be prosecuted in his own country should he be caught, he should 

sail under that country's flag." Aybar-Ulloa, 987 F.3d at 9. The 

majority subsequently describes its holding as limited "to vessels 

flouting order and custom on the high seas by eschewing the 

responsibilities and protections of the flag-state system." Id.

at 13; see also id. at 8 (quoting United States v. Furlong, 18 

U.S. (5 Wheat.) 184, 198 (1820), for the proposition that "the 
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distinction between foreign vessels and stateless vessels serves

to avoid 'offensive interference with the governments of other 

nations'"). In the same vein, the concurring opinion in AybarUlloa notes the "fair amount of support" for the view that Congress 

lacks authority under Article I's Define and Punish Clause "to 

subject foreign nationals to our criminal laws" for acts occurring 

on foreign vessels on the high seas. Id. at 15 (Barron, J., 

concurring).11

In sum, we see in Aybar-Ulloa multiple signals that the 

majority of judges on our court do not view the protective 

principle as supporting U.S. jurisdiction over drug-trafficking 

11 Elsewhere, the Aybar-Ulloa concurrence notes that "the 

application of the MDLEA to Aybar[-Ulloa]'s conduct in this case" 

-- i.e., conduct aboard a stateless vessel -- would likely be 

consistent with international law,

[e]ven if we were to assume that the law of 

nations places limits on Congress's power 

under the Define and Punish Clause to subject 

foreign nationals on foreign vessels in 

international waters to our domestic criminal 

laws, and even if we were to assume that the 

United States may not assert protective 

jurisdiction over drug trafficking merely 

because it occurs on stateless vessels in 

international waters, see Robinson, 843 F.2d 

at 3-4.

987 F.3d at 20. Although the Aybar-Ulloa concurrence does not 

take a position on those hypotheticals, we view them -- and the 

reiterated citation to Robinson -- to indicate a level of doubt 

about the applicability of the protective principle, at a minimum, 

to drug-trafficking activity by foreign nationals on foreign 

vessels.
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activity conducted on the high seas by foreign nationals on foreign 

vessels.12 Hence, in light of Aybar-Ulloa, we decline to rely on 

the protective principle to uphold appellants' convictions. 

Rather, the question we must answer is whether -- as the United 

States claims -- appellants' vessel was properly deemed stateless, 

bringing the vessel and its occupants within the scope of the 

holding in Aybar-Ulloa.

Before addressing that question, however, we review and 

elaborate on our reasons, set forth in the withdrawn panel opinion,

for rejecting the government's argument that appellants waived 

their claims of constitutional error. See Dávila-Reyes, 937 F.3d 

at 60-61.

III.

The government contends that Reyes-Valdivia and DávilaReyes waived their right to appeal in two distinct ways: by the 

express appellate waiver provisions in their plea agreements and 

by entry of unconditional guilty pleas to drug trafficking in 

violation of the MDLEA. With respect to Reyes-Valdivia, the 

government is wrong in arguing that his appeal is barred by his 

plea agreement. As described above, the district court declined 

12 Of course, consent by the flag nation changes the calculus, 

as acknowledged by one commentator who has advocated for use of 

the protective principle in the context of drug-trafficking on the 

high seas. See Casavant, supra, at 223 (noting that "consent of 

the flag or coastal state" is a "check on the exercise of U.S. 

criminal jurisdiction").
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to follow the parties' recommended term of 57 months and instead 

sentenced him to a 70-month term of imprisonment. Because ReyesValdivia's sentence exceeded the recommendation, the waiver 

provision plainly does not apply.13 

Dávila-Reyes, however, received a 120-month sentence 

that aligns with the recommendation in his plea agreement. He 

argues that, despite the enforceable waiver, we should exercise 

our inherent authority to consider his claims to avoid "a 

miscarriage of justice." United States v. Teeter, 257 F.3d 14, 

25-26 (1st Cir. 2001). He contends that his appeal raises 

"important questions of law and [of] first impression" -- including 

the constitutionality of § 70502(d)(1)(C) of the MDLEA -- and that 

preventing him from bringing his appeal would be unjust. 

We agree that the constitutional issue Dávila-Reyes 

raises is significant and that the other factors allowing us to 

exercise our discretion to disregard the appellate waiver also are 

sufficiently present. See, e.g., United States v. Ortiz-Vega, 860 

F.3d 20, 27-28 (1st Cir. 2017). Particularly important is the 

lack of prejudice to the government, given Reyes-Valdivia's 

13 The government contends that Reyes-Valdivia is nonetheless 

bound by the waiver provision because he failed to explain in his 

opening brief why it is inapplicable. However, it is apparent on 

the face of the plea agreement that Reyes-Valdivia was not 

sentenced in accordance with the sentencing recommendation 

provision, and he was not obligated to make that obvious point in 

his opening brief. See United States v. Colón-Rosario, 921 F.3d 

306, 310-11 (1st Cir. 2019).
- 15 -

presentation of the same issues as Dávila-Reyes. See id. at 27. 

Moreover, the potential for relief should not depend on the 

happenstance that the district court added an enhancement to ReyesValdivia's sentence. Thus, we exercise our discretion and decline 

to enforce Dávila-Reyes's appellate waiver. 

Nor do appellants' guilty pleas foreclose their right to 

challenge the constitutionality of the MDLEA. The Supreme Court 

held in Class v. United States that "a guilty plea by itself" does 

not bar "a federal criminal defendant from challenging the 

constitutionality of the statute of conviction on direct appeal." 

138 S. Ct. 798, 803 (2018). In their briefing and oral argument, 

appellants present claims that are permissible under Class. 

Although they conceded through their guilty pleas that the MDLEA, 

by its terms, allows the government to prosecute them under U.S. 

law, they argue that Congress exceeded constitutional limits with 

the enactment of the applicable provision. In other words, 

appellants contend that their convictions were within the scope of 

the statute but nonetheless unconstitutional. Such claims may 

proceed notwithstanding an unconditional guilty plea. See id. at 

805 (holding that a guilty plea does not bar claims that challenge 

"the Government's power to criminalize [the defendant's] 

(admitted) conduct" because "[t]hey thereby call into question the 

Government's power to 'constitutionally prosecute him'" (quoting 

United States v. Broce, 488 U.S. 563, 575 (1989))).
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The government asserts that Class does not apply here 

because appellants "admitted without qualification that their 

vessel was one 'subject to the jurisdiction of the United States,'" 

without limiting the basis for jurisdiction to § 70502(d)(1)(C)

(whose text is reproduced in footnote 7).14 Appellee's Supp. Br. 

at 18-19. In making that assertion, the government cites to the 

appellants' general acknowledgment of guilt at their change-ofplea hearing but disregards their specific admissions. The 

prosecution -- and, accordingly, appellants' admissions of guilt 

-- was premised on their vessel's statelessness under 

§ 70502(d)(1)(C). The indictment stated generally that 

jurisdiction was based on appellants' vessel being one without 

14 The statutory phrase "a vessel subject to the jurisdiction 

of the United States" in the MDLEA concerns legislative

jurisdiction -- in other words, Congress's authority to enact 

legislation "regulat[ing] drug trafficking on [] ships" -- rather 

than the subject-matter jurisdiction of the federal courts. 

United States v. González, 311 F.3d 440, 443 (1st Cir. 2002); see

also United States v. Prado, 933 F.3d 121, 130 (2d Cir. 2019) 

(adopting and elaborating on this interpretation and rejecting the 

alternative approach of other circuits). But see United States v. 

Miranda, 780 F.3d 1185, 1192 (D.C. Cir. 2015) (agreeing with the 

Fifth and Eleventh Circuits that "the question of whether a vessel 

is 'subject to the jurisdiction of the United States' is a matter 

of subject-matter jurisdiction"). "Unlike Congress's employment 

in other statutes of one-factor jurisdictional elements such as 

'by a Federal Reserve Bank,' or 'affect[ing] interstate commerce,' 

the facts that may cause a vessel to be 'subject to the 

jurisdiction of the United States' [under the MDLEA] involve 

numerous complex alternatives, which are spelled out at length in 

§ 70502 under 'Definitions.'" Prado, 933 F.3d at 149. Although 

appellants assert that their challenge to their prosecution 

implicates subject-matter jurisdiction, our precedent, as noted 

above, holds otherwise. 
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nationality, see 46 U.S.C. § 70502(c)(1)(A),15 but the Department 

of State Certification that subsequently was filed specified that 

"the Government of the United States determined the vessel was 

without nationality in accordance with 46 U.S.C.

§ 70502(d)(1)(C)," Reyes-Valdivia, ECF No. 46-2, at 3 (Mar. 25, 

2016) (Dep't of State Certification) (emphasis added). 

Appellants' plea agreements also identified § 70502(c)(1)(A) --

i.e., the subsection referring to vessels "without nationality" -

- as the basis for U.S. jurisdiction, see id., ECF Nos. 68, 72, 

at 1-2 (Apr. 4, 2016), and the "Government's Version of the Facts," 

incorporated into those agreements, set forth the facts concerning 

the vessel's status in language tracking the requirements of

§ 70502(d)(1)(C): the master's claim of Costa Rican nationality 

and the response from the government of Costa Rica "that it could 

neither confirm nor refute the registry of the suspect vessel," 

id. at 11. The same facts were recounted by the government at the

change-of-plea hearing. See id., ECF No. 117, at 26 (Oct. 3, 

2016).16 The government's Motion in Limine and Memorandum of Law 

15 As previously noted, § 70502(c)(1) lists "a vessel without 

nationality" among the list of vessels that are "subject to the 

jurisdiction of the United States." 46 U.S.C. § 70502(c)(1)(A). 

Other types of vessels on the list include "a vessel registered in 

a foreign nation if that nation has consented or waived objection 

to the enforcement of United States law by the United States," id.

§ 70502(c)(1)(C), and "a vessel in the customs waters of the United 

States," id. § 70502(c)(1)(D).

16 At the plea hearing, the government was asked to "give a 

brief explanation of the theory to be presented to prove each 
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in Support of Jurisdiction17 likewise asked the district court to 

"find, as a matter of law, that [appellants'] vessel was subject 

to the jurisdiction of the United States, as defined in 

. . . Sections 70502(c)(1)(A) and (d)(1)(C)." Id., ECF No. 46, at 

4 (Mar. 25, 2016).18

Defendant guilty if a trial were to be held." Id. at 25. In 

relevant part, the prosecutor stated:

The vessel was tracked by aircraft and 

eventually came to a stop. The U.S. Coast 

Guard boarding team approached the vessel and 

commenced right of approach questioning.

The master claimed Costa Rican 

nationality for the vessel but provided no 

registration[] paperwork, and there was no 

indicia of nationality on the vessel.

The Government of Costa Rica was 

approached. They responded they could neither 

confirm nor refute the registry of [the] 

suspect vessel.

The vessel was determined to be one 

without nationality.

Id. at 25-26.

17 In a 1996 amendment to the MDLEA, Congress stated that 

jurisdictional issues under the statute "are preliminary questions 

of law to be determined solely by the trial judge." 46 U.S.C. 

§ 70504(a); see also González, 311 F.3d at 442-43. Appellants 

moved to change their pleas a week after the government filed the 

Motion in Limine, and the district court therefore did not rule on 

it. See Reyes-Valdivia, ECF Nos. 59, 63 (Apr. 1, 2016).

18 The government has continued to rely on § 70502(d)(1)(C) 

before us. In its initial brief, the government quoted the 

provision in full and then described appellants' admission 

consistently with the provision's terms -- i.e., "that Costa Rica 

did not confirm the registry of their vessel (which had no indicia 

of nationality) and that their vessel was determined to be one 

without nationality." Appellee's Br. at 36. In addition, in 

asserting that the MDLEA provided sufficient and unambiguous 

notice of the MDLEA's applicability to appellants, the government 
- 19 -

Appellants thus pleaded guilty based on the government's 

assertion of jurisdiction pursuant to § 70502(d)(1)(C), in 

accordance with the facts stated in their plea agreements. In 

other words, they admitted that they "did what the indictment 

alleged" and that the government accurately described the facts

giving rise to U.S. jurisdiction under § 70502(d)(1)(C). Class, 

138 S. Ct. at 804. Hence, their challenge to the constitutionality 

of § 70502(d)(1)(C) does not "contradict the terms of the

indictment or the written plea agreement," and, as in Class, the 

constitutional claim can "be 'resolved without any need to venture 

beyond th[e] record.'" Id. (quoting Broce, 488 U.S. at 575). 

Appellants' constitutional challenge is premised on the facts set

forth by the government and legal principles that, they claim,

invalidate § 70502(d)(1)(C)'s definition of a "vessel without 

nationality" as a basis for subjecting them to U.S. jurisdiction. 

We need not go outside the existing record to address that question 

of law. Consequently, appellants' guilty pleas do not bar this 

direct appeal. See id. at 805.

The government also appears to argue, however, that it 

is entitled to sidestep appellants' claim that § 70502(d)(1)(C) is

stated: "The absence of an assertion by the Costa Rican government 

rendered the Appellants' boat a 'vessel without nationality,' [46

U.S.C.] § 70502(d)(1), and thus a 'vessel subject to the

jurisdiction of the United States,' id. § 70502(c)(1)(A)." Id. at 

38. 
- 20 -

unconstitutional because, it says, their vessel could have been 

deemed without nationality based on other jurisdictional theories

and other facts. In its supplemental brief, the government asserts 

that Reyes-Valdivia's failure to produce registration paperwork or 

otherwise substantiate his verbal claim of nationality would 

suffice to "render[] the vessel stateless as a matter of domestic

and international law." Appellee's Supp. Br. at 9 (emphasis 

omitted).19 The government further notes that the vessel could be 

deemed stateless because it "had no indicia of nationality other 

than the master's say-so, and even he presented conflicting 

information, having initially stated the vessel had no 

nationality." Id. at 11 (internal quotation marks omitted). But 

these jurisdictional theories are not the basis on which the 

government relied to arrest and prosecute appellants, and to obtain 

their guilty pleas. The defendants therefore had no reason or 

opportunity to consider those rationales for deeming their vessel 

stateless before deciding to forgo their right to contest the MDLEA 

charges,20 which relied on the undisputed facts establishing 

19 This theory also plays a part in the government's defense 

of § 70502(d)(1)(C), and we address it in that context in Section 

V.C. 

20 In his supplemental brief, Reyes-Valdivia challenges the 

government's assertion that the vessel bore no indicia of 

nationality. He contends that "[p]hotos of the vessel clearly 

show the civil ensign of Costa Rica painted, albeit vertically, on 

the port and starboard sides of the ship's bow," and he points out 

that "the Costa Rica ensign was prominent enough for a Marine 

Patrol Aircraft ['MPA'] to recognize it from overhead." 
- 21 -

statelessness under § 70502(d)(1)(C).21 It is now simply too late 

for the government to proffer alternative bases for jurisdiction. 

Cf. United States v. Mitchell-Hunter, 663 F.3d 45, 50 n.7 (1st 

Cir. 2011) (stating that jurisdiction under the MDLEA may be 

established "any time prior to trial" (emphasis added)).

In sum, neither of the government's waiver-of-appeal

arguments has merit.

Appellants' Supp. Br. at 18 n.4. The assertion of visibility from 

the air was based on the statement of Customs Officer Luis Rosado 

recounting that the MPA had detected a go-fast vessel "with a Costa 

Rican flag painted on the bow." Reyes-Valdivia, ECF No. 46-1, at 

1 (Mar. 25, 2016). The government properly points out that 

appellants admitted in their plea agreements to a version of the 

facts stating that their vessel bore no indicia of nationality and 

argues that appellants "may not pursue any contention on appeal 

that 'would contradict' that admission." Appellee's Supp. 

Response Br. at 5 (quoting United States v. Sarmiento-Palacios, 

885 F.3d 1, 4 (1st Cir. 2018)). However, the government, too,

must abide by the facts on which it relied to obtain appellants' 

pleas. 

21 We also note that the government has argued, on the one 

hand, that "[t]he MDLEA is . . . clear about how the United States 

decides whether a vessel is stateless," citing 46 U.S.C. 

