International Judicial Monitor
Published by the International Judicial Academy, Washington, D.C., with assistance from the
American Society of International Law

Spring 2011 Issue

General Principles of International Law

Piracy and the Law of the Seas

Taylor G. StoutBy: Taylor G. Stout, Reporter, International Judicial Monitor

Until recently, piracy was relatively lost to the consciousness of the international community.  The days of bands of thugs roving the seas pillaging and plundering seemed to be a relic of past centuries. Although the scourge of piracy has never been completely eradicated, for decades its existence has been mostly confined to a few isolated parts of the world, and consequently it is a subject that the world community has given little consideration.  But the explosion in acts of piracy committed off the coast of Somalia near the Gulf of Aden has grabbed the world’s attention and reignited discussion of the issue of piracy. The specter of Somali pirates has replaced the popularized, romantic conception of Jolly Roger flags and hidden treasure. 

Piracy is an ancient practice and is perhaps the quintessential violation of international law.  The rise of international exploration and trade beginning in the sixteenth and seventeenth centuries saw the rise of piracy on a grand scale. By the nineteenth century, international law had developed a legal regime to address the threat of piracy.  States viewed piracy as a breach of jus cogens, a fundamental principle of international law adopted by the international community from which no deviation is permissible.  The world community viewed piracy as a crime against humanity.

The law of the seas, a branch of international law, made piracy the first universal crime.  Universal jurisdiction grants any nation the authority to prosecute those who violate certain international law norms, even where the crime, the defendant, and the victim have no connection to the prosecuting country. Pirates represented such a serious threat that the nations of the world branded it a crime that any nation could suppress anywhere in the world.  Universal jurisdiction historically applied only to the crime of piracy, but in modern times it has been extended to crimes against humanity, war crimes, and torture.  The prohibition against piracy developed as customary international law, and the fundamental elements of this customary international law persist today and have become codified in international law. 

The contemporary framework of the law of the seas with respect to piracy is set out in the 1958 Geneva Convention on the High Seas and the 1982 United Nations Convention on the Law of the Sea (UNCLOS). These two conventions generally reflect the customary international law on piracy and recognize the universal jurisdiction of all states to suppress acts of piracy.  The UNCLOS defines piracy as an act of violence, detention, or depredation committed by the crew of one ship against another ship on the high seas, done for private ends. 

States’ geographic sovereignty normally extends 12 nautical miles beyond their coastline.  This zone is known as a state’s territorial sea. Adjoining their territorial waters, states enjoy a 200-nautical-mile exclusive economic zone. Although the customary international law of the seas extended universal jurisdiction over piracy nearly to the coastline of every state, the UNCLOS limits the universal jurisdiction to arrest and prosecute pirates to crimes committed on the “high seas.”  The UNCLOS definition of the “high seas” includes the exclusive economic zone of nation states, but it does not include territorial seas.  Thus, UNCLOS excludes aggressive action by members of one ship against another that occur within 12 miles of a state’s coastline from the definition of piracy.  Where piracy-like acts occur within that 12-mile radius, law enforcement and prosecution is left entirely to the state in whose territorial waters the act occurs.

This limitation on the universal jurisdiction over piracy creates a two-fold problem.  First, most pirate attacks in the world occur within the 12-mile radius of a states’ territorial waters.  Thus, despite the broad jurisdiction over piracy recognized by the international law of the seas, that jurisdiction fails to reach most offenders.  This limitation on the universal jurisdiction over piracy makes little difference in the waters of states capable of policing their territorial seas. But many states are not capable of ensuring the safety of their coastal waters, Somalia perhaps representing the chief example. 

Somali pirates take advantage of this gap in the enforcement of the international law of the seas.  They attack ships in the Gulf of Aden, a narrow seaway through which ships traveling to and from the Suez Canal must pass. Because the gulf is narrow, Somali pirates can attack ships in international waters and then quickly escape to Somali territorial waters, thus avoiding the reach of the universal jurisdiction to interdict and prosecute pirates.  The pirates hijack ships and demand a ransom for their release, often successfully.  Pirate attacks in the Gulf of Aden have skyrocketed, prompting over 20 countries to dispatch naval vessels to patrol the area, in light of Somalia’s inability to assert control over its coastal waters. The effectiveness of these patrols has been limited, however, by the jurisdictional constraints of the international law of the seas.  The patrols have warded off some attacks, but until recent action taken by the United Nations, the patrols could not pursue the pirates into Somali waters.

In response to this state of affairs, the UN Security Council passed several resolutions beginning in 2008. The Security Council passed each of these resolutions under Chapter VII of the UN Charter, which authorizes the Security Council to sanction military force to counter threats to international security.  Resolution 1816, passed in June 2008, extends the universal jurisdiction to arrest pirates to include Somali territorial waters, thus enabling the international naval patrols to pursue pirates into what were previously safe waters for them. The government of Somalia consented to this measure.  In December 2008, the Security Council passed Resolution 1851, which authorized the use of military force in land-based operations in Somalia.  Although the language of the resolution is vague, presumably this resolution also encompasses the authority to use Somali airspace to conduct air raids on pirate strongholds.

These resolutions extend authority to interdict pirates far beyond the authority recognized by the traditional customary international law of the seas. Some nations that have piracy problems fear that the measures taken by the Security Council in Somalia may be used to threaten their sovereignty. But the Security Council has assured the world community that these expansions of legal jurisdiction to apprehend pirates are limited to the Somali situation.  Indeed, the transitional Somali government has welcomed the foreign aid, as it is incapable of policing its own waters.  And, as an additional safeguard, any military action taken in Somali territory must first be approved by the transitional Somali government.

The final issue presented by the surge in piracy and the new measures created to counter it is what to do with captured Somali pirates.  Because of the legal challenges presented by this problem, many patrols simply chase pirates off and purposefully do not capture them.  Others simply release the pirates back to Somalia.  Turning the pirates over to the Somali government for trial has not been considered a realistic option, since Somalia’s government is barely functional.  Great Britain and the United States have experimented with turning the pirates over to third-party countries, such as Kenya, for trial.  But this solution may violate UNCLOS Article 105, which mandates that pirates captured on the high seas must be prosecuted by the capturing state.  The legality of third party prosecutions is unclear because many of the captures take place not on the high seas, but in Somali territorial waters. One alternative source of authority for prosecuting pirates is the Convention for the Suppression of Unlawful Acts Against the Safety of Maritime Navigation (SUA), which gives authority to prosecute pirates that is not subject to the “high seas” limitation of customary international law and the UNCLOS.  But the SUA has rarely been invoked and has not been ratified by Somalia, rendering questionable its use as authority for prosecuting pirates.  The clearly legal solution to this problem is prosecution in the courts of the capturing nations, but nations have so far proven unwilling to transport pirates all the way to domestic courts for trial.  The end result is that although the UN has extended the authority to capture pirates, that authority may not include the authority to prosecute them. 

Although the international efforts to counter the threat of piracy have produced a somewhat disjointed legal response, the international community has proven extraordinarily unified in its resolve to ensure the safety of the seas. With so many new legal questions raised by the issue of piracy, the international law of the seas promises to be a dynamic area of law for the foreseeable future. 


Brownlie, Principles of Public International Law, 6th ed., Oxford University Press 2003.

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with assistance from the American Society of International Law.

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