100

SEPARATE OPINION OF JUDGE JIMENEZ DE ARECHAGA*

PART J. INTERPRETATION OF THE SPECIAL AGREEMENT

1. The Parties’ Submissions

1. The Parties presented different views as to the role to be performed
by the Court in this case. Tunisia contended that the task of the Court was,
first, to determine the principles and rules of international law applicable
to this delimitation and then, as a second question, to identify and indicate
the practical method or methods to be followed for that delimitation, and
to do so with such clarity and in such detail “as to enable the experts of the
two countries to delimit these areas without any difficulties”. For Tunisia,
the role of the experts consists “in the substantial but technical task of
constructing the line of delimitation and establishing the boundary line”.
This is to be done within a period of three months and, during this period,
the Parties are to conclude an agreement providing legal sanction to
the line arrived at by the experts on the basis of the Judgment of the
Court.

2. Libya, on its part, advanced a more restrictive view of the role of the
Court, and, consequently, a much larger view of the task of the experts. It
contended that the application by the Parties and their experts of the
principles and rules set forth in the Judgment could not be restricted to a
mere mechanical plotting of co-ordinates or drawing of lines from point to
point. According to Libya, the Court was “invited to indicate the consi-
derations and factors which should be taken into account” but not “to
indicate a very precise method of delimitation’, since this would be, for all
intents and purposes “the same as taking over the task of drawing the
line”.

In support of this view Libya recalled that Article 3 of the Special
Agreement mentions the need of a further “agreement” between the Par-
ties, and pointed out that this instrument is to be interpreted against the
background of the fundamental principle that delimitation is to be settled
by agreement.

3. The divergence of views of the Parties as to the degree of precision
which the judgment of the Court should possess was reflected in their
respective final Submissions, that is to say, in what they asked the Court to
adjudge and declare. In consonance with its interpretation of the Special
Agreement, Libya framed its Submissions in such broad and general terms
that their acceptance would still have left wide room for substantive

* A synoptical table of contents appears at the end

86
101 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

negotiations and for substantial disagreements between the Parties. The
adoption by the Court of Submissions framed in such terms would not
have advanced the settlement of the dispute to any great extent, nor would
it have complied with the requirement of the second section of paragraph 1
of the Special Agreement, namely :

“to clarify the practical method for the application of these principles
and rules in this specific situation, so as to enable the experts of the
two countries to delimit these areas without any difficulties”.

The Tunisian Submissions were, on the contrary, very precise but they
asked the Court to endorse and adopt certain methods of delimitation
which, for reasons of substance, the Court could not accept.

4. What then had to be done in view of this lack of correspondence
between the Parties’ Submissions and the task assigned to the Court in the
Special Agreement ? The Court has followed its established jurisprudence
to the effect that, in order to determine the precise points which require
decision in the operative part of a judgment, when the case has been
brought by Special Agreement,

“it is rather to the terms of this agreement than to the submissions of
the Parties that the Court must have recourse in establishing the
precise points which it has to decide” (“Lotus” case, P.C_I.J., Series A,
No. 10, p.12). (Cf. also Serbian Loans case, P.CIJ., Series A,
Nos. 20/21, p. 47; River Oder case, P.C.I.J., Series A, No. 23, p. 18
and Minquiers and Ecrehos case, I.C.J. Reports 1953, p. 52.)

2. The Role of the Court and the Subsequent Role
of the Experts

5. I concur with the Judgment in preferring the Tunisian interpretation
of the Special Agreement as to the role of the Court and the subsequent role
of the experts, But this conclusion is not, in my view, one to be based on
minor exegetical points such as whether one or two questions have been
put to the Court or whether the words “avec précision” are to be read into
the French translation of the text of the Special Agreement or, finally,
whether there is a real distinction between “practical method of delimi-
tation” and “practical method for the application of principles and rules
that may be applied for the delimitation”.

6. There is a more fundamental reason for preferring the Tunisian
interpretation of the Special Agreement in respect to the role of the Court.
The Libyan interpretation envisages the role of the experts as that of
diplomatic representatives who will negotiate the final delimitation within
a vague and very general framework of pronouncements from the Court
described as mere indications or “guidance”. Thus, the Libyan interpre-
tation of the Special Agreement, combined with the broad submissions

87
102 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

Libya presented, would in fact have made the implementation of the
Court’s Judgment depend upon the subsequent agreement of the Par-
ties.

7. Confronted with a situation in a case where there were two possible
interpretations of a Special Agreement, one of them making the Judgment
dependent on a subsequent agreement of the Parties, the Permanent Court
decided :

“it is hardly possible to suppose that the Parties intended to adopt a
clause which would be incompatible with the Court’s function ; as,
accordingly, if it is possible to construe paragraph 2 of Article 2 of the
Special Agreement in such a way as to enable the Court to fuifil its
task, whilst respecting the fundamental conception on which that
paragraph is based, such a construction is the one which must be
preferred ;

Whereas it is certainly incompatible with the character of the
judgments rendered by the Court and with the binding force attached
to them by Articles 59 and 63, paragraph 2, of its Statute, for the
Court to render a judgment which either of the Parties may render
inoperative.” (Free Zones of Upper Savoy and the District of Gex, Order
of 6 December 1930, P.C.IJ., Series A, No. 24, p. 14.)

And in the final Judgment in that case, the Permanent Court reiterated the
same position :

“After mature consideration, the Court maintains its opinion that it
would be incompatible with the Statute, and with its position as a
Court of Justice, to give a judgment which would be dependent for its
validity on the subsequent approval of the Parties.” (Free Zones of
Upper Savoy and the District of Gex, Judgment, 1932, P.C.LJ., Series
A/B, No. 46, p. 161.)

8. In the light of these pronouncements it must be concluded that, in
making the choice between the two conflicting interpretations of the Spe-
cial Agreement, the one to be preferred is that which is compatible with the
character of judgments rendered by the Court and with the binding force
attached to them by Articles 59 and 63, paragraph 2, of the Statute.

It would certainly be incompatible with the Statute and with the Court’s
position as a Court of Justice to accept an interpretation of the Special
Agreement leading to a judgment which would not advance the settlement
of the dispute and which would be dependent for its application on the
subsequent agreement of the Parties.

9. However, in my view, the operative part of the Judgment should have
been framed on the basis, not of degrees of latitude or longitude but of
concepts such as the line perpendicular to the coast at Ras Ajdir, going as
far as the parallel of the westernmost point in the Gulf of Gabes, and from
that point successive veerings parallel to the successive inclinations of the
coast of the Tunisian mainland, all of these geographical facts to be
determined by the experts. On the other hand, it should have indicated that

88
103 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

the perpendicular line applicable for the first sector is that of 22°, because
this is the one resulting from the historical records, in particular the
recognition made by the French Resident-General in Tunisia (cf. para. 90
below).

10. There is no contradiction in indicating in this sector a perpendicular
line defined by degrees as the 22° line because the principles and rules of
international law applicable in this segment of the boundary are, in them-
selves, so precise as to result in a concrete line of delimitation established
by history. By proclaiming that 22° line the Court would not have invaded
the function of the experts but would have performed its own task of
determining the existence and applicability of a rule of law which is, in
itself, of absolute precision.

3. The Geographical Scope of Equitable Principles

11. The fundamental rule authorizing the Court to apply equitable
principles in the decision of this case is to be found in the Special
Agreement which provides in its first paragraph that “the Court shall
take its decision according to equitable principles”. This authoriza-
tion refers to the decision concerning “the delimitation of the area of
the continental shelf appertaining to the Republic of Tunisia and to
the area of the continental shelf appertaining to the Socialist People’s
Libyan Arab Jamahiriya”. Consequently, it does not place any geogra-
phical limitation on the applicability of equitable principles ; on the con-
trary, the Special Agreement refers to the whole area at issue between the
Parties and not just to the marginal or overlapping segments of that
area.

12. However, as a consequence of their rigid view of natural prolonga-
tion, both Parties assigned in their written and oral pleadings a limited and
subordinate role to equitable principles in the decision of the case. It is
striking that one of the few manifestations of express agreement by the
Parties during the oral hearings was their coincidence in subordinating
“equitable principles” to their own conceptions of “natural prolonga-
tion”.

13. The reason for this coincidence was, of course, that both Parties
contended that their respective geomorphological and geological concep-
tions of “natural prolongation” should control the delimitation and that
equitable principles should come into play successively and only where the
physical facts of “natural prolongation” were no longer of assistance in
determining the respective limits of the two shelf areas : in other words,
equity would operate merely as a corrective criterion, and only in over-
lapping, doubtful or marginal segments of the continental shelf, such as,
according to Libya, in the zone north to the latitude of Ras Yonga, or in
what Tunisia described as the borderland area. But neither Party in its

89
104 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

pleadings regarded “equitable principles” as a basic principle of law gov-
erning the delimitation of the area as a whole and as its starting point.

14. This approach of the Parties is not in accordance with the prin-
ciples and rules of international law declared by the Court in 1969, con-
firmed by the 1977 Arbitral Award between the United Kingdom and
France and codified in Article 83 of the draft convention on the Law
of the Sea. And, what is more important, such a position is not in accor-
dance with the terms of the Special Agreement, as quoted in paragraph 11
above. °

15. The Court, in 1969, after it had discarded the principle of equidis-
tance as a mandatory rule of customary international law, did not accept
that there was a “lacuna” in the law of nations on the subject ; it stated, on
the contrary, that “there are still rules and principles of law to be applied”
(LCJ. Reports 1969, p. 46). It found that the first of these rules is that
delimitation should be agreed or decided in accordance with equitable
principles. The Court referred to “equitable principles” in the operative
part of its 1969 Judgment, under letter (C), when defining “the principles
and rules of international law applicable to the delimitation”. There it
assigned the first place and not a secondary or successive one to “equitable
principles”, adding afterwards relevant circumstances, natural prolonga-
tion and non-encroachment. So, in the Court’s Judgment, “equitable
principles” have pride of place and apply from the start to the whole area
subject to delimitation and not just to marginal or overlapping segments of
that area.

16. A similar position was adopted by the Anglo-French Court of
Arbitration which, far from subordinating “equitable principles” to
“natural prolongation”, did the opposite when it stated that it is clear

“from the emphasis on ‘equitable principles’ in customary law that the
force of the cardinal principle of ‘natural prolongation of territory’ is
not absolute, but may be subject to qualification in particular situa-
tions” (para. 191).

Consequently, the award proclaimed that the principle of natural prolon-
gation, having a relative character, is subordinated to the necessity of
reaching an equitable delimitation.

17. Finally, Article 83, paragraph 1, of the draft convention on the Law
of the Sea makes clear that the only goal of delimitation on the basis of
international law is “to achieve an equitable solution”. This text does not
place geographical limits nor does it qualify in any other way the equitable
solution which is to be achieved of a dispute concerning “the delimita-
tion of the continental shelf between States with opposite or adjacent
coasts”.

90
105 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

4. The Meaning of Equity : Equity, Equidistance
and Relevant Circumstances

18. The opinion has been expressed that in deciding a case of this nature
the point of departure should always be the line of equidistance, and that
this line should be altered only to the extent that it is found to produce
inequitable results. Naturally, in all cases the decision-maker looks at the
line of equidistance, even if none of the parties has invoked it. But the
question is whether he is obliged to depart from it and confine his task to
the correction or moderation of the line of equidistance to the extent that it
is found to lead to inequitable results.