§ 70502(d), Appellee's Br. at 35, but, on the other hand, has not 

identified a statutory provision that matches its newly offered 

theories of jurisdiction. As described more fully infra, the two 

other circumstances for classifying a vessel as "without

nationality" expressly stated in § 70502(d)(1) -- the denial of a 

claim by the named country and the master's refusal to make a claim 

upon request -- do not apply here. See 46 U.S.C. § 70502(d)(1)(A), 

(B). Although § 70502(d)(1)'s categories of stateless vessels are 

non-exclusive (the provision states that "the term 'vessel without 

nationality' includes" the three listed examples (emphasis 

added)), the government cannot reasonably expect defendants to 

assess their options if it invokes a particular statutory basis 

for jurisdiction but reserves the right to shift 

theories -- including to theories beyond the statute's express 

language.
- 22 -

IV.

We must consider one last issue before reaching the 

merits of appellants' claims. As our colleague notes in his 

concurrence, the jurisdictional provision relied on by the 

government to prosecute appellants, 46 U.S.C. § 70502(d)(1)(C), 

refers to a vessel master's having made a claim of registry, but

Reyes-Valdivia claimed Costa Rican nationality, not registry. The 

parties initially appeared to agree that § 70502(d)(1)(C) 

nonetheless applies to the facts of this case. In a supplemental 

brief submitted in response to questions from the court, however, 

appellants argued for the first time that the provision is inapt 

where the master of the vessel asserts only a nationality claim.

We are unpersuaded that this distinction between a claim 

of registry and a claim of nationality provides a basis for 

vacating appellants' convictions. Although the terms 

"nationality" and "registry," in formal usage, are not 

interchangeable,22 the MDLEA treats them as such throughout 

22 In general, the "nationality" of a vessel refers to the 

country that has certain "international rights and duties . . . in 

connection with a given ship and its users." Herman Meyers, The 

Nationality of Ships 129 (1967). The term "registration" refers 

to the recording of nationality "on land and under the supervision 

of a government body." Id.; see also id. at 129-30 ("The purpose 

of a register is to declare the nationality of a vessel engaged in 

trade with foreign nations, and to enable her to assert that 

nationality wherever found." (quoting The Mohawk, 70 U.S. (3 Wall.) 

566, 571 (1865))). 
- 23 -

§ 70502. Section 70502(e), for example, jointly defines a "claim 

of nationality or registry" to "include[] only":

(1) possession on board the vessel and 

production of documents evidencing the 

vessel's nationality as provided in article 5 

of the 1958 Convention on the High Seas;[23]

(2) flying its nation's ensign or flag; or

(3) a verbal claim of nationality or registry 

by the master or individual in charge of the 

vessel.

46 U.S.C. § 70502(e). By allowing the act of flying a national 

flag or the possession of documents of nationality to suffice as 

a claim to either nationality or registry, the MDLEA effectively 

treats the distinction between nationality and registry as 

irrelevant. Congress's use of the two terms interchangeably, or 

at least inconsistently, is even more evident in § 70502(d)(1)(C), 

where the rejection of a master's claim of registry is premised on 

the named country's failure to confirm nationality.

Yet, this variation in terminology does not undermine 

what is otherwise Congress's clear intention to require

verification when a master identifies a vessel as 

"foreign" -- whether by claiming nationality or registry -- and

thereby seeks to avoid the jurisdiction possessed by the United 

States (and all nations) over stateless vessels. As we shall 

23 Article 5 states, in part, that "[e]ach State shall issue 

to ships to which it has granted the right to fly its flag documents 

to that effect." United Nations Convention on the High Seas art. 

5, Apr. 29, 1958 ("1958 Convention on the High Seas"), 13 U.S.T. 

2312.
- 24 -

explain, we think it evident that Congress used the term "claim of 

registry" in the first part of § 70502(d)(1)(C) to also encompass

a "claim of nationality" -- a common, albeit imprecise, choice of 

language.

 More than fifty years ago, one scholar noted the tendency 

to use the term registration to signify the broader concept of 

nationality. See Herman Meyers, The Nationality of Ships 28 (1967) 

(noting that "[t]he phrase 'registered in', and other word 

combinations in which the term register is used," are sometimes 

imprecisely "used as synonymous with nationality"); id. at 127 

(noting that, because "in the great majority of cases" nationality 

and registration, along with documentation and flying the flag,

"occur in combination," "the differences between the terms have 

sometimes been neglected and a pars pro toto [a part taken for the 

whole] use of the word registration . . . is by no means rare in 

the doctrine or in the sources of international law"). Indeed, a 

claim of registry is also a claim of nationality. See supra note 

22. Thus, the variable word choice in § 70502(d)(1)(C) does not 

have the import that it might have in other contexts. See

generally DePierre v. United States, 564 U.S. 70, 83 (2011) (noting 

the usual assumption that a legislature intends different meanings 

when it uses different words, but also recognizing that "Congress 

sometimes uses slightly different language to convey the same 

message"). 
- 25 -

Importantly, notwithstanding the prior reference to a 

claim of registry in § 70502(d)(1)(C), Congress's ultimate demand 

in that same provision is for confirmation of nationality. We can 

detect no reason why Congress would require affirmative 

confirmation when a vessel's master makes a claim of registry, 

while allowing a claim of nationality to stand on its own. 

Excluding claims of nationality from the provision's scope would 

allow drug traffickers to evade the verification requirement 

simply by asserting a claim of nationality. Appellants attribute

that glaring loophole to Congress's deference to foreign nations

and its intention to stay within the bounds of international law. 

They note that a claim of nationality "presents a more complicated 

scenario since not all national ships are registered," making it 

more difficult for the claimed nation "to confirm or refute the 

nationality claim." Appellants' Supp. Br. at 8-9. Appellants do 

not explain, however, why that concern would prompt Congress, in 

effect, to nullify the verification provision by encouraging 

vessel masters to claim foreign nationality rather than registry. 

Inescapably, then, the reference in the first part of 

§ 70502(d)(1)(C) solely to "a claim of registry" must be

attributable to the not infrequent practice of treating a "claim 

of registry" and a "claim of nationality" as essentially 

synonymous, even though the former term is technically narrower 

than the latter.
- 26 -

Our view that § 70502(d)(1)(C) is not reasonably 

construed as limited to claims of registry is reinforced when the 

provision is considered in the context of the MDLEA as a whole and 

in light of its legislative history. See, e.g., Abramski v. United 

States, 573 U.S. 169, 179 n.6 (2014) ("[A] court should not 

interpret each word in a statute with blinders on, refusing to 

look at the word's function within the broader statutory 

context."); United Sav. Ass'n of Tex. v. Timbers of Inwood Forest 

Assocs., Ltd., 484 U.S. 365, 371 (1988) ("Statutory construction 

. . . is a holistic endeavor. A provision that may seem ambiguous 

in isolation is often clarified by the remainder of the statutory 

scheme -- because the same terminology is used elsewhere in a 

context that makes its meaning clear, or because only one of the 

permissible meanings produces a substantive effect that is 

compatible with the rest of the law." (citations omitted)). The 

MDLEA reflects Congress's intention to enable the aggressive 

prosecution of maritime drug trafficking. See 46 U.S.C. § 70501

("Congress finds and declares that . . . trafficking in controlled 

substances aboard vessels is a serious international problem, is 

universally condemned, and presents a specific threat to the 

security and societal well-being of the United States . . . ."). 

Indeed, § 70502(d)(1)(C) was among several provisions added to the 

MDLEA in 1996 to "expand the Government's prosecutorial 

effectiveness in drug smuggling cases." H.R. Rep. No. 104-854, at 
- 27 -

142 (1996) (Conf. Rep.), reprinted in 1996 U.S.C.C.A.N. 4292, 4337. 

Given this statutory backdrop, the majority observed in United 

States v. Matos-Luchi that "Congress did not expect courts to 

render a cramped reading of the statute." 627 F.3d 1, 7 (1st Cir. 

2010). 

In addition, other portions of the MDLEA's legislative 

history indicate that Congress's specific reference to a claim of 

registry in subsections (A) and (C) of § 70502(d)(1) -- both 

involving the claimed nation's response (or lack thereof)24 -- may 

reflect the fact that registry claims appear to have been the 

common way in which drug-trafficking defendants asserted their

foreign nationality. There are multiple references to the 

difficulty faced by prosecutors in producing "judicially 

admissible documentary evidence" of the foreign nation's "consent 

[to board] or denial of a claim of registry." S. Rep. No. 99-530, 

at 15 (1986) (emphasis added); see also, e.g., USCG Authorizations

and Load Lines: Hearing on H.R. 1362 Before the S. Subcomm. on 

Merchant Marine of the Comm. on Commerce, Sci. & Transp., 99th 

Cong. 39-40 (1986) (Responses of Adm. James Gracey to questions 

24 Like § 70502(d)(1)(C), see supra note 7, subsection 

(d)(1)(A) specifically references a claim of registry, stating 

that a "vessel without nationality" includes any vessel "aboard 

which the master or individual in charge makes a claim of registry 

that is denied by the nation whose registry is claimed."
- 28 -

from Sen. Hollings).25 But whatever the exact explanation for the 

chosen language, given the legislative background, together with 

25 This hearing, in May 1986, preceded the adoption that year 

of the MDLEA. Asked to "describe the kinds of problems the Coast 

Guard and federal prosecutors have encountered" in responding to 

jurisdictional objections from accused drug traffickers at trial, 

Admiral Gracey responded, in part, as follows:

The princip[al] problems that have arisen 

involve the difficulty of proving vessel 

status. For [e]xample, if upon inquiry by the 

Coast Guard, a vessel makes a claim of 

registry, the U.S. must confirm that registry 

with the claimed flag state. If the flag state 

denies registry, the vessel is stateless, 

i.e., a "vessel subject to the jurisdiction of 

the United States" . . . . At this point, the 

U.S. may under international law take law 

enforcement action against that vessel. 

However, to prove the element of the offense 

in court, the U.S. must obtain a formal 

certification from the claimed flag state 

attesting that the vessel is not registered in 

that state. On the other hand, i[f] the 

claimed state verifies registry, the U.S. 

obtains that state's consent to take law 

enforcement action. . . . However, to prove 

the element of the offense in court, the 

United States must obtain a formal 

certification from the flag state verifying 

registry and confirming its consent for the 

U.S. to take law enforcement action. The 

difficulties in obtaining these documents from

foreign governments in a timely manner, and in 

a form acceptable to our courts under the 

Federal Rules of Evidence, have been 

considerable.

USCG Authorizations and Load Lines: Hearing on H.R. 1362 Before 

the S. Subcomm. on Merchant Marine of the Comm. on Commerce, Sci. 

& Transp., 99th Cong. 39-40.

A focus on registry as the common indicator of nationality 

also appears in the legislative history of the MDLEA's predecessor, 

the Marijuana on the High Seas Act, Pub. L. No. 96-350, 94 Stat. 
- 29 -

Congress's blending of the concepts of nationality and registry 

elsewhere in the MDLEA, a reading of § 70502(d)(1)(C) that excludes

claims of nationality would "produce[] a substantive effect that 

is [in]compatible with the rest of the law." United Sav. Ass'n of 

Tex., 484 U.S. at 371.

We note, in addition, that this court has treated claims 

of registry and nationality synonymously in multiple cases. For 

example, in Matos-Luchi, the majority cited § 70502(d)(1)(A) and 

(C) -- both of which refer only to a claim of registry -- as 

applicable to a "claim of nationality [that] is made but rejected

[(d)(1)(A)] or not backed up by the nation invoked [(d)(1)(C)]." 

627 F.3d at 6; see also United States v. Cuevas-Esquivel, 905 F.2d 

510, 513-14 (1st Cir. 1990) (noting the absence of a claim of 

nationality but citing to a provision in an earlier codification 

of the MDLEA that referenced only registry (46 U.S.C. App. 

§ 1903(c)(2)(A))); United States v. Maynard, 888 F.2d 918, 925 

(1st Cir. 1989) ("Since a 'claim of nationality' was made, the 

1159 (1980). See, e.g., Stopping "Mother Ships" -- A Loophole in 

Drug Enforcement: Hearing Before the S. Subcomm. to Investigate

Juvenile Delinquency of the Comm. on the Judiciary, 95th Cong., at 

52 (1978) (Statement of Morris Busby, Acting Deputy Assistant Sec. 

of State for Oceans and Fisheries Affairs) (noting the "wellestablished principle under international law . . . that a country 

may exercise jurisdiction on the high seas over a vessel without 

nationality, one that is not registered in any foreign state"); 

id. at 53 (explaining that, when the master or crew make "a claim 

of nationality," the Coast Guard's protocol involves contacting 

the claimed flag state to "request[] that the government verify 

the registry of the vessel"). 
- 30 -

[vessel] can be classified as a stateless vessel only if the 'claim 

is denied by the flag nation whose registry is claimed.'" (quoting

§ 1903(c)(2)(A))).

Other courts have likewise used the terms 

interchangeably. See United States v. Alarcon Sanchez, 972 F.3d 

156, 162-63 (2d Cir. 2020) (stating that "[a] claim of registry 

may be made" by "'a verbal claim of nationality or registry,'" 

quoting 46 U.S.C. § 70502(e) and relying on § 70502(d)(1)(C) in 

discussing the master's assertion of nationality); United States

v. Prado, 933 F.3d 121, 130 (2d Cir. 2019) ("[A] verbal assertion 

of nationality by the master constitutes a claim, which is then 

tested by a U.S. officer's inquiry of the nation's registry 

authority."); United States v. Hills, 748 Fed. App'x 252, 253 (11th 

Cir. 2018) (per curiam) (finding that the defendant's vessel was 

without nationality based on § 70502(d)(1)(C) where the defendant 

"told [the Coast Guard] that he was the master of the vessel and 

identified the vessel as Costa Rican"); United States v. Rosero, 

42 F.3d 166, 171 (3d Cir. 1994) (referring to "a false claim of 

nationality or registry" even though the provision at issue, 46 

U.S.C. App. § 1903(c)(2)(A), referred only to "a claim of 

registry"); id. at 174 ("[T]he prosecution can establish that a 

vessel is stateless by showing that the master or person in charge 
- 31 -

made a claim of nationality or registry that was denied by the 

flag nation whose registry was claimed.").26 

We therefore see no basis for departing from our prior 

understanding of § 70502(d)(1)(C)'s scope.27 Congress's reference 

solely to claims of registry in the first part of § 70502(d)(1)(C) 

is not reasonably construed to exclude from that subsection's 

verification requirement claims of nationality that are phrased 

without reference to registration.28

26 The government in this case also blended the two concepts. 

Despite the claim solely of nationality, the United States asked 

Costa Rica to confirm "registry or nationality." Costa Rica then 

"replied that it could not confirm [the] vessel's registry." See

Reyes-Valdivia, ECF No. 46-2, at 1 (Mar. 25, 2016) (Dep't of State 

Certification).

27 In so concluding, we note that, contrary to appellants' 

assertion, the statutory imprecision here is not an instance of 

ambiguity requiring application of the rule of lenity. The rule 

of lenity, which "requires that ambiguity in a criminal statute be 

resolved in favor of the accused," United States v. Jimenez, 507 

F.3d 13, 20 (1st Cir. 2007), "does not apply if the ambiguous 

reading relied on is an implausible reading of the congressional 

purpose," Caron v. United States, 524 U.S. 308, 316 (1998). As we 

have described, Congress clearly intended to subject a claim of 

nationality that is not premised on registry to the same 

verification requirement as a claim of registry. Accordingly, the 

rule of lenity does not come into play. See Moskal v. United 

States, 498 U.S. 103, 108 (1990) ("[W]e have always reserved lenity 

for those situations in which a reasonable doubt persists about a 

statute's intended scope even after resort to the language and 

structure, legislative history, and motivating policies of the 

statute." (internal quotation marks omitted)).

28 Although we do not rely on waiver in rejecting appellants' 

belated argument that § 70502(d)(1)(C) does not apply to the facts 

of this case, we note that a request for supplemental briefing 

does not revive a claim that a party has failed to preserve. See

United States v. Galíndez, 999 F.3d 60, 69 n.10 (1st Cir. 2021). 
- 32 -

V.

Having addressed these threshold issues, we turn to 

appellants' constitutional challenge to 46 U.S.C. 

