Delimitation of the Continental Shelf between the United Kingdom of Great Britain and Northern Ireland, and the French Republic

Although I agree with a very large part of the reasoning of the Court in the present Decision, I have felt considerable doubts regarding the conclusion with respect to the course of the boundary westwards of Point M which, finally, it draws from that reasoning; and these doubts I think it right to express.

I accept that the solution prescribing a boundary based upon equidistance but giving only half-effect to the Scilly Isles was adopted by the Court in the context of a decision that the particular location of the Scillies, in the light of all the geographical circumstances, constituted a "special circumstance" having a distorting effect on the delimitation of an equidistance boundary. I also accept that this method of delimitation was decided upon by the Court ad hoc as a device to abate the effects of a particular "special circumstance" and remedy a particular inequity resulting from that particular "special circumstance". It follows that I likewise accept that the half-effect solution was adopted by the Court as an equidistable variant of the equidistance principle expressing a necessarily approximate appreciation of diverse considerations; and that the method for implementing it was devised as a modified, rather than as a strict, application of the equidistance method. The ad hoc character of the device, as the Court states, is evidenced by the Court’s selection of two particular pairs of base-points for the calculation of the equidistance lines determining the half-effect boundary rather than all the potentially relevant points on the respective coastlines. When all is said, however, after making its appreciation of all the pertinent geographical and other circumstances, the Court did decide not only upon the half-effect solution but upon a specific method for its implementation, which it in large measure defined. In consequence, whatever element of approximation there may have been in the Court’s appreciation of the pertinent geographical and other circumstances ultimately crystallized into a specific method and one that it had in large measure defined.

This method specifies as the course of the boundary from Point M westwards a line bisecting the area formed by two equidistance lines, one to give full effect and the other no effect to the Scilly Isles, and each line being delimited from a prescribed pair of base-points, specifically named and identified. It is, therefore, a quite specific frame of reference for the calculation and delimitation of the boundary from Point M westwards, though with the important exceptions of the projection of the charts and the system of calculation and delimitation—geodesic or loxodrome—to be used in its application. These technical elements are not specified in the Decision; moreover, taking them to fall essentially within the domain of hydrographical technique and not appreciating their possible implications for the course of the boundary, the Court did not itself examine them or give directions to the Expert regarding them.

I agree with the Court that the question for decision is not whether the two loxodromes in fact employed in the Expert’s calculations may be considered a simplified form of "strict" or "true" equidistance lines, but whether they can and ought to be considered as "equidistance lines" within the meaning and for the purpose of the half-effect method defined in paragraphs 251, 253 and 254 of the Decision of 30 June 1977. This method, in my view, is necessarily the specific one defined, but not completely defined, in those paragraphs, and not some other approximation to that method not specified in the Decision. At the same time, I accept that the general context in which the method was adopted by the Court may be relevant in appreciating whether the two loxodromes calculated by the Expert should be considered compatible with the method of delimitation prescribed by the Court.

I agree generally with the Court’s observations regarding the somewhat qualified manner in which the equidistance principle is often applied in maritime boundary delimitations; and I also subscribe generally to its account of the circumstances in which the Expert’s calculations of the two loxodrome "equidistance" lines and of the bisector line determining the boundary from Point M westwards came to be made and adopted by the Court. Where I feel that I may differ from the Court is in the weight which, in appreciating whether these three lines are compatible with the method prescribed by the Court, I would give to the omission to apply corrections for scale error in the latitudes of the Atlantic region and over the very long distances involved.

Each of the two loxodrome "equidistance" lines, as defined in the Expert’s Technical Report, diverges at every point westwards from Point M from the real equidistance line drawn so as to reflect the curvature of the earth’s surface. If for a short distance along each line the divergence may be minimal and negligible, it becomes more and more appreciable as the loxodrome diverges northwards from the "real" equidistance line continuously and increasingly over distances respectively of 160 and 180 nautical miles to the 1,000-metre isobath. The divergence is all one way in favour of one Party, so that there is no question of balancing of gains against losses which is characteristic of a "simplified" equidistance line; and the total area of this divergence all one way out to the 1,000-metre isobath is substantial, so that it can hardly be discounted as "minimal" or "negligible". Point N itself, so far from being an equidistant point, is the point on the line which diverges furthest from "real" equidistance on the earth’s surface.

