A remarkable feature of the law of maritime delimitation is that the law has been developed
through international courts and tribunals. Three distinct phases may be identified in the
development of jurisprudence in this field.
The First Phase (1969–1992)
The development of modern jurisprudence in the field of maritime delimitation commenced
with the 1969 North Sea Continental Shelf judgment. In this judgment, the ICJ held that
‘delimitation must be the object of agreement between the States concerned, and that such
agreement must be arrived at in accordance with equitable principles’. After the judgment,
equitable principles as customary law came to be at the heart of the law of maritime
delimitation. However, the Court rejected the existence of any obligatory method of
continental shelf delimitation. According to the Court, ‘there [is] no other single method
of delimitation the use of which is in all circumstances obligatory’. The Court continued
that ‘it is necessary to seek not one method of delimitation, but one goal’. In the Court’s
view, it is the goal which should be stressed, and the law of maritime delimitation should be
defined only by this goal, i.e. the achievement of equitable results. In this sense, one could
speak of a result-orientated equity approach. This approach allows international courts to
decide, case-by-case, on the equitable results to be achieved without being bound by any
method of maritime delimitations. Thus, the result-orientated equity approach emphasises
maximum flexibility of the law of maritime delimitation.
However, the Arbitral Tribunal, in the 1977 Anglo-French Continental Shelf case,
followed a line of argument different from that adopted in the North Sea Continental Shelf
judgment. Unlike the ICJ in the North Sea Continental Shelf cases, the Court of Arbitration
equated Article 6 of the 1958 Geneva Convention on the Continental Shelf, as a single
combined equidistance–special circumstances rule, with the customary law of equitable
principles. On the basis of this interpretation, the Court of Arbitration applied the equidistance
method with modification in the Atlantic region. In this regard, the Court of
Arbitration made an important pronouncement:
The Court notes that in a large proportion of the delimitations known to it, where a particular
geographical feature has influenced the course of a continental shelf boundary, the method of
delimitation adopted has been some modification or variant of the equidistance principle
rather than its total rejection . . . it seems to the Court to be in accord not only with the legal
rules governing the continental shelf but also with State practice to seek the solution in a
method modifying or varying the equidistance method rather than to have recourse to a wholly
different criterion of delimitation.
The Court of Arbitration thus accepted the applicability of the equidistance method as a
starting point, even where a particular geographical element exists in a situation of lateral
delimitation. In so doing, the Court of Arbitration considered equity to be a corrective
element. In this sense, one may call this methodology the corrective-equity approach.
According to this approach, the equidistance method is applied at the first stage of delimitation
and, at the second stage, a shift of the equidistance line may be envisaged if relevant
circumstances warrant it. Equidistance is the only predictable method for ensuring predictability
of results in the sense that once the base points are fixed, the delimitation line is
mathematically determined. The corrective-equity approach thus highlights predictability
in the law of maritime delimitation. In summary, two contrasting approaches appeared in
the 1969 and 1977 decisions on the basis of equitable principles.
In the 1982 Tunisia/Libya case concerning continental shelf delimitation, the ICJ further
promoted the result-orientated equity approach. The Court pronounced:
The result of the application of equitable principles must be equitable . . . It is, however, the
result which is predominant; the principles are subordinate to the goal. The equitableness of a
principle must be assessed in the light of its usefulness for the purpose of arriving at an
In this case, the Court accepted neither the mandatory character of equidistance, nor some
privileged status of equidistance in relation to other methods. According to the Court’s
approach, the application of equitable principles would be broken down into relevant
circumstances in specific situations, ruling out any predetermined method.
In the 1984 Gulf of Maine case relating to the delimitation of a single maritime boundary, the
Chamber of the ICJ also echoed the result-orientated equity approach. In this case, the Chamber
pronounced a ‘fundamental norm’ applicable to every maritime delimitation between neighbouring
States. The first part of the norm is that maritime delimitation must be sought and
effected by means of an agreement in good faith. The second part of the norm is:
In either case, delimitation is to be effected by the application of equitable criteria and by the
use of practical methods capable of ensuring, with regard to the geographic configuration of
the area and other relevant circumstances, an equitable result.
In this formulation, ‘an equitable result’ should be achieved by resort to ‘equitable criteria’ and
a ‘practical method’. According to the Chamber, there has been no systematic definition of
equitable criteria because of their highly variable adaptability to different concrete situations.
Thus, ‘equitable criteria’ are excluded from the legal domain. The same is true regarding the
‘practical method’, since the latter would be selected on a case-by-case basis, relying on actual
situations. In the view of the Chamber, the law defines neither the equitable criteria nor the
practical method, simply advancing the idea of ‘an equitable result’.
The full Court, in the Libya/Malta case of 1985, also stressed the result to be achieved, not
the means to be applied. At the stage of establishing the continental shelf boundary,
however, the Court applied the equidistance method as a first provisional step, and the
equidistance line was adjusted in a second stage on account of relevant circumstances.
In so doing, the Court adopted the corrective-equity approach for the delimitation of
the continental shelf between opposite coasts at the operational stage. It may be said that
the Libya/Malta judgment has a hybrid character in the sense that two approaches were
used. The result-orientated approach was echoed by the 1985 Guinea/Guinea-Bissau
Arbitration and the 1992 St. Pierre and Miquelon Arbitration. Overall it can be observed
that between 1969 and 1992 international courts and tribunals basically took the resultorientated
The Second Phase (1993–2007)
However, the law of maritime delimitation was to change towards the corrective-equity
approach. A turning point was the 1993 Greenland/Jan Mayen judgment. The Greenland/Jan Mayen case involved a maritime delimitation between the continental shelf and the FZ. In this case, there was no agreement on a single maritime boundary and, thus, the law applicable to the continental shelf and to the EEZ/FZ had to be examined separately. Both Parties had ratified the Convention on the Continental Shelf. In this case, the Court attempted to achieve assimilation at three levels.