§ 70502(d)(1)(C). As described above, we have construed that

provision to allow U.S. authorities to deem a vessel "without 

nationality" -- i.e., stateless -- when a claim of either registry 

or nationality asserted by the vessel's occupants is neither 

confirmed nor denied by the claimed country. See, e.g., MatosLuchi, 627 F.3d at 6. Under Aybar-Ulloa, a determination of 

statelessness has a significant consequence: it permits

prosecution under U.S. law of any foreign national aboard the 

vessel. See 987 F.3d at 3. Appellants contend that 

§ 70502(d)(1)(C) exceeds Congress's authority under the "Define 

and Punish Clause" of Article I, which gives Congress the power 

"[t]o define and punish Piracies and Felonies committed on the 

high Seas, and Offences against the Law of Nations." U.S. Const. 

art. I, § 8, cl. 10.

It is undisputed that the "vessel without nationality" 

provisions of the MDLEA were enacted solely pursuant to Congress's 

authority to "define and punish . . . Felonies committed on the 

high Seas" ("the Felonies Clause").29 See United States v. 

29 Although it may be more accurate to refer to the "Felonies 

Clause" as the "Felonies Sub-Clause," given that it is contained 

within the Define and Punish Clause, we use the "Felonies Clause" 

designation for simplicity.
- 33 -

Cruickshank, 837 F.3d 1182, 1187 (11th Cir. 2016) (stating that 

the MDLEA "was enacted under Congress's authority provided by the 

Felonies Clause"). Appellants argue that the definition of "vessel 

without nationality" in § 70502(d)(1)(C) conflicts with 

international law and thus authorizes the arrest and prosecution

of foreign nationals aboard vessels on the high seas that the 

Constitution does not permit. This assertion of U.S. jurisdiction

is incompatible with the Constitution, appellants contend, because

Congress's authority under the Felonies Clause is constrained by 

international law. Put another way, appellants ask us to conclude 

that, under longstanding principles of international law, their 

vessel was not properly deemed stateless, and because Congress's 

authority in this instance is limited by international law, 

appellants' arrests and prosecution were unconstitutional. 

We review appellants' challenge to the constitutionality 

of a federal statute de novo. See United States v. Booker, 644 

F.3d 12, 22 (1st Cir. 2011). We begin by describing existing law 

on the MDLEA, and then consider the origins and meaning of the 

Define and Punish Clause generally, and the Felonies Clause 

specifically, before assessing whether § 70502(d)(1)(C) of the 

MDLEA violates the jurisdictional limits imposed by the Felonies 

Clause.
- 34 -

A. Statutory Background and Overview of Case Law on the MDLEA

The MDLEA makes it unlawful for persons "on board a 

covered vessel . . . [to] knowingly or intentionally . . . 

manufacture or distribute, or possess with intent to manufacture 

or distribute, a controlled substance." 46 U.S.C. § 70503(a)(1). 

The MDLEA's prohibitions apply "even though the act is committed 

outside the territorial jurisdiction of the United States," id.

§ 70503(b), and "a covered vessel" includes, inter alia, any 

"vessel subject to the jurisdiction of the United States," id.

§ 70503(e)(1).30 As relevant here, the Act defines "vessel subject 

to the jurisdiction of the United States" to include any "vessel 

without nationality." Id. § 70502(c)(1)(A). 

A vessel is expressly considered "without nationality"

-- or stateless -- under the MDLEA in three circumstances. First, 

that label applies when "the master or individual in charge fails," 

when asked by U.S. law enforcement, "to make a claim of nationality 

or registry for th[e] vessel." Id. § 70502(d)(1)(B). As noted 

above, a claim of nationality or registry can be made by presenting

documents demonstrating nationality, "flying [the claimed]

nation's ensign or flag," or verbally asserting nationality or 

30 Another subsection of the statute defines "covered vessel" 

to include "any other vessel if the individual [allegedly engaged 

in drug activity] is a citizen of the United States or a resident 

alien of the United States." 46 U.S.C. § 70503(e)(2). At issue 

in this case is U.S. jurisdiction over foreigners, and we therefore 

do not consider the MDLEA's application to U.S. nationals. 
- 35 -

registry. Id. § 70502(e)(1)-(3). Second, a vessel is considered

stateless if its master does make a claim of nationality or 

registry, but the nation identified denies the claim when contacted 

by U.S. officials. Id. § 70502(d)(1)(A). Third, a vessel is 

considered stateless when the country whose nationality is claimed 

"does not affirmatively and unequivocally assert that the vessel 

is of its nationality." Id. § 70502(d)(1)(C). This last situation

-- the foundation for appellants' arrest and prosecution -- is the 

focus of the constitutional challenge now before us.31

Despite the frequency with which MDLEA cases arise in 

this circuit, waiver and other threshold procedural issues have

prevented us from fully addressing the merits of a challenge under 

Article I to any portion of the MDLEA. See United States v. 

Sarmiento-Palacios, 885 F.3d 1, 3-4 (1st Cir. 2018) (finding a 

challenge to the constitutionality of the MDLEA waived where the 

defendant failed to develop the argument and conceded that "the 

MDLEA is a valid exercise of Congress's Article I powers"); United 

States v. Díaz-Doncel, 811 F.3d 517, 518 (1st Cir. 2016) (holding, 

before Class, that the defendant had waived the right to challenge 

the constitutionality of the MDLEA on appeal by entering an 

31 A vessel also may be treated as stateless under the MDLEA 

if it displays more than one country's flag "and us[es] them 

according to convenience." 1958 Convention on the High Seas, 

supra, art. 6 (incorporated into the MDLEA at 46 U.S.C. 

§ 70502(c)(1)(B)).
- 36 -

unconditional guilty plea); United States v. Nueci-Pena, 711 F.3d 

191, 196-98 (1st Cir. 2013) (addressing defendant's Article I 

challenge to the MDLEA under plain error review because the 

argument was not raised in the district court and concluding that 

there was no plain error in light of the lack of First Circuit and 

Supreme Court precedent addressing the constitutionality of the 

MDLEA); United States v. Cardales-Luna, 632 F.3d 731, 737-38 (1st 

Cir. 2011) (holding that, because the constitutionality of the 

MDLEA did not implicate the court's subject matter jurisdiction, 

it was not appropriate for the court to raise the issue sua 

sponte).

In Aybar-Ulloa, the en banc court was presented with a 

preserved constitutional challenge. The defendant argued that 

Article I did not give Congress the authority to assert U.S. 

jurisdiction over stateless vessels that have no nexus to the 

United States, basing his argument on the asserted existence of a 

nexus requirement in international law. See 987 F.3d at 15 

(Barron, J., concurring) (elaborating Aybar-Ulloa's constitutional 

claim). The en banc court did not address Congress's authority 

under the Constitution, however, because it concluded that 

international law permits the United States to prosecute foreign 

nationals engaged in drug trafficking on any stateless vessel, at 

least when U.S. authorities have boarded and seized the vessel

pursuant to the right of boarding recognized under international 
- 37 -

law. Id. at 6, 14.32 The court expressly did not "reach the 

question of whether the application of the MDLEA to Aybar[-Ulloa]

would be constitutional were international law otherwise." Id. at 

3. Aybar-Ulloa does not govern this case. Unlike the defendant 

there -- who admitted that his vessel was stateless -- ReyesValdivia and Dávila-Reyes insist that their vessel was not properly 

deemed "without nationality." They assert that the method of 

determining statelessness in § 70502(d)(1)(C) expands U.S. 

jurisdiction beyond the bounds permitted by the Constitution.

We have passed upon some related questions, such as 

whether another of the "without nationality" provisions of the 

MDLEA is consistent with international law, see Matos-Luchi, 627 

F.3d at 6-7 (noting that 46 U.S.C. § 70502(d)(1)(B) is consistent 

32 The concurring judge in Aybar-Ulloa declined to join the 

majority's approach, finding "no clear support in either case law 

or commentary for the comparatively modest proposition that 

persons on stateless vessels that a foreign country's officials 

have seized and boarded pursuant to their recognized right to visit 

it are subject to that country's territorial jurisdiction under 

international law." 987 F.3d at 18 (emphasis added). More 

particularly, the Aybar-Ulloa concurrence observed that 

international law experts have "long noted the disagreement that 

exists over" whether "the prevailing view of the law of nations is 

that the interdicting country acquires the same territorial 

jurisdiction over the vessel's occupants as it acquires over the 

vessel itself." Id. at 17. Given this lack of support for the 

majority's approach, and related concerns, see id. at 20-22, the 

concurring opinion instead rejected Aybar-Ulloa's challenge based 

on "the more than two-century-old precedent" addressing "the 

United States' power to prosecute defendants of a range of 

citizenships and circumstances" "for their felonious conduct on 

stateless vessels in international waters." Id. at 22, 26 (relying 

on United States v. Holmes, 18 U.S. (5 Wheat.) 412 (1820)).
- 38 -

with international law allowing a vessel to be deemed stateless if 

the master refuses to claim a nationality),33 and whether the 

MDLEA's flag-nation consent provisions provide due process, see

Cardales, 168 F.3d at 553 (holding that "due process is satisfied 

when the foreign nation in which the vessel is registered 

authorizes the application of United States law to the persons on 

board the vessel"). Along with Aybar-Ulloa, these cases provide 

a useful backdrop to our discussion of the constitutionality of 

§ 70502(d)(1)(C), but they do not answer the question now before 

us.

Although several of our sister circuits have addressed

whether the MDLEA is, in general, a constitutional exercise of 

Congress's authority under the Felonies Clause, it appears that no 

circuit has considered the specific authority for

§ 70502(d)(1)(C)'s definition of a "vessel without nationality." 

Instead, courts have assumed that the MDLEA applies only to vessels 

that would be subject to U.S. jurisdiction under international 

33 In Matos-Luchi, the panel majority made the broad statement 

that "the MDLEA is consistent with international law." 627 F.3d 

at 6. Read in context, however, that statement refers only to the 

jurisdictional provision at issue there -- § 70502(d)(1)(B). The 

discussion that follows focuses on deeming a vessel stateless when 

there is an attempt "to avoid national identification," and 

concludes by asserting that "the instances specified by Congress 

-- pertinently, the refusal 'aboard' the vessel to claim 

nationality, 46 U.S.C. § 70502(d)(1)(B) -- are not departures from 

international law but merely part of a pattern consistent with 

it." Id. at 7 (emphasis added).
- 39 -

law, i.e., U.S. vessels and those meeting the international law 

definition of statelessness. See, e.g., United States v. 

Ballestas, 795 F.3d 138, 146-47 (D.C. Cir. 2015) (holding that 

Congress had authority under the Felonies Clause to punish a 

defendant for conduct committed by his co-conspirators aboard a 

stateless vessel on the high seas); United States v. Campbell, 743 

F.3d 802, 810 (11th Cir. 2014) (stating that "we have long upheld 

the authority of Congress to 'extend[] the criminal jurisdiction 

of this country to any stateless vessel in international waters 

engaged in the distribution of controlled substances'" (quoting 

United States v. Marino-Garcia, 679 F.2d 1373, 1383 (11th Cir. 

1982)) (alteration in original)); United States v. Estupinan, 453 

F.3d 1336, 1338 (11th Cir. 2006) (holding that the MDLEA's 

punishment of drug trafficking "on board a vessel subject to the 

jurisdiction of the United States" is within Congress's 

constitutional authority); United States v. Moreno-Morillo, 334 

F.3d 819, 824 (9th Cir. 2003) (citing United States v. Davis, 905 

F.2d 245, 248 (9th Cir. 1990), for the proposition that "this court 

clearly has held that the MDLEA is constitutional" in a case where 

the statelessness of the vessel was uncontested). We have thus 

found no precedent squarely addressing the argument that 

appellants make here: that the definition of a "vessel without 

nationality" in § 70502(d)(1)(C) is broader than the definition of 
- 40 -

a stateless vessel under international law and is therefore 

unconstitutional.34

Thus, although we draw on prior cases addressing the 

constitutionality of the MDLEA and its relationship with 

international law, the issue before us appears to be one of first 

impression for the federal courts. 

B. Constitutional Limits on Congress's Authority to Define and 

Punish Felonies

As described above, appellants contend that 

§ 70502(d)(1)(C) of the MDLEA defines "vessel without nationality" 

to encompass vessels -- including their own -- that are not in 

fact without nationality under international law. A conflict 

exists, they explain, because the provision treats a vessel as 

34 Although the same MDLEA provision was at issue in United 

States v. Bravo, the defendants argued only that their prosecution 

was flawed because the government failed to satisfy a nexus 

requirement -- i.e., "that the marijuana transported in the vessel 

would affect the United States." 489 F.3d 1, 7 (1st Cir. 2007). 

We rejected the challenge, stating that "[w]e do not read the MDLEA 

to require a jurisdictional nexus." Id. Hence, we were not 

confronted with the argument asserted here -- that Congress acted 

beyond its constitutional authority in adopting § 70502(d)(1)(C). 

We note that the author of Bravo subsequently rejected the position 

taken in that case. See United States v. Trinidad, 839 F.3d 112, 

116 (1st Cir. 2016) (Torruella, J., dissenting) ("I can no longer 

support the approach taken by this and our sister circuits in 

embracing the sweeping powers asserted by Congress and the 

Executive under the [MDLEA.]"). Trinidad also involved 

§ 70502(d)(1)(C), but the defendant there did not challenge the 

government's determination that his vessel was "without 

nationality" under that provision or argue that "his plea agreement 

must be vacated because Congress exceeded its constitutional

authority under Article I in enacting the MDLEA." Id. at 113 n.1.
- 41 -

stateless despite a claim of nationality being made through a 

method long acceptable under international law -- specifically, in 

their case, the master's verbal claim -- if the named country does 

not "affirmatively and unequivocally assert that the vessel is of 

its nationality." 46 U.S.C. § 70502(d)(1)(C). In other words, 

appellants maintain that § 70502(d)(1)(C) rejects a claim of 

nationality in circumstances where international law accepts the 

claim. According to appellants, because of this disconnect between 

the MDLEA and international law, U.S. authorities who rely on the 

definition of a "vessel without nationality" contained in 

§ 70502(d)(1)(C) will impermissibly arrest and prosecute foreign 

nationals on a foreign vessel -- which is what they say occurred 

in this case.

Appellants' assertion of improper arrest and prosecution 

depends on two propositions involving international law: first,

that Congress's authority to "define and punish . . . Felonies 

committed on the high Seas," U.S. Const. art. I, § 8, cl. 10, is 

limited by principles of international law and, second, that 

§ 70502(d)(1)(C) allows the United States to deem vessels 

stateless even when they would not be deemed stateless under

international law. If both propositions are correct, 

§ 70502(d)(1)(C) would unconstitutionally permit U.S. authorities 

to assert jurisdiction over vessels that would not be stateless 

under international law. In that scenario, the United States would 
- 42 -

be imposing its law on foreign individuals on foreign vessels --

an extension of jurisdiction that ordinarily is impermissible. 

See, e.g., Aybar-Ulloa, 987 F.3d at 5 (noting that "the flag-state 

system guarantees freedom of navigation in international waters, 

as states generally may not interfere with the passage on the high 

seas of ships lawfully flying the flag of another state" (citing 

Richard A. Barnes, "Flag States," in The Oxford Handbook on the 

Law of the Sea 313 (Rothwell et al. eds. 2015))); id. at 12 (noting 

"the presumption of exclusive flag-state jurisdiction" over 

vessels with identified nationality).

Hence, resolving this case requires us first to examine 

the intersection between the Felonies Clause and international 

law. To be clear, the claim here is not that international law 

itself constrains Congress's authority to enact statutes.35

Rather, appellants contend that the Felonies Clause of the 

Constitution, by original design, requires Congress to adhere to 

the jurisdictional limits of international law with respect to

35 The MDLEA states that a person charged under the statute 

"does not have standing to raise a claim of failure to comply with 

international law as a basis for a defense." 46 U.S.C. § 70505. 

The provision further states that "only . . . a foreign nation" 

may raise such a claim and that "[a] failure to comply with 

international law does not divest a court of jurisdiction and is 

not a defense to a proceeding under this chapter." Id. This bar 

does not apply here precisely because defendants are not arguing 

that international law itself constrains Congress's authority.
- 43 -

determining statelessness.36 We thus begin our discussion by 

examining how the Framers would have understood the authority given 

to Congress by the Felonies Clause.