19. In support of the above opinion it is contended that equity is to be
viewed as a discretionary or moderating influence superadded to the rigour
of formulated law ; that it consists in the correction of a general rule when
that rule, by reason of its generality, works hardship in a concrete case and
produces results which are felt to be unfair.

20. There is no denying that this is a current conception of equity, which
may be a correct one in the municipal legal field. However, it is not the
conception of equity applicable to continental shelf delimitation, as pro-
claimed by the Court in 1969 and developed by the arbitral tribunal in
1977.

21. Moreover, in order to apply that view of equity to this branch of
international law it would be necessary to assume that equidistance con-
stitutes the general rule of law which is to be corrected or moderated in a
concrete case in proportion to the unfairness of its results. However, the
1969 Judgment of the Court proclaimed that equidistance was not a
binding rule of law but merely one method among others which could lead
to an equitable solution in some cases but produce inequitable results in
others. From this Judgment it follows that the above-described conception
of equity is not valid in the field of continental shelf delimitation, by reason
simply of the absence of a general rule of law which is to be moderated or
corrected in its concrete application.

22. What, then, is the meaning of equity in this field ? The 1977 Arbitral
Award gave a positive content to the notion of equitable principles as
applicable in this context, by linking them to the circumstances of each
case. It thus recognized implicitly that each case is necessarily different
from all others, by reason of the varying reciprocal relationship between
the geographical configuration of the coasts concerned and the historical
and political factors which established the land frontiers separating the
States parties to each dispute.

23. And what is more important, that award expressly linked the notion
of equity to those particular circumstances, when it stated :

“this Court considers that the appropriateness of the equidistance
method or any other method for the purpose of effecting an equitable

91
106 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

delimitation is a function or reflection of the geographical and other
relevant circumstances of each particular case. The choice of the
method or methods of delimitation in any given case, whether under
the 1958 Convention or customary law, has therefore to be deter-
mined in the light of those circumstances and of the fundamental
norm that the delimitation must be in accordance with equitable
principles.” (Para. 97.)

24, Consequently, in the context of the law of continental shelf delimi-
tation, the making of the decision “according to equitable principles”, as
the Court is ordered to do under the Special Agreement, compels the
judges to determine what are the relevant circumstances in each specific
case and to make an evaluation of their relative importance and weight. To
resort to equity means, in effect, to appreciate and balance the relevant
circumstances of the case, so as to render justice, not through the rigid
application of general rules and principles and of formal legal concepts,
but through an adaptation and adjustment of such principles, rules and
concepts to the facts, realities and circumstances of each case. As was well
stated by the 1977 Court of Arbitration, equity is “to be looked for in the
particular circumstances of the present case” (para. 195). In other words,
the judicial application of equitable principles means that a court should
render justice in the concrete case, by means of a decision shaped by and
adjusted to the relevant “factual matrix” of that case. Equity is here
nothing other than the taking into account of a complex of historical and
geographical circumstances the consideration of which does not diminish
justice but, on the contrary, enriches it.

25. For the notion of justice is not divorced from or opposed to that of
equity. Its having authority to apply equitable principles does not entitle a
court to reach a capricious decision in each particular case, but to reach
that decision which, in the light of the individual circumstances, is just and
right for that case. Equity is thus achieved, not merely by a singular
decision of justice, but by the justice of that singular decision.

26. This conception of equity, not as a correction or moderation of a
non-existent rule of law, but as a “lead rule” well adapted to the shape of
the situation to be measured, is the one which solves the fundamental
dilemma arising in all cases of continental shelf delimitation : the need to
maintain consistency and uniformity in the legal principles and rules
applicable to a series of situations which are characterized by their multiple
diversity.

5. Non-Existence of a Presumption in Favour of Equidistance

27. A second and related view has also been expressed. This gives to
equidistance the rank of a privileged method, enjoying, as it were, a
presumption in its favour, so that it must be applied unless those arguing

92
107 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

for the rejection of its application succeed in demonstrating that its results
are extraordinary, unnatural or unreasonable. If this demonstration fails,
then, according to this view, equidistance should be followed strictly.

28. Such a view does not correspond to the law on the subject, as it was
declared in the 1969 Judgment of the Court, developed in the 1977 Arbitrai
Award, codified at the Third Conference on the Law of the Sea and
established by the Parties to this case in their Special Agreement. Accord-
ing to all those precedents no method is privileged or enjoys the advantage
of a presumption in its favour. All are to be judged by their results and
applied only to the extent that they lead to an equitable solution.

29. The Court in 1969 not only found that equidistance was not obli-
gatory ; it also said that this method was likely to produce inequitable
results, particularly in delimitations between adjacent States. The Court
said that “in certain geographical configurations, which are quite frequently
met with, the equidistance method, despite its known advantages, leads
unquestionably to inequity” (para. 89, emphasis added). And in the opin-
ion of the Court this occurs when, for instance, there is a concave coast or a
straight coastline with the coasts of adjacent countries protruding imme-
diately at a right angle.

30. Furthermore, the 1977 Award asserted that between the notions of
equidistance and special circumstances there was not the relationship
which exists between a rule and its exceptions, and concluded that Article 6
of the 1958 Convention “gives particular expression to a general norm” of
customary law requiring the application of equitable principles, as
declared by the Court in 1969. Thus “the question whether another boun-
dary is justified by special circumstances is an integral part of the rule
providing for application of the equidistance principle” (para. 68). For this
reason the Court of Arbitration rejected the United Kingdom’s claim that
France had the onus of proving the existence of special circumstances. This
rejection signifies that there is no presumption in favour of equidis-
tance.

31. The law established in 1969 and 1977 was codified in the successive
texts of the Third Conference on the Law of the Sea. If one compares all
these texts with Article 6 of the 1958 Convention one cannot avoid the
conclusion that the emphasis has been displaced from equidistance to
equity, equidistance being simply one method available among others for
reaching an equitable solution. One of the main protagonists of the Con-
ference, commenting on the new accepted trends on the subject has stated
that at the Conference, in the various versions of the texts, there was a
“toning down of the significance attached to the median line principle '”.
This “toning down” has gone so far that the terms “equidistance” or

1 Cited in E. D. Brown, “The Continental Shelf and the Exclusive Economic Zone :
The Problem of Delimitation at UNCLOS III” in Maritime Policy and Management,
1977, 4, p. 400.

93
108 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

“median line” have disappeared altogether from the text of Article 83 of
the draft convention. According to the new text, in order to be applicable,
any method must ensure an equitable solution. Consequently, the onus
probandi, the need to demonstrate the attainment of an equitable result
rests equally on those who advocate equidistance as on those who advocate
a different method.

6. New Accepted Trends at the Third UNCLOS

32. Article 83 was recently incorporated in the draft convention, after a
long and protracted negotiation of what became one of the most difficult
“hard core” issues at the Conference. It is true that the significance to be
attached to Article 83 of the draft convention and to previous texts of the
Conference has been questioned on the ground that they cannot be con-
sidered as having already become rules of customary international law.

While the Special Agreement empowers and even obliges the Court to
take into consideration “the new accepted trends at the Third Conference
on the Law of the Sea”, both Parties have agreed that the Court is not
empowered to regard as principles and rules of international law new
trends merely because they have emerged during the Conference and have
gained a place in the negotiating texts. They have pointed out that accord-
ing to the Special Agreement they must be “accepted trends”, in other
words, they must be, or have become, rules of customary international
law.

33. There is, however, a certain difference between the Parties. While
Libya has maintained that position strictly, Tunisia has advanced a some-
what broader interpretation of the clause in the Special Agreement. It
observed that if such an interpretation is rigidly maintained, then “the
mention of this category in the Compromis would have added nothing to
the principles and rules of international law” and consequently, this ref-
erence to “new accepted trends” would have no legal effect at all. The
submission was then made by Tunisia that even if a new accepted trend
does not yet qualify as a rule of customary law, it still may have a bearing
on the decision of the Court, not as part of applicable law, but as an
element in the interpretation of existing rules or as an indication of the
direction in which such rules should be interpreted.

34. This is, in my opinion, the correct view of the Special Agreement and
the only one which assigns practical effect and an independent meaning
and significance to the reference to new accepted trends. As the Court has
said, “no method of interpretation would warrant the conclusion” that this
reference is meaningless (I.C.J. Reports 1971, p. 35).

94
109 CONTINENTAL SHELF (SEP. OP. JIMENEZ, DE ARECHAGA)

35. Therefore, it is legitimate to take into consideration that the whole
process of the Conference is indicative of a new accepted trend, which is to
minimize and “tone down” the role assigned to equidistance in Article 6 of
the 1958 Convention. These Conference texts signify that equidistance is a
method and not a principle ; that it is no longer a privileged method or one
having pride of place ; that, like all others, it must be judged by its success
in achieving an equitable solution, and, finally, that the application of
equidistance and of equitable principles are not to be viewed as two
distinct and successive phases, nor as requiring that equitable principles
are only to be resorted to after applying equidistance, in order to correct its
result. There is no such succession in time and the process must be a
simultaneous one. All the relevant circumstances are to be considered and
balanced ; they are to be thrown together into the crucible and their
interaction will yield the correct equitable solution of each individual
case.

36. Finally, the “toning down” of equidistance has been reflected in the
terms of the Special Agreement, which orders the Court to apply equitable
principles and does not mention equidistance at all. This is confirmed by
the fact that neither of the Parties invoked equidistance in its pleadings or
submissions.

PART II. THE CONCEPT OF NATURAL PROLONGATION

1. The Parties’ Contentions

37. The two Parties agreed in considering that the fundamental and
most relevant circumstance in this case consists in the fact that the shelf
area to be delimited constitutes the “natural prolongation” of their respec-
tive territories. The Parties also agreed in that they regard the concept of
“natural prolongation” as one primarily or exclusively determined by
certain physical facts, and their disagreement only appeared at the stage of
identifying the precise facts which constituted, for each of them, the
external evidence of that “natural prolongation”. For Tunisia, its “natural
prolongation” was evidenced by the geomorphology of the sea-bed, which,
so it was contended, reproduces the contours of the Tunisian coast, and by
its bathymetry, which provides identifiable limits to the shelf and shows
that its “natural prolongation”, with the sequence of shelf, slope and rise,
has an eastwards direction. Libya, on its part, invoked the geological
evidence and the theory of plate tectonics to demonstrate its contentions as
to the affinity between the shelf and the landmass to the south, and thus to
show that the “natural prolongation” occurred in a northerly direction.
This it confirmed by the existence of a fault line and a parallel “hingeline”
from west to east. Both Parties also coincided in considering “natural
prolongation”, thus understood, as the unqualified and controlling prin-

95
110 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

ciple or circumstance which should govern, above everything else, the
delimitation of the area.

38. As a result of the position adopted by the two Parties the Court was
placed in the situation of being asked to decide this case exclusively on the
basis of the conflicting scientific evidence presented to it by expert ocean-
ographers and geologists. Such evidence, even if very ably explained by the
Parties’ respective counsel, was not only of a very specialized and some-
what speculative character, but it was strongly contested by the other side,
not only as to its relevance and interpretation, but also in respect of the
facts alleged in support. The impression gained from the lengthy and
instructive discussion was that the criticism by each Party of the scientific
arguments presented by the other was far stronger and more convincing
than their affirmative contentions. The consequence was that the Court
could not decide the case either on the basis of the data of bathymetry and
geomorphology, disputed as to the facts and running contrary to judicial
precedents and State practice, nor on the basis of a sea-floor spreading,
tectonic plate and continental drift idea which is still a theory described by
one of its proponents as an “essay in geopoetry '”.

