This primer is intended to provide policy makers, the military, and other interested persons with an introduction to the basic principles of the law of the sea as they affect U.S. security, commercial, and scientific interests. To do so, it focuses on key elements of the law of the sea that touch on those interests, including provisions of the United Nations Convention of the Law of the Sea (LOSC), a highly detailed and comprehensive treaty that has been signed by 168 parties. While the U.S. is not a party to the LOSC, it takes the view that with limited exceptions the Convention reflects the rules of customary international law. The U.S. actively seeks the observance of those rules by all States.

The law of the sea forms the basis for the conduct of maritime commerce critical to our economy; codifies the rules of freedom of navigation that are essential to national security; and enables the U.S. to conserve, regulate, and exploit the resources of our neighboring waters and continental shelf for the benefit of the environment and economy. America’s commercial and military position in the world is preserved by the rule of law at sea.

This primer outlines the key maritime zones agreed to in the LOSC, ranging from internal waters controlled by individual sovereign States to the high seas where all States enjoy unhindered freedom of navigation. That discussion underscores a central tenet of the law of the sea, which is the fair balancing of the desire by coastal States to protect their sovereign rights and to conserve and exploit natural resources of neighboring waters with the desire of maritime States to freely navigate the world’s oceans in pursuit of their own economic and security interests. As a country with significant coastal resources and as the world’s leading naval power, the U.S. has an abiding interest in both aspects of that balance.

The primer also discusses how the law of the sea works to protect the oceans from abuse, whether as a space for illegal activities which threaten peace and security such as piracy, human trafficking, or smuggling components of weapons of mass destruction; degradation through environmental abuse and pollution as a result of avoidable disasters like the Exxon Valdez spill; or deliberate and destructive State conduct like the construction of artificial islands by China in the South China Sea (SCS).

The law of the sea also embodies certain key underlying legal concepts, including:

  • Sovereign immunity, protecting warships and other government vessels and aircraft from search and seizure by foreign States without permission.
  • Environmental and safety regimes that allocate responsibility among the flag States with which vessels are registered, the coastal States that they transit, and the port States that they visit.
  • A systematic and flexible regime of dispute resolution intended to facilitate the peaceful settlement of disputes while providing compulsory dispute resolution when parties are unable to reach agreement on their own.

The primer summarizes each of these concepts in the maritime context.

The primer specifically looks at the application of the law of the sea in certain contexts that raise current and pressing policy questions. For example:

  • It discusses the 2016 arbitration regarding the SCS, which denied Chinese claims of broad rights in the sea, found China responsible for violations of applicable environmental and safety regulations, and made important determinations regarding maritime features and zones in the region.
  • It reviews the law relating to critical waterways like the Strait of Hormuz, where the free conduct of international commerce and normal naval operations are subject to the threat of illegal interference by coastal States.
  • It discusses important issues governed by the law of the sea in the Arctic, as reduction in the size of the polar icecap increases the level of commerce in the region and opens up the opportunity to exploit energy and mineral resources which until now have been inaccessible.

Finally, the primer addresses key questions concerning the U.S. and law of the sea, including the considerations surrounding why the U.S. has declined to ratify the LOSC, the position currently taken by the U.S. on the applicability of the LOSC as the embodiment of customary international law regarding most issues relating to law of the sea, and the policy arguments, pro and con, concerning ratification.

The legal principles described in this primer raise issues that must be addressed on an ongoing basis by policy makers, sometimes in familiar contexts and at other times arising out of new and unanticipated developments. The law of the sea is not static, and its core principles remain under recurring risk of erosion by contrary State practices. From the challenges to freedom of navigation through vital chokepoints like the Straits of Malacca and Hormuz, to the preservation of critical fishing stocks, to China’s ongoing efforts to limit freedom of navigation in the SCS, the application of the law of the sea to preserve U.S. interests will remain a pressing national priority. This primer is intended to aid those who are charged with that critical responsibility.

A few background notes regarding this primer follow:

The United Nations Convention on the Law of the Sea is referred to throughout as either the LOSC or the Convention. The full text is available here.

Countries are referred to as States within the text of the LOSC and this primer.

A nautical mile is defined as 1852 meters (6,076 feet), or about 15% greater than a regular mile. (A nautical mile historically represented one minute (1/60 of a degree) of latitude at the Equator.)

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