What Makes a Pirate? Updating U.S. Piracy Law to Address an Age-Old Scourge

The “golden age” of piracy may have ended in the 17th century, but the scourge continues to the present day from the Red and Somali seas to the Gulf of Guinea, wreaking havoc on the global economy, amassing an unspeakable human toll, fueling and financing terrorism and other crimes, and triggering a cascade of increasingly alarming activity. In February 2024, the U.S. State Department issued a statement condemning recent missile and drone attacks by Houthi rebels on ships in the Red Sea from Houthi-controlled territory as “piracy”; however, it is unclear which definition of piracy the department invoked. In fact, as the latest report of the Special Rapporteur at the International Law Commission of the UN on Prevention and Repression of Piracy and Armed Robbery at Sea (Special Rapporteur) highlights, it is unclear whether the rebels’ conduct could be construed as piracy at all. Countries and the polities that came before them have coordinated efforts to fight piracy since as early as 1400, viewing pirates as hostis humani generis, or “enemy of all mankind.” In 1982, modern nation-states etched their commitments to cooperate in ending piracy into the proverbial stone. Today, 169 parties have ratified the United Nations Convention on the Law of the Sea (UNCLOS) and its Article 101, defining piracy. The United States, however, is not one of them.

Nevertheless, the U.S. largely abides by UNCLOS’s terms, considering it representative of customary international law, and is party to the 1958 Convention on the High Seas (HSC), the language of which regarding piracy was largely retained in UNCLOS. The U.S. Congress, empowered by the express authority to define “piracies” under Article I, § 8, cl.10 of the U.S. Constitution, has also provided for both criminal penalties and civil remedies for piracy by reference to the “law of nations.” U.S courts have sought to elucidate the phrase since 1820, with the recent trend in the circuit courts being to adopt UNCLOS’s definition of piracy, treating it as emblematic of current customary international law. Unfortunately, lower court judicial interpretations only go so far. As a result, U.S. piracy law has remained frozen in time since its enactment and, while certain circuit courts may seek to chart their own path, disunity and confusion due to the lack of judicial and legislative updating at the highest levels may nevertheless hinder the dispensation of justice. Furthermore, independent action by circuit courts does nothing to bring U.S. piracy law into greater accord with piracy jure gentium—or to keep courts from circumnavigating its limitations.

Considering the continued threat piracy poses today and the shared responsibilities of countries to repress it, two affirmative domestic actions are required to properly empower U.S. courts, prosecutors, and litigants to enforce U.S. law and support the country’s customary and treaty law commitments to curbing piracy. First, should the opportunity present itself, the Supreme Court should grant cert to unequivocally overrule the assertion in United States v. Smith, the canonical U.S. piracy case, that the U.S. crime of piracy, as defined by the “law of nations,” requires robbery on the high seas. Second, shy of ratifying UNCLOS, Congress should amend current criminal piracy law under 18 U.S.C. § 1651 to clarify what is encompassed by the “law of nations,” address inconsistencies between U.S. and international piracy law, and logically connect the statute with other relevant parts of the U.S. Code.

The Historical Development of U.S. Piracy Law

In a testament to the significance of piracy—in terms of both its parasitic effects and its symbolism of federal power—at the time of the United States’s founding, the framers of the U.S. Constitution elected to include the authority to “define and punish Piracies and Felonies committed on the High Seas, and Offences against the Law of Nations” as one of Congress’s enumerated powers. Under that authority, Congress passed legislation criminalizing piracy in 1790. However, shortly after the Supreme Court ruled in United States v. Palmer that, because the 1790 legislation criminalized only “offenses against the United States, not offenses against the human race,” it did not confer universal jurisdiction in cases of piracy. Congress thus enacted new legislation in 1819 making its desire to punish piracy as a universal jurisdiction crime clear, providing that whoever “on the high seas, commit[s] the crime of piracy, as defined by the law of nations” and is thereafter in the United States, is to be punished by death. Much of that language has been retained to the present day in § 1651, although the penalty is now life in prison.