39. Moreover, the case could not be decided by choosing one of the rival
scientific theories of “natural prolongation” for a more fundamental rea-
son, namely that the basic premise upon which both Parties based their
cases is not, in my view, a correct one. This is so, in the first place, because
the legal concept of continental shelf, as defined by the applicable rules of
international law, is not determined by the facts of “natural prolongation”
as they have been understood and alleged by both Parties. It is incorrect,
furthermore, because continental shelf delimitation is not governed in an
unqualified and exclusive manner by such a notion of “natural prolonga-
tion”. For these reasons it must be concluded, as the Court has concluded,
that the decision of this case is to be based on legal principles, putting aside
the expert evidence submitted by the Parties.

2. The Legal Definition of Continental Shelf
not Based on Geology or Geomorphology

40. A definition of the continental shelf was made in Article 1 of the
1958 Convention, a provision which the Court considered in 1969 “as
reflecting, or as crystallizing, received or at least emergent rules of cus-
tomary international law relative to the continental shelf” (para. 63). As is
confirmed by its travaux préparatoires, this Article divorced the legal
definition of continental shelf from the geological and geomorphological

1 Hess, as cited by John Noble Wilford, The Mapmakers, New York, 1981,
p. 292.

96
111 CONTINENTAL SHELF (SEP. OP. JIMÉNEZ DE ARÉCHAGA)

facts which were at the origin of the doctrine. It is true, as the Court
recognized in 1969, that “the institution of the continental shelf has arisen
out of the recognition of a physical fact”, a physical fact present in “most
coastal States” (para. 95) (or “generally” as the United States press release
of 1945 says) namely, the existence of a species of platform which extends
around the continent until a substantial break in gradient occurs, leading
to abyssal ocean depths.

41. However, in the process of codification and progressive develop-
ment of this doctrine, an important element of contemporary codification
practice made itself felt ; the interaction between legal experts and gov-
ernmental observations. The International Law Commission and the 1958
Conference were confronted with the observations raised by certain States
on whose coasts the physical facts which were at the origin of the doctrine
presented themselves in a different manner or did not exist at all. Chile, for
instance, observed to the International Law Commission that that country,
as well as other Latin American States on the Pacific coast, had no con-
tinental shelf in the geomorphological or geological sense, or had only a
very narrow one owing to the fact that the sea reached oceanic depths at a
very short distance from the shore. It pointed out that a purely geological
definition of the continental shelf would discriminate against them.

42. In order to deal with this situation, and thus preserve the principle of
equality of coastal States, the International Law Commission, following
the recommendation of an Inter-American Specialized Conference, added
the test of “exploitability” in its final draft, which was discussed and finally
accepted at the 1958 Conference. It is clear from the text of Article 1 that
the right of the coastal State to explore and exploit the submarine areas
adjacent to its coast does not depend on the existence of a continental shelf
in the geological or geomorphological sense. This is confirmed by the
travaux préparatoires, for the International Law Commission commentary
to this Article states :

“the Commission decided not to adhere strictly to the geological
concept of the continental shelf. The mere fact that the existence of a
continental shelf in the geological sense might be questioned in regard
to submarine areas where the depth of the sea would nevertheless
permit of exploitation of the subsoil in the same way as if there were a
continental shelf, could not justify the application of a discriminatory
legal régime, to these regions.” (International Law Commission Year-
book, 1956, Vol. H, p. 297, subpara. 6.)

43. A similar point, which was also considered by the International Law
Commission and the Conference, was raised by Norway, which pointed
out that :

97
112 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

“There may be a stretch of deep water near the coast and areas of
shallow waters further out. That is for instance the case outside the
coast of Norway . .. It would obviously be most unfair if Denmark,
Germany, the Netherlands and the United Kingdom should share
between them the whole North Sea, while Norway should be excluded
because of the above-mentioned belt of deep water.” (International
Law Commission Yearbook, 1953, Vol. II, p. 261.)

44. This situation was covered when the purely bathymetrical definition
of the shelf, which had been adopted by the Commission in 1953, was
modified and enlarged in 1956 by the addition of the “exploitability” test.
In consequence, treaties were entered into by Norway with other countries
bordering the North Sea, according to whose terms the existence of the
Norwegian trough did not prevent Norway having sovereign rights in the
sea-bed beyond it. All this demonstrates that the facts of geomorphology,
as well as those of geology, did not constitute a controlling factor in the
legal definition of the continental shelf or in the recognition of sovereign
rights for its exploration and exploitation.

3. The 1969 Judgment and the 1958 Definition

45. Both Parties relied extensively on the use of the term “natural
prolongation” employed by the Court in several passages of its 1969
Judgment. They invoked this expression as constituting a sort of definition
of the concept and nature of the continental shelf. However, in the light of
the text and history of Article 1 of the 1958 Convention, the use by the
Court of that formula cannot be interpreted in the sense and with the
meaning attributed to it by the two Parties.

46. Such an interpretation would imply that the Court meant in 1969 to
reject the existence of a continental shelf and to deny the exercise of
continental shelf rights in those cases in which it could not be said (as in the
cases of Chile and Norway) that there was a “natural prolongation”, in the
geological or geomorphological sense, of the continental shelf beyond the
shore. That would be attributing to the Court the intention, by using these
terms, of revising or amending the definition contained in Article 1 of the
1958 Convention. This would be unthinkable, when it is also recalled that
the same Judgment proclaimed that Article 1 represented a rule of cus-
tomary international law. Consequently, it is not possible to interpret the
term “natural prolongation” in the 1969 Judgment as reintroducing into
the definition of the continental sheif the geological and geomorphological
elements which had been left out by the International Law Commission in
1956 and by the Conference in 1958.

47. If “natural prolongation” were to be interpreted as requiring the

existence of certain facts of geology or geomorphology in order to define
the nature of the continental shelf, this would entail that the existence of

98
113 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

those physical facts would be decisive for the recognition or denial of
continental shelf rights. The phrase, thus understood, would then put in
question and challenge rights possessed ab initio by virtue of Articles 1 and
2 of the Convention by those States which could not show the existence of a
“natural prolongation” from the geological or geomorphological point of
view. Far from making such a challenge, the Court in 1969 referred, in
general terms, to the right of “the coastal States” in respect of the “sub-
marine areas concerned” and described it as an inherent right. And it
clearly recognized that a physical shelf was not present in every case, since
it stated that “the continental shelf is, by definition, an area physically
extending the territory of most coastal States into a species of platform”
(para. 95, emphasis added).

48. This interpretation is confirmed by the fact that several Members of
the Court in 1969 had taken an active part in the work of the International
Law Commission and the Geneva Conference, where these questions were
discussed. Others, like Judge Ammoun, cited in his separate opinion the
following quotation from Professor Henkin :

“since geology was not crucial to the legal doctrine, it was difficult to
resist claims of coastal States that had no geological shelf, whether in
the Persian Gulf or in Latin America” (CJ. Reports 1969, p. 111,
footnote 5).

49. Since geomorphology and geology were not admitted as the tests for
the existence and recognition of the right to explore and exploit adjacent
submarine areas, they cannot constitute by themselves valid grounds or
applicable criteria for continental shelf delimitation. It would be contra-
dictory to recognize that Chile, Peru or Norway possess continental shelf
rights, as was done in 1958, despite the existence of deep depressions and
regardless of the geological identity of the rock strata, and at the same time
to deny these same rights to State A or to State B, setting a limit to their
continental shelf rights, on the sole ground of the existence of a trough or
depression, or by reason of the sea-bed contour, or of a certain change in
the geological composition of the subsoil.

4. The New Definition in the Draft Convention
at the Third UNCLOS Conference

50. It has been said that the Court’s formula of “natural prolongation”
received new vigour and a definite physical meaning by its inclusion in
Article 76 (1) of the draft convention at the Third UNCLOS. However, the
phrase “natural prolongation” was incorporated in Article 76 (1) because
its connotation — of a projection seaward from land — was of use in
justifying the extension of the continental shelf doctrine to comprise both

99
114 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

the continental slope and the continental rise “to the outer edge of the
continental margin”. Thus, the Court’s formula, with a meaning different
from that attributed to it in the 1969 Judgment, became a trump card for
the States which were successful in advocating at the Conference what has
been described as the “broad shelf school”.

51. But the new definition in Article 76 (1) provides, as a second alter-
native, that a coastal State is entitled to a continental shelf “to a distance of
200 nautical miles from the baselines” when the outer edge does not extend
to that distance. This second alternative has, even more categorically than
did Article 1 of the 1958 Convention, done away with the requirement of a
geological or geomorphological continental shelf, thus destroying the con-
ception of “natural prolongation” advocated by both Parties in this case.
What makes this conclusive is that, despite certain ambiguities in its
drafting, the alternative 200-mile definition is obviously made indepen-
dent of the criterion of natural prolongation : in the second part of the
formula, after the word or, the requirement of “natural prolongation”
ceases to apply. This new method of defining the continental shelf by
laying down an agreed distance from the baselines definitively severs any
relationship it might have with geological or geomorphological facts. The
continental shelf extends, regardless of the existence of troughs, depres-
sions or other accidental features, and whatever its geological structure, to
a distance of 200 miles from the baselines, unless the outer edge of the
continental margin is to be found beyond that distance.

52. Libya had advanced the argument that while the first part of Arti-
cle 76, paragraph 1, represents “existing customary law”, the second part
of the formula, the distance test, “is not customary law”. In my view, if a
distinction is to be made in respect of the legal status of the two criteria
in Article 76 (1), it would have rather to be in the opposite sense. The
extension of the shelf to the outer edge of the continental margin still
encounters some opposition, and on the question of a corresponding
payment of compensation by the States with a broad shelf a final con-
sensus has not yet been reached (Official Records, UNCLOS I, Vol. VIII,
p. 69). On the other hand, the criterion of “exploitability”, which was
designed to deal with the position of coastal States without a geological
shelf, but was dangerously open-ended, has now been replaced by a cri-
terion stated in terms of distance, which has the same objective. It is safe to
assert that today the distance test of 200 miles has abrogated the exploi-
tability test and consequently must be considered as having already crys-
tallized as a rule of customary international law.

53. This is so because the exploitability test was formulated in Article 1

100
115 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

of the 1958 Convention, which the Court considered in 1969 to represent a
rule of customary international law. A rule of customary international law,
judicially recognized as such, has been abrogated or superseded by a new
definition. In order to have this abrogating effect the new rule must
necessarily partake of the nature of a rule of customary law. Only a legal
rule may abrogate a pre-existing one. This is confirmed by the observation
that it would be unthinkable that a State would try to exploit the submarine
areas off the coasts of another State at less than 200 nautical miles from the
shore, claiming in doing so that such an area “lies beyond the edge of the
continental margin”. This leads to another accepted new trend at the Third
UNCLOS Conference.

5. The Exclusive Economic Zone and Shelf Delimitation

54. A confirmation of this conclusion and a further divorce from geo-
logical and geomorphological requirements results from another accepted
trend at the Third UNCLOS, which is the widespread recognition of an
Exclusive Economic Zone comprising the sea-bed and subsoil and the
superjacent waters up to 200 miles from the baselines. In that area the
coastal State has sovereign rights, for the purpose of exploring and
exploiting all natural resources. The provisions of the negotiating texts and
of the draft convention, and the consensus which emerged at the Confer-
ence, have had in this respect a constitutive or generating legal effect,
serving as the focal point for and as the authoritative guide to a consistent
and uniform practice of States. The proclamation by 86 coastal States of
economic zones, fishery zones or fishery conservation zones, made in
conformity with the texts of the Conference, constitutes a widespread
practice of States which has hardened into a customary rule, an irreversible
part of today’s law of the sea.