I agree with the Court’s conclusion that the information available does not appear to establish that the delimitation of a maritime boundary by a loxodrome line on a standard navigational chart based on Mercator projection without correction for scale error is either inadmissible in law or so outmoded in practice as to make its use open, in general, to challenge. It is necessary, on the other hand, to consider the possible impact in this connexion of the great extension seawards of the boundary in the present case, combined with the lateral relation of the coasts of the United Kingdom and France in the Atlantic region. The Court, as it has recognized, made this combination of circumstances one of the cardinal elements in its decision to allow only half-effect to the Scilly Isles. Expressing its conclusions on this point in paragraph 242 of the Decision of 30 June 1977, the Court said:

What is important is that, in appreciating the appropriateness of the equidistance method as a means of effecting a "just" or "equitable" delimitation in the Atlantic region. the Court must have regard both to the lateral relation of the two coasts as they abut upon the continental shelf of the region and to the great distance seawards that this shelf extends from those coasts.

It emphasised this element in the geographical situation in the Atlantic region for the same reason that had led the International Court of Justice in the North Sea Continental Shelf cases to emphasise the distinction between the cases of delimitation between "opposite" coasts and between laterally related coasts (I.C.J. Reports 1969, paragraph 59); namely that, owing to the lateral relation and the great extension of the shelf seawards, the effect of any distorting geographical feature on the areas of shelf allocated to each State under the equidistance method is automatically magnified, the greater the distance from the shore (Decision of 30 June 1977, paragraph 86).

This consideration clearly has relevance in considering the effects of scale error in distorting the allocation of areas of shelf under the equidistance method, since these are increased with every nautical mile that the boundary extends to seawards. Accordingly, the delimitation of the half-effect boundary in the Atlantic region by loxodrome without correction for scale error at least has the appearance of disregarding an equitable consideration that the Court made one of the foundations of its decision with respect to this region. As I have said, I accept that the delimitation of a maritime boundary by a loxodrome without correction for scale error is not so outmoded as to make its use, in general, open to challenge. At the same time, every case has to be considered in its own context, and in the present one the Court is faced with laterally related States and a very great extension seawards of the continental shelf. Admittedly, some examples may be found where such a loxodrome boundary has been accepted by agreement. But the present case is before a Court of Arbitration, and the question arises whether the applicable principles which the Court has itself laid down may require that, in the circumstances of the Atlantic region, a delimitation by reference to the equidistance method should take account of scale distortion in the application of that method.

Clearly, the Decision of 30 June 1977 must be considered as directed to the actual geographical facts rather than to their cartographical representation on nautical charts. No court could do otherwise and, as appears from the Decision itself, this Court took into consideration a number of specific geological and geographical facts, such as the geological continuity of the continental shelf in the region and the fact that both Ushant and the Scilly Isles form an integral part of the land masses of their respective countries. On the other hand, the Court’s findings in paragraphs 251, 253 and 254 of the Decision were inevitably made not only on the basis of the geographical facts as they appeared from the information and arguments presented to it but also as they were depicted on the charts of the region. These charts are of the finest quality and reproduce the geographical facts with a high degree of precision, subject only to the question of scale error resulting from the curvature of the earth.

The present case is not, therefore, like those in some arbitrations where, through inadequate information concerning the terrain, a land map used in a treaty or by an arbitral tribunal had erroneously depicted a physical feature forming an element in the delimitation of the boundary. Here there is no such misplacement of physical features, otherwise than in regard to the difference between the plane geometry and the curved surface of the earth. Even then, the geographical features are not really misrepresented on the charts, since the standard navigational charts in question do not purport to be anything but charts on Mercator projection, leaving it to the users to make such adjustments for scale distortion as may be thought necessary for the purpose in hand. Consequently, any error, if error should arise, can come only through the misreading or misapplication of the charts.

