On December 10, 2025, the U.S. government boarded and seized the oil tanker, “The Skipper,” in execution of an arrest warrant issued by a federal judge for potential violations of U.S. law. U.S. Coast Guard Forces led the boarding in international waters, with support from both the U.S. Navy and the U.S. Marine Corps. According to reports, the initial boarding revealed that the vessel appeared to be registered in Guyana, a claim Guyana ultimately denied, rendering the ship stateless under international law (see also here and here).
Since September, the U.S. government has heightened its focus on the U.S. Southern Command area of responsibility through a combination of law enforcement and military operations targeting illicit regional maritime activity. This hybrid approach has generated divergent opinions on whether particular actions constitute law enforcement activities or military operations, thereby raising further questions about the applicable legal framework, including the seizure of The Skipper.
The Coast Guard (the United States’s primary maritime law enforcement entity), leading this boarding, pursuant to a federal arrest warrant, undoubtedly makes it a maritime law enforcement engagement. Accordingly, the applicable legal framework for the operation derives from the “peacetime” rules set forth in the United Convention on the Law of the Sea (UNCLOS) and customary international law rather than the laws of armed conflict or the law of naval warfare.
Within the “peacetime” legal framework, the lawfulness of any maritime law enforcement engagement turns on the related concepts of authority and jurisdiction. This article explores those principles under both international and U.S. domestic law, specifically focusing on the law pertinent to the boarding and seizure of The Skipper, especially as similar actions may repeat.
Authority
Authority refers to the legally recognized power or right to act. In international law, it derives from State sovereignty, a foundational principle that affirms a State’s supreme authority within its territory, protects its freedom from external interference, and confers its legal capacity to engage independently in international relations. A State’s exclusive competence to prescribe, enforce, and adjudicate law within its territory and, where international law permits, beyond it, derives from its sovereignty.
States typically exercise sovereign authority through designated actors. This designation is generally affected through domestic legislation that assigns specific powers and responsibilities to certain entities. In the United States, congressional statutes have vested primary maritime law enforcement responsibility in the Coast Guard, granting it broad authority to, “make inquiries, examinations, inspections, searches, seizures, and arrests upon the high seas and waters over which the United States has jurisdiction, for the prevention, detection, and suppression of violations of laws of the United States” (see 14 United States Code (U.S.C.) § 522).
As an armed force, the Coast Guard is unique in that it is the only military service vested with direct law enforcement authority. By contrast, U.S. law generally prohibits the Navy and Marine Corps from direct involvement in civilian law enforcement activities, absent express congressional authorization, reflecting a statutory extension of the principles underlying the Posse Comitatus Act (see 10 U.S.C. § 275). Notwithstanding this restriction, the Navy and the Marine Corps may, and frequently do, provide indirect support to civilian law enforcement entities in accordance with U.S. law and policy. Support includes intelligence sharing, logistics, training, and, depending on the circumstances, operational assistance.
Of note, the Navy and the Coast Guard maintain a long-standing operational partnership in support of the Coast Guard’s maritime counter-narcotics law enforcement mission. That support includes the provision of ships from which Coast Guard Law Enforcement Detachment Teams (LEDETs) operate, maritime domain awareness capabilities, and interception support (see 10 U.S.C. § 279 and here). U.S. courts have further ruled that Naval personnel may accompany Coast Guard boarding teams onto suspect vessels, so long as they act under the Coast Guard command and limit participation to logistical support and backup security (see United States v. Khan, 35 F.3d 426 (9th Cir. 1994)). In sum, while the United States assigns direct maritime law enforcement authority to the Coast Guard, the other armed forces, including the Navy, provide an integral form of indirect support to maritime law enforcement operations at sea.
Jurisdiction: Where and Against Whom May Maritime Enforcement Power be Exercised?
Having established how authority for maritime law enforcement matters is allocated amongst U.S. federal agencies, it is important to understand the concept of jurisdiction, which determines where and against whom the United States may lawfully exercise its maritime enforcement power.
Jurisdiction consists of two interrelated components: prescriptive jurisdiction, which concerns a State’s ability to make laws, and enforcement jurisdiction, which addresses a State’s ability to compel compliance with said laws (see here and here).
Regarding prescriptive jurisdiction, international law recognizes that States may enact (“prescribe”) rules and regulations that govern persons, property, and activities within their sovereign territory and beyond its borders, provided a sufficient nexus to the State’s legitimate interests exists. Many States, including the United States, routinely enact such laws in which the nexus is supported by a variety of internationally recognized factors such as nationality (of the perpetrator or victim), location of the activity, national security, or the effect of the activity on the State’s interest.
A State’s ability to make or “prescribe” laws that apply outside of its territory does not, by itself, necessarily permit a State to take enforcement action for violations of those laws when they occur beyond its borders. For example, in international law, it is fundamental that States must respect each other’s sovereignty. This means that even if a State has a law criminalizing bribery and it applies to its citizens abroad, the State cannot send its law enforcement agents into another country’s territory to make an arrest. Enforcement of such laws across borders typically requires treaties or agreements, such as extradition treaties, that enable cooperation between States.