1. The Constitution and International Law

The delegates who gathered to draft the Constitution had 

a primary goal of improving the new nation's ability to meet its 

obligations to other countries under international law. See Ryan 

Goodman & Derek P. Jinks, Filartiga's Firm Footing: International 

Human Rights and Federal Common Law, 66 Fordham L. Rev. 463, 464 

(1997) ("[T]he Framers held the Constitutional Convention in large 

part due to the perceived inability of the Confederation to uphold 

American obligations under international law.").37 When the 

Governor of Virginia, Edmund Randolph, introduced the "Virginia 

Plan" that was to become the basis for the Constitution,38 he 

36 Of course, where possible, we construe statutes to be 

consistent with international law. See Murray v. The Schooner 

Charming Betsy, 6 U.S. (2 Cranch) 64, 118 (1804); Garcia v. 

Sessions, 856 F.3d 27, 41 (1st Cir. 2017).

37 In Filartiga v. Pena-Irala, 630 F.2d 876 (2d Cir. 1980), 

the Second Circuit held that plaintiffs could bring actions under 

the Alien Tort Statute ("ATS") "based on modern human-rights laws 

absent an express cause of action created by an additional 

statute." Jesner v. Arab Bank, PLC, 138 S. Ct. 1386, 1398 (2018). 

The plaintiffs in Filartiga were the family members of a young man 

who had been tortured and murdered by Paraguayan police officers, 

one of whom was living in New York. The suit was filed in the 

United States District Court for the Eastern District of New York, 

and the appeals court found jurisdiction existed under the ATS.

38 The Virginia Plan was a set of fifteen "republican 

Principles" introduced by Randolph for discussion at the 

Constitutional Convention. 1 Records of the Federal Convention of 
- 44 -

criticized the Articles of Confederation because they did not allow 

the federal government to punish states that "act[] against a 

foreign power contrary to the laws of nations or violate[] a 

treaty" or to compel states to punish their citizens who violate 

the law of nations by, for example, "invad[ing]" the rights of an 

ambassador. 1 Records of the Federal Convention of 1787 24-25

(Max Farrand ed., 1911) (hereinafter "Farrand's Records"). 

Likewise, James Madison wrote to James Monroe in 1784 that 

"[n]othing seems to be more difficult under [the Articles of 

Confederation] than to impress on the attention of our [state] 

Legislatures a due sense of those duties which spring from our 

relations to foreign nations." Letter from James Madison to James 

Monroe (Nov. 27, 1784), in 2 The Writings of James Madison 93 

(Gaillard Hunt ed., 1901).

These statements reflect the Framers' concern that, 

without the power to "enforce national treaties against 

recalcitrant states, compel their compliance with the law of 

1787 27-28 (Max Farrand ed., 1911). It described in general terms 

the governmental structure that was later adopted in significant 

part by the Constitution: a bicameral legislature, a national 

executive (albeit one elected by the legislature), and a judiciary 

with, among other powers, the authority to "determine Piracies, 

Captures, [and] Disputes between Foreigners and Citizens." Id. 

Before introducing this plan, Randolph listed five ways in which 

the Articles of Confederation did not fulfill "the objects for 

which it was framed." Id. at 24. The first of these, as explained 

above, was its failure to ensure compliance with international 

law. Id. at 24-25. 
- 45 -

nations, punish offenses against that law, regulate foreign 

commerce, and so on, the new republic would be unable to obtain 

commercial advantages and, given its military weakness and 

perilous geographic situation, would face external threats." 

David M. Golove & Daniel J. Hulsebosch, A Civilized Nation: The 

Early American Constitution, the Law of Nations, and the Pursuit 

of International Recognition, 85 N.Y.U. L. Rev. 932, 980 (2010); 

see also id. at 934-35 (explaining that "[d]iplomatic frustrations 

resulting from state violations of the Treaty of Peace [with 

England], in particular, helped create the atmosphere of crisis 

that motivated profederal forces to organize and write a 

constitution").

In drafting a new constitution, the Framers thus aimed

"to provide a national monopoly of authority in order to assure 

respect for international obligations." Stewart Jay, The Status 

of the Law of Nations in Early American Law, 42 Vand. L. Rev. 819, 

829 (1989). The Framers were "commit[ted] to protecting sovereign 

interests through rigorous enforcement of the law of nations." 

Douglas J. Sylvester, International Law as Sword or Shield? Early 

American Foreign Policy and the Law of Nations, 32 N.Y.U. J. Int'l 

L. & Pol. 1, 9 (1999); see also Jesner v. Arab Bank, PLC, 138 S. 

Ct. 1386, 1417 (2018) (Gorsuch, J., concurring) ("[W]hen the 

framers gathered to write the Constitution they included among 

their chief priorities endowing the national government with 
- 46 -

sufficient power to ensure the country's compliance with the law 

of nations."); Golove & Hulsebosch, supra, at 988 (stating that 

the Framers "carefully designed the new Constitution to ensure 

that the new nation would uphold its duties under the law of 

nations"); Louis Henkin, Foreign Affairs and the United States

Constitution 234 (2d ed. 1996) ("The Framers assumed that the new 

federal government would carry out the obligations of the United 

States under international law."); Anthony J. Bellia Jr. & Bradford 

R. Clark, The Law of Nations as Constitutional Law, 98 Va. L. Rev. 

729, 751 (2012) ("Of all the rights that can belong to a nation, 

sovereignty is, doubtless, the most precious, and that which others 

ought the most scrupulously to respect, they would not do it an 

injury." (quoting 1 Emmerich de Vattel, The Law of Nations, bk. 

II, § 54, at 138 (London, J. Newberry et al., 1759), "the most 

well-known work on the law of nations in England and America at 

the time of the Founding," id. at 749)); Beth Stephens, The Law of

Our Land: Customary International Law as Federal Law after Erie, 

66 Fordham L. Rev. 393, 397 (1997) (stating that "the intent of 

the framers, incorporated into the Constitution, was to ensure 

respect for international law by assigning responsibility for 

enforcement of that law to the three branches of the federal 

government"). Laws governing interactions on the high seas were 

of particular concern: "The framers of the Constitution were 

familiar with [the law of the sea] and proceeded with it in mind. 
- 47 -

Their purpose was not to strike down or abrogate the system, but 

to place the entire subject . . . under national control, because 

of its intimate relation to navigation and to interstate and 

foreign commerce." Panama R. Co. v. Johnson, 264 U.S. 375, 386 

(1924).

The Framers' commitment to international law principles 

was both pragmatic and ideological. See Jay, supra, at 822 

(explaining that, "[i]n the eighteenth century a consensus existed 

that the law of nations rested in large measure on natural law," 

and thus the Framers viewed following the law of nations as a moral 

imperative); Beth Stephens, Federalism and Foreign Affairs: 

Congress's Power to "Define and Punish . . . Offenses Against the 

Law of Nations", 42 Wm. & Mary L. Rev. 447, 465 (2000) (describing 

the Framers' belief that "[e]nforcement of international law norms 

was . . . a moral obligation"). Indeed, the Framers believed that 

to be a "nation," the United States must honor the law of nations.39

39 At the time of the founding, the phrase "law of nations" 

was generally used to refer to customary international law (i.e., 

law established by universal practice rather than by agreement in 

a treaty). See United States v. Bellaizac-Hurtado, 700 F.3d 1245,

1251 (11th Cir. 2012) (stating that "[w]e and our sister circuits 

agree that the eighteenth-century phrase, the 'law of nations,' in 

contemporary terms, means customary international law," and 

collecting cases). However, it was also used as a broader term 

for international law, including treaties. See Sarah H. Cleveland 

& William S. Dodge, Defining and Punishing Offenses under Treaties, 

124 Yale L.J. 2202, 2206-07 (2015) (arguing that "Offences against 

the Law of Nations" includes treaty violations). In this case, 

where no treaty is at issue, we need not consider the precise 

meaning of the term "law of nations" as used by the Framers, and 
- 48 -

See Chief Justice John Jay, Charge to the Grand Jury of the 

District of New York (Apr. 4, 1790), reprinted in N.H. Gazette

(Portsmouth 1790) (stating, in a charge to a grand jury, that "[w]e 

had become a nation -- as such, we were responsible to others for 

the observance of the Laws of Nations"). Hence, as they embarked 

on drafting a constitution, the Framers saw a federal system

capable of upholding international law as an imperative for the 

United States to achieve equal status in the community of nations. 

See Aybar-Ulloa, 987 F.3d at 26 (Barron, J., concurring) ("The 

founding generation was attentive to the strictures of the law of 

nations.").

With this backdrop, we think it apparent that the Framers 

viewed international law as a restraint on Congress's enumerated 

powers bearing on foreign relations. As John Quincy Adams 

explained, "[t]he legislative powers of Congress are . . . limited 

to specific grants contained in the Constitution itself, all 

restricted on one side by the power of internal legislation within 

the separate States, and on the other, by the laws of nations."

John Quincy Adams, The Jubilee of the Constitution 71 (1839)

(emphasis added).

we henceforth use the modern term "international law" to refer to 

the body of law that includes both customary international law and 

treaties. 
- 49 -

There is a particular justification for interpreting the 

Define and Punish Clause in relation to the Framers' understanding 

of international law principles. The Define and Punish Clause, of 

which the Felonies Clause is a part, refers to "Offences against 

the Law of Nations," "Piracies," and "Felonies" -- all concepts 

taken directly from international law. See Banco Nacional de Cuba

v. Sabbatino, 376 U.S. 398, 451 & n.13 (1964) (White, J., 

dissenting) (noting that the language of the Define and Punish 

Clause shows the Framers' belief that "the law of nations is a 

part of the law of the land"); Golove & Hulsebosch, supra, at 1009 

(stating that "[t]his deliberate borrowing suggest[s] that the 

established principles of the law of nations might define the scope 

of the [congressional] powers themselves"). These phrases, found 

in the leading international law treatises of the day, were

familiar shorthand for complex international law concepts. Their 

use in the Constitution is thus strong evidence that the Framers 

intended the Define and Punish Clause to align with the 

international law understanding of those terms. See 3 Emmerich de 

Vattel, The Law of Nations 295 (1758) (Charles G. Fenwick trans., 

1916) (referencing "offenses against the Law of Nations"); 4 

William Blackstone, Commentaries *67-71 (discussing "offences 

against the law of nations," and defining "piracy" as one such 

offense); 3 Sir Edward Coke, The Institutes of the Laws of England
- 50 -

111 (1644) (describing "Piracies, and felonies . . . done on the 

sea").

International law thus informs our inquiry into the 

meaning of the Define and Punish Clause and, specifically, the 

Felonies portion of the Clause.

2. The Meaning of the Felonies Clause

As noted above, the Define and Punish Clause grants 

Congress the following authority: "To define and punish Piracies 

and Felonies committed on the high Seas, and Offences against the 

Law of Nations." U.S. Const. art. I, § 8, cl. 10. We discuss 

below primarily the text that precedes the comma -- i.e., the 

authority with respect to "Piracies and Felonies committed on the 

high Seas." That is so because, as we have noted, it is undisputed 

in this case that the MDLEA was enacted pursuant to Congress's 

authority under the Felonies Clause. Although the reference to 

"Piracies" -- a crime "committed on the high Seas" and appearing 

alongside the term "Felonies" -- necessarily plays a role in our 

analysis, the separate clause referencing "Offences against the 

Law of Nations," which applies to crimes committed both on land 

and at sea, sheds no light on the scope of U.S. jurisdiction on 

the high seas. We therefore focus solely on the authority 

specifically given to Congress over crimes "on the high Seas."

That focus requires us to determine what the Framers 

intended by the words they chose. In so doing, we seek guidance 
- 51 -

on the Framers' understanding of international law principles, 

including international law terminology, from contemporaneous 

sources. See U.S. Steel Corp. v. Multistate Tax Comm'n, 434 U.S. 

452, 461-62 & n.12 (1978) (explaining the Framers' separate use of 

the terms "treaty," "compact," and "agreement" in Article I of the 

Constitution by reference to treatises on international law with 

which the Framers would have been familiar); Waring v. Clarke, 46 

U.S. 441, 441 n.1 (1847) (stating that "[t]he Constitution . . . 

refers to the law of nations for the meaning of" the terms 

"admiralty" and "maritime," and thus interpreting those terms in 

light of their meaning in international law); see also Zivotofsky 

ex rel. Zivotofsky v. Kerry, 576 U.S. 1, 12 (2015) (looking to 

"prominent international scholars" from "the time of the founding"

to elucidate the meaning of the Reception Clause, Article II, 

section 3, of the Constitution).

Just as it does today, at the time the Framers were 

drafting the Constitution the term "Felonies" meant serious 

crimes, such as treason, murder, arson, burglary, robbery, and

rape. See Blackstone, supra, at *94; 2 Timothy Cunningham, A New 

and Complete Law Dictionary 23-28 (3d ed. 1783). Before the 

Constitution became the governing law, all such crimes, whether 

committed on land or at sea, were defined by state statutes or 

state common law and punished in state courts. In the only 

statement at the Constitutional Convention regarding the inclusion
- 52 -

of the term "Felonies," James Madison explained that, "[i]f the 

laws of the states were to prevail on [the meaning of "Felonies"], 

the citizens of different states would be subject to different 

punishments for the same offence at sea. There would be neither 

uniformity nor stability in the law." 5 Debates on the Federal 

Constitution 437 (Jonathan Elliot ed., 2d ed. 1836). As voiced by 

Madison, then, the constitutional drafters recognized the need to 

create a uniform system of crimes and punishments on the high seas

that would apply to all U.S. citizens. There was no mention, 

however, of conduct committed by foreigners on foreign vessels.

Nonetheless, the independent inclusion of "Piracies" in 

the Define and Punish Clause provides a clue to the Framers' intent 

regarding U.S. jurisdiction over felonies committed on foreign 

vessels. The separate references to "Piracies" and "Felonies"

inescapably reflects the Framers' view that Congress's power over 

each category was meant to be distinct. See generally The 

Federalist No. 42, at 233 (James Madison) (E.M. Scott ed., 1898)

(discussing the necessity of defining each term). That distinction 

has its origin in international law.

Piracy, as defined by international law -- i.e., 

"robbery upon the sea," United States v. Smith, 18 U.S. 153, 162 
- 53 -

(1820)40 -- is a crime of "universal jurisdiction,"41 meaning that 

it can be punished by any country no matter where it is committed 

or by whom. At the time the Constitution was drafted, this feature 

of piracy under international law was well established. See

40 A more expansive definition of the universal crime of 

piracy, updated to include the realm of aviation, is as follows:

Piracy includes any illegal act of 

violence, detention or depredation committed 

for private ends by the crew or passengers of 

a private ship (or aircraft) against another 

ship (or aircraft) or persons or property on 

board it, on (or over) the high seas[.]

R.R. Churchill & A.V. Lowe, The Law of the Sea 209-10 (3d ed. 

1999).

41 As stated in modern international law, the doctrine of 

universal jurisdiction provides that "a nation may prosecute 

certain serious offenses even though they have no nexus to its 

territory or its nationals, and no impact on its territory or its 

citizens." Cardales-Luna, 632 F.3d at 740 (Torruella, J., 

dissenting); see also Restatement (Third) of Foreign Relations Law 

of the United States § 404 (1987) (noting that "[a] state has 

jurisdiction to define and prescribe punishment for certain 

offenses recognized by the community of nations as of universal 

concern," even where there is no nexus between the offense and the 

state). Crimes may be universal jurisdiction offenses if they 

are "contrary to a peremptory norm of international law" and are 

"so serious and on such a scale that they can justly be regarded 

as an attack on the international legal order." Kontorovich, 

Beyond the Article I Horizon, supra, at 1224 n.228 (quoting 

Universal Jurisdiction: National Courts and the Prosecution of 

Serious Crimes under International Law 178-79 (Stephen Macedo ed., 

2004)). At present, in addition to piracy, the crimes generally 

recognized as subject to universal jurisdiction are the "slave 

trade, attacks on or hijacking of aircraft, genocide, war crimes, 

and perhaps certain acts of terrorism." See Restatement (Third) 

of Foreign Relations Law of the United States § 404. Drug 

trafficking is not recognized as a universal jurisdiction crime. 

