A. Definition
Maritime delimitation may be defined as the process of establishing lines separating the spatial ambit of coastal State jurisdiction over maritime space where the legal title overlaps with that of another State. This definition calls for five comments:
(i) The maritime delimitation is to be effected where there is an overlap of legal titles between States over the same maritime space. Hence, the maritime delimitation does not relate to separating maritime spaces under coastal State jurisdiction from the high seas or the international Seabed Area, to which no State has legal title.
(ii) In view of the point mentioned above, a distinction should be made between maritime limits and maritime delimitation. The establishment of maritime ‘limits’ consists of drawing lines that define the maritime spaces of a single State, that is to say, spaces that are not in contact with those of another coastal State. Accordingly, the objective of maritime limits is to delineate maritime spaces under coastal State jurisdiction, considered in isolation. In that sense, the act of establishing ‘limits’ is a unilateral one. In general, the outer limits of a maritime zone form at the same time the inner limit of another zone. For instance, the outer limit of the internal waters constitutes the inner limit of the territorial sea, and the outer limit of the latter is also the inner limit of the contiguous zone, the EEZ, and the continental shelf. The outer limit of the EEZ, whose breadth extends to a maximum of 200 miles from the baseline used for measuring the breadth of the territorial sea, marks the beginning of the high seas, of the international Seabed Area, and of the outer continental shelf beyond 200 miles if the natural prolongation of the land territory extends that far. The end of the outer continental shelf forms the landward limit of the International Seabed Area.
On the other hand, ‘maritime delimitation’ is an operation to be effected between two or more States, as its object is to separate overlapping areas where legal titles of coastal States compete and each State attempts to exercise spatial jurisdiction over the same maritime space. This fact highlights an essential characteristic of maritime delimitation:
international character. The Chamber of the ICJ in the Gulf of Maine case affirmed this view as an element of the ‘fundamental norm’ of the law of maritime delimitation: ‘No maritime delimitation between States with opposite or adjacent coasts may be effected unilaterally by one of those States.’ Thus, maritime delimitation has always had an international character in the sense that it is not a unilateral act, but must be effected between a plurality of States.
(iii) According to the definition given, the phenomenon of maritime delimitation is confined to States. Hence, delimitation problems among the members of federations are excluded from the present study. Furthermore, international organisations, inter alia, the International Sea-Bed Authority, are not subjects of maritime delimitation. In fact, the limit of the International Seabed Area is decided unilaterally by coastal States, not the International Sea-Bed Authority. Having fixed the outer limit of the continental shelf, the duty of a coastal State is restricted to filing a copy of a chart or list of geographical co-ordinates with the Secretary General of the Authority (Article 84(2) of the UN Convention on the Law of the Sea).
(iv) The delimitation of maritime spaces relates to the separation of spatial ambits of State jurisdiction. The State jurisdiction to be delimited is of a spatial nature; it can be regarded as spatial, as it differs from personal or any other type of jurisdiction. In fact, coastal State jurisdiction over internal waters and the territorial sea is undoubtedly of territorial, ie, spatial character. In addition, jurisdiction over the EEZ and the continental shelf may also be considered as spatial in the sense that it can be exercised solely within the space in question, although it must be distinguished from territorial sovereignty proper. It is true that coastal State jurisdiction over the EEZ and the continental shelf is limited to the matters defined by international law. However, in these matters, the coastal States may exercise sovereign rights, regardless of the nationality of the objects within the EEZ and the continental shelf. In addition, such sovereign rights are exercised exclusively. Jurisdiction over the EEZ and the continental shelf can be understood only as spatial jurisdiction, not as personal or any other type.
(v) In this connection, it may be relevant to touch on an issue of terminology relating to ‘delimitation line’ and ‘boundary’. According to Caflisch, while the expression ‘boundary’ is reserved for land territory and other spaces under full sovereignty, regarding maritime spaces where coastal States exercise functional powers, not full sovereignty, the terms ‘limits’ or ‘lines of delimitation’ are appropriate. The Chamber of the ICJ in the Gulf of Maine case appears to support this view. On the other hand, the Court of Arbitration in the Guinea/Guinea-Bissau case held that practice has not always accurately reflected the distinction. In fact, in the North Sea Continental Shelf cases, the ICJ used the expressions ‘boundary’ or ‘boundary line’ in the authentic English text, while the words ‘limites’ or ‘lignes de délimitation’ were used in the French translation.
In the Greenland/Jan Mayen case, the ICJ referred to ‘boundary’ for the continental shelf and fishery zone in the authentic English text, while the word ‘délimitation’ was used in the French translation. In the Anglo–French Continental Shelf case, the Court of Arbitration used the term ‘boundary’ in the English text. In the Guinea/Guinea-Bissau award, the
term ‘frontière’ was adopted in the authentic text in French, and the Guinea-Bissau/Senegal award referred to ‘frontières maritimes’.
In treaty practice, the expression ‘maritime boundary’ tends to be used for the delimitation of the continental shelf and/or the EEZ/FZ. This cursory review shows, as Caflisch himself accepted, that the distinction between ‘delimitation line’ and ‘boundary’ has not been clearly made. In particular, a delimitation line for the continental shelf and the EEZ/FZ is
often called a ‘single maritime boundary’ in the case law and writers’ views. Thus, in this study, the words ‘delimitation line’ and ‘boundary’ will be used interchangeably.
Some writers establish further distinctions regarding the legal nature of maritime delimitation. The first is that between delimitation and apportionment, and the second relates to the difference between ‘délimitation déclarative’ (declaratory delimitation) and ‘délimitation constitutive’ (constitutive or man-made delimitation). It seems, however, that both distinctions are open to question.