55. It is significant that in the 1977 Arbitration, France contended that
the 1958 Convention on the continental shelf was no longer in force by
reason of the consensus on the Exclusive Economic Zone arrived at at the
Third UNCLOS. The Tribunal could not accept this extreme view, but it is
difficult to deny that, at least in the case of continental shelves not
extending beyond 200 miles, the notion of the continental shelf is in the
process of being assimilated to, or incorporated in that of the Exclusive
Economic Zone (cf. Arts. 56 (3) and 60 of the draft convention).

56. As this process reaches its conclusion, the facts alleged by the Parties
to govern delimitation of their continental shelves will completely lose any
possible relevance or raison d’étre. At least in the large majority of normal
cases, the delimitation of the Exclusive Economic Zone and that of the
continental shelf would have to coincide. The reason is that both of these
delimitations are governed by the same rules, as is shown by the fact that at

101
116 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

the Third UNCLOS the corresponding Articles 74 and 83 are identical,
and have been discussed jointly. This being so, and since delimitation
would then comprise not just the sea-bed and subsoil, but also the super-
jacent waters for fishery rights and other uses, it would be even less
justifiable to take into account geological and geomorphological factors of
the sea-bed in order to effect such delimitation.

6. The Real Meaning of “Natural Prolongation”
in the 1969 Judgment

57. The question which remains to be answered is what was the positive
meaning attributed by the Court to the phrase “natural prolongation” used
in numerous passages of the 1969 Judgment. The insistent use of this
expression by the Court arose from the fact that all the Parties in the North
Sea Continental Shelf cases constantly relied upon the principle of natural
prolongation (para. 43 of the Judgment). But the Court, while accepting
the concept, did not agree with the interpretation given to it by the Parties.
In rejecting the Danish and Dutch interpretation, the Court gave a clear
idea of its own understanding of the formula, when it stated, in the crucial
paragraph 44 of the Judgment :

“As regards equidistance, it clearly cannot be identified with the
notion of natural prolongation or extension, since, as has already been
stated (paragraph 8), the use of the equidistance method would fre-
quently cause areas which are the natural prolongation or extension of
the territory of one State to be attributed to another, when the con-
figuration of the latter’s coast makes the equidistance line swing out
laterally across the former’s coastal front, cutting it off from areas
situated directly before that front.”

58. This statement makes it quite clear that for the Court “natural
prolongation” is a concept divorced from any geomorphological or geo-
logical requirement and that it merely expresses the continuation or
extension seawards of each State’s coastal front. It means that the con-
tinuation of the territory into and under the sea has to be based on the
actual coastline, as defined by the land frontiers of the States in question,
since it is from the actual coastline of each State that the land territory
continues into and under the sea. Consequently, the basic corollary of
“natural prolongation” is the need to avoid the “cutting-off” of areas
“situated directly before that front”. For this reason the Court referred in
paragraph 95 to the fact of “the appurtenance of the shelf to the countries
in front of whose coastline it lies” and in paragraph 58 it reiterated that “a
lateral equidistance line often leaves to one of the States concerned areas
that are a natural prolongation of the territory of the other”.

59. Thus, the meaning attributed to the expression “natural prolonga-

102
117 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

tion” in the 1969 Judgment, when properly analysed, is that it signifies the
continuation or extension of the coastal front of the territory of every
coastal State into and under the sea, “via the bed of its territorial sea”
(para. 43), a territorial sea to which all maritime States are entitled. This
“natural prolongation” exists in every case, whatever may be the charac-
teristics of depth or geological composition of the sea-bed. To enjoy
continental shelf rights all that a State needs is a coastal front to the sea,
which is then naturally prolonged “via the bed of the territorial sea”. And
the “most natural prolongation” is that which continues or extends more
directly into the sea and is not “cut off” by the extension or prolongation of
the coastal front of another State. From this meaning of “natural prolon-
gation” results the corresponding principle which both Parties in this case
have recognized to be the other side of the coin of the principle of “natural
prolongation” : the principle of “non-encroachment”, a fundamental prin-
ciple of equity to be examined later.

7. Geological Structure in the 1969 and 1977 Judgments

60. It is true that, as pointed out in the hearings, the Court referred, in
the operative part of the 1969 Judgment, to “the physical and geological
structure, and natural resources, of the continental shelf areas involved”.
But these factors were not mentioned under letter (C) of the operative part,
which prescribes the principles and rules of international law governing the
delimitation of shelf areas, but were mentioned separately of “natural
prolongation”, under letter (D), which indicates the factors which may “be
taken into account” by the Parties “in the course of the negotiations”. In
other words, these physical and geological facts were not placed by the
Court among the legal rules which govern or determine delimitation, as has
been claimed in this case, but as factors which the Parties may take into
account in negotiating their delimitation.

61. And there is a world of difference between the two situations.
Physical features such as depressions, channels, sea-bed contours, geo-
logical structure, etc., cannot by themselves govern the determination of
continental shelf boundaries. Likewise, natural land features, such as
valleys, mountain crests, river thalwegs, etc., cannot by themselves deter-
mine boundaries between States. We would otherwise retrogress to the
dangerous doctrine of “natural frontiers”, which Rousseau demolished
when he observed “qu’elles aboutissaient à faire de l’ordre politique l'ouvrage
de la nature”. Those natural features can only become dry land boundaries
when they have been subject to human occupation or have been agreed in
treaties entered into by the neighbouring States as constituting their
political frontiers.

62. But the area of the sea-bed and subsoil is barren of human popu-
lation and cannot be acquired by occupation ; consequently, the political

103
118 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

and historical factors which have led to the establishment of natural
frontiers on land are not present in the sea-bed. This means that conti-
nental shelf boundaries based solely on geological or geomorphological
facts may only result from the agreement of the interested States, since
there is no rule of international law prescribing the use of these features as
dividing boundaries. And this is the reason for the distinction in para-
graphs (C) and (D) in the operative part of the 1969 Judgment.

63. Likewise, the 1977 award refused to accept the Hurd Deep Fault
Zone as a “feature capable of exercising a material influence on the
determination of the boundary” (para. 107), stating that this feature “is
placed where it is simply as a fact of nature, and there is no intrinsic reason
why a boundary along that axis should be the boundary” (para. 108).
Moreover, the Court of Arbitration added that :

“to attach critical significance to a physical feature like the Hurd
Deep-Hurd Deep Fault Zone in delimiting the continental shelf
boundary in the present case would run counter to the whole ten-
dency of State practice on the continental shelf in recent years”
(para. 107).

64. When referring to State practice the Court of Arbitration probably
had in mind not just the agreements made by Norway which disregarded
the Norwegian trough, but also unilateral acts such as decrees and con-
cessions which have been granted by numerous States which disregard
deep depressions, including trenches and submarine canyons, and incor-
porate them as part of their shelf. This is the case, for instance, of the Soviet
Union, Norway off its northern coast, Brazil, Venezuela, Canada and the
United States off the coasts of California. (Prescott, The Political Geo-
graphy of the Oceans, pp. 159-160 and E. D. Brown, The Legal Régime
of Hydrospace, pp. 18 ff.)

PART III. THE EQUITABLE PRINCIPLE OF NON-ENCROACHMENT

65. In the operative part, letter (C), of its 1969 Judgment, the Court
proclaimed the principles of “natural prolongation” and “non-encroach-
ment” as two correlative principles, when it concluded that delimitation
had to be effected :

“in such a way as to leave as much as possible to each Party all those
parts of the continental shelf that constitute a natural prolongation of
its land territory into and under the sea, without encroachment on the
natural prolongation of the land territory of the other” (para. 101 (C)

(1)).

66. It is common ground between the Parties that there are here two

104
119 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

fundamental and complementary conditions, since the principle of non-
encroachment is inherent in the principle of natural prolongation ; the two
are inextricably interwoven, and one is a reflection of the other. However,
the Parties have expressed a fundamental disagreement as to how the
principle of non-encroachment ought to be interpreted.

1. The Parties’ Divergent Interpretations

67. Libya understands it is a prohibition upon either State crossing over
to the other side of the appropriate line running seaward from the terri-
torial sea-boundary, stating as the rationale of the principle, thus under-
stood, that coastal States will not tolerate a sea-bed area immediately in
front of their coasts being used by a foreign power.

68. Tunisia has taken issue with this interpretation, observing that by
means of a series of semantic shifts, Libya

“goes on to deduce a prohibition against encroachment on areas of
continental shelf in front of the coasts of Libya, which, I think it will
be agreed, is something quite different from the encroachment on the
natural prolongation... Yet the Libyan Reply systematically uses the
expression, encroachment of the shelf in front of the Libyan coasts, as
synonymous with encroachment on the natural prolongation of
Libya’s land territory”.

2. The Correct Interpretation of the Principle

69. The solution of this disagreement is to be found in the meaning
which is to be attributed to the correlative notion of “natural prolonga-
tion”. If, as stated above, the Court used this expression to describe the
continuation of the coastal front of every coastal State, and not with a
geological or geomorphological meaning, then the “non-encroachment” in
front of and close to the coasts of a State is the correct interpretation of the
principle. It is true that there may be geographical configurations in which
a boundary line cannot avoid “cutting across” the coastal front of one
State or of both. But the principle of non-encroachment, being an equi-
table principle, is not a rigid one. It admits a corrective element, which is
the factor of distance from the coast. If the above-described geographical
situation occurs, then the “cutting-off” effect should be allowed to take
place at a point as far as it may be possible to go, seawards, from the coastal
front of the affected State.

70. This interpretation is confirmed by the very raison d’être of the
institution of the continental shelf as it appeared and developed in the
middle of the present century. The reason which explains the wide and
immediate acceptance of the doctrine was not so much the possibility it
offered of exploiting the natural resources of the shelf, but rather the fact
that it authorized every coastal State to object to the exploitation of the

105
120 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

sea-bed and subsoil in front of its coasts being undertaken by another
State. At that time, only a handful of industrialized States possessed
the technology required for such exploitation. Yet, all coastal States ac-
cepted the doctrine without hesitation mainly because of its negative
consequences, namely, that it prevented a rush and grab for sea-bed
resources being undertaken by a few States on the basis of the Grotian
dogma of “freedom of the seas”. It is for this reason that the 1958 Conven-
tion does not subordinate the acquisition ab initio of sovereign rights to
actual exploitation or occupation, or even to a proclamation of these
rights.

3. The German Proposal and the Reaction at the
1958 Conference

71. It is instructive in this connection to recall what happened at the
1958 Conference when the Federal Republic of Germany proposed to
declare that “anyone is free to explore and exploit the subsoil of the sea
outside the territorial sea” (Official Records, Vol. VI, p. 126). This proposal
was forcefully and unanimously rejected. The strongest objection was
made by the delegate from Peru, who pointed out that such a view:

“would produce the absurd consequence that a State could exploit the
natural resources of the continental shelf at a short distance from the
coast of another State” (ibid, p. 11).

Other delegations criticized the proposal on similar grounds, observing
that :

“it was necessary for a coastal State to protect itself against the
possibility that other States might undertake exploitation of its con-
tinental shelf at short distance from its shores” (Lebanon, p. 14)

“There would be a great ado if one State started exploiting the
submarine resources within a very short distance of the coast of
another State without first obtaining its agreement” (Brazil, p. 36)

since

“One of those realities [of international life] was that no State could
countenance the presence of foreign installations in a zone immedi-
ately opposite its coastal defences.” (Argentine, p. 43.)