Leaving aside the question of scale distortion inherent in the projection, it is agreed that the Court’s Expert calculated the two loxodrome "equidistance" lines and the bisector forming the boundary with meticulous accuracy on the Boundary-Line Chart; and the Court has no reason to suppose that he did otherwise on the standard navigational charts which it used as working documents. Consequently, the Court having taken no decision and given no directions concerning the technical questions of chart projection and system of delimitation (geodesic or loxodrome) to be used, the issue of the compatibility of the line M-N with the findings of the Court in paragraphs 251, 25.3 and 254 turns on two closely related questions. The first is whether the loxodrome "equidistance" lines calculated by the Expert can be regarded as passing for "equidistance" lines for the purpose of the method of delimitation prescribed by the Court; and the second is whether the resulting bisector line can be regarded as passing for a boundary giving half-effect to the Scilly Isles.

On the first question, I have already indicated my serious doubt as to whether a loxodrome "equidistance" line delimited over distances of 160 and 180 nautical miles without correction for scale distortion ought to be regarded by the Court as passing for one of the "approximate" kinds of equidistance lines found in practice. In many cases, as the Court has noted, either because of the short distances involved in territorial sea and internal waters delimitations or because of the low latitudes of the regions concerned, the divergence from geodetic equidistance is slight enough for the approximate character of the line as an equidistance line to be neglected. The question, it seems to me, is one of degree dependent, in the case of a boundary between laterally related States delimited seawards from two basepoints, on the length of the loxodrome and, correspondingly, the extent of the area of its divergence from geodetic equidistance. In the latitudes and particular geographical circumstances of the Atlantic region, my doubt remains whether it is fully consonant with the rationale of the equitable principle applied by the Court in its Decision of 30 June 1977 for the effects of the divergence from geodetic equidistance over the great distances mentioned above to be passed over. Thus, if the matter were now to be open to reconsideration, I am of the opinion that the Court ought certainly to take account of the effect of the curvature of the earth on the operation of the equidistance principle over great distances such as those in the Atlantic region. Even so, in the light of the information before the Court regarding State practice in the matter, it might be going too far to say that the "equidistance" lines calculated by the Expert fall wholly outside the concept of what may pass for equidistance lines in maritime boundary delimitations. As to the second question, the half-effect solution being a device adopted ad hoc to remedy the inequitable effects of a "special circumstance", it may be difficult to maintain that there is any precise, accepted concept of the technique to be used to effect such a solution. Accordingly, and in the light of the observation just made concerning the calculation of the "equidistance" lines by the Expert, it might again be going too far to say that the method applied in the present instance falls wholly outside the concept of what may pass for a half-effect boundary.

While it is my opinion that there is an element of contradiction between the application of the Court’s findings in regard to the Atlantic region and the rationale of those findings, it is another question whether that element of contradiction amounts to a "material error" such as can bring into play the Court’s inherent power to rectify material errors. A majority of the Court takes the view that, even if it were open to the Court to review the problem of the appropriate technique for applying the half-effect solution, this could be done only after a fresh examination of all pertinent factors and considerations as well as of the several possible techniques and the courses of the boundaries resulting from their use. The Decision of 30 June 1977 in regard to the Atlantic region, it considers, was a particular one on the basis of the applicable rules of international law, providing a particular equitable solution and after studying the boundaries resulting from the application of other techniques, I, too, recognize that the method of applying the half-effect solution, including the selection of the particular base-points, and the half-effect solution itself were adopted after a complex balancing of diverse considerations and in the light of an appreciation of the results of applying different techniques illustrated by the Expert on standard navigational charts. I entertain some doubts as to whether the substitution of geodesic for loxodrome lines would have affected the Court’s appreciation either of the problem or of the base-points to be selected. But, whatever these doubts, it is difficult to discount altogether the possibility that the United Kingdom’s request for the rectification of the line M-N may involve some element of reappraisal of the problem of the Atlantic region and some slight adjustment of the technical framework of the method of delimitation laid down by the Court in paragraph 254 of the Decision. For this reason, I have come to the conclusion that I ought not to press these doubts to the point of dissenting from the Court’s finding that to reopen the question of the method applied by the Expert and the Court in the proceedings in 1977 appears to go beyond the function of interpretation entrusted to the Court under Article 10 of the Arbitration Agreement as well as its inherent power to correct a material error. I do so with reluctance in view of the substantial issue raised in the Application.