Applying enforcement jurisdiction to the world’s oceans is a bit more challenging. On land, States clearly define and enforce borders, facilitating the exercise of full sovereignty. By contrast, the oceans lack those natural boundaries, creating vast, interconnected spaces where jurisdictional control by States is less clear. UNCLOS largely resolves these uncertainties through a comprehensive framework that defines maritime zones and the extent of State authority within them. Although the United States has not ratified UNCLOS, it has formally acknowledged that it observes most of its provisions, including those discussed here, as they reflect customary international law.
Exclusive Flag State Jurisdiction
UNLCOS requires all ships operating on the high seas to be registered or “flagged” with a single State. Further, that State of registry then exercises exclusive jurisdiction over the vessel on the high seas, with few exceptions (See UNCLOS Art. 92). Exclusive jurisdiction ensures ships operating on the high seas remain subject to a State authority, thereby avoiding disorder and “complete chaos,” since States have no territorial jurisdiction over those waters.
While ensuring ships are beholden to a single authority on the high seas, exclusive flag State jurisdiction also generally prohibits other States from exercising enforcement jurisdiction on registered/flagged vessels. For example, if a U.S.-registered/flagged vessel were suspected of engaging in illegal fishing while on the high seas, only the U.S., as the flag State, has the authority to conduct maritime enforcement action against that vessel, including boarding, search, arrest, etc., or alternatively to grant permission for another State to do the same.
Despite the term “exclusive,” international law treats flag States’ authority more as a rule of exclusion rather than “true exclusivity” as exceptions to the rule exist. (see UNCLOS Commentary p. 702). Article 110 of UNCLOS, for example, authorizes warships to conduct right of visit boardings on non-sovereign immune foreign vessels (meaning vessels other than warships or those on other government service) without prior flag State consent, if reasonable grounds exist to suspect that the ship is engaged in certain activities.
One qualifying activity is statelessness, meaning the vessel is not registered/flagged with any State. In these circumstances, warship personnel are authorized to board the ship and conduct a limited inquiry/search to determine whether there is any evidence of registration, such as papers or statements from the ship’s master, that identify a State of registration. If evidence is found, the warship will typically follow a standardized diplomatic process to contact the State of claimed registry to verify the claim. If the State denies the registration claim, the vessel is deemed stateless.
International law also deems vessels as stateless if no claim/no evidence of registration is found during the right of visit boarding or if conflicting evidence is found (i.e., visible signs it is registered in State A but claimed to be registered in State B). Once a vessel is deemed stateless, the “jurisdictional impediments” of exclusive flag State jurisdiction are removed (since there is no flag State) (see here and here).
Stateless Vessels
International law clearly establishes the criteria for determining whether a vessel is stateless. It further recognizes that statelessness removes the jurisdictional enforcement barriers associated with exclusive flag State jurisdiction on the high seas. What remains unsettled is whether, and to what extent, any State may exercise enforcement jurisdiction over these vessels (see here). Regarding this issue, treaty law, including UNLCOS, is silent. As a result, one must look at customary international law, i.e., State practice and opinio juris, to determine the applicable rule. State practice, however, is divided.
Some States hold that stateless vessels are subject to the jurisdiction of any State and therefore may be arrested by any State as they “enjoy the protections of none.” Other States believe that statelessness itself does not create such a vast entitlement, only that it removes the barrier of exclusive flag State jurisdiction, allowing other States that have some other jurisdictional nexus to the vessel, such as the citizenship of the people onboard, the citizenship of the vessel owners, etc., to have enforcement options. Because States continue to adhere to each of these competing views, international law has not developed a uniform rule for this issue. So long as the rule remains unsettled, both options remain legally supportable under international law.
The United States has long maintained that a vessel’s statelessness subjects it to the jurisdiction of any State and routinely enforces U.S. law against such vessels, particularly in cases involving the Maritime Drug Law Enforcement Act and Drug Trafficking Vessel Interdiction Act (see NWP 1-14M (2022) para 3.11.2.3, and here). This position is well articulated in U.S. case law, where one opinion held that,
“Vessels without nationality are international pariahs. They have no internationally recognized right to navigate freely on the high seas. Moreover, flagless vessels are frequently not subject to the laws of a flag-state. As such, they represent ‘floating sanctuaries from authority’ and constitute a potential threat to the order and stability of navigation on the high seas” (see U.S. vs. Marino-Garcia, 679 F.2d 1379 (11th Cir. 1982)).
The effect of this approach is not without legal significance. Adopting this approach, any State may treat a stateless vessel as if the ship were one of its own (meaning the same as if it were registered/flagged in the United States), thereby permitting that State to assert complete enforcement jurisdiction over that vessel, to include holding it accountable for violations of the interdicting State’s domestic law. Accordingly, this includes seizing a stateless vessel on the high seas, including pursuant to a court-authorized arrest warrant, for alleged breaches of the interdicting States’ domestic law.
Concluding Thoughts
U.S. maritime law enforcement operations rest on a long-standing and well-developed legal framework grounded in principles of authority and jurisdiction, designed to preserve order at sea. The U.S. Coast Guard has broad authority to conduct these operations, including on the high seas, for violations of U.S. law – so long as they are executed in a manner consistent with international law. While stateless vessels occupy a unique position within the international legal framework, certainly the seizure of a stateless ship on the high seas for alleged violations of U.S. law is consistent with international law and the United States’ long-standing position and practice regarding the treatment of stateless vessels on the high seas as subject to complete U.S. enforcement jurisdiction.