In a similar vein, it was pointed out that :

“the exploitation of the natural resources of the continental shelf was
generally connected with the erection of permanent installations
which necessarily entailed the exercise of a State’s authority” (USSR,
p. 20)

106
121 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

and such exploitation

“might — particularly where the extraction of petroleum was con-
cerned — interfere with deposits within that territory. Both legally and
politically, the presence of installations belonging to a foreign State
would constitute a constant threat to the security of the coastal State”
(Vietnam, p. 24).

72. Already the Truman Proclamation had invoked in its preamble the
need for “self-protection” which “compels the coastal nation to keep close
watch over the activities off its shores which are of the nature necessary for
the utilization of these resources”. There was, therefore, an immediate and
almost instinctive rejection by all coastal States of the possibility that
foreign States, or foreign companies or individuals, might appear in front
of their coasts, outside their territorial sea but at a short distance from their
ports and coastal defences, in order to exploit the sea-bed and erect fixed
installations for that purpose.

73. Thus, the fact that a trough or ridge may appear close to the shore-
line of a State, or that the strata of rock may be similar to that of certain
sediments in another land territory, cannot be valid grounds for attributing
a certain area of shelf to a certain State to the detriment of another “in
front of whose coastline it lies” (para. 95 of the 1969 Judgment). This is the
proper meaning of “natural prolongation” and of the correlative principle
of “non-encroachment” of that natural prolongation.

4. The Principle of Non-Encroachment and Its Effects
in the Present Case

74. In the light of the foregoing, none of the extreme positions claimed
or suggested by the Parties — neither the prolongation northward of the
terminal point of the land boundary, nor the eastward line determined by
the crest of the ridges — could be accepted as compatible with the basic
principles of international law on continental shelf delimitation, as
expressed in the concepts of “natural prolongation” and “non-encroach-
ment”.

75. Encroachment is particularly to be avoided when a proposed boun-
dary line brings a foreign State too close to the main ports of the other. The
reason is that, as Judge Jessup recalled in his separate opinion in the North
Sea Continental Shelf cases, quoting from the German pleadings :

“From the point of view of exploitation and control of such sub-
marine areas, the decisive factor is not the nearest point on the coast,
but the nearest coastal area or port from which exploitation of the
seabed and subsoil can be effected. The distance of an oil, gas or
mineral deposit from the nearest point on the coast is irrelevant for
practical purposes, even for the laying of a pipe-line, if this point on
the coast does not offer any possibilities for setting up a supply base

107
122 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

for establishing a drilling station or for the landing of the extracted
product.” (LCJ. Reports 1969, pp. 67-68.)

The two boundaries suggested in the Memorials of the two Parties come
too close to the main ports which are the basis for their respective offshore
exploitation : Sfax on the Tunisian coast and Tripoli on the Libyan
one.

76. It is therefore necessary to examine what other principles and rules
of international law on the subject and what other relevant circumstances
of fact in the case may lead to an intermediate solution that, while res-
pecting the principles of “natural prolongation” and “non-encroach-
ment”, as properly understood, will effect a more appropriate and equi-
table balance between the respective claims and interests of the Parties.

PART IV. Historic FISHERY RIGHTS
1. Existence of Historic Fishery Rights

77, A circumstance which is relevant to the shelf delimitation which is
the object of the present case is the existence of historic rights with respect
to sponge fisheries. Historic fishery rights have been invoked by Tunisia
with respect to two kinds of fishery : the sedentary sponge fisheries and the
fisheries which are conducted by means of fixed installations in the shallow
waters close to the Kerkennah Islands and the El-Biban shoals. Only the
first type of fishery is relevant for the delimitation, since the second takes
place too close to the shore to have any influence upon it. The existence of
Tunisian rights over sponge fisheries has not been questioned by Libya.

78. While Tunisia has been the party emphasizing the relevance of
historic rights with respect to sponge fisheries, Libya has also demon-
strated that it has possessed and exercised rights identical with those of
Tunisia with respect to the sponge fishery off the coasts of Tripolitania.
The Tripolitanian fishermen have exploited sponge banks off their coasts
at least since 1893 and rights of surveillance over sponge fisheries were
invoked and exercised off the Tripolitanian coast after the Italian annex-
ation in 1911. When becoming the authority in Tripolitania, the Italian
Government regulated sponge fisheries off that coast in a manner analo-
gous to that adopted by the French Protectorate in Tunisia. And these
rights over sponge fisheries were recognized by the French Protectorate,
whose authorities stated that the two “nations concerned had the strict
right of exercising surveillance over the sponge-banks situate well outside
the boundaries of their territorial waters”.

2. Relevance of Historic Fishery Rights to
Continental Shelf Delimitation

79. Generally speaking, the existence of historic fishery rights is a cir-
cumstance which is relevant to continental shelf delimitation. The travaux

108
123 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

préparatoires of Article 6 of the 1958 Convention, where the notion of
“special circumstances” originated, leave no doubt that fishery rights in
general were then considered as one of the “special circumstances” which
might influence delimitation. (Official Records of the 1958 Conference,
Vol. VI, p. 93.)

80. The argument has been propounded that the 1958 Convention on
the Territorial Sea and the Continental Shelf, as well as the Third
UNCLOS draft convention refer to historic rights only in the context of
territorial sea delimitation, but not of that of the continental shelf. The
explanation, however, is simple. It is not that historic rights are irrelevant
or unimportant for shelf delimitation, but that there are, in this case,
besides the historic factor, other special circumstances equally relevant.
Consequently, the historic factor is included in the wider formula of
“special circumstances”, as the travaux préparatoires of 1958 indicate, and
is undoubtedly contained within the broad terms of the Special Agree-
ment : “the relevant circumstances which characterize the area ”’.

81. And the relevance of historic rights with respect to sponge fisheries
is decisive in this particular case, when account is taken of the fact that the
taking of sponges adhering to the sea-bed constitutes a form of exploita-
tion of one of the natural resources of the shelf, according to Article 2,
paragraph 4, of the Continental Shelf Convention — a provision which the
Court found in 1969 to be part of customary international law. The taking
of sponges, as of other living resources permanently attached to the sea-
bed at the harvestable stage was considered by the International Law
Commission and defined in the 1958 Convention, not as a sedentary
fishery, but as a form of shelf exploitation, as much as is the extraction of
oil or of gas. Consequently, the taking of sponges in the area was really an
exploitation of shelf resources, which began in Tunisia and Tripolitania in
the last century, and continued into the present century, thus long ante-
dating the Truman proclamation.

82. It has been contended, however, that since continental shelf rights
are defined as rights owned “ab initio”, then those historic rights which
were acquired before the Truman proclamation should be set aside, and
denied the nature of continental shelf rights, since they were not acquired
“ab initio” but from occupation. This objection is fallacious. Naturally,
rights with respect to sponge fisheries could only result from occupation
because the “ab initio” doctrine did not appear until 1958. It was adopted at
the Geneva Conference as a means of protecting coastal States which had
not made a proclamation of their continental shelf rights and had no means
of exploring or exploiting their resources. However, when the continental
shelf doctrine was first enunciated, its proponents, including President
Truman’s advisers, found support in the existence of historic fisheries
involving exploitation of natural resources attached to the sea-bed. A new

109
124 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

legal concept, consisting in the notion introduced in 1958 that continental
shelf rights are inherent or “ab initio”, cannot by itself have the effect of
abolishing or denying acquired and existing rights. That would be contrary
to elementary legal notions and to basic principles of intertemporal law. It
would be absurd to contend that the Truman proclamation or the 1958
Convention abolished or disregarded pre-existing rights over the conti-
nentai shelf, when, on the contrary, they embodied or assimilated those
rights into the new doctrine.

83. Other minor objections have been made with respect to the rele-
vance and decisive character which must be attributed in this case to the
taking of sponges from the sea-bed. It has been pointed out that these
activities were carried out not by nationals of the Tunisian Protectorate or
of Tripolitania but mostly by foreigners. This does not mean, however, that
sovereign rights of the respective countries are not involved. Gas and oil
exploration and exploitation are likewise generally carried out by foreign
companies ; yet no one denies the sovereign rights of the coastal State
which has granted the required concessions, licences or permits for those
activities.

84. A similar objection is that sponge taking was only carried out in
certain sparsely located banks. However, mineral resources are also
extracted from certain sparsely located wells, but the sovereign rights of
the coastal State extend to the whole area over which exploration permits
are granted. In both cases what determines the political and economic
interests of the coastal State is the control over offshore resources, rather
than the control over an area.

3. The Tunisian Claim for a ZV 45° Line

85. The conclusion to be drawn from the foregoing is that there was in
the area to be delimited an exploitation of shelf resources which was
carried out in parallel by two sovereignties : Tunisia under French pro-
tectorate and Tripolitania under Italian administration. It was a conti-
guous shelf exploitation, and, as a consequence of the frequent problems
that inevitably arose, a modus vivendi was reached, which constituted in
fact a tacit shelf delimitation.

86. Tunisia has claimed that the area of its historic fishery rights over
sponges “is defined laterally on the side towards Libya by the line ZV 45°”
(Submission I.2). It is true that in 1902 the Tunisian authorities claimed
that line as the easternmost lateral limit of their “zone de surveillance” over
sponge fisheries. The record presented to the Court explains, however, the
reason why the French authorities claimed the ZV 45° line before 1910 but
dropped that claim in 1911 and afterwards. When the French authorities
thought, before 1910, that the land frontier would follow the Wadi Fassi,
the prolongation of that boundary into the sea had a 45° angulation (as

110
125 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

shown by Map No. 8 in the Libyan Memorial). But when the French
authorities succeeded in 1910 in extending the land frontier to the Wadi El
Mokta, the prolongation of that new land frontier into the sea had a
different and considerably smaller angulation and the thesis of the pro-
longation of the land frontier was no longer convenient to Tunisia. This
was the reason given by the Resident-General in Tunisia in a letter to Prime
Minister and Foreign Minister Doumergue, to justify his recommendation
not to insist on the 45° line based on the prolongation of the land fron-
tier.

4. The Orfeo Incident : French Protest and Italian Answer

87. The record also shows that after the annexation of Tripolitania by
Italy, the Tunisian claim for a ZV 45° line was consistently and firmly
opposed by the Italian authorities, and that such opposition resulted in the
establishment of a régime different from that of the ZV 45° line. An
important part of that record is the correspondence filed by Libya relating
to the incident between Tunisian and Italian authorities arising out of the
arrest of three Greek fishing boats possessing Tunisian fishing licences,
made by the Italian torpedo boat Orfeo on 26 August 1913. The arrest was
made at a point 11° 42’ 14” east of the Greenwich meridian, that is to say,
within the ZV 45° line claimed by Tunisia.

88. The French authorities, through their embassy in Rome, presented
to the Italian Foreign Ministry a formal protest stating that “the sponge-
bank where the Greek vessels were carrying on their trade belongs to the
body of banks over which the Tunisian Fisheries Department exercise
surveillance”. In consequence, the Note Verbale added that :

“the Government of the Protectorate can in these circumstances only
maintain its assertion of its rights, which are directly infringed by the
seizure of vessels fishing with a Tunisian licence on a bank recognized
to be Tunisian”.

