558 international law
However, a completely different situation operates where the foreign
vessel involved is a warship. In such cases, the authorisation of the captain
or of the flag state is necessary before the coastal state may exercise its
jurisdiction over the ship and its crew. This is due to the status of the
warship as a direct arm of the sovereign of the flag state.
20
Baselines
21
The width of the territorial sea is defined from the low-water mark around
the coasts of the state. This is the traditional principle under customary
international law and was reiterated in article 3 of the Geneva Convention
on the Territorial Sea and the Contiguous Zone in 1958 and article 5 of
the 1982 Convention, and the low-water line along the coast is defined ‘as
marked on large-scale charts officially recognised by the coastal state’.
22
In the majority of cases, it will not be very difficult to locate the low-
water line which is to act as the baseline for measuring the width of the
territorial sea.
23
By virtue of the 1958 Convention on the Territorial Sea
and the 1982 Law of the Sea Convention, the low-water line of a low-tide
elevation
24
may now be used as a baseline for measuring the breadth of the
territorial sea if it is situated wholly or partly within the the territorial sea
Entry into Maritime Ports in International Law’, 14 San Diego Law Review, 1977, p. 597,
and O’Connell, International Law of the Sea, vol. II, chapter 22. See also the Dangerous
Vessels Act 1985.
20
See The Schooner Exchange v. McFaddon 7 Cranch 116 (1812). See also 930 HC Deb., col.
450, Written Answers, 29 April 1977.
21
See e.g. W. M. Reisman and G. S. Westerman, Straight Baselines in International Mar-
itime Boundary Delimitation, New York, 1992; J. A. Roach and R. W. Smith, United States
Responses to Excessive Maritime Claims, 2nd edn, The Hague, 1996, and L. Sohn, ‘Base-
line Considerations’ in International Maritime Boundaries (eds. J. I. Charney and L. M.
Alexander), Dordrecht, 1993, vol. I, p. 153.
22
See Qatar v. Bahrain, ICJ Reports, 2001, pp. 40, 97 and Eritrea/Yemen (Phase Two: Maritime
Delimitation), 119 ILR, pp. 417, 458. See also Churchill and Lowe, LawoftheSea,chapter2;
O’Connell, International Law of the Sea,vol.I,chapter5;Oppenheim’s International Law,
p. 607, and M. Mendelson, ‘The Curious Case of Qatar v. Bahrain in the International
Court of Justice’, 72 BYIL, 2001, p. 183.
23
See the Dubai/Sharjah Border Award 91 ILR, pp. 543, 660–3, where the Arbitral Tribunal
took into account the outermost permanent harbour works of the two states as part of the
coast for the purpose of drawing the baselines.
24
See article 11(1), Convention on the Territorial Sea, 1958 and article 13(1), Law of the
Sea Convention, 1982. A low-tide elevation is a naturally formed area of land which is
surrounded by and above water at low tide, but submerged at high tide. See e.g. G. Marston,
‘Low-Tide Elevations and Straight Baselines’, 46 BYIL, 1972–3, p. 405, and D. Bowett,
‘Islands, Rocks, Reefs and Low-Tide Elevations in Maritime Boundary Delimitations’ in
Charney and Alexander, International Maritime Boundaries, vol. I, p. 131.