Aybar-Ulloa, 987 F.3d at 14.
- 54 -

Blackstone, supra, at *71 (stating that "every community has a 

right" to punish piracy because it "is an offense against the 

universal law of society"); 1 James Kent, Commentaries on American 

Law 174 (1826) (stating that "piracy, under the law of nations, is 

an offence against all nations, and punishable by all"). As 

Justice Story explained in an early piracy case: 

Pirates may, without doubt, be lawfully 

captured on the ocean by the public or private 

ships of every nation; for they are, in truth, 

the common enemies of all mankind, and, as 

such, are liable to the extreme rights of war. 

And a piratical aggression by an armed vessel 

sailing under the regular flag of any nation 

may be justly subjected to the penalty of 

confiscation for such a gross breach of the 

law of nations. 

The Marianna Flora, 24 U.S. (11 Wheat.) 1, 40-41 (1825); see also

Cardales-Luna, 632 F.3d at 741 (Torruella, J., dissenting) ("Until 

recently, piracy was the only crime which was punishable by all 

nations . . . ."); United States v. Yousef, 327 F.3d 56, 104 (2d 

Cir. 2003) ("The class of crimes subject to universal jurisdiction 

traditionally included only piracy.").

That the Framers understood the term "Piracies" to refer 

to the specific offense subject to universal jurisdiction is 

supported by their statements describing piracy as a term borrowed 

from international law. For example, at the Virginia Convention, 

James Madison explained that "Piracies" was "[a] technical term of 

the law of nations." 3 Farrand's Records, supra, at 332. Thus, by 
- 55 -

separating the term "Piracies" from "Felonies," the Framers 

plainly intended to refer to the specific crime that, under 

international law, could be punished by Congress even when it was 

committed by foreign nationals on foreign vessels.

Just as plainly, then, the phrase "Felonies committed on 

the high Seas" was intended to reference other types of serious 

crimes committed on vessels. At the time, it was a well-accepted 

principle of international law that countries could enact statutes 

criminalizing conduct on the high seas other than piracy, but only 

as to a given country's own nationals or on vessels over which the 

country could exercise jurisdiction pursuant to international law.

See Blackstone, supra, at *71 (describing acts that would be 

punished as felonies only if committed by an English "subject" at 

sea); Letter from Thomas Jefferson to Edmond Charles Genet (June 

17, 1793) (explaining that a country's jurisdiction over crimes 

such as murder "on the high seas . . . reaches its own citizens 

only"); William Rawle, A View of the Constitution of the United 

States of America 107 (2d ed. 1829) (explaining that Congress's

power to punish felonies applies to anyone "except the citizens or 

subjects of a foreign state sailing under its flag," but that 

piracy is "punishable in our courts, and in the courts of all 

nations" (emphasis added)); Henry Wheaton, Elements of 

International Law 164 (Richard Henry Dana, Jr., ed., 8th ed. 1866) 

(observing that countries could enact laws punishing conduct at 
- 56 -

sea, but such conduct could "only be tried by that State within 

whose territorial jurisdiction" or "on board of whose vessels, the 

offence thus created was committed"). 

Confusingly, these other serious crimes, which would be 

denominated felonies if committed on land, were often referred to 

as "piracies" when committed on the high seas, even though they 

were not "Piracy" as defined by international law. See Wheaton, 

supra, (explaining that "[t]here are certain acts which are 

considered piracy by the internal laws of a State, to which the 

law of nations does not attach the same signification"); Hon. John 

Marshall, Speech Delivered in the House of Representatives (Mar.

7, 1800), at 10 ("A statute may make any offence piracy, committed 

within the jurisdiction of the nation passing the statute, and 

such offence will be punishable by that nation."); Kent, supra, 

(explaining that, under international law, "[t]he statute of any 

government may declare an offence committed on board its own 

vessels to be piracy, and such an offence will be punishable 

exclusively by the nation which passes the statute"). As one 

scholar explains, the term piracy "had a popular meaning of serious 

or capital offense on the high seas," Eugene Kontorovich, The 

"Define and Punish" Clause and the Limits of Universal 

Jurisdiction, 103 Nw. L. Rev. 149, 166 (2009), and the term was 

thus used colloquially to refer to any felony committed at sea,

see John Marshall Speech at 10 ("It is by confounding general 
- 57 -

piracy with piracy by statute, that indistinct ideas have been 

produced, respecting the power to punish offences committed on the 

high seas."). 

The Framers' separation of "Piracies" and "Felonies" in 

the Define and Punish Clause avoids this confusion and reserves

the precise meaning of "Piracy" under international law for that 

specific crime. The Framers' use of the separate terms "Piracies" 

and "Felonies" thus manifests an intent to distinguish between 

crimes with different jurisdictional limits under international 

law: classic piracy, which can be punished no matter where 

committed or by whom, and Felonies, which can be punished only if 

committed by U.S. nationals42 or on vessels subject to U.S. 

jurisdiction under international law. As noted in the Aybar-Ulloa

concurrence, "the United States itself early on took the position 

before the Supreme Court that the Define and Punish Clause" "is 

42 As stated supra, we do not address here the MDLEA's 

application to U.S. citizens and resident aliens. However, the 

sources quoted above indicate that the Framers would have 

understood the Felonies Clause to permit U.S. authorities to 

exercise jurisdiction over U.S. nationals on foreign vessels in at 

least some circumstances. See Skiriotes v. Florida, 313 U.S. 69, 

73 (1941) (stating that "the United States is not debarred by any 

rule of international law from governing the conduct of its own 

citizens upon the high seas or even in foreign countries when the 

rights of other nations or their nationals are not infringed"); 

United States v. Kaercher, 720 F.2d 5, 5 (1st Cir. 1983) (per 

curiam) (quoting the Restatement of Foreign Relations Law of the 

United States for the proposition that "[a] state has jurisdiction 

to prescribe a rule of law . . . attaching legal consequences to 

conduct of a national of the state wherever the conduct occurs" 

(alteration and omission in original)).
- 58 -

impliedly limited by the law of nations in ways that constrain 

Congress's authority to rely on that Clause to subject foreign 

nationals to our criminal laws for conduct that they engage [in] 

while they are on foreign vessels -- even when those vessels are 

on the high seas." 987 F.3d at 16 n.7, 15 (Barron, J., concurring); 

see id. at 16 n.7 (quoting the argument of Mr. Blake on behalf of 

the United States in United States v. Palmer, 16 U.S. (3 Wheat.) 

610, 620 (1818): "A felony, which is made piracy by municipal 

statutes, and was not such by the law of nations, cannot be tried 

by the courts of the United States, if committed by a foreigner on 

board a foreign vessel, on the high seas; because the jurisdiction 

of the United States, beyond their own territorial limits, only 

extends to the punishment of crimes which are piracy by the law of 

nations.").

3. Jurisdiction on the High Seas under International Law

Given the Framers' clear intention to draw a 

jurisdictional distinction between "Piracies" and "Felonies," the 

question of when a vessel sailing on the high seas may be subject 

to U.S. jurisdiction under international law -- i.e., the question 

at the heart of this case -- has constitutional significance. It 

is a bedrock principle of the international law of the sea, 

recognized long before the founding of this country, that "all 

nations have an equal and untrammelled right to navigate on the 

high seas." Marino-Garcia, 679 F.2d at 1380; see also United 
- 59 -

States v. Maine, 475 U.S. 89, 96 n.11 (1986) (explaining that 

"since the days of Grotius, the principle of the freedom of the 

high seas found an ever wider currency" and "crystallized into a 

universally accepted principle of international law" by "the 

beginning of the nineteenth century" (quoting Yehuda Z. Blum, 

Historic Titles in International Law § 61, at 242-43 (1965))); 

Hugo Grotius, The Freedom of the Seas 44 (Ralph V.D. Magoffin 

trans., 1916) ("It is clear . . . that he who prevents another 

from navigating the sea has no support in law."); United Nations

Convention on the Law of the Sea ("UNCLOS") art. 90, Dec. 10, 1982, 

1833 U.N.T.S. 397.43 To ensure this right of free navigation, 

43 Although the Senate has not ratified the UNCLOS, it was 

signed by the President and is generally recognized by the United 

States as reflecting customary international law, i.e., universal 

practice. See United States v. Alaska, 503 U.S. 569, 588 n.10 

(1992) (acknowledging the U.S. government's position that the 

UNCLOS provisions are part of customary international law); see

also Aybar-Ulloa, 987 F.3d at 5 n.2 (citing the UNCLOS "as evidence 

of the customs and usages of international law"); United States v. 

Hasan, 747 F. Supp. 2d 599, 635 (E.D. Va. 2010) ("[T]he United 

States has consistently accepted UNCLOS as customary international 

law for more than 25 years."). Moreover, "many of the provisions 

of the [UNCLOS] follow closely provisions in the 1958 conventions 

to which the United States is a party and which largely restated 

customary law as of that time." Restatement (Third) of Foreign 

Relations Law of the United States, Part V, Introductory Note; see

also Mayagüezanos por la Salud y el Ambiente v. United States, 198 

F.3d 297, 304 n.14 (1st Cir. 1999) (referring to the "UNCLOS only 

to the extent that it incorporates customary international law," 

and noting that, as a signatory, "the United States 'is obliged to 

refrain from acts that would defeat the object and purpose of the 

agreement'" (quoting Restatement (Third) of Foreign Relations Law 

of the United States § 312(3))). The UNCLOS provisions defining 

a stateless vessel discussed infra have long been part of the 

international law of the sea and are largely identical to those in 
- 60 -

"international law generally prohibits any country from asserting

jurisdiction over foreign vessels on the high seas," and "vessels 

are normally considered within the exclusive jurisdiction of the 

country whose flag they fly."44 Marino-Garcia, 679 F.2d at 1380; 

see also Aybar-Ulloa, 987 F.3d at 5; John Marshall Speech at 5 

(stating that "the opinion of the world is, that a fleet at sea, 

is within the jurisdiction of the nation to which it belongs").

To preserve this system of flag-state jurisdiction, 

"every vessel must sail under the flag of one and only one state; 

those that sail under no flag . . . enjoy no legal protection." 

Matos-Luchi, 627 F.3d at 5; see also, e.g., Aybar-Ulloa, 987 F.3d 

at 6 (noting that "international law renders stateless vessels 

'susceptible to the jurisdiction of any State'" (quoting Barnes, 

supra, at 314)); United States v. Pinto-Mejia, 720 F.2d 248, 260 

(2d Cir. 1983) (explaining that "a stateless vessel, which does 

not sail under the flag of one state to whose jurisdiction it has 

submitted, may not claim the protection of international law and 

does not have the right to travel the high seas with impunity"); 

United States v. Rubies, 612 F.2d 397, 403 (9th Cir. 1979) ("'In 

the 1958 Convention on the High Seas, which has been ratified by 

the United States. See supra, arts. 5 & 6.

44 Although the nationality of a vessel is often referred to 

as its "flag," there is no requirement that a vessel fly a physical 

flag to maintain its nationality. See Matos-Luchi, 627 F.3d at 5. 

Rather, "[s]hips have the nationality of the State whose flag they 

are entitled to fly." UNCLOS art. 91, § 1 (emphasis added).
- 61 -

the interest of order on the open sea, a vessel not sailing under 

the maritime flag of a State enjoys no protection whatever, for 

the freedom of navigation on the open sea is freedom for such 

vessels only as sail under the flag of a State.'" (quoting Lassa 

Oppenheim, International Law 546 (7th ed. 1948))). Therefore, it 

has long been understood that the United States -- and any other 

country -- may exercise jurisdiction over vessels that are 

considered stateless under international law. We confirmed that 

understanding in Aybar-Ulloa. See, e.g., 987 F.3d at 12 

("[S]tateless vessels are treated as subject to the exercise of 

authority by any nation."); see also, e.g., Matos-Luchi, 627 F.3d 

at 6 (noting that "international law . . . treats the 'stateless 

vessel' concept as informed by the need for effective enforcement," 

and, hence, "a vessel may be deemed 'stateless,' and subject to 

the enforcement jurisdiction of any nation on the scene, if it 

fails to display or carry insignia of nationality and seeks to 

avoid national identification"); Andrew W. Anderson, Jurisdiction 

over Stateless Vessels on the High Seas: an Appraisal Under 

Domestic and International Law, 13 J. Mar. L. & Com. 323, 337 

(1982) ("[T]he extension of United States jurisdiction over 

stateless vessels seems not only to be a reasonable claim but 

completely consistent with both customary and treaty international 

law.").
- 62 -

These general principles of jurisdiction on the high 

seas are not disputed in this case, and, indeed, the Supreme Court 

applied these principles in the decades immediately following the 

Constitution's adoption. In 1790, Congress passed a law making

murder and robbery committed by "any person" on the high seas 

punishable under U.S. law. See Palmer, 16 U.S. (3 Wheat.) at 626. 

It was an open question, however, whether the statute extended to 

conduct by foreigners on foreign vessels. When he was a 

congressman, John Marshall argued that the Define and Punish Clause

can never be construed to make to the 

government a grant of power, which the people 

making it, did not themselves possess. It has 

already been shown that the people of the 

United States have no jurisdiction over 

offences, committed on board a foreign ship, 

against a foreign nation. Of consequence, in 

framing a government for themselves, they 

cannot have passed this jurisdiction to that 

government.

John Marshall Speech at 24-25.

Not surprisingly, then, the Supreme Court in United 

States v. Palmer, in an opinion written by now Chief Justice 

Marshall, held that the statute did not extend U.S. jurisdiction

to foreigners on foreign vessels for the common law form of 

robbery, as distinguished from classic piracy. See 16 U.S. (3 

Wheat.) at 630-34. The Court reiterated its holding on the 

statute's reach two years later, concluding that it did not 

criminalize the murder of a foreigner on a foreign vessel on the
- 63 -

high seas because Congress knew it "had no right to interfere" in 

such cases. Furlong, 18 U.S. (5 Wheat.) at 198; see also id. at 

197 (observing that "punishing [murder] when committed within the 

jurisdiction, or, (what is the same thing,) in the vessel of 

another nation, has not been acknowledged as a right, much less an 

obligation"). By contrast, the Supreme Court recognized the

classic form of piracy as "a crime within the acknowledged reach 

of the punishing power of Congress" even when "committed by a 

foreigner upon a foreigner in a foreign ship," id. at 197, and 

noted in other cases that "[m]urders committed by and against 

foreigners on stateless vessels . . . could be prosecuted in the 

United States," Aybar-Ulloa, 987 F.3d at 7 (citing United States

v. Klintock, 18 U.S. (5 Wheat.) 144, 151 (1820) and United States

v. Holmes, 18 U.S. (5 Wheat.) 412, 417-18 (1820)).45

Thus, in light of these well-established limitations on 

Congress's ability to criminalize the conduct of foreign nationals 

45 As noted above, the concurring opinion in Aybar-Ulloa also 

reports the historical support, in caselaw and commentary, for the 

contention that Congress lacks authority under the Define and 

Punish Clause to punish foreign nationals for conduct committed on 

foreign vessels, "even when those vessels are on the high seas." 

987 F.3d at 15-16 & n.7 (Barron, J., concurring); see also id. at 

22-26 (discussing the cases "decided just decades after the 

Constitution's ratification" that "dealt with the United States' 

power to prosecute defendants of a range of citizenships and 

circumstances who shared the attribute of having been indicted in 

our country pursuant to our criminal justice system for murder, 

robbery, or other wrongdoing on the high seas").
- 64 -

aboard foreign vessels on the high seas,46 the question that arises

when the United States seeks to impose its law on foreigners on 

the high seas is how to identify a vessel that is not within any 

other country's jurisdiction -- potentially exposing those aboard 

to every country's jurisdiction.47 In other words, when may a 

vessel be characterized as stateless? Stateless vessels do not 

appear to have been a primary focus at the time of the Framers, 

and we have found no explicit statements in their deliberations on 

when a vessel should be deemed stateless. That silence, of course, 

is unsurprising, given the focus on avoiding improper intrusions 

into the affairs of foreign nations.