89. The answer to the preceding communication was given by the
Italian Government in a Note Verbale of 2 October 1913 which reads
in part :

“Since a delimitation must exist between the water, and the sponge-
banks thereof, appertaining to the Regency of Tunis and those of
Tripolitania, the Ministry of Colonies has instructed the Governor of
Tripolitania, for the time being and awaiting for the question to be
settled by agreement between the two Governments, to limit his
jurisdiction on sponge-fishing westwards within a straight line that,
starting from the coastal boundary point with Tunisia, extends on the

111
126 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

sea normally to the direction of the coast at that point. That line,
bearing approximately north-northeast, would appear provisionally
to settle the question in the most natural and equitable way without
compromising, even in a seaward direction, the rights of the two
Governments over the sponge-banks appertaining to each of them
respectively.”

90. The record does not contain any reply from the Tunisian authorities
to this communication. However, Libya has furnished two documents
from French archives which explain why no answer was given. The first is
an official letter of 2 February 1914 from the Resident-General in Tunis to
the French Prime Minister and Minister for Foreign Affairs, M. Doumer-
gue, referring to the arrests made by the Orfeo, where he examines “the
position of the point of capture in relation to the imaginary line marking
the maritime boundary of Tunisian and Tripolitanian waters”. The Resi-
dent-General compares the ZV 45° line with the Italian line “starting from
the Tunisian frontier and extending seawards NNE at right angles to the
direction of the coast at this point”, asserting that “the discrepancy of 23°
between the Italian and Tunisian delimitations is of some importance”.
This constitutes a significant recognition by the French authorities of the
fact that the perpendicular line proposed by the Italian administration was
that of 22°. The official Note concludes by saying :

“There would thus be an evident advantage if the French Govern-
ment could cause the Royal Government to accept as the limit of the
Tuniso-Tripolitan waters a line starting from the frontier pyramid
taking the direction N 45° E, but the question is not sufficiently im-
portant for us to insist on the maintenance of a possession which is
not supported by tangible signs, and we can do no more than refer to
Your Excellency’s judgment as to whether one should not accept as
the offshore boundary (‘frontiére de mer’) the line perpendicular to the
general direction of the coast which has been indicated by Italy, as
being a rational solution to a dispute which it is important to settle
and for which the evidence is not sufficiently precise.”

91. Libya has also presented a personal letter dated 29 January 1914,
from the Resident-General to the French Prime Minister and Minister for
Foreign Affairs, M. Doumergue, where, referring to the preceding official
communication, he states that he had examined with Navy experts

“the question of our maritime frontier, and we agreed that it was
necessary to modify the conclusion in the report which is to be
addressed to you, and which, when in the form of a minute, called on
you to insist that our line should be made to prevail over the Italian
line”.

112
127 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

The following reason is stated in explanation of this change of posi-
tion :

“Our line was roughly the prolongation of our land frontier. How-
ever, when that frontier was modified by the Treaty of Tripoli, we did
not prolong the new line seaward. If the Italians were to draw it, the
line would be more advantageous to them than a perpendicular to the
general direction of the coast. It would give them part of the channel
leading to the pocket of 3-metre depths, whereas at present they
regard as theirs part of the pocket, but none of the channel.”

5. The French-Italian “Modus Vivendi”

92. In the light of these documents, counsel for Libya contended in the
hearings that “the situation which had arisen following the Italian Note of
1913 and the silence observed by the Franco-Tunisians” signified that the
provisional solution suggested by Italy “had been tacitly accepted by the
Franco-Tunisians”. Undoubtedly the French Prime Minister and Minster
for Foreign Affairs, advised by the French Resident-General in Tunisia,
was fully competent to decide not to insist on the diplomatic claim which
had been submitted to the Italian Government and thus tacitly accept the
Italian proposal. A further indication of the tacit acceptance of the Italian
line is that the Italian instructions of 16 April 1919, on the surveillance of
maritime fishing in the waters of Tripolitania and Cyrenaica provided in
Article 3 that :

“As far as the sea border between Tripolitania and Tunisia is
concerned, it was agreed to adopt as a line of delimitation the line
perpendicular to the coast at the border point, which is, in this case,
the approximate bearing north-northeast from Ras Ajdir.” (Emphasis
added.)

It is significant that on the frontier of Cyrenaica with Egypt the same
Article establishes a line east-north-east but no mention is made of the
existence of an agreement.

93. Counsel for Tunisia, in replying to these contentions, pointed out
that the Italian Instructions of 1919 created on each of the Tunisian and
Egyptian borders of Libya a buffer zone in the following terms :

“I establish that the lines of delimitation mentioned above be
moved in a direction parallel to their own selves, until the first shail
have as its point of origin Ras Makabez! ... In such a way there will
be two areas of about eight miles each, the one toward Tunisia,
included within the two lines with a NNE direction, passing one
through Ras Ajdir and the other through Ras Makabez ; and that
toward Egypt...”

1 Ras Makabez is located seven nautical miles east of Ras Ajdir.

113
128 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

Counsel also stated that :

“Tf one carefully examines the extent of this buffer zone and com-
pares it with the ZV 45°, it will be found that the zone in question
covered almost the whole sea area adjacent to the ZV 45° line.”

He then argued that :

“in its concern to avoid conflicts with Tunisia, Italy attributed to the
area claimed by its neighbour a special nature, a nature different from
that of the waters over which the Italian authorities intended to
exercise their full sovereignty. In that area Italian ships could not seize
foreign fishing boats.”

In conclusion, he asserted that :

“these instructions were the result of the firm attitude of the French
authorities, and the subsequent desire of Italy to find what it called a
provisional solution, a compromise. This compromise, which was
lacking in certitude but was nevertheless fruitful, since no further
incident occurred, was to continue until the end of the second world
war.”

94. In analysing more deeply the nature of what counsel for Tunisia had
described as a provisional solution or a compromise which lasted until the
end of the Second World War, counsel for Libya observed that the Italian
Instructions provided with respect to the buffer zones that :

“in these two areas, although the conditions for prohibition of fishing
and the right to perform an on board inspection are still standing, the
boats flying a foreign flag and not in possession of the Italian mari-
time authorities’ permit shall not be seized, but rather ordered away,
unless the position of the site within the borders where such boats
were fishing illegally can be demonstrated in an irrefutable manner
even afterwards”.

Consequently, the buffer zone was not excluded from Italian naval juris-
diction, since foreign boats could be detained and inspected and ordered
off, “which certainly presupposed that the waters of the buffer zone were
Italian waters, because you may only order a vessel out of a zone which
belongs to you”. Furthermore, if the incident had occurred beyond all
doubt within the limits, the Italian naval units “were under orders to
proceed to seizure ; the tolerance was not to continue if the location of the
infringement had been irrefutably established”.

95. Both Parties thus recognized before the Court that a de facto com-
promise, a provisional solution or “modus vivendi” had been achieved by
means of the buffer zone. But clearly the buffer zone proclaimed in the
Italian Instructions presupposed the existence of Tripolitanian and not
Tunisian jurisdiction up to the end of that buffer zone, that is to say,

114
129 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

laterally as far as the line perpendicular to the coast at Ras Ajdir, and
seawards as far as the more removed sponge banks. A map furnished by
Tunisia shows that the dense sponge banks off the Tripolitanian coast
extended to the north well beyond the 34th parallel. Consequently, that
perpendicular line extending beyond the 34th parallel constituted the
compromise or the “modus vivendi” for the delimitation of the surveillance
of sponge fishing in the area. Other documents emanating from the French
authorities in Tunisia recognized that such surveillance of sponge fishing
was effectively exercised by the Italian authorities in Tripolitania, since in
these documents reference is made to “the frequent presence of Italian
torpedo boats, which pursue (foreign fishermen) as soon as they cross the
boundary”.

6. Equitable Reasons which Compel Respect for
the Historic Lateral Delimitation

96. There are fundamental reasons of equity and of law which compel
respect for the historic lateral delimitation established along the perpen-
dicular line NNE from Ras Ajdir. The most important of these equitable
reasons was forcefully stated by counsel for Tunisia, in the following
terms :

“where any part of that zone has from time immemorial been exclu-
sive to one of the coastal States, as in the case of Tunisia, the equities
surely demand that it remain so ; not just for the positive reason of
respecting those rights as they are today, but even more so because it is
unthinkable that an area which has from time immemorial been
exclusive to one State should as a result of the determination of the
boundary of sea-bed and subsoil rights, now and henceforward
become the exclusive fishery of the other State. That result cannot be
right in law or equity.”

97. Itis obvious that this elementary principle of equity cannot operate
only to the benefit of Tunisia, but must be equally valid for both Parties. As
has been well said, “the principle in equity is that if a party invokes an
argument against the opposing party, the argument must carry equal
weight against itself”. It is therefore unthinkable, to borrow the term used
by Tunisian counsel, that the delimitation which existed during the colo-
nial period should be revised or abolished and that a part of the shelf which
was for almost 50 years exploited and controlled by Tripolitanian autho-
rities should be transferred to Tunisia. Italian torpedo boats excluded from
that area Tunisian sponge-fishing boats or foreign sponge fishermen pos-
sessing a Tunisian licence. This exclusion constituted an act of sovereignty
and, as was contended in the Tunisian pleadings, such exploitation and

115
130 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

control resulted in the acquisition and exercise of sovereign rights over the
continental shelf.

98. Both Parties were asked the question whether, if one Party has
demonstrated possession of historic fishery rights over sedentary species in
certain specified waters, it is possible to attribute to the other Party the
exclusive right to exploit the mineral resources of the shelf below the
sea-bed to which the sedentary species are attached. Tunisia, after in-
voking paragraphs 1, 2 and 4 of Article 2 of the 1958 Convention, and
Article 77 of the draft convention on the Law of the Sea, answered
in the negative :

“Tt follows that, in the modern Law of the Sea, the exclusive rights
of fishing of sedentary species, and the exclusive rights over the
non-living resources, cannot be dissociated and belong to two differ-
ent States. Such a division would furthermore involve insurmountable
difficulties in practice.”

Libya, for its part, answered the same question in the affirmative,
because :

“to allow an existing fishery for sedentary species to set the geogra-
phical limits of the continental shelf boundary would be... tanta-
mount to allowing prior rights, acquired by a form of occupation, to
override the inherent de jure rights of a coastal State based upon
natural prolongation”.

After indicating several instances in State practice of “vertical superim-
position of rights”, it pointed out that the incompatibility between fishing
for sedentary species and oil-drilling might be avoided by directional
drilling, by abstention from oil drilling or by compensation for the loss of
catch.

99. The uniqueness which characterizes the sovereign rights of the
coastal State with respect to all the natural resources of the shelf indicates
that a dual régime, as suggested by Libya, cannot result from the rules of
general international law. There may be examples in State practice of a
“vertical superimposition of rights” but they can only result from special
agreements accepted by the Parties and are not imposed by the general
rules of international law which the Court is called upon to identify as
applicable in the present case. Consequently, it is impossible to accept that,
if one of the Parties to this case has demonstrated the existence of historic
fishery rights over sedentary species in certain specified waters, the other
Party can be recognized as having the exclusive right to exploit the mineral
resources of the shelf below the sea-bed to which the sedentary species are
attached. These equitable considerations determine the impossibility of
accepting as the line of continental shelf delimitation in that area any line
other than a straight line starting from Ras Ajdir and extending seawards
beyond the 34th parallel perpendicularly to the direction of the coast at
Ras Ajdir.

