The Continental Shelf

In one line

The continental shelf is the seabed beyond the territorial sea, and the coastal State's rights over it exist automatically, without claim or occupation.

In the wording a student can write in an exam: under article 76 of the Convention on the Law of the Sea the continental shelf of a coastal State comprises the seabed and subsoil of the submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of two hundred nautical miles from the baselines where the outer edge of the margin does not extend that far. Under article 77 the coastal State exercises over the shelf sovereign rights for the purpose of exploring it and exploiting its natural resources, and those rights do not depend on occupation, effective or notional, or on any express proclamation.

Where the doctrine came from

Geology first, law second. Beyond most coasts the seabed slopes gently for some distance and then falls away steeply. The gentle part is the shelf; the drop is the slope; and beyond it lies the rise and then the deep ocean floor.

The Truman Proclamation of 28 September 1945 turned the geology into law. The United States claimed the natural resources of the subsoil and seabed of the continental shelf beneath the high seas contiguous to its coasts, and within a few years many States had made similar claims. The North Sea judgment describes it as the starting point of the positive law on the subject and notes that its chief doctrine, that the coastal State had an original, natural and exclusive right to the shelf off its shores, came to prevail over all others.

The 1958 Geneva Convention on the Continental Shelf codified it with a definition tied to depth and exploitability, which was unsatisfactory because technology kept moving the limit outward. Article 76 of the 1982 Convention replaced that with a definition tied to geology and distance.

The definition: article 76

Article 76(1). The continental shelf comprises the seabed and subsoil of the submarine areas that extend beyond the territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured where the outer edge of the continental margin does not extend up to that distance.

Two limbs, and it is important to see that they are alternatives.

The distance limb. Every coastal State gets two hundred miles of shelf whatever the geology, so a State whose margin stops at eighty miles still has two hundred.