B. Arguments on the Distinction between Delimitation and Apportionment
It was the ICJ which, in the North Sea Continental Shelf cases of 1969, stressed the distinction between delimitation and apportionment. In examining the notion of ‘a just and equitable share’ referred by the Federal Republic of Germany, the Court clearly distinguished between delimitation and apportionment, saying that:
[I]ts task in the present proceedings relates essentially to the delimitation and not the apportionment of the areas concerned, or their division into converging sectors. Delimitation is a process which involves establishing the
boundaries of an area already, in principle, appertaining to the coastal State and not the determination de novo of such an area. Accordingly, in the Court’s view, the notion of ‘a just and equitable share,’ which pertains to the idea of apportionment, is incompatible with the idea of delimitation. Nevertheless, it seems that the distinction so defined is in reality tenuous.
In fact, in the same judgment, the Court ruled that ‘if, in the application of the preceding sub-paragraph [which postulated the application of equitable principles], the delimitation leaves to the Parties areas that overlap, these are to be divided between them in agreed proportions or, failing agreement, equally.’ However, the very idea of a division in agreed proportions or of an equal division will lead to the idea of apportionment. The same is true for the recourse to proportionality between the extent of the continental shelf areas appertaining to the coastal State and the length of its coast measured in the general direction of the coastline. By its very definition, the idea of proportionality is linked to the concept of the apportionment of the continental shelf. Hence, it is inevitable to conclude that, in the Court’s view, the concept of maritime delimitation includes some aspects of apportionment.
C. Arguments on the Distinction between Declaratory and Constitutive Delimitation
The second question to be examined is the distinction between ‘délimitation déclarative’ (declaratory delimitation) and ‘délimitation constitutive’ (constitutive or man-made delimitation). This distinction also has its roots in the North Sea Continental Shelf cases. Having specified the fundamental principle governing the continental shelf – natural prolongation – the Court ruled that this principle was inconsistent with the notion of ‘a just and equitable share’:
More important is the fact that the doctrine of the just and equitable share appears to be wholly at variance with what the Court entertains no doubt is the most fundamental of all the rules of law relating to the continental shelf, enshrined in Article 2 of the 1958 Geneva Convention, though quite independent of it – namely that the rights of the coastal State in respect of the area of continental shelf that constitutes a natural prolongation of its land territory into and under the sea exist ipso fact and ab initio, by virtue of its sovereignty over the land, and as an extension of it in an exercise of sovereign rights for the purpose of exploring the seabed and exploiting its natural resources. In short, there is here an inherent right.
In so doing, the Court employed the fundamental rule of natural prolongation as one of the touchstones for rejecting the notion of ‘a just and equitable share’.
Some argue that, according to the Court’s theory, the boundary of the continental shelf is already fixed by the geological fact of the natural prolongation, since delimitation involves establishing the boundaries of an area already appertaining to the coastal State and not the determination de novo of such an area. If this is so, the delimitation simply consists of discovering how far the natural prolongation of each State extends under the sea. Weil called this view ‘declaratory delimitation’. In criticising this conception, Weil contrasts it with the idea of constitutive or man-made delimitation, which regards the maritime delimitation as the fruit of the will of States or of decisions of international courts. Having noted these two conceptions of maritime delimitation, Weil argues that the concept of declaratory delimitation has transformed itself into one of constitutive delimitation.
It is doubtful, however, whether the ICJ, in the North Sea Continental Shelf cases, considered maritime delimitation as declaratory. The concept of the declaratory delimitation presupposes natural prolongation as a geophysical and geological fact. Yet, it is not evident that the Court accepted such a concept of natural prolongation. In fact, the Court affirmed that ‘a median line divides equally between the two opposite countries’ areas that can be regarded as being the natural prolongation of the territory between them.’ This shows that the Court did not consider the natural prolongation as a purely geophysical and geological concept, since it is inconceivable that the natural prolongation of each State always ceases in the middle. Furthermore, the concept of declaratory delimitation is hard to reconcile with the Court’s judgment itself. In fact, the operative part of the judgment solely requires that the natural prolongation of each Party should be preserved ‘as much as possible’. This indicates that the delimitation of the continental shelf is not effected exclusively by resorting to natural prolongation, although the latter plays an important role. Moreover, as pointed out, the Court held that overlapping areas were to be divided in agreed proportions. In addition, it mentioned natural resources and a reasonable degree of proportionality as elements to be taken into account. In so doing, it is clear that the Court considered the continental shelf delimitation to be constitutive, and not declaratory, ie, based solely on natural prolongation.
In this connection, one may wonder that a delimitation could be a declaratory in the sense that there is only one ‘correct’ delimitation line for each set of geographical and non-geographical circumstances. If this is the case, the role of international courts and tribunals is solely to ‘discover’ the ‘correct’ delimitation line. It is doubtful, however, that such the only one ‘correct’ delimitation line could exist when a maritime delimitation dispute is entrusted to international courts and tribunals. As will be shown below, the core of the law of maritime delimitation is the notion of equity and equitable principles. By its very nature, an interpretation of the concept of equity may be variable and there is no single ‘correct’ interpretation of that concept. There is evidently a certain degree of difference between judges in judging the equitableness of maritime boundaries. Accordingly, the application of equitable principles does not necessarily lead to the same maritime boundary. In fact, as will be illustrated below, international courts and tribunals exercise a large degree of discretion when drawing maritime boundaries. It could be contended, thus, that maritime delimitation is a man-made process of identifying and evaluating a delimitation method and relevant circumstances. In other words, it is always constitutive.
Yoshifumi Tanaka