Baselines and the Territorial Sea

In one line

The baseline is the line the sea is measured from, and the territorial sea is the twelve-mile belt of sovereignty beyond it.

In the wording a student can write in an exam: under article 3 of the Convention on the Law of the Sea every State has the right to establish the breadth of its territorial sea up to a limit not exceeding twelve nautical miles, measured from baselines determined in accordance with the Convention. The normal baseline under article 5 is the low-water line along the coast as marked on large-scale charts officially recognised by the coastal State; where the coastline is deeply indented and cut into, or where there is a fringe of islands along the coast in its immediate vicinity, article 7 permits the method of straight baselines joining appropriate points.

The breadth: an argument that took four hundred years

Article 3. Every State has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from baselines determined in accordance with the Convention.

Article 4. The outer limit is the line every point of which is at a distance from the nearest point of the baseline equal to the breadth of the territorial sea.

Two things about article 3 are examinable. It is a maximum, not a fixed width: a State may claim less, and Norway claimed four miles at the time of the Fisheries case. And it took until 1982 to settle: the traditional figure was three miles, from Bynkershoek's cannon-shot rule, and both the 1958 and 1960 conferences failed to agree, as [The Law of the Sea] records.

India claims the full twelve under section 3(2) of the Maritime Zones Act 1976: the limit of the territorial waters is the line every point of which is at a distance of twelve nautical miles from the nearest point of the appropriate baseline. Section 3(1) states that the sovereignty of India extends and has always extended to the territorial waters.

The baselines

The normal baseline

Article 5. Except where otherwise provided, the normal baseline is the low-water line along the coast as marked on large-scale charts officially recognised by the coastal State.

Low water rather than high water, because it favours the coastal State: the lower the line, the further out everything sits.

Straight baselines

Article 7(1). In localities where the coastline is deeply indented and cut into, or if there is a fringe of islands along the coast in its immediate vicinity, the method of straight baselines joining appropriate points may be employed.

Article 7 also deals with unstable coastlines where a delta and other natural conditions make the low-water line highly unstable, with the requirement that straight baselines must not depart to any appreciable extent from the general direction of the coast and that the sea areas within must be sufficiently closely linked to the land domain, and with the taking into account of economic interests peculiar to the region evidenced by long usage.