Baselines, Historic bays

25 October 2012 | Article



"The normal baseline is the low-water mark as indicted on large-scale charts, officially recognized by the coastal State (SHOM charts in France, for example). In some cases (coasts that are deeply indented or edged by small islands, deltas, sufficiently deep bays), straight baselines, which must not depart from the general direction taken by the coast, can simplify the limit of the territorial sea and enable the coastal State to extend the surface area of its internal waters. The choice of these lines, aiming to maximise the country's maritime surface area while observing the rules of the 1982 Convention, requires a precise and well-documented study presenting the various possibilities." [1]

Baselines can also be traced across the mouth of a bay. The UNCLOS defines conditions under which this type of line can be traced. Two cases must, however, be distinguished: that of normal bays, and that of historic bays [2]. In the first case, the conditions laid down by the Convention are sufficiently precise (the bay's dimensions, the width of its mouth) to avoid an overly extensive boundary line being used to incorporate excessively large portions of marine areas into a State's internal waters, which could restrict navigation significantly.

In the case of so-called "historic" bays, the conditions for their integration into internal waters are not precisely specified in the Convention and may prove to be a source of conflict, especially in an area as cramped as the Mediterranean. By way of example, the declaration made by the Libyan Jamahiriya in 1973 that it regarded the Gulf of Sirte as an historic bay over which it claimed sovereignty immediately raised international protests and led, later on, to several confrontations between Libyan and American forces.

The major problem raised by the delimitation of internal waters is linked to the fact that it establishes the starting-point for all other delimitations. Therefore, no delimitation of other areas controlled by the State, in particular the territorial sea or Exclusive Economic Zone (EEZ), can be carried out without precise reference to the baselines.

Furthermore, delimitation of baselines may have a reductive effect on the surface area of the EEZ or continental shelf, as the boundaries of these zones are determined as a distance of 200 nautical miles from the baseline coordinates.

Finally, it should be pointed out that determination of the baselines which will delineate the contour of internal waters is performed unilaterally by the coastal State, which can use any method it chooses. It must, however, be used in all good faith and in accordance with the rules laid down by international law. The result of such an operation must also be reported to other States which can oppose it if they consider that it does not comply with the law.

In the Mediterranean, where distances between two coasts are less than 400 nautical miles, determination of the baselines is a major issue in the field of regional jurisdictionalisation.

[1] Service Hydrographique et Océanographique de la Marine.

[2] UNCLOS. Articles 10.6 and 298.1.a. 

Mediterranean landscape