1271 
The result of this new development is, therefore, that states could have a very 
clear choice. Unless satisfied with a new limit on the shelf, as contained in a 
revised treaty on the subject, states may continue to rely on the customary defi- 
nition in which the key terms are “exploitability” and “adjacency”. In practice 
some states have interpreted these terms to authorize extension of their shelf to 
points much deeper than 200 meters and more than 100 miles from their baseline. 
The United States, it should be noticed, is one of the leaders in this extension 
of the shelf, claiming areas more than 100 miles from the coast and at depths 
much greater than 200 meters. 
For these reasons the content of the customary law on the shelf limit is of 
special significance and the Court’s treatment of this matter is of particular 
interest. The decision contains pronouncements which appear to indicate that 
in the Court’s view the present shelf limit (200 meters or exploitability, as 
modified by adjacency) is a rather narrow one. Unfortunately virtually all 
these pronouncements are mere dictum and appear to have been made without 
any reference whatsoever to state practice. Moreover some of the Court’s 
observations appear to be contradictory of others, leaving it rather difficult to 
envisage precisely which views are predominant. 
The Court’s treatment of the concept of ‘‘adjacency” is especially significant 
since it is this term which establishes the limit on exploitability as a means of 
expanding the shelf limit. The Court referred to a number of terms used in 
State proclamations and in treaties—“near’, “close to its shores’, “off its 
coasts”, “opposite”, “in front of the coast”, “in the vicinity of’, “neighboring 
the coast”, “adjacent to’, ‘“contiguous’—and said they were all ‘‘terms of a some- 
what inprecise character which, although they convey a reasonably clear 
general idea, are capable of a considerable fluidity of meaning.” The Court 
examined one of these terms: i 
To take what is perhaps the most frequently employed of these terms, 
namely ‘‘adjacent to’, it is evident that by no stretch of imagination can a point 
on the continental shelf situated say a hundred miles, or even much less, from 
a given coast, be regarded as ‘adjacent’ to it, or to any coast at all, in the 
normal sense of adjacency, even if the point concerned is nearer to some one 
coast than to any other. This would be even truer of localities where, physically, 
the continental shelf begins to merge with the ocean depths. 
While these remarks were made essentially to demonstrate that ‘“‘adjacent” 
and “proximity” do not possess the same meaning in the context of a three- 
state delimitation problem, the suggestion is that the “continental shelf’ 100 
miles from the coast, or even less than that distance. does not fall within the 
sovereign rights of any coastal state. Thus for all its reliance on the “natural 
prolongation” doctrine as the fundamental basis for the legal concept of the 
continental shelf, the Court apparently does not accept that the legal shelf is 
always coextensive with the natural prolongation. At some point, even “much less 
than” 100 miles, present customary law puts an end to coastal control. Or so the 
Court seems to say. 
Unfortunately the message is perhaps not so clear as these passages seem to 
suggest. The Court also states that the entire North Sea area is composed of 
continental shelf, being shallower than 200 meters, and appears to regard its 
pareelling out by the bordering states as permissible under the Convention and 
customary law. Yet there are parts of the North Sea that are much more than 
100 miles from any of the surrounding states. Unless such parts are “adjacent” 
they could not be lawfully claimed as shelf by any of the states concerned. At no 
place does the Court suggest that the North Sea area is unique, calling for a 
different set of laws. 
Whatever the scope of the Court’s statements on adjacency, there is a very 
clear implication that in the Court’s view the present limit on the shelf does not 
necessarily embrace the slope and rise, i.e., if the slope and rise are part of the 
‘natural prolongation” of the continental land mass, as they seem to be, it does 
not follow that they are part of the legal shelf. If any part of this “natural pro- 
longation” were automatically within the shelf there would be little of significance 
in the Court’s remarks about adjacency. 
On the other hand if the NPC position is not now the international law of the 
sea, the Court’s opinion may well provide strong support for the proposal that 
this position is to be preferred when states do finally establish a certain limit for 
the shelf. The Court’s rationale for the very existence of a legal shelf, i.e., it is 
a prolongation of territory over which an adjacent state exercises sovereignty, 
may now appear also to be a suitable rationale for locating the limit on such 
sovereign rights. 