The Supreme Court had the chance to interpret the 1819 legislation shortly after its enactment in a series of piracy cases, the most significant of which being Smith. In his majority opinion, Justice Joseph Story made three major determinations for the purposes of U.S. piracy jurisprudence. First, the Constitution does not require Congress to provide a detailed enumeration when defining piracy—rather, a “reference to crimes having a technical name” suffices. Second, “the crime of piracy is defined by the law of nations,” particularly customary international law, “with reasonable clarity.” And third, piracy, under the (customary) law of nations, requires a robbery, or forcible depredation, animo furandi, on the high seas. That conception of piracy—rooted in an early 19th century understanding of piracy jure gentium—has not been overturned, even though other countries have since rejected that notion. For example, in In Re Piracy Jure Gentium, England’s Privy Council expressly rejected the Supreme Court’s approach in Smith in 1934, finding that “[a]ctual robbery is not an essential element in the crime of piracy jure gentium” because “international law has not become a crystallized code at any time, but is a living and expanding branch of the law.” The Smith-ian definition of piracy has also endured despite the overwhelming majority of nations having accepted the broader definition of piracy articulated in UNCLOS Article 101:

Piracy consists of any of the following acts:

(a) any illegal acts of violence or detention, or any act of depredation, committed for private ends by the crew or the passengers of a private ship or a private aircraft, and directed:

(i) on the high seas, against another ship or aircraft, or against persons or property on board such ship or aircraft;

(ii) against a ship, aircraft, persons or property in a place outside the jurisdiction of any State;

(b) any act of voluntary participation in the operation of a ship or of an aircraft with knowledge of facts making it a pirate ship or aircraft;

(c) any act of inciting or of intentionally facilitating an act described in subparagraph (a) or (b).

Before discussing current trends in the lower courts in the absence of Supreme Court action, it is also worth noting that Congress, in the early years of the republic, adopted additional legislation—28 U.S.C. § 1350, or the Alien Tort Statute (ATS)—granting district courts jurisdiction over civil actions brought by noncitizens for “violation[s] of the law of nations or a [U.S.] treaty.” Such violations, for the purposes of the ATS, were interpreted by the Court in Sosa v. Alvarez-Machain to include “offenses against ambassadors, violation of safe conducts, and piracy,” reaffirming the approach of defining piracy in the U.S. legal context with specific reference to and regard for international law. There, however, the Court did leave the door slightly ajar for district courts to recognize claims, “based on the present-day law of nations” that were sufficiently compatible to the three aforementioned recognized offenses.

To date, the Supreme Court has only in dicta nodded toward the view that “a general reference to ‘the crime of piracy as defined by the law of nations’ incorporates a definition of piracy ‘that changes with advancements in the law of nations’” and has refused to grant cert in several cases that provided the opportunity to clearly put U.S. jurisprudence in line with contemporary international piracy law. Nevertheless, circuit courts have charged forward, deciding for themselves that Smith is an anachronism and interpreting “law of nations” in §§ 1651 and 1350 to evolve with changes to international law, including in custom. The Fourth Circuit has led the way, articulating its newfangled approach to piracy under § 1651 most clearly in a pair of cases in the early 2010s.

The first of these cases, United States v. Dire, which was decided in 2012, involved the conviction of Somali nationals for the act of piracy committed on the high seas against the U.S.S. Nicholas. On appeal, the Somalis argued that they could not be convicted of piracy under § 1651 because the crime had been narrowly construed for the purposes of § 1651 to require robbery at sea—and they had merely fired at the Nicholas. The U.S. Court of Appeals for the Fourth Circuit rejected this argument and affirmed the district court’s reasoning, finding that the attack was covered by a definition of piracy under the law of nations that “had for decades encompassed [such] violent conduct.” The court specially endorsed the district court’s application of UNCLOS’s definition of piracy as customary international law and went on to cite a United Nations Security Council (of which the United States is a permanent member) resolution concerning piracy around Somalia that reaffirmed UNCLOS as setting out the relevant legal framework for combating piracy at sea.