116
131 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

7. Reasons of Law which Compel Respect for
the Historic Lateral Delimitation

100. Most African States, including the Parties to the case, have ac-
cepted the status quo of colonial boundaries at the time of independence.
According to the resolution adopted by the African States in Cairo in 1964,
the Assembly of African Heads of State and Government, “solemnly
declare that all Member States pledge themselves to respect the borders
existing on their achievement of colonial independence”. The terms of this
pledge determine its applicability not just to those borders established by
treaty or existing on dry land. It also includes boundary arrangements and
even tacit compromises concerning maritime frontiers which divide zones
of sedentary fisheries.

101. Tunisia has accepted that the principle of stability of African
colonial frontiers as well as the principle of State succession apply to this
delimitation, despite the fact that this is a maritime boundary, and one not
established by treaty but resulting from the conduct and the history of the
relations of the former colonial powers. In the memorandum the Govern-
ment of Tunisia circulated to the Secretary-General of the United Nations,
the OAU and the Arab League, and to diplomatic missions accredited in
Tunis, on 3 May 1976, referring to the ZV 45° line, it stated :

“5. On this basis, and according to the preamble and Article II of
the Charter of the Organization of African Unity which stipulate that
African States should recognize the borders resulting from their
independence, and the stability of such borders, the sea boundaries
delimitation referred to in paragraph 2 is unalterable.

6. On the other hand, international practices and jurisprudence are
unanimous in that the new State which replaces the colonial power (as
is the case with both Tunisia and Libya) is bound, and shall continue
to be bound, by any agreements fixing boundaries which may have
been concluded by the colonial power.”

It results from the foregoing that both principles of international law
invoked by Tunisia in the above memorandum, namely, the colonial uti
possidetis agreed by the African States and the principles of State succes-
sion compel respect for the delimitation resulting from the French-Italian
“modus vivendi”.

102. The objection is made that the record does not contain positive
evidence of the express acceptance by the authorities of the Tunisian
Protectorate of the perpendicular line. This is true, but this is not the
crucial point. The decisive and material points are, first, that there is
conclusive evidence that the Italian authorities exercised effective surveil-
lance of sponge fisheries off the Tripolitanian coasts, laterally, to the 22°
line and seawards, beyond the 34th parallel ; second, that during a period
of more than 30 years the Franco-Tunisian authorities did not oppose but
acquiesced in such an exercise of effective surveillance ; third, that sponge

117
132 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

fisheries constitute a form of shelf exploitation avant la lettre ; fourth, that
such surveillance confers sovereign rights over the sea-bed of the area in
question, as convincingly contended in the Tunisian pleadings ; fifth, that
it would be unthinkable for the Court to assign to one Party an area which
was controlled by the other for more than 30 years, and, finally, that the
international law principles of uti possidetis of African boundaries and of
succession of States in respect to frontier delimitation also apply to the
colonial delimitation of sponge fisheries, as was contended by Tunisia,
with respect to the ZV 45° line, in its memorandum of 3 May 1976. Even if
one denies the existence of an agreement, there was a de facto delimitation
for the exploitation of sea-bed areas which was acquiesced to and thus it is
one which the Court cannot now revise or ignore. Libyan proven historic
rights are as worthy of respect as those invoked by Tunisia.

PART V. GEOGRAPHICAL CONFIGURATION

1. General Relevance of the Circumstance

103. Geographical configuration, that is to say the relationship between
the coasts of the States in dispute, is undoubtedly a most relevant circum-
stance in any continental shelf delimitation. The Court said in its 1969
Judgment :

“the principle is applied that the land dominates the sea ; it is con-
sequently necessary to examine closely the geographical configura-
tion of the coastlines of the countries whose continental shelves are to
be delimited” (1. C.J. Reports 1969, p. 51, para. 96).

And the 1977 Court of Arbitration stated that the validity of any method
“as a means of achieving an equitable delimitation of the continental shelf
is always relative to the particular geographical situation” (para. 84).

2. Substantive Inequity of Equidistance in this Case

104. By reason of the geographical configuration of the coasts of the
respective countries the line of equidistance would in this case produce
inequitable and disproportionate results to the detriment of Libya. This
line would impinge on the basic principle of non-encroachment, producing
a cutting-off effect by pulling the line too close to Tripoli, from which port
all offshore oil exploration and exploitation is made by that country. This
cutting-off effect was taken into account and rejected by the Court in 1969.
It is true that the specific effect which the Court rejected in the North Sea
Continental Shelf cases was the cutting off of the German coast resulting

118
133 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

from the combined effect of the two equidistance lines with the Nether-
lands and Denmark, which pulled the boundary inwards in the direction of
the concavity of the German coast. In this case, the concavity of the Gulf of
Gabes would not influence the line of equidistance, because the islands of
Jerba and Kerkennah control that line.

105. However, with respect to the 1969 Judgment, the Arbitral Award
of 1977 made the following pertinent remark :

“Although its observations on this aspect of ‘adjacent States’ situ-
ations were directed to the particular content of a concave coastline
formed by the adjoining territories of three States, they reflect an evi-
dent geometrical truth and clearly have a more general validity.”

This is confirmed by the fact that in 1969, when deciding against the
binding character of the method of equidistance, the Court had before it
various maps and diagrams, not limited to the case of concave coasts,
which illustrated the inequitable results produced by certain geographical
configurations, if the equidistance method was applied rigorously in all
cases of adjacent States. One of these illustrations is the geographical
situation of Haiti and the Dominican Republic, which is shown in the map
appearing in the second volume of Pleadings in that case, at page 28. The
geographical relationship between the coasts of these two States is very
similar to that existing in the present case, with one coast protruding at a
right angle to the other and the presence of an island which, like Kerken-
nah and Jerba, swings considerably the equidistance line to the detriment
of Haiti.

106. When introducing this map Professor Jaenicke, Agent and Counsel
of the Federal Republic of Germany, stated that it illustrated :

“the effect which the configuration of the coast has on the direction of
the equidistance line if it is drawn for a boundary between countries
lying adjacent to one another, a so-called lateral boundary. I men-
tioned that a very striking example of how much the equidistance line
diverts the boundary before the coast of another State is the actual
geographical situation before the coast of the Dominican Republic
and Haiti ... The fact that the coast of the Dominican Republic
projects here for some miles causes a diversion of the equidistance line
to quite a considerable extent.” (.C.J. Pleadings, North Sea Conti-
nental Shelf, Vol. IL p. 27.)

107. The Court expressly took into account these maps and diagrams,
saying :

“It would however be ignoring realities if it were not noted at the
same time that the use of this method, partly for the reasons given in
paragraph 8 above and partly for reasons that are best appreciated by

119
134 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

reference to the many maps and diagrams furnished by both sides in the
course of the written and oral proceedings, can under certain circum-
stances produce results that appear on the face of them to be extra-
ordinary, unnatural or unreasonable.” (Para. 24, emphasis added.)

And in paragraph 8 of the Judgment, the Court did not refer exclusively to
the case of concave coasts, for it said that :

“The effect of concavity could of course equally be produced for a
country with a straight coastline, if the coasts of adjacent countries
protruded immediately on either side of it.”

Again in paragraph 59 the Court made express reference to the maps and
diagrams when it stated :

“As was convincingly demonstrated in the maps and diagrams fur-
nished by the Parties, and as has been noted in paragraph 8, the
distorting effects of lateral equidistance lines under certain conditions
of coastal configuration are nevertheless comparatively small within
the limits of territorial waters, but produce their maximum effect in
the localities where the main continental shelf areas lie further
out.”

108. This observation of the Court refers to the well-known fact that the
effect of any distorting geographical feature upon adjacent countries by
the use of the equidistance method is automatically magnified the greater
the distance from the shore. Counsel for the Federal Republic of Germany
had referred in this context to “the extreme, and even sometimes bizarre,
results reached by strictly applying the equidistance method” (U.CJ.
Pleadings, Vol. IL p. 57), which “can only be properly applied at short
distances from the coast” (ibid., p. 62). In this particular case the distorting
effect would be such that Tunisian islands of no more than 180 square
kilometres would attract about 2,000 square kilometres of shelf area. And
if account is taken, as it should be, of the shelf area acquired by Tunisia by
its 1973 law, five years after the critical date when the dispute arose, the
equidistance line wouid give to Tunisia 70 per cent of the disputed area,
leaving to Libya less than one-third of it. This would not be an “equitable
solution” as required by the applicable law codified in the new accepted
trends at the Third UNCLOS.

3. Procedural Inequity of Equidistance in this Case

109. The Court is not confronted in this case with the procedural sit-
uation existing in the North Sea Continental Shelf or Anglo-French cases,
where one side advocated equidistance, the other pointed out its inequity
in the case and the Court or the Tribunal rejected that method or varied it
by diminishing its effects. Here the two Parties are in agreement that the

120
135 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

equidistance method not only is not of general application, but must be
discarded in this particular case, on the ground that it does not lead to
equitable results. Moreover, the Parties have admitted, in the Special
Agreement, the existence of relevant circumstances and have imposed
upon the Court the obligation to take them into account in its decision ; the
existence of these circumstances logically excludes the application of the
equidistance method.

110. While Tunisia had invoked this method in the diplomatic corres-
pondence prior to the submission of the case to the Court, it abandoned
that position completely in its Memorial and subsequent Pleadings. This
had irreversible consequences. The Court has not received arguments for
or against the general applicability of this method or concerning its geo-
graphical details in the particular circumstances of this case, other than a
brief rejection in the Libyan Memorial, on the grounds of its inequitable
results. For the Court to resort proprio motu to a method not advocated but
strongly rejected by both sides would not only take the Parties by surprise,
but it would imply deciding the case without the benefit of the Parties’
assistance, and without having afforded them the opportunity of submit-
ting arguments for or against its applicability to this particular geographi-
cal configuration. These would have included complicated issues of fact,
such as a deeper analysis of the legality of the baselines, the effect of the
islands and low-tide elevations on the line and the geographical determi-
nation of the controlling points. In this respect it is of significance that
there have appeared marked divergences as to the effect to be given to
islands and low-tide elevations in the opinions which advocate equidis-
tance in the present case. This illustrates the danger of applying equidis-
tance motu proprio. These are not mere procedural objections, but involve
important considerations with respect to the right of defence in judicial
proceedings and the reception of the Court’s Judgment by the Parties.

4. The Configuration of the Tunisian Coastline

111. The most important geographical feature to take into account as a
relevant circumstance in this case is that the Tunisian coast, which extends
from Ras Ajdir to the west in a general direction facing north-east, turns at
a certain point in the Gulf of Gabes, in a north-northeast direction. The
line perpendicular to the coast established historically by the colonial
Powers extends to the sponge fishing banks located further from the shore
line. However, if that perpendicular line were to continue in the same
north-northeast direction, after the point at which the Tunisian coast
turns, then an effect of encroachment would be produced, particularly in
respect of the port of Sfax, the banks and shoals of the Kerkennah Islands

121
136 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

and the promontory of the Sahel. Account must be taken, therefore, of the
change of direction of that coast as it turns inside the Gulf of Gabes and
then runs to the north-east.

112. In order to take into account this relevant geographical circum-
stance, and reflect the configuration of the Tunisian coast, a veering to the
east should be introduced in the line of delimitation, parallel to the line of
that coast. The first point at which such a change of direction begins to
occur is in the neighbourhood of a locality in the Gulf of Gabes named “la
Skira”, some 15’ north of the 34th parallel. This coastal configuration
should in my view have been taken into account by a first veering of the line
of delimitation at this latitude, reflecting exactly the same angle of diver-
gence which exists in the direction of the coastline. The exact location of
the parallel where the change of direction occurs and the angle of incli-
nation should have been left, in my view, to be determined by the experts of
the Parties.