As we have concluded, however, there can be no doubt 

that the Constitution's drafters intended that Congress's 

46 There are, of course, exceptions to the broad principle 

that Congress cannot extend U.S. criminal jurisdiction to crimes 

like common law robbery or murder committed by foreigners against 

foreigners on foreign vessels. For example, a country may 

prosecute such crimes with the consent of the foreign nation. See

Matos-Luchi, 627 F.3d at 7; see also 46 U.S.C. § 70502(c)(1)(C). 

But these exceptions are not pertinent here.

47 We use the word "potentially" because we declined in AybarUlloa to decide "whether the United States may prosecute a foreign 

citizen engaged in drug trafficking on a stateless vessel where 

the United States never boarded and seized the vessel." 987 F.3d 

at 14. We note, in addition, the observation in the Aybar-Ulloa

concurrence that the Third and Fourth Restatements of Foreign 

Relations Law of the United States do not "establish that the 

prevailing view of the law of nations is that the interdicting 

country acquires the same territorial jurisdiction over the

[stateless] vessel's occupants as it acquires over the vessel 

itself." Id. at 17 (Barron, J., concurring).
- 65 -

authority under the Define and Punish Clause, including the

Felonies portion of it, be constrained by currently applicable 

international law whenever Congress invokes that Clause to assert 

its authority over foreign nationals and their vessels on the high 

seas. The Framers sought to ensure that Congress would respect 

the sovereignty of other nations, and the limits placed on the 

prosecution of other countries' nationals is an essential 

component of the international system of mutual respect. 

Necessarily, then, that constraint applies when Congress passes 

legislation deeming vessels on the high seas stateless. If the 

Constitution instead permitted Congress to define a vessel as 

stateless in any way it wished, there would be a risk that Congress 

could contravene international norms determining when a country 

may prosecute felonies committed by foreign nationals on the high 

seas. It therefore follows that the Felonies Clause requires 

Congress to abide by international law principles in defining 

statelessness. We thus review those principles.

4. Statelessness under International Law

International law allows each nation to decide for 

itself the process through which it will grant its nationality to 

a vessel. See Lauritzen v. Larsen, 345 U.S. 571, 584 (1953) ("Each 

state under international law may determine for itself the 

conditions on which it will grant its nationality to a merchant 

ship, thereby accepting responsibility for it and acquiring 
- 66 -

authority over it."); UNCLOS art. 91, § 1 ("Every State shall fix 

the conditions for the grant of its nationality to ships, for the 

registration of ships in its territory, and for the right to fly 

its flag."); 5 J.H.W. Verzijl, International Law in Historical 

Perspective 146 (1972) (describing an 1801 proclamation by the 

King of England regarding the conditions under which merchant ships 

may fly the British flag, and noting "[t]he general principle

. . . that it is within the domestic jurisdiction of any State 

. . . to determine on what conditions it will allow a sea-going 

vessel to fly its flag and thus grant her its 'nationality'"). 

The simplest definition of a stateless vessel under international

law is thus a vessel that has not been granted nationality by any 

state. Pursuant to that definition, a vessel will lack 

nationality, for example, "if no state has ever authorized [the 

vessel] to fly its flag, if a state has cancelled its 

authorization, or if the political entity that authorized a ship 

to fly its flag is not recognized as an international person." 

Rosero, 42 F.3d at 171; see also id. ("[A] vessel is without 

nationality if it is not authorized to fly the flag of any 

state."); Matos-Luchi, 627 F.3d at 16 (Lipez, J., dissenting) 

("Under international law, a stateless vessel is simply one that 

does not have a valid grant of nationality from any country.").

Authorities encountering a vessel on the high seas would 

not be aware of some of these circumstances -- e.g., if a state 
- 67 -

has cancelled a vessel's registration -- and thus will be unable 

to definitively determine nationality by sight even if a vessel is 

flying a flag. Nonetheless, international law recognizes a 

presumption of nationality in the flag-flying situation, among 

others. We have noted that "[b]y custom, a vessel claims 

nationality by flying the flag of the nation with which it is 

affiliated or carrying papers showing it to be registered with 

that nation." Matos-Luchi, 627 F.3d at 5 (citing Lassa Oppenheim, 

International Law § 261, at 594-96 (H. Lauterpacht ed., 8th ed. 

1955)); see also United States v. Bustos-Guzman, 685 F.2d 1278, 

1280 (11th Cir. 1982) (per curiam) (noting that flying a flag is 

generally "prima facie proof" of nationality under international 

law); The Chiquita, 19 F.2d 417, 418 (5th Cir. 1927) ("The flag 

under which a merchant ship sails is prima facie proof of her 

nationality.").

Absent a flag or papers, "a vessel may also traditionally 

make an oral claim of nationality when a proper demand is made." 

Matos-Luchi, 627 F.3d at 5; see also Aybar-Ulloa, 987 F.3d at 5 

(quoting Matos-Luchi, 627 F.3d at 5); United States v. Obando, 891 

F.3d 929, 939 (11th Cir. 2018) (Black, J., specially concurring) 

(noting that, under "longstanding principles of admiralty law," 

the master "speak[s] on behalf of the ship" and must be the one to 

make a verbal claim of nationality); The Little Charles, 26 F. 

Cas. 979, 982 (Marshall, Circuit Justice, C.C. Va. 1818) ("The 
- 68 -

vessel acts and speaks by the master."); Anderson, supra, at 341 

(noting that a vessel may claim nationality "by showing its flag, 

presenting its documents, or making some other outward or oral 

claim to a nationality" (emphasis added)). The MDLEA itself 

recognizes this form of asserting nationality, stating that "[a] 

claim of nationality or registry under this section includes 

. . . a verbal claim of nationality or registry by the master or 

individual in charge of the vessel." 46 U.S.C. § 70502(e)(3).

International law also recognizes two specific 

circumstances in which a vessel may be deemed stateless regardless 

of its actual status and absent any effort to determine its 

nationality: when the vessel refuses to claim any nationality or

when it claims more than one nationality. See Matos-Luchi, 627 

F.3d at 6-7 (stating that "a vessel may be deemed 'stateless' . . . 

if it fails to display or carry insignia of nationality and seeks 

to avoid national identification" by "refus[ing], without 

reasonable excuse, to reveal its" nationality (quoting Meyers, 

supra, at 322) (internal quotation marks omitted)); UNCLOS art. 

92, § 2 (stating that "[a] ship which sails under the flags of two 

or more States . . . may be assimilated to a ship without 

nationality"); The Commander's Handbook on the Law of Naval 

Operations ¶ 3.11.2.4 (2017), 

https://www.gc.noaa.gov/pdfs/CDRs_HB_on_Law_of_Naval_Operations_

AUG17.pdf (stating that "[a] vessel may be assimilated to a vessel
- 69 -

without nationality," inter alia, "when the vessel makes multiple 

claims of nationality . . . or the master's claim of nationality 

differs from the vessel's papers").48

Hence, whether authorities are seeking to ascertain 

nationality in the first place -- by examining documents or 

eliciting a verbal claim -- or to resolve a concern about

nationality that was declared by means of a flag, they may need 

close contact with the vessel and its master. It is therefore

48 The 2017 version of the Commander's Handbook -- applicable 

to the U.S. Navy, Marine Corps, and Coast Guard -- also states 

that a vessel may be "treated as one without nationality" when, 

among other factors, it displays no "identifying characteristics," 

when -- consistent with § 70502(d)(1) -- the master makes no claim 

of nationality or registry, or when "[t]he claim of registry or 

the vessel's display of registry is either denied or not 

affirmatively and unequivocally confirmed by the State whose 

registry is claimed." Commander's Handbook ¶ 3.11.2.3 (2017), 

supra; see also id., References 4 (listing MDLEA, 46 U.S.C. 

§§ 70501-70507). Interestingly, the Handbook's previous version, 

in effect when appellants were detained, did not include the 

failure-to-verify scenario that mirrors § 70502(d)(1)(C) of the 

MDLEA. Rather, its list of characteristics of a stateless vessel 

all relied on inconsistencies in a vessel's presentation of 

nationality to observers or the absence of, or refusal to provide, 

identification. See Commander's Handbook ¶ 3.11.2.4 (2007), 

https://www.marines.mil/Portals/1/Publications/MCTP%2011-

10B%20(%20Formerly%20MCWP%205-12.1).pdf?ver=2017-07-11-151548-

683 (providing "a partial list of factors that should be considered 

in determining whether a vessel is appropriately assimilated to 

stateless status: (1) No claim of nationality; (2) Multiple claims 

of nationality; (3) Contradictory claims or inconsistent 

indicators of nationality (e.g. master's claim differs from 

vessel's papers; homeport does not match nationality of flag); (4) 

Changing flags during a voyage; (5) Removable signboards showing 

different vessel names and/or homeport; (6) Absence of anyone 

admitting to be the master; displaying no name, flag, or other 

identifying characteristics; and (7) Refusal to claim 

nationality").
- 70 -

understood that international law's so-called "right of visit"

permits authorities to inquire, board, and conduct a limited search 

"designed to elicit information about the vessel's identification 

and registration." Cuevas-Esquivel, 905 F.2d at 513; see also

Aybar-Ulloa, 987 F.3d at 6 (recognizing that a "clearly-marked law 

enforcement ship of any state may board [a private ship] . . . if 

there is reason to suspect that the ship . . . is without 

nationality" (quoting Restatement (Third) of Foreign Relations Law 

of the United States § 522(2)(b) (1987)) (omissions in original));

United States v. Cortes, 588 F.2d 106, 109 (5th Cir. 1979) (stating 

that, under international law, "stateless vessels are subject to 

this type of examination").49 The question in this appeal, 

addressed in Section V.C infra, is whether international law 

49 The "right of visit" under international law allows a 

"warship" (which would include a law enforcement ship like the 

Coast Guard vessel here) to stop and question a foreign ship if 

"there is reasonable ground for suspecting that the ship is engaged 

in piracy," slave trading, or illegal broadcasting, "is without 

nationality," or, although flying a foreign flag, is actually of 

the same nationality as the warship. UNCLOS art. 110, § 1. 

However, the right of visit does not provide an independent ground 

for exercising jurisdiction over a vessel, and certainly does not 

allow a state to apply its domestic laws to those aboard that 

vessel. Rather, it is simply a mechanism for a state to 

investigate suspected wrongdoing and then take actions within its 

authority under international law. See, e.g., Penelope Mathew, 

Address - Legal Issues Concerning Interception, 17 Geo. Immigr. 

L.J. 221, 224-25 (2003) (discussing the limited nature of the right 

of visit and noting that "a State would have to rely on some 

positive basis of jurisdiction . . . to exercise jurisdiction over 

persons on a stateless ship"). 
- 71 -

permits Congress to dictate the results of such an inquiry as 

provided in § 70502(d)(1)(C) of the MDLEA.

5. Summary: The Felonies Clause and Stateless Vessels

Our review of the law governing jurisdiction on the high 

seas thus reveals clear signs in multiple sources -- the historical 

record, the well-established perspective in the late eighteenth 

century on the role of individual nations in the international 

sphere, and contemporaneous legal precedent -- that the Framers' 

invocation of international law terminology in the Define and 

Punish Clause was deliberate. Seeking to ensure their new nation's 

compliance with international law, the Framers invoked principles 

drawn from that law in drafting the Define and Punish Clause 

generally and the Felonies Clause specifically. In particular, 

they knew the distinction in international law between "Piracies,"

which can be punished by any country wherever they occur, and other 

serious crimes on the high seas, which can be punished by a country 

only when committed by individuals subject to its jurisdiction. 

The Framers' goal of incorporating respect for international norms 

into the federal system thus makes clear that, under the Felonies 

Clause, Congress's authority to set the boundaries of domestic law 

on the high seas must be consistent with international law 

principles. Pursuant to those principles, the key to determining 

whether Congress can apply domestic law to foreign nationals on a 

non-U.S. vessel on the high seas ordinarily will depend on whether 
- 72 -

international law would deem the vessel to be "without nationality"

-- i.e., stateless. Finally, international law recognizes that an 

oral claim by the vessel's master constitutes prima facie proof of 

the vessel's nationality. 

With that understanding of the applicable law, we turn 

to the question of whether Congress exceeded its power to "define 

and punish . . . Felonies committed on the high Seas" in the 

challenged provision of the MDLEA.

C. Constitutionality of § 70502(d)(1)(C)

The MDLEA reflects Congress's objective of addressing, 

to the full extent of its authority, the scourge of drugs entering 

the United States from abroad. See Matos-Luchi, 627 F.3d at 11 

(Lipez, J., dissenting) (noting that the MDLEA and its predecessor, 

the Marijuana on the High Seas Act, Pub. L. No. 96-350, 94 Stat. 

1159 (1980), manifest Congress's objective to "give the Justice 

Department the maximum prosecutorial authority permitted under 

international law" (quoting S. Rep. 96-855, at 2 (1980))); id. at 

7 ("The MDLEA was responding to repeatedly frustrated efforts to 

prosecute maritime drug trafficking."). Undoubtedly mindful of 

the prohibition against applying domestic law to foreigners 

traveling on foreign vessels on the high seas, Congress plainly 

sought in the MDLEA provision defining a stateless vessel to reach 

as broadly as possible through an expansive definition of 

statelessness. The statute, however, can reach no farther than 
- 73 -

the authority granted to Congress by the Felonies Clause, which, 

as we have determined, is constrained by the norms of international 

law.

As detailed above, the MDLEA provides three descriptions

for a "vessel without nationality" in § 70502(d)(1). See 46 U.S.C. 

§ 70502(d)(1).50 Two are clearly consistent with international 

law: when the nation whose registry is claimed denies the claim, 

id. § 70502(d)(1)(A), and when the individual in charge of a vessel 

fails to make a claim of nationality or registry for the vessel 

upon request of an authorized United States officer, id.

§ 70502(d)(1)(B); see, e.g., Matos-Luchi, 627 F.3d at 6 (involving 

50 For convenience, we provide here the full text of 

§ 70502(d)(1):

In this chapter, the term "vessel without nationality" 

includes --

(A) a vessel aboard which the master or 

individual in charge makes a claim of registry 

that is denied by the nation whose registry is 

claimed;

(B) a vessel aboard which the master or 

individual in charge fails, on request of an 

officer of the United States authorized to 

enforce applicable provisions of United States 

law, to make a claim of nationality or 

registry for that vessel; and

(C) a vessel aboard which the master or 

individual in charge makes a claim of registry 

and for which the claimed nation of registry 

does not affirmatively and unequivocally 

assert that the vessel is of its nationality.

46 U.S.C. § 70502(d)(1).
- 74 -

a refusal to make a claim of nationality). The third definition, 

however -- the one at issue here -- allows a vessel to be treated 

as stateless where there is a claim of nationality recognized by

international law but the identified country neither confirms nor 

denies that claim. See 46 U.S.C. § 70502(d)(1)(C).

This provision thus treats a response that reports only 

that the named country is unable to confirm nationality -- or the 

country's failure to respond at all to U.S. inquiry -- as evidence 

that is equivalent to an outright denial of a master's claim of 

nationality or registry. In other words, § 70502(d)(1)(C) 

displaces the prima facie showing of nationality that arises from 

an oral assertion of nationality or registry -- made in accordance 

with international law -- without any affirmative evidence to the 

contrary. See Bustos-Guzman, 685 F.2d at 1280 (referring to the 

"prima facie proof" of nationality that arises from flying a flag); 

The Chiquita, 19 F.2d at 418 (same); 46 U.S.C. § 70502(e) (listing 

flying a flag and a verbal claim as alternative methods of making 

a claim of nationality). In so doing, § 70502(d)(1)(C) adds a new 

category to the limited circumstances in which international law 

deems a vessel stateless (the refusal to claim a nationality,

claiming more than one nationality, and disavowal of a claim of 

nationality by the named country). A response stating only that 

the country is unable to confirm nationality, or the country's 

failure to provide any response, suffices to nullify even an 
- 75 -

unequivocal claim of nationality or registry made by the person in 

charge of the vessel.