The second case, United States v. Said, decided in 2015, pertained to the prosecution of a different group of Somali nationals for piracy committed against the U.S.S. Ashland. Although the defendants were convicted of, inter alia, piracy under § 1651, the district court judge declined to impose the statutorily mandated life sentences, believing that it would contravene the Eighth Amendment. Both parties appealed, the government on the issue of sentencing and the defendants on their convictions. The U.S. Court of Appeals for the Fourth Circuit, drawing on its recent reasoning in Dire, rejected the defendants’ claims “that the meaning of piracy for purposes of § 1651 ‘was fixed in the early Nineteenth Century,’” and found that piracy has, for decades, been defined by the law of nations in accordance with the HSC and UNCLOS. In so doing, the court affirmed the various convictions, vacating the defendants’ sentences and remanding them for resentencing.

While Dire and Said are likely the most notable piracy cases to come out of the Fourth Circuit in the past decade and a half, they are not the only ones. Indeed, the court has turned to UNCLOS in the two other piracy cases it has decided in recent years. In United States v. Beyle, the court employed UNCLOS’s definitions of the high seas and exclusive economic zone (EEZ) to find that an alleged crime of piracy occurring “thirty to forty nautical miles off [Somalia’s] coast” was not within the country’s territorial sea. And its opinion in United States v. Shibin relied heavily on an interpretation of UNCLOS Article 101(c) to find that piracy includes aiding and abetting for § 1651 purposes.

The Fourth Circuit, however, has not been alone. In United States v. Ali, for example, the U.S. Court of Appeals for the D.C. Circuit relied on UNCLOS’s definition of piracy to determine that, although conspiracy to commit piracy is not encompassed by the “law of nations” under § 1651, aiding and abetting the crime of piracy is. The court thus reversed the defendant’s conviction on the charge of the former but affirmed the latter. In so doing, the court rejected the argument that it should ignore UNCLOS’s definition in favor of the limited one provided by the HSC and the scholarship on which it was modeled. It also reaffirmed the notion that piracy “is no ordinary offense” and that pirates remain hostis humani generis.

Unfortunately, the court used traditional American tools of statutory interpretation to reason that because the geographic limitation “on the high seas” (or the EEZ) in UNCLOS Article 101(a) is not repeated in Article 101(c) (regarding inciting or intentionally facilitating an act of piracy), the latter is not likewise territorially circumscribed. However learned the court’s decision to bring U.S. piracy law into the 21st (or, at the very least, 20th) century by referencing UNCLOS for a definition of piracy jure gentium may be, such a reading of the convention appears in contravention with the zone-based regime UNCLOS establishes.

What’s more, the U.S. Court of Appeals for the Ninth Circuit provides a helpful illustration of the interpretation of the ATS in the context of piracy. In Institute of Cetacean Research v. Sea Shepherd Conservation Society, the court, expressly following Dire’s logic, relied on UNCLOS’s definition of piracy to interpret the crime of piracy under the “law of nations” for the purposes of the ATS. In doing so, it found that UNCLOS’s articulation of piracy as illegal acts of, inter alia, violence directed against another ship on the high seas in pursuit of private ends was broad enough to cover the anti-whaling protest conduct of the Sea Shepherd (that is, “[r]amming ships, fouling propellers and hurling fiery and acid-filled projectiles”) toward a Japanese whale research ship. The court concluded that “private ends” under UNCLOS “include those pursued on personal, moral or philosophical grounds, such as Sea Shepherd’s professed environmental goals.” Interestingly, the court reached its conclusion through a mixture of both traditional American tools of statutory interpretation and reference to international jurisprudence, citing Castle John v. NV Mabeco, a 1986 Belgian case wherein environmental activism was deemed to qualify being toward private ends. Five years prior, the court, in United States v. Shi, ruled that violations of 18 U.S.C. § 2280, which codifies U.S. obligations under the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (SUA), constituted piracy—in seeming contravention with current international legal understandings, as discussed below—and thus that U.S. courts had universal jurisdiction over such offenses.

These paradigmatic decisions across three circuits demonstrate how lower courts have chosen for themselves to abandon the Smith-ian interpretation of piracy under the “law of nations,” construing it instead to encompass modern international legal understandings of the crime—most prominently those articulated in UNCLOS, which they treat as customary international law. Nevertheless, without clear direction from either the Supreme Court or Congress regarding the scope of § 1651 and what constitutes “piracy as defined by the law of nations,” the courts are left without any protective guardrails to keep them from grievously misinterpreting international piracy law, as in Ali, or from going in a diametrically opposed direction by following the only Supreme Court precedent on the books, leaving district courts to fend for themselves and opening the possibility of a circuit split. Furthermore, the actions of a few circuit courts do nothing to remedy the fact that § 1651 is itself in tension with UNCLOS, since the statute appears to restrict “piracy as defined by the law of nations” to the high seas and the high seas alone—without regard for UNCLOS’s EEZ regime as applied to piracy. That additional limitation matters because of the importance of domestic law in international efforts to repress piracy.