113. Further to the north, at the latitude of Ras Yonga, the eastwards
projection of the Tunisian coast is accentuated and, consequently, a sec-
ond veering of the line of delimitation should have taken place, reflecting
again exactly the change of direction of the Tunisian coast at this latitude.
Such a veering, the exact angle of which should have been left to be
determined by the experts, would maintain within Tunisian jurisdiction
the banks and shoals of the Kerkennah Islands and all the sponge banks
traditionally exploited under the surveillance of Tunisian authorities.

114. This means that the historic rights over sponge fishing traditionally
exercised by Tunisia, as well as those of Libya, would be respected and
preserved in the continental shelf delimitation. But these historic rights,
based as they are on prolonged exercise, and having an exceptional char-
acter, by their very nature, cannot be invoked or used as having a potential
effect which would make them capable of a projection seaward, and thus as
the basis for more extended and different maritime claims. Historic rights
must be respected and preserved, but as they were and where they were,
that is to say, within the limits established by usage and history. In par-
ticular, to transform these historic waters into internal or territorial waters
in order to project a further claim to a continental shelf beyond them is
unjustified.

115. An objection has been made to the above veering. It has been
pointed out that this solution would only take into account the inclination
of the Tunisian coast, while ignoring the south-easterly inclination of the
Libyan coast. An immediate answer is that the alteration in the perpen-
dicular line established by history is only caused by the inclination of the
Tunisian coast, which, if ignored, would produce an effect of encroach-
ment. A further reply is that the suggestion that exact consideration should
be given to both coasts is, really, only another way of advocating the
application of the equidistance method, which is unacceptable in this case
for the reasons already given. Finally, the point is made that after the 34th
parallel the two coasts cease to be adjacent and become opposite. This,

122
137 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

from a geographical point of view, is not so. After the 34th parallel, as well
as before, the areas of shelf to be delimited lie off and not between the
coasts of the two countries. This means that this is not a delimitation
between opposite States but one which continues to be a lateral delimi-
tation between adjacent States. This conclusion is confirmed by the find-
ings of the 1977 arbitral award. In that case, the two States were opposite in
the Channel area but the Court of Arbitration considered that in the
Atlantic region, where the areas of shelf lie off, rather than between their
two coasts, an analogy could be drawn with a lateral delimitation. The
Court of Arbitration said :

“in the Atlantic region the situation geographically is one of two
laterally related coasts, abutting on the same continental shelf...
Indeed, the Court notes that so evident is this lateral relation of the
two coasts, geographically, that both Parties in their pleadings saw
some analogy between the situation in the Atlantic region and the
Situation of ‘adjacent’ States.” (Para. 241.)

5. The Test of Proportionality

116. In the North Sea Continental Shelf cases, the Court indicated as a
possible pertinent factor in negotiations what it described as :

“a reasonable degree of proportionality which a delimitation effected
according to equitable principles ought to bring about between the
extent of the continental shelf appertaining to the States concerned
and the lengths of their respective coastlines” (1.C.J. Reports 1969,
p. 52, para. 98).

117. The 1977 Court of Arbitration in the Anglo-French dispute
rejected what it described as “nice calculations of proportionality” and
refined this concept into a test of the equity of the results reached in a
delimitation, saying :

“In short, it is disproportion rather than any general principle of
proportionality which is the relevant criterion or factor. The equitable
delimitation of the continental shelf is not, as this Court has already
emphasized in paragraph 78, a question of apportioning — sharing out
— the continental shelf amongst the States abutting upon it. Nor isit a
question of simply assigning to them areas of the shelf in proportion
to the length of their coastlines ; for to do this would be to substitute
for the delimitation of boundaries a distributive apportionment of
shares ... Proportionality, therefore, is to be used as a criterion or
factor relevant in evaluating the equities of certain geographical

123
138 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

situations, not as a general principle providing an independent
source of rights to areas of continental shelf.” (Para. 101.)

In the light of this pronouncement, proportionality is linked with the
application of equitable principles, and its function is to test the equitable
character of the method of delimitation used, in the light of the results to
which it leads. It constitutes a test to be applied ex post facto to the results
obtained through the appreciation of the relevant circumstances, and not a
relevant circumstance or independent factor in itself.

118. Moreover, it is necessary to establish clearly and with fairness the
basic premises which need to be adopted in order to make a comparison of
proportionality possible. The first of these premises concerns the area to be
taken into consideration. In this respect the Judgment defines it as de-
limited by Ras Kaboudia and Ras Tajoura and this appears as generally
acceptable. Another premise is the measurement of the length of the
relevant coasts. In this respect the 1969 Judgment is clear when it states
that the coastlines are to be measured

“according to their general direction in order to establish the neces-
sary balance between States with straight, and those with markedly
concave or convex coasts, or to reduce very irregular coastlines to their
truer proportions” (.C.J. Reports 1969, p. 52, para. 98).

119. The most serious disagreement concerns the determination of the
areas of shelf covered by waters appertaining to each Party which are to be
taken into account in order to make this comparison. Libya has contended
that in evaluating the effect of a proposed shelf delimitation one should
consider all areas of shelf, whether under the waters of the high seas, the
waters of exclusive fishing zones, the waters of the territorial sea and even
any internal waters lying beyond the actual coast. Tunisia, basing its
argument on the legal definition of the continental shelf as lying beyond
the territorial sea, has contended, on the contrary, that territorial and
internal waters are not to be taken into account in any comparison of
equitable results.

120. This is not an issue that could be decided in the abstract and in a
general way, but must be decided — as other questions involved in an
equitable delimitation — in the light of the circumstances of the particular
case. One such circumstance has to do with the baselines adopted by
Tunisia in 1973. These baselines are, to say the least, of doubtful legality
since they do not conform to the only restriction established by the Court’s
Judgment of 1951 in the Norwegian Fisheries case, namely, that the base-
lines should follow the general direction of the coast. These baselines, with
a seaward point going as far as El-Mzebla, form a triangle which lies
against the concavity of the Gulf of Gabes and which is not just different
but opposite to the general direction of the coast. Furthermore, these

124
139 CONTINENTAL SHELF (SEP. OP. SIMENEZ DE ARECHAGA)

baselines are drawn on the basis of low-tide elevations, some of which are
always below water while the applicable rules of international law forbid
their use unless lighthouses or similar installations have been built upon
them. It is obvious that lightbuoys on the water cannot fulfil this require-
ment nor is there any record of stationary fishing gear that far out to
sea.

121. However, the legality of these baselines is not the question to be
decided here. What is important is whether these baselines are opposable
to Libya for the purposes of the application of the proportionality test.
This question is determined conclusively by the fact that these baselines
were proclaimed by Tunisia in 1973, five years after the critical date when
the dispute arose, and that the 1973 law and decree modified radically the
pre-existing Tunisian laws which did not constitute these waters either as
internal or as territorial. Tunisia thus unilaterally appropriated a large
expanse of the disputed continental shelf and this makes it difficult to
claim with fairness that such an area should not be counted and should be
left out of any comparison with the portion of shelf which each party will
obtain from the Court’s Judgment. In the Minquiers and Ecrehos case the
Court said that acts subsequent to the critical date should be taken into
consideration “unless the measure in question was taken with a view to
improving the legal position of the Party concerned” (C.J. Reports 1953,
p. 59). And this is the case here.

122. Furthermore, it would seem that in a case such as the present,
which is different in this respect from the North Sea Continental Shelf cases
in that there is an enormous difference between the areas of water claimed
as internal and territorial by each Party, it would be inequitable not to take
into account, for the overall evaluation of fairness and proportionality, the
whole expanse of water, on the sole ground that legally the continental
shelf begins at the outer limit of the territorial sea. To do so would be to
commit the sin of formalism ; to allow that form of inequity which the
Romans called subtilitas, that is to say, an exaggerated adherence to the
strict letter of the law when equity demands a broader approach for the
purposes of comparison.

123. Taking the above into account, a line as the one suggested of 22°
with a veering parallel to that of the Tunisian coast, would have resulted in
assigning to each Party almost 50 per cent of the area in dispute. Such a line
of delimitation would thus have complied with the test of a reasonable
degree of proportionality, and have achieved an equitable result.

PART VI. THE JUDGMENT’S FINAL CONCLUSIONS
124. It results from the foregoing that I have certain doubts and diver-

gences concerning some of the final conclusions in the operative part of the
Judgment. In particular, it seems to me that not sufficient significance has

125
140 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

been attributed to the 22° historic line and that a veering of 52° is too
pronounced.

However, since I concur fully with most of the Court’s legal reasoning,
and the above indicated differences do not result in too great a disagree-
ment with respect to the line of delimitation, I consider that I ought not to
press these differences and doubts to the point of dissenting from the
Court’s decision.

(Signed) Eduardo JIMENEZ DE ARECHAGA.

126
141

CONTINENTAL SHELF (SEP. OP. JIMÉNEZ DE ARÉCHAGA)

SYNOPTICAL TABLE

PART I. INTERPRETATION OF THE SPECIAL AGREEMENT

1. The Parties’ submissions

2. The role of the Court and the subsequent role of the experts
3.

4. The meaning of equity : equity, equidistance and relevant cir-

The geographical scope of equitable principles

cumstances

5. Non-existence of a presumption in favour of equidistance
6.

New accepted trends at the Third UNCLOS

PART IL. THE CONCEPT OF NATURAL PROLONGATION

1.
2.

3.
4.

5.
6.

7.

The Parties’ contentions

The legal definition of continental shelf not based on geo-
logy or geomorphology

The 1969 Judgment and the 1958 definition

The new definition in the draft convention at the Third
UNCLOS Conference

The Exclusive Economic Zone and shelf delimitation

The real meaning of “natural prolongation” in the 1969 Judg-
ment

Geological structure in the 1969 and 1977 Judgments

Part III. THE EQUITABLE PRINCIPLE OF NON-ENCROACHMENT

1.
2.
3.

4.

The Parties’ divergent interpretations

The correct interpretation of the principle

The German proposal and the reaction at the 1958 Confer-
ence

The principle of non-encroachment and its effects in the pres-
ent case

PART IV. HISTORIC FISHERY RIGHTS

Pe

nun

127

Existence of historic fishery rights

Relevance of historic fishery rights to continental shelf delimi-
tation

The Tunisian claim for a ZV 45° line

The Orfeo incident : French protest and Italian answer

The French-Italian “modus vivendi”

Equitable reasons which compel respect for the historic lateral
delimitation

Reasons of law which compel respect for the historic lateral
delimitation

Paragraphs
1-36

1-4

5-10

11-17
18-26

27-31
32-36

37-64
37-39

40-44
45-49

50-53
54-56

57-59
60-64

65-76

67-68
69-70

71-73
74-76

77-101
771-78
79-84
85-86
87-91
92-95
96-99

100-102
142 CONTINENTAL SHELF (SEP. OP. JIMENEZ DE ARECHAGA)

PART V. GEOGRAPHICAL CONFIGURATION

General relevance of the circumstance
Substantive inequity of equidistance in this case
Procedural inequity of equidistance in this case
The configuration of the Tunisian coastline
The test of proportionality

We wWN

Part VI. THE JUDGMENT’S FINAL CONCLUSIONS

128

Paragraphs

103-123

103
104-108
109-110
111-115
116-123

124