The government contends that this variation on deeming 

a vessel stateless is implicitly, if not explicitly, recognized in

international law. The government asserts that international law 

requires a vessel not only to make a claim of nationality, but

also to "'be in a position to provide evidence of [nationality].'"

Appellee's Br. at 29 (quoting Matos-Luchi, 627 F.3d at 6). 

Consequently, the government proposes, an absence of 

"affirmative[] and unequivocal[]" confirmation from the claimed 

country may properly be relied upon in deeming the vessel

stateless. Id. at 36.

In making this assertion, the government relies heavily 

on dicta in Matos-Luchi, a case in which the defendants had 

declined to make a claim of nationality in response to a request 

from Coast Guard personnel. See 627 F.3d at 2.51 As we have 

described, avoiding national identification is a well-established 

basis for deeming a vessel stateless, and it is incorporated into

the MDLEA in § 70502(d)(1)(B). See supra note 50; see also, e.g., 

Meyers, supra, at 322 ("[A] ship which obscures the cognoscibility 

of its allocation repeatedly, deliberately, and successfully may 

51 In Matos-Luchi, when the Coast Guard approached a small 

vessel whose crew members were suspected of drug trafficking, the 

crew initially fled and, when subsequently apprehended, "declined 

to make a claim of nationality" for their vessel. 627 F.3d at 2.
- 76 -

be treated as stateless." (internal quotation marks omitted)). 

However, the Matos-Luchi majority went beyond that indisputable 

basis for deeming a vessel stateless -- and the facts before it -

- to suggest that an oral declaration of nationality is inadequate 

if the vessel's master provides no other evidence of the claimed

nationality. See 627 F.3d at 6. Stated without examination of 

the issue, the majority's dicta, which is not binding on another 

panel, does not support the government's contention that 

international law allows a vessel to be deemed stateless based 

solely on the absence of confirming evidence of the master's verbal 

claim. As the government acknowledges, the MDLEA recognizes "a

verbal claim of nationality or registry by the master" as a "claim 

of nationality or registry" equivalent to flying a flag or 

producing "documents evidencing the vessel's nationality." 46 

U.S.C. § 70502(e). Rejecting a verbal claim of nationality based 

solely on a lack of substantiating evidence effectively negates 

that distinct method for claiming nationality recognized both by 

the MDLEA and by international law. 

The government also directly invokes international law 

to support its position. In its supplemental brief, the government 

cites articles 17(1) and (2) of the United Nations Convention 

against Illicit Traffic in Narcotic Drugs and Psychotropic 

Substances, Dec. 20, 1988, 1582 U.N.T.S. 95 ("UN Narcotics 

Convention"), and article 5(2) of the 1958 Convention on the High 
- 77 -

Seas, supra, in arguing that the United States may deem a vessel 

stateless if neither its master nor the claimed nation 

substantiates a verbal claim of nationality. Neither of these 

sources supports that proposition. The first cited provision of

the UN Narcotics Convention calls for cooperation "to suppress 

illicit traffic by sea, in conformity with the international law 

of the sea," id. art. 17(1), and the second states that a party 

with "reasonable grounds to suspect that a vessel flying its flag 

or not displaying a flag or marks of registry is engaged in illicit 

traffic may request the assistance of other [p]arties in 

suppressing its use for that purpose," id. at 17(2). These 

principles of cooperation do not speak to the circumstances in 

which international law deems a vessel stateless.

The provision of the 1958 Convention on the High Seas

cited by the government provides that "each state shall issue to 

ships to which it has granted the right to fly its flag documents 

to that effect." The UNCLOS contains a nearly identical provision,

see UNCLOS art. 91, § 2, and another UNCLOS provision specifically 

addresses registration, requiring states to "maintain a register 

of ships containing the names and particulars of ships flying its 

flag, except those which are excluded from generally accepted 

international regulations on account of their small size," id.

art. 94, § 2(a). The government suggests that such provisions 

create an expectation that all vessels will carry documents and 
- 78 -

that, if a vessel's master does not substantiate a verbal claim 

with documents or other evidence, the claimed country of 

nationality "has accepted through its international treaty 

obligations that the vessel may be deemed stateless." Appellee's 

Supp. Br. at 16.

However, these treaty provisions demanding that 

countries issue documents evidencing vessel nationality say 

nothing about when a vessel may be deemed stateless. Nor can the

provisions reasonably be construed to provide consent to the 

exercise of jurisdiction over a signatory's vessel by all other 

signatories based solely on the master's failure to produce 

documents in support of a claim of nationality. Indeed, as we 

have noted, consent by the country whose nationality is claimed 

provides a separate basis for jurisdiction under the MDLEA, see 46 

U.S.C. § 70502(c)(1)(C), and the statute specifies that consent 

"may be obtained by radio, telephone, or similar oral or electronic 

means," id. § 70502(c)(2)(A). The government's theory of implicit 

consent is at odds with this scheme.

The government also attempts to infer from treaty 

provisions a principle of international law that when a country 

both fails to confirm a claim of registration or nationality and

the vessel carries no registration or other identifying documents

the vessel may be deemed stateless. This theory conflates two 

discrete international law issues. Even accepting documentation
- 79 -

requirements as within customary international law, it does not 

follow that a country's failure to issue identifying documents or 

"maintain a register" renders a vessel stateless when its master 

has verbally claimed that country's nationality. The relevant 

question is not whether the claimed country has satisfied its 

obligations under international law. Rather, the question is what 

type of inquiry and response suffices to permit the United States

to deem a vessel stateless despite a claim of nationality

recognized by international law. On that question, the government 

cites no source of international law expressly recognizing a lack 

of documents, or the claimed country's failure to confirm 

nationality (instead of an outright denial), as a basis for 

overcoming the prima facie showing of nationality arising from the 

master's oral declaration.

That lack of support for the government's proposition is 

unsurprising. As we have explained, the master's oral declaration 

has long sufficed under international law to establish a 

presumption of nationality. See, e.g., N.P. Ready, Ship 

Registrations 3 (3d ed. 1998) ("A vessel may be considered as 

possessing the nationality of a State even though she is 

unregistered, possesses no documents evidencing that nationality, 

nor even flies the flag of that State."); see also Aybar-Ulloa, 

987 F.3d at 5 (observing that, "[w]ithout a flag or papers, a 

vessel may also traditionally make an oral claim of nationality 
- 80 -

when a proper demand is made" (quoting Matos-Luchi, 627 F.3d at 

5)).52 That presumption is sensibly overcome by the named country's 

express denial of the claim, a scenario long embedded in 

international law.

However, a response stating that the country can neither 

confirm nor deny the claim, or the named country's failure to 

respond at all, may say very little about the veracity of the 

master's assertion of nationality. Indeed, the inability to 

confirm the claim may have more to do with the responding country's 

bureaucracy than with the vessel's status. The facts in United 

States v. Hernandez, 864 F.3d 1292 (11th Cir. 2017), graphically 

illustrate the problem with § 70502(d)(1)(C). The captain of a 

vessel told Coast Guard officers that his boat was registered in 

Guatemala -- a truthful claim -- and he and the other three crew 

52 In addition to the traditional methods of claiming 

nationality discussed above -- flying the flag, presenting

documents, and oral declaration -- authorities may in some 

instances look to the nationality of the vessel's owner. See, 

e.g., The Chiquita, 19 F.2d at 418 ("If [a vessel] is not properly 

registered, her nationality is still that of her owner."). 

However, whether the owner's nationality establishes that of the 

vessel will depend on the practice of the particular country. As 

discussed above, "a State is absolutely independent in framing the 

rules concerning the claim of vessels to its flag." Oppenheim 

(8th ed.), supra, at 595; see also id. (noting that Great Britain 

"allow[s] only such vessels to sail under [Great Britain's] flags 

as are the exclusive property of their citizens or corporations 

established on their territory," while "[o]ther [countries] allow 

vessels which are the property of foreigners" to do so); Churchill 

& Lowe, supra, at 213 n.19 (noting that a country may not register 

small ships but may "regard such ships as having its nationality 

if they are owned by its nationals"). 
- 81 -

members all identified themselves as Guatemalan citizens. Id. at 

1297. Indeed, at some point, Guatemalan registration documents 

were found on the vessel. Id. Nonetheless, when asked by the 

Coast Guard to confirm the registry claim, the government of 

Guatemala responded that it could neither confirm nor deny it. 

Id. Although the vessel plainly was not stateless, the court 

rejected the defendants' challenge to their convictions under the 

MDLEA because Guatemala had not "'affirmatively and unequivocally 

assert[ed]' the ship's registry." Id. at 1299 (quoting 

§ 70502(d)(1)(C)).53 In other words, the vessel was deemed 

53 The defendants in Hernandez contended that jurisdiction 

under the MDLEA was improper because their vessel was in fact 

registered and because the Coast Guard had identifying information 

about their vessel "that would easily have confirmed its registry," 

but "failed in bad faith to convey that information" to the 

Guatemalan government. 864 F.3d at 1299. In rejecting those 

contentions, the court observed that "[t]he MDLEA does not state 

what information the United States must convey to the foreign 

government during its communication, and it does not state that 

actual registry overrides the [Department of State] 

certification's proof of statutory statelessness." Id. "MDLEA 

statelessness," the court explained, "does not turn on actual 

statelessness, but rather on the response of the foreign 

government." Id. The court further observed that, given the 

MDLEA's "clear terms" deeming their vessel stateless, "any 

diplomatic consequences of the criminal prosecution" -- including 

any violation of international law -- were the responsibility of 

the executive branch and not a basis for undoing the convictions. 

864 F.3d at 1297.

One defendant in Hernandez also argued "that the MDLEA is an 

unconstitutional assertion of Congressional power because it 

reaches stateless vessels on the high seas without a proven nexus 

to the United States" -- an argument rejected there as foreclosed 

by Eleventh Circuit precedent. 864 F.3d at 1303. The Hernandez

defendants did not make the argument asserted here that 

§ 70502(d)(1)(C) is unconstitutional because Congress acted beyond 
- 82 -

"stateless" even when verification of its nationality should have 

been easily accomplished. 

Moreover, where -- as in Hernandez and here -- the 

master's oral declaration of nationality is consistent with the 

citizenship or nationality of all individuals aboard the vessel, 

the declaration is particularly forceful. To reject the master's 

declaration of nationality in such circumstances based solely on 

the claimed country's failure to provide affirmative and 

unequivocal confirmation -- or its failure to respond at all --

would eviscerate a method long accepted for identifying a vessel's 

nationality under international law. We cannot infer displacement 

of that method merely based on treaty provisions imposing 

obligations on signatory countries to register vessels or issue 

other documents.54

That is not to say that the government's emphasis on 

registration or documentary evidence of nationality is wholly

misplaced. International law does, in general, promote a system 

its authority under the Felonies Clause in defining a vessel 

without nationality to include a vessel whose master makes a verbal 

claim of nationality that is not affirmatively and unequivocally 

confirmed by the identified country.

54 Importantly, § 70502(d)(1)(C) on its face applies not only 

to verbal claims of nationality, but to any claim of registration 

or nationality, even one based on documentation. By its terms, 

therefore, it allows the United States to reject a claim of 

registration or nationality that is supported by documentary 

evidence based solely on an equivocal response, or no response at 

all, from the identified country. 
- 83 -

of registration.55 It is reasonable to expect that registered 

vessels would have documents onboard, and, if not, that the claimed 

country of nationality would be able to easily confirm a legitimate 

claim by checking its registry. However, not all vessels must be 

registered. Small vessels are excluded from the UNCLOS registry 

requirement, see UNCLOS art. 94, § 2(a), perhaps because some 

countries typically do not register small vessels -- whether 

defined by length or by tonnage. In the United States, for 

example, the registration of smaller boats is generally left to 

individual states. See 46 U.S.C. § 12102(b) (providing that "[a] 

vessel of less than 5 net tons may engage in a trade without being 

55 As we recognized in Aybar-Ulloa, it is important that some

country exercise jurisdiction over a vessel. See 987 F.3d at 5.

A flag state

has several responsibilities [under 

international law], including the 

responsibility to ensure that its ships comply 

with domestic and international law and 

regulations. . . . Most notably, a state 

must exercise "jurisdiction and control [over 

its fleet] in administrative, technical, and 

social matters." Control includes ensuring 

that ships are seaworthy and comply with 

relevant labor regulations and criminal laws.

Allyson Bennett, Note, That Sinking Feeling: Stateless Ships, 

Universal Jurisdiction, and the Drug Trafficking Vessel 

Interdiction Act, 37 Yale J. Int'l L. 433, 439 (2012) (second 

alteration in original) (footnotes omitted) (citing various 

provisions of the UNCLOS); see also Purchase of Ships of 

Belligerents by Neutrals, 6 Op. U.S. Att'y Gen. 638, 640 (1854) 

("The law of nations and common sense combine to require that every 

ship shall have a nationality[.]").
- 84 -

documented"); id. § 12301 (providing that "[a]n undocumented 

vessel equipped with propulsion machinery of any kind shall have 

a number issued by the proper issuing authority in the State in 

which the vessel principally is operated"); see also U.K. Mar. & 

Coastguard Agency, Guidance: Vessel Classification and 

Certification (2018), https://www.gov.uk/guidance/vesselclassification-and-certification#certification-requirements-foruk-vessels (stating that, in the United Kingdom, a certificate of 

registry is optional for "small commercial vessel[s]," defined as 

vessels under 24 meters (roughly 79 feet)); R.R. Churchill & A.V. 

Lowe, The Law of the Sea 213 n.19 (3d ed. 1999) (noting that "a 

State may not require, or permit, the registration of ships below 

a certain size"); Meyers, supra, at 160 ("Many states . . . do not 

issue documents to ships with a tonnage below a given figure.").56 

56 We note that 24 meters (roughly 79 feet) is a cutoff point 

for the applicability of several major international conventions. 

See, e.g., International Convention on Tonnage Measurement of 

Ships art. 4, June 23, 1969, 1291 U.N.T.S. 4 (exempting "ships of 

less than 24 metres (79 feet) in length"); International Convention 

on Load Lines art. 5, Apr. 5, 1966, 9159 U.N.T.S. 134 (same); see

also Gudrun Petursdottir, Olafur Hannibalsson & Jeremy M.M. 

Turner, Part II: International Conventions and Guidelines on 

Safety at Sea, in Safety at Sea as an Integral Part of Fisheries 

Management, Food & Agric. Org. of the United Nations (2001), 

available at https://www.fao.org/3/X9656E/X9656E01.htm (stating 

that recommendations and conventions developed by the 

International Maritime Organization and International Labor 

Organization "are aimed at large vessels, primarily the merchant 

fleet on international voyages" and observing that "[s]ome 

conventions explicitly exempt fishing vessels, and most do not 

apply to vessels under 24m thus leaving out the majority of fishing 

vessels and transport boats in the developing countries"). 
- 85 -

Hence, proof of a vessel's nationality via a centralized registry 

or other evidence of registration may be unavailable, and a country 

whose citizens have properly claimed nationality on behalf of their 

vessels thus may be unable either to confirm or deny those claims

when contacted by the U.S. Coast Guard or other authorities.57

Importantly, we do not suggest that international law 

requires the United States to accept a bare assertion of 

nationality where there is conflicting evidence and attempts to 

resolve the conflict prove fruitless. Although the master's oral 

declaration constitutes prima facie proof of nationality, that 

verbal assertion can be undermined by contrary evidence, as is the 

case for any prima facie showing. For example, if the vessel's

claimed nationality differs from the nationality of most crew 

According to the government, appellants' boat was 35 feet in 

length. See supra note 4.

57 That may be what occurred in this case. The Department of 

State's Certification, which describes the measures taken to 

verify the master's claim of nationality, indicates that, on the 

day the Coast Guard encountered the vessel -- October 29, 2015 --

U.S. officials "requested that the Government of the Republic of 

Costa Rica confirm the registry or nationality of the suspect 

vessel, and, if confirmed, provide disposition instructions." 