Why Definitions of Piracy Matter

Although the definition of piracy in UNCLOS Article 101 is certainly broader than that conceived of in Smith, it is ascribed strict limitations in order to afford respect for countries’ delimited jurisdictional zones as part of UNCLOS’s “package deal” and part of a larger international architecture promoting safety at sea. As defined by UNCLOS, piracy is any illegal act of violence, detention or depredation committed on the high seas (or EEZ or “in a place outside the jurisdiction of any State”) for private ends by a private ship/aircraft directed against another ship/aircraft. States only have universal jurisdiction over acts constituting piracy so defined. The practical implications of these constraints were brought to bear by the 1985 Achille Lauro incident, a hijacking and hostage taking by members of the Palestine Liberation Front against an Italian cruise vessel. The International Maritime Organization (IMO) responded to the incident, which failed to meet Article 101’s two-ship requirement, by ultimately adopting SUA in 1988, which was expanded in 2005 to include terrorism-related offenses. SUA essentially includes unlawful acts other than piracy (as defined in UNCLOS) committed on/by ships navigating to/from the high seas—including in the territorial sea—and is subject to neither a two-ship nor private-means requirement.

According to the IMO, SUA encompasses universal jurisdiction through Article 6(4)—a view the United States seems to have affirmed and that is reflected in § 2280(b)(1)(C). The IMO also issued a Code of Practice for the Investigation of the Crimes of Piracy and Armed Robbery against Ships first in 2002, and then in 2009, against the backdrop of increasing piracy worldwide to fill the gap left by UNCLOS and SUA. The code provides that acts that would otherwise be piracy but for occurring in a state’s internal waters, archipelagic waters, or territorial sea are “armed robbery against ships” and are not subject to universal jurisdiction (but rather likely enveloped by UNCLOS Article 27, which lays out the regime’s approach to criminal jurisdiction on board a foreign ship).

These jurisdictional limitations are highly salient today, as, according to the Special Rapporteur:

[I]t is clear that piracy can no longer be confined to defined geographical limits of the sea, since pirates are moving from the high seas to the coasts and are operating in the internal waters and in the territorial seas of coastal States, committing criminal acts that are in all respects similar to acts of maritime piracy as defined in article 101.

As such, domestic laws play a critical role in global efforts against piracy under the UNCLOS regime. States have the discretionary power to prosecute alleged pirates, “decide upon the penalties to be imposed, and … determine the action to be taken with regard to the ships, aircraft or property” seized. Additionally, some leading scholarship, including the influential Virginia Commentary, suggests that what constitutes “illegal acts” for Article 101 purposes “is determined by the courts of the State which seizes a pirate ship or aircraft.” Domestic laws may also broaden definitions of municipal crimes of piracy—and associated penalties—to encompass a wider array of acts, including those covered under international law by SUA rather than UNCLOS. Nevertheless, to remain faithful to the “law of nations” in the context of piracy, states must observe its limitations and understand how all its aforementioned pieces fit together.

