Pursuant to article 5, the normal baseline used for measuring the breadth of the territorial sea is the low-water line along the coast. U.S. practice is consistent with this rule.
Roofs. In accordance with article 6, in the case of islands situated on atolls or of islands having fringing reefs, the normal baseline is the seaward low-wa-ter line on the drying reef charted as being above the level of chart datum. While the Convention does not address reef closing lines, any such line is not to adversely affect rights of passage, freedom of navigation, and other rights for which the Convention provides.
Straight BaselInes
Purpose. The purpose of authorizing the use of straight baselines is to allow the coastal State, at its discretion, to enclose those waters which, as a result of their close interrelationship with the land, have the character of internal waters. By using straight baselines, a State may also eliminate complex patterns, including enclaves, in its territorial sea, that would otherwise result from the use of normal baselines in accordance with articles. Properly drawn straight baselines do not result in extending the limits of the territorial sea significantly seaward from those that would result from the use of normal baselines.
With the advent of the EEZ, the original reason for straight baselines (protection of coastal fishing interests) has all but disappeared. Their use in a manner that prejudices international navigation, overflight, and communications interests runs counter to the thrust of the Convention's strong protection of these interests. In light of the modernization of the law of the sea in the Convention, it is reasonable to conclude that, as the Convention states, straight baselines are not normal baselines, straight baselines should be used sparingly, and, where they are used, they should be drawn conservatively to reflect the one rationale for their use that is consistent with the Convention, namely the simplification and rationalization of the measurement of the territorial sea and other maritime zones off highly irregular coasts.
Areas of ApplIcatIon. Straight baselines, in accordance with article 7, may be used only in two specific geographic circumstances, that is, (a) in localities where the coastline is deeply indented and cut into, or (b) if there is a fringe of islands along the coast in the immediate vicinity of the coast. Even if these basic geographic criteria exist in any particular locality, the coastal State is not obliged to employ the method of straight baselines, but may (like the United States and other countries) instead continue to use the normal baseline and permissible closing lines across the mouths of rivers and bays.
"Localities Where the Coastline Is Deeply Indented and Cut Into."
"Deeply indented and cut into" refers to a very distinctive coastal configuration. The United States has taken the position that such a configuration must fulfill all of the following characteristics:
In a locality where the coastline is deeply indented and cut into, there exist at least three deep indentations;
The deep indentations are in close proximity to one another, and
The depth of penetration of each deep indentation from the proposed straight baseline enclosing the indentation at its entrance to the sea is, as a rule, greater than half the length of that baseline segment.
The term "coastline" is the mean low-water line along the coast; the term "localities" refers to particular segments of the coastline.
"Fringe of Islands Along the Coast in the Immediate Vicinity of the Coast." "Fringe of islands along the coast in the immediate vicinity of the coast" refers to a number of islands, within the meaning of article 121(1).
The United States has taken the position that a such a fringe of islands must meet all of the following requirements:
The most landward point of each island lies no more than 24 miles from the mainland coastline;
Each island to which a straight baseline is to be drawn is not more than 24 miles apart from the island from which the straight baseline is drawn; and
The islands, as a whole, mask at least 50% of the mainland coastline in any given locality.
Criteria for Drawing Straight
Baseline Segments. The United States has taken the position that, to be consistent with article 7(3), straight baseline segments must:
Not depart to any appreciable extent from the general direction of the coastline, by reference to general direction lines which in each locality shall not exceed 60 miles in length;
Not exceed 24 miles in length; and
Result in sea areas situated landward of the straight baseline segments that are sufficiently closely linked to the land domain to be subject to the regime of internal waters.
Minor Deviations. Straight baselines drawn with minor deviations from the foregoing criteria are not necessarily inconsistent with the Convention.
Economic Interests. Economic interests alone cannot justify the location of particular straight baselines. In determining the alignment of particular straight baseline segments of a baseline system which satisfies the deeply indented or fringing islands criteria, in accordance with article 7(5), only those economic interests may be taken into account which are peculiar to the region concerned and only when the reality and importance of the economic interests are clearly evidenced by long usage.
Basepoints. Except as noted in article 7(4), basepoints for all straight baselines must be located on land territory and situated on or landward of the low-water line. No straight baseline segment may be drawn to a basepoint located on the land territory of another State.
Use of Low-tide Elevations as Basepoints In a System of Straight Baselines. In accordance with article 7(4), only those low-tide elevations which have had built on them lighthouses or similar installations may be used as basepoints for establishing straight baselines. Other low-tide elevations may not be used as basepoints unless the drawing of baselines to and
