Law of the Sea

The United Nations Convention on the Law of the Sea (UNCLOS) is the international agreement that resulted from the third United Nations Conference on the Law of the Sea, which took place between 1973 and 1982. UNCLOS defines the rights and responsibilities of nations in their use of the world's oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources. The Convention concluded in 1982 replaced four 1958 treaties. UNCLOS came into force in 1994, and to date 155 countries and the European Community have joined in the Convention. The United States has signed the treaty, but the Senate has not ratified it.

The UN has no direct operational role in the implementation of the Convention. However there is a role played by UN organizations such as the International Maritime Organization, the International Whaling Commission, and the International Seabed Authority.

The convention set the limit of various areas, measured from a carefully defined baseline. (Normally, a sea baseline follows the low-water line, but when the coastline is deeply indented, has fringing islands or is highly unstable, straight baselines may be used.) The areas are as follows:

Internal waters
Covers all water and waterways on the landward side of the baseline. The coastal state is free to set laws, regulate use, and use any resource. Foreign vessels have no right of passage within internal waters.

Territorial waters
Out to 12 nautical miles from the baseline, the coastal state is free to set laws, regulate use, and use any resource. Vessels were given the right of "innocent passage" through any territorial waters, with strategic straits allowing the passage of military craft as "transit passage", in that naval vessels are allowed to maintain postures that would be illegal in territorial waters. "Innocent passage" is defined by the convention as passing through waters in an expeditious and continuous manner, which is not “prejudicial to the peace, good order or the security” of the coastal state. Fishing, polluting, weapons practice, and spying are not “innocent", and submarines and other underwater vehicles are required to navigate on the surface and to show their flag. Nations can also temporarily suspend innocent passage in specific areas of their territorial seas, if doing so is essential for the protection of its security.

Archipelagic waters
The convention set the definition of Archipelagic States in Part IV, which also defines how the state can draw its territorial borders. A baseline is drawn between the outermost points of the outermost islands, subject to these points being sufficiently close to one another. All waters inside this baseline will be Archipelagic Waters and included as part of the state's territorial waters.

Contiguous zone
Beyond the 12 nautical mile limit there was a further 12 nautical miles or 24 nautical miles from the territorial sea baselines limit, the contiguous zone, in which a state could continue to enforce laws regarding activities such as smuggling or illegal immigration.

Exclusive economic zones (EEZs)
Extend 200 nautical miles from the baseline. Within this area, the coastal nation has sole exploitation rights over all natural resources. The EEZs were introduced to halt the increasingly heated clashes over fishing rights, although oil was also becoming important. The success of an offshore oil platform in the Gulf of Mexico in 1947 was soon repeated elsewhere in the world, and by 1970 it was technically feasible to operate in waters 4000 metres deep. Foreign nations have the freedom of navigation and overflight, subject to the regulation of the coastal states. Foreign states may also lay submarine pipes and cables.

Continental shelf
The continental shelf is defined as the natural prolongation of the land territory to the continental margin’s outer edge, or 200 nautical miles from the coastal state’s baseline, whichever is greater. State’s continental shelf may exceed 200 nautical miles until the natural prolongation ends, but it may never exceed 350 nautical miles, or 100 nautical miles beyond 2,500 meter isobath, which is a line connecting the depth of 2,500 meters. States have the right to harvest mineral and non-living material in the subsoil of its continental shelf, to the exclusion of others.

Aside from its provisions defining ocean boundaries, the convention establishes general obligations for safeguarding the marine environment and protecting freedom of scientific research on the high seas, and also creates an innovative legal regime for controlling mineral resource exploitation in deep seabed areas beyond national jurisdiction, through an International Seabed Authority.