It is also worth noting that, in the U.S. context, Chapter 81 of Title 18, where § 1615 is found, includes separate statutes covering specific acts that constitute piracy under U.S. law, which may today also fall under UNCLOS’s definition; however, the crimes enumerated therein carry much lower penalties. For example, the crime of “attack to plunder a vessel” under § 1659 carries a sentence of only a fine, a maximum 10 years’ imprisonment, or both, compared with § 1651’s penalty of life imprisonment. As such, defining an action as “the crime of piracy as defined by the law of nations” is a kind of sentencing enhancement, not unlike identifying an action as “transcending national boundaries” under 18 U.S.C. § 2332b in the terrorism space. As the Dire court explained, it was necessary to have distinct provisions for piracy jure gentium and municipal piracy because of the far-reaching consequences of universal jurisdiction. Referencing language from Dole v. New England Mutual Marine Insurance Co., an 1864 case from the then-Circuit Court for the District of Massachusetts, the Dire court reasoned that, while municipal piracy could be flexible, covering nearly any act Congress defines as piracy, the prosecution of those acts turns on whether they “‘have a jurisdictional nexus with the United States.’” By contrast, because piracy under the law of nations is a crime of universal jurisdiction created by international consensus, it must be “restricted in substance to those offenses that the international community agrees constitute piracy.” Indeed, in debating the Define and Punish Clause at the Constitutional Convention, James Madison observed: “There is a general power to provide courts to try felonies and piracies committed on the high seas—Piracy is a word which may be considered as a term of the law of nations—Felony is a word unknown to the law of nations.”

Recommendations for Defining Piracy

Amending § 1651 in 1948 in “light of far-reaching developments in … international law and foreign relations,” Congress lamented that its updates were confined to “some obvious and patent corrections,” recommending “that at some opportune time in the near future, the subject of piracy be entirely reconsidered and the law bearing on it modified and restated in accordance with the needs of the times.” Considering the introductory situation regarding Houthi rebels, perhaps that time is now. The International Chamber of Commerce’s International Maritime Bureau recorded 33 incidents of piracy and armed robbery against ships in the first three months of 2024, with increasing concerns regarding the possible resurgence of Somali piracy. The Maritime Administration of the U.S. Department of Transportation also currently lists three active U.S. Maritime Advisories regarding piracy. Furthermore, according to the Special Rapporteur:  “[h]igh seas piracy is … turning into coastal piracy,” moving increasingly toward coastlines and “being committed in ports and their approaches.”

These trends in conjunction with the aforementioned challenges regarding both current U.S. court interpretations of piracy and UNCLOS’s definition create a necessary impulse to bring U.S. piracy law into the modern age and ensure its effective application, requiring action from both the Supreme Court and Congress. Regarding the former, the Supreme Court should grant cert to the next case it considers regarding the definition of “the law of nations” vis-a-vis piracy and overrule Smith’s limited conception of piracy jure gentium as requiring robbery in favor of one affirming UNCLOS’s broadening conceptualization as the accurate modern-day definition, under customary international law.

As for the legislature, notwithstanding Justice Story’s finding in Smith, Congress should undertake a series of amendments to § 1651, exercising its full constitutional powers to provide greater guidance to courts and litigants in an area of international law that has evolved greatly (and continues to) since the statute’s initial enactment. First, considering the above-mentioned rationales for separate provisions for piracy jure gentium and municipal piracy, Congress should maintain the language of “the law of nations” but add language encompassing both the high seas and EEZ to match the jurisdictional reach of piracy under UNCLOS and keep courts in line with its limitations as customary international law. Doing so will also make the distinction between § 1651 and the municipal piracy provisions in Chapter 81 clearer to both the prosecutors enforcing and the courts adjudicating them.

Second, Congress should explicitly clarify that the interpretation of “law of nations” in the context of piracy is to evolve as the law itself changes. Congress can also connect § 1651 with other relevant statutes by express mention. This should include § 1315, demonstrating its intent to incorporate updates regarding piracy under the “law of nations” into that statue’s own “law of nations” phrase. Congress  should also clarify § 1651’s relationship with § 2280 to elucidate § 1651’s limits for courts and litigants, making sure they remain faithful to the modern architecture of piracy jure gentium described in Part II and promoting greater utilization of SUA to combat all the navigational security threats that fall within its regime and that might otherwise be technically misconstrued as “piracy.” What’s more, recognizing current trends of where piratical acts are occurring, Congress can add a subsection to § 1651 recognizing the separate crime of armed robbery against ships as defined by the IMO but affirm its significance notwithstanding its non-universal jurisdiction status by, for example, applying the same punishment as for traditional piracy jure gentium. These amendments will not only bring U.S. piracy law in line with contemporary international understandings of piracy but also bolster the country’s contributions to global efforts to repress piracy by providing greater guidance to courts and litigants and accounting for changes in modern pirates’ modus operandi or methods.