The Law of the Sea

In one line

The law of the sea divides the ocean into zones measured outward from the coast, and the further out you go the less the coastal State may do.

In the wording a student can write in an exam: the law of the sea is codified in the United Nations Convention on the Law of the Sea 1982, which came into force on 16 November 1994. It divides the sea into internal waters, the territorial sea, the contiguous zone, the exclusive economic zone, the continental shelf, the high seas and the Area, and confers on the coastal State rights that diminish with distance from the coast, from full sovereignty in internal waters to no rights at all on the high seas.

The two competing ideas, and their long argument

Everything in this module descends from a seventeenth-century quarrel, and knowing it makes the modern rules intelligible.

Mare liberum, the free sea. Grotius argued in 1609 that the sea cannot be owned by any nation and must be open to all. He wrote it for Dutch commercial reasons, and it became the freedom of the high seas, dealt with in [The High Seas].

Mare clausum, the closed sea. John Selden replied in 1635 that the sea could be appropriated like land, an argument that suited a State claiming the seas around its coast.

The compromise was distance. The coastal State gets sovereignty near the shore and everybody gets freedom beyond it. Bynkershoek's cannon-shot rule, that control extends as far as a cannon can fire, produced the traditional three-mile territorial sea, and the whole modern law is an elaboration of that compromise, with the line moved steadily outward.

How the Convention came about

Custom first. The law of the sea was customary until the twentieth century, and the great cases of that period, the Fisheries case and the Corfu Channel case, are decisions about customary rules.

The Truman Proclamation of 28 September 1945 is where the modern expansion begins. The United States claimed the natural resources of the continental shelf adjacent to its coast, and within a few years many States had done the same. The North Sea judgment, worked in [Custom], describes it as the starting point of the positive law on the subject.

UNCLOS I, Geneva 1958, produced four conventions: on the territorial sea and the contiguous zone, on the high seas, on fishing and conservation, and on the continental shelf. They codified much and left the breadth of the territorial sea unsettled.

UNCLOS II, Geneva 1960, failed to settle it.

UNCLOS III ran from 1973 to 1982 and produced a single Convention of 320 articles and nine annexes, opened for signature on 10 December 1982 at Montego Bay, Jamaica. It was negotiated as a package deal by consensus, which is why it admits no reservations: article 309 provides that no reservations or exceptions may be made unless expressly permitted by other articles.