Reyes-Valdivia, ECF No. 46-2, at 1 (Mar. 25, 2016) (emphasis 

added). The Certification reports that, nearly three months later, 

"the Government of Costa Rica replied that it could not confirm 

[the] vessel's registry." Id. (emphasis added). Separately, 

although not presented as an issue on appeal, the time lag between 

the defendants' initial detention and Costa Rica's response to the 

verification request strikes us as problematic, given that the 

status of a vessel determines whether U.S. law enforcement 

officials may proceed with prosecuting the crew members under the 

MDLEA.
- 86 -

members, or if a small vessel is interdicted far from the claimed 

country,58 U.S. authorities could properly seek verification of the 

master's claim. In other words, where surrounding facts provide 

legitimate reason to doubt an oral claim of nationality, 

international law would permit the United States to treat the 

vessel as stateless absent the sort of confirmation required by

§ 70502(d)(1)(C). See, e.g., Commander's Handbook (2017), supra, 

¶ 3.11.2.4 (stating that "[a] vessel may be assimilated to a vessel 

without nationality" if, inter alia, there are contradictory or 

inconsistent indicators of nationality).

Put differently, when U.S. authorities are presented 

with mixed signals about the nationality of a vessel, it would be 

permissible under international law for the United States to seek 

confirmation from the country of asserted nationality and, if none 

is forthcoming, to treat the vessel as stateless. As we have 

described, a vessel may be deemed stateless under international 

law both when it "seeks to avoid national identification," MatosLuchi, 627 F.3d at 6, and when it "sails under the flags of two or 

58 The government posits such a scenario, asserting that it 

would be absurd to require countries to accept unconfirmed verbal 

claims of nationality because "[d]rug traffickers . . . could 

falsely claim their vessels are the nationals of a small 

Micronesian island or, more perplexingly, a country like North 

Korea with limited diplomatic contacts." Appellee's Supp. Br. at 

15. We do not disagree. Our analysis permits further inquiry 

when a vessel's master claims a nationality that is at odds with 

surrounding circumstances, including the vessel's location or the 

nationality of the master and crew.
- 87 -

more States," UNCLOS art. 92, § 2 -- two situations that produce 

ambiguity concerning the vessel's nationality.59 International 

law, by inference, likewise permits treating a vessel as stateless 

when its master makes a verbal claim of nationality that is both

unsubstantiated and inconsistent with other relevant indicators of 

the vessel's nationality. As when the master of a vessel avoids

claiming a nationality or when a vessel indicates that it is 

attempting to claim multiple nationalities, conflicting signals of 

nationality create an ambiguity that properly gives rise to inquiry 

and, absent confirmation, permits designation of the vessel as 

"without nationality."60

59 These two circumstances are reflected in the MDLEA's 

provisions addressing vessels without nationality. As we have 

described, § 70502(d)(1)(B) covers the avoidance scenario, 

defining a "vessel without nationality" to include one for which 

the master fails "to make a claim of nationality or registry" upon 

inquiry. The scenario of multiple identities is covered in 

§ 70502(c)(1)(B), which states that a "vessel subject to the 

jurisdiction of the United States" includes "a vessel assimilated 

to a vessel without nationality under paragraph (2) of article 6 

of the 1958 Convention on the High Seas." Paragraph (2) of the 

Convention states: "A ship which sails under the flags of two or 

more States, using them according to convenience, may not claim 

any of the nationalities in question with respect to any other 

State, and may be assimilated to a ship without nationality." 1958 

Convention on the High Seas, supra, art. 6.

60 As described above, the government in its supplemental 

briefing suggests that the circumstances here involved mixed 

signals because, according to a Coast Guard officer's statement, 

Reyes-Valdivia initially stated that the vessel lacked a 

nationality. Although the government noted the reported 

disclaimer of nationality in its Motion in Limine in support of 

jurisdiction, it chose for whatever reason not to include that 

fact in the version of the facts presented at appellants' changeof-plea hearing or in appellants' plea agreements. See supra. 
- 88 -

However, that conflicting-signals limitation is not part 

of § 70502(d)(1)(C) as currently enacted. Rather, as we have 

described, even where the circumstances offer no rationale for 

displacing the prima facie showing of nationality established 

through a verbal claim, § 70502(d)(1)(C) treats a vessel as 

stateless based solely on the named country's failure to respond 

"affirmatively and unequivocally" to U.S. inquiry. The statute on 

its face is thus inconsistent with international law,61 and we have 

no license to rewrite it to satisfy constitutional requirements. 

See Iancu v. Brunetti, 139 S. Ct. 2294, 2301 (2019) (stating that, 

although the Court "may interpret 'ambiguous statutory language' 

Accordingly, as indicated in our discussion of the government's 

Class argument, see Section III supra, it may not rely now on that 

untested fact. Moreover, any attempt to raise a new theory of 

prosecution at this juncture would raise serious due process 

questions.

61 Although the government in its briefing at times depicts 

appellants' claim that § 70502(d)(1)(C) is unconstitutional as an 

as-applied challenge, that characterization is inapt. The 

classification of a vessel as stateless based solely on the named 

country's indecisive response to inquiry, or its failure to 

respond, is a "constitutional flaw evident in the statutory terms 

themselves." Marc E. Isserles, Overcoming Overbreadth: Facial 

Challenges and the Valid Rule Requirement, 48 Am. U.L. Rev. 359, 

365 (1998); cf. Wash. State Grange v. Wash. State Republican Party, 

552 U.S. 442, 449-50 (2008) ("In determining whether a law is 

facially invalid, we must be careful not to go beyond the statute's 

facial requirements and speculate about 'hypothetical' or 

'imaginary' cases."). The mere fact that a cognizable legal 

challenge by necessity concerns the application of a statute to 

individuals does not transform a facial challenge into an asapplied challenge. See generally Richard H. Fallon, Jr., AsApplied and Facial Challenges and Third-Party Standing, 113 Harv. 

L. Rev. 1321 (2000).
- 89 -

to 'avoid serious constitutional doubts,' . . . '[w]e will not 

rewrite a law to conform it to constitutional requirements'" (first 

quoting FCC v. Fox Television Stations, Inc., 556 U.S. 502, 516 

(2009), and then quoting United States v. Stevens, 559 U.S. 460, 

481 (2010))); see also Jennings v. Rodriguez, 138 S. Ct. 830, 843 

(2018) ("Spotting a constitutional issue does not give a court the 

authority to rewrite a statute as it pleases."). It is up to 

Congress to narrow the language of § 70502(d)(1)(C) if it so 

chooses.62

Even the absence of conflicting evidence of nationality, 

however, does not mean that foreign nationals engaged in drug 

trafficking on the high seas can evade prosecution based solely on 

a verbal claim -- whether true or false -- of a vessel's 

nationality. The Coast Guard and other countries' authorities can 

always ask the claimed country of nationality for consent to arrest 

and prosecute the individuals onboard. See 46 U.S.C. 

§ 70502(c)(1)(C) (stating that a "vessel subject to the 

jurisdiction of the United States" includes "a vessel registered 

62 We recognize that the three examples of vessels without 

nationality listed in § 70502(d)(1) are not exclusive, and the 

government might argue in future cases -- as the government 

belatedly argued in this case -- that a vessel may be properly 

deemed without nationality under the MDLEA based solely on mixed 

signals, without the need to make any inquiry of the sort required 

by § 70502(d)(1)(C). We need not, and therefore do not, consider 

the viability of such an argument, including whether reliance on 

a rationale for deeming a vessel without nationality that is not 

expressly described in the MDLEA would raise due process concerns. 
- 90 -

in a foreign nation if that nation has consented or waived 

objection to the enforcement of United States law by the United 

States"); see also, e.g., Cardales-Luna, 632 F.3d at 736 (noting 

that the United States obtained consent from the government of 

Bolivia, which "waived objection to the enforcement of U.S. laws 

by the United States with respect to the vessel . . . , including 

its cargo and all persons onboard" (quoting State Department 

certification)); Matos-Luchi, 627 F.3d at 18 (Lipez, J., 

dissenting) (noting that the government in that case had failed to 

obtain consent from the likely country of nationality, "which could 

have provided a fallback position in the event that the evidence 

of statelessness proved deficient").

Indeed, it is common practice for countries, including 

the United States, to negotiate bilateral and multi-lateral 

agreements to facilitate the apprehension of drug traffickers

operating on the high seas. See, e.g., Casavant, supra, at 205 

(stating that the United States has entered into twenty-seven such 

agreements, including with countries in South America, Central 

America, and the Caribbean, providing a "process by which the two 

[or more] nations can operate to suppress drug trafficking while 

also respecting flag state jurisdiction").63 The United States 

63 As previously noted, the United States relied on such an 

agreement to board appellants' vessel. The State Department's 

Certification reports that "United States law enforcement 

personnel boarded the vessel" "pursuant to Article V of the 
- 91 -

also can address its concerns about maritime drug trafficking by

seeking to persuade other countries to take enforcement action 

against their own vessels and nationals. See generally James 

Kraska, Broken Taillight at Sea: The Peacetime International Law 

of Visit, Board, Search, and Seizure, 16 Ocean & Coastal L.J. 1, 

11 (2010) ("Nowhere is collaboration [among countries] so 

ingrained than in counter-drug operations at sea."). In this 

regard, a 2021 report by the U.S. Department of State noted that 

the Coast Guard of Costa Rica -- the claimed flag-state here --

"is a successful regional partner with the United States for 

maritime interdiction." See U.S. Dep't of State, Bureau of Int'l 

Narcotics & Law Enforcement Affairs, Int'l Narcotics Control 

Strategy Report, Vol. 1, Mar. 2021, at 117; see also id. at 119

("[A] bilateral agreement between the United States and Costa Rica 

is regularly used in maritime drug interdiction operations[.]").

What the United States cannot do consistently with the 

Constitution, however, is arrest and prosecute foreigners on 

foreign vessels by relying on a concept of statelessness that 

conflicts with international law. And that is what

§ 70502(d)(1)(C) allows. It overrides international law by

treating a country's failure to supply an "affirmative[] and 

Agreement between the Government of the United States of America 

and the Government of the Republic of Costa Rica Concerning 

Cooperation to Suppress Illicit Traffic." Reyes-Valdivia, ECF No. 

46-2, at 1 (Mar. 25, 2016).
- 92 -

unequivocal[]" confirmation of nationality -- including a failure 

to respond at all -- as evidence sufficient to invalidate an oral 

claim of foreign nationality even when there are no mixed signals 

that would call the claim into doubt. That is, the MDLEA treats

as stateless a vessel that, under international law, would be a 

vessel with nationality. Accordingly, the prosecution of foreign 

nationals traveling on such a vessel for a violation of U.S. law 

is impermissible under the Felonies Clause of the Constitution, 

the only source of authority asserted for Congress's adoption of 

the MDLEA. See Aybar-Ulloa, 987 F.3d at 4 (referring to 

"Congress's power under Article I '[t]o define and punish Piracies 

and Felonies committed on the high Seas'" (quoting U.S. Const. 

art. 1, § 8, cl.10)); Mitchell-Hunter, 663 F.3d at 49 n.3

(explicitly stating that "[t]he MDLEA is derived from Congress' 

power to 'define and punish Piracies and Felonies committed on the 

high Seas'" (quoting U.S. Const. art. 1, § 8, cl.10)); Cruickshank, 

837 F.3d at 1187 (same).

VI.

The Framers intended international law to be a 

constraint on Congress's authority "[t]o define and punish . . . 

Felonies committed on the high Seas." Two centuries ago, the 

Supreme Court held that Congress lacked authority under the 

Felonies Clause to extend U.S. jurisdiction to felonies committed 

by foreign nationals on foreign vessels. See Furlong, 18 U.S. (5 
- 93 -

Wheat.) at 198; Palmer, 16 U.S. (3 Wheat.) at 632-34. With 

§ 70502(d)(1)(C), Congress violated this principle, extending U.S. 

jurisdiction beyond the limits of international law and, hence,

beyond the authority conferred by the Felonies Clause.

In this case, relying on the authority provided by 

§ 70502(d)(1)(C), the Coast Guard treated a vessel whose master 

made a claim of Costa Rican nationality cognizable under 

international law as a "vessel without nationality." The United 

States government improperly relied on that classification -- in 

violation of constitutional limits -- to arrest and prosecute Costa 

Rican citizens, Reyes-Valdivia and Dávila-Reyes. We therefore 

vacate their convictions and remand the case to the district court 

with instructions to dismiss the MDLEA charges against them.64

So ordered.

-CONCURRING OPINION FOLLOWS64 Because we vacate appellants' convictions based on their 

Felonies Clause argument, we do not reach their due process 

challenges to the MDLEA or Reyes-Valdivia's appeal from the

district court's application of the "captain" sentencing 

enhancement. 
- 94 -

HOWARD, Chief Judge, concurring in the result. As noted 

in the majority opinion, we withdrew our prior panel opinion and 

granted panel rehearing after the en banc court issued its opinion 

in Aybar-Ulloa. In Aybar-Ulloa, the en banc court did not address 

arguments raised by the parties about the protective principle. 

In light of the now uncertain status of our protective principle 

precedent, like my colleagues I am reluctant to unquestioningly 

rely on the protective principle to affirm the convictions 

underlying these appeals. Unlike my colleagues, I would not decide 

these appeals on constitutional grounds. 

I would instead reverse these convictions on the basis 

that the agreed facts do not support the statelessness claim 

charged by the government.65 The government claims the vessel is 

stateless per 46 U.S.C. § 70502(d)(1)(C), which provides that

'vessels without nationality' include: 

65 Although this ground for reversal of the convictions was 

not initially raised in the appeals, the panel was concerned enough 

about the mismatch that we requested that the parties brief the 

issue, and they complied. That the issue was addressed by the 

parties through supplemental briefing may not by itself be reason 

enough for us to bypass appellate waiver -- including not only the 

failure to raise the issue on appeal but also, in the case of 

Dávila-Reyes, the affirmative waiver of appeal contained in the 

plea agreement. But the majority's constitutional analysis 

depends in part on an equivalency between "nationality" and 

"registry" that it finds in § 70502(d)(1)(C). My disagreement 

about whether that equivalency exists is consequential, such that 

it should not be relegated to a dicta detour along the way to 

finding waiver. At this stage of the proceedings, the gap in the 

statelessness determination under § 70502(d)(1)(C) is stark enough 

for me to join the majority, albeit in result only.
- 95 -

a vessel aboard which the master or individual in charge 

makes a claim of registry and for which the claimed 

nation of registry does not affirmatively and 

unequivocally assert that the vessel is of its 

nationality.

The majority asserts that the facts here meet the criteria 

described above in § 70502(d)(1)(C) because § 70502 treats 

"registry" and "nationality" synonymously. But I find no support 

for that observation in the text of § 70502 or in our cases. 

To reach its conclusion that "registry" and 

"nationality" are used interchangeably in the statute, the 

majority argues that interpreting these terms to have independent 

meanings would leave an incongruous hole in statutory coverage; 

how, the majority wonders, could Congress have intended to cover 

a situation in which a master asserts Costa Rican registration, 

but not Costa Rican nationality? 

The answer becomes apparent when we examine the overall 

legal terrain. Section 70502(d)(1) establishes three avenues to 

find statelessness. But this list is not exclusive, and leaves in 

place other ways in which the government can establish lack of

nationality. See United States v. Matos-Luchi, 627 F.3d 1, 4 (1st 

Cir. 2010); id. at 15 (Lipez, J., dissenting) ("As the majority 

correctly holds, Congress did not intend those three examples [in 

§ 70502(d)(1)] to be exhaustive. The MDLEA extends to vessels 

that are considered stateless under international law, even if 

those vessels do not fall within one of the specifically 
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enumerated categories."); see also United States v. Miranda, 780 

F.3d 1185, 1197 (D.C. Cir. 2015) ("[T]he statute contains three 

nonexclusive examples of 'vessels without nationality,' each of 

which turns on the 'registry' of the vessel."); United States v.

Rosero, 42 F.3d 166, 171 (3d Cir. 1994) (Alito, J.). Thus, giving 

meaning to all the terms in § 70502(d)(1) does not immunize vessel 

masters who claim foreign nationality rather than registry.

Here, the master asserted Costa Rican nationality for 

the vessel; at no point did he assert Costa Rican registry. 

Accordingly, by its terms, § 70502(d)(1)(C) is not applicable, nor 

did the government assert an alternative basis for finding 

statelessness when prosecuting appellants. I would reverse the 

convictions on that ground and go no further.