First, the Court equated Article 6 of the Convention on the Continental Shelf with
customary law by relying on a passage of the 1977 award of the Court of Arbitration in
the Anglo-French Continental Shelf case. The Court ruled:
[I]n respect of the continental shelf boundary in the present case, even if it were appropriate to
apply, not Article 6 of the 1958 Convention, but customary law concerning the continental
shelf as developed in the decided cases, it is in accord with precedents to begin with the median
line as a provisional line and then to ask whether ‘special circumstances’ require any
adjustment or shifting of that line.
Second, with respect to the law applicable to the FZ, the Court equated the customary law
applicable to the FZ with that governing the EEZ on the basis of the agreement of the
Third, quoting the Anglo-French Arbitral Award, the Court assimilated the law of
continental shelf delimitation with that of the FZ at the customary law level. In this regard,
the Court took the view that ‘both for the continental shelf and for the fishery zones in this
case, it is proper to begin the process of delimitation by a median line provisionally
drawn’. Furthermore, the Court held:
It cannot be surprising if an equidistance–special circumstances rule produces much the same
result as an equitable principles–relevant circumstances rule in the case of opposite coasts,
whether in the case of a delimitation of continental shelf, of fishery zone, or of an all-purpose
Thus, for the first time in the case law of the ICJ, the Court applied the corrective-equity
approach as customary law. It is important to note that under this approach, the equidistance
method is incorporated into the domain of customary law.
Later on, basically the corrective-equity approach was echoed by jurisprudence relating to
maritime delimitations. In the 1999 Eritrea/Yemen Arbitration (Second Phase), the Arbitral
Tribunal applied the corrective-equity approach under Articles 74 and 83 of the LOSC. In the
2001 Qatar/Bahrain case, the ICJ accepted the applicability of the corrective-equity approach
as customary law in the delimitation between States with adjacent coasts. Furthermore, the
ICJ, in the 2002 Cameroon/Nigeria case, broke new ground by applying the corrective-equity
approach under Articles 74 and 83 of the LOSC. According to the Court’s interpretation, a
specific method, i.e. the equidistance method, should be incorporated into Articles 74 and 83.
Considering that any reference to a specific delimitation method was omitted in drafting those
provisions, it may be said that this is a creative interpretation by the Court.
In the 2006 Barbados/Trinidad and Tobago Arbitration, the Arbitral Tribunal did not
admit a mandatory character of any delimitation method. Nevertheless, the Arbitral Tribunal
took the view that ‘the need to avoid subjective determinations requires that the method
used starts with a measure of certainty that equidistance positively ensures, subject to its
subsequent correction if justified’. Thus the Arbitral Tribunal applied the corrective-equity
approach in the operation of maritime delimitation under Articles 74 and 83 of the LOSC.
The Arbitral Tribunal, in the 2007 Guyana/Suriname Arbitration, applied the correctiveequity
approach more clearly under Articles 74 and 83 of the LOSC. The view of the Arbitral
Tribunal deserves to be quoted:
The case law of the International Court of Justice and arbitral jurisprudence as well as State
practice are at one in holding that the delimitation process should, in appropriate cases, begin
by positing a provisional equidistance line which may be adjusted in the light of relevant
circumstances in order to achieve an equitable solution. The Tribunal will follow this method in
the present case.
However, the ICJ, in the 2007 Nicaragua/Honduras case, took the view that the application
of the equidistance method at the first stage of maritime delimitation is not obligatory. Owing
to the very active morphodynamism of the relevant area, the Court found itself that it could
not apply the equidistance line in the Nicaragua/Honduras case. Accordingly, the Court
established a single maritime boundary by applying the bisector method. Nonetheless, the
Court prudently added that ‘equidistance remains the general rule’. In fact, with respect to
the delimitation around the islands in the disputed area, the Court applied, without any
problem, the corrective-equity approach by referring to the Qatar/Bahrain case. It can be
considered, therefore, that the departure from the previous jurisprudence is only partial.
The Third Phase (2009–present)
The third phase of the law of maritime delimitation commenced with the 2009 Black Sea
case. In this case, the ICJ, for the first time in its jurisprudence, clearly formulated the socalled
three-stage approach to maritime delimitations under Articles 74 and 83 of the LOSC.
According to the Court, the process of maritime delimitation will be divided into three
stages. The first stage is to establish the provisional delimitation line. It is in principle an
equidistance line. At the second stage, the Court is to examine whether there are relevant
circumstances calling for the adjustment of the provisional equidistance line in order to
achieve an equitable result. At the third and final stage, the Court will verify whether the
delimitation line does not lead to an inequitable result by applying the test of disproportionality.
It is noteworthy that the disproportionality test was given its own independent
stage. Considering that this test aims to check for an equitable outcome to maritime
delimitation, it may be argued that the three-stage approach in the Black Sea case can be
regarded as a variation of the corrective-equity approach developed through judicial
practice in the field of maritime delimitation. The three-stage approach, which is also
called ‘the equidistance/relevant circumstances method’, was adopted by ITLOS in the 2012
Bangladesh/Myanmar case. In this case, the Tribunal formulated that approach:
[A]t the first stage it will construct a provisional equidistance line, based on the geography of
the Parties’ coasts and mathematical calculations. Once the provisional equidistance line has
been drawn, it will proceed to the second stage of the process, which consists of determining
whether there are any relevant circumstances requiring adjustment of the provisional
equidistance line; if so, it will make an adjustment that produces an equitable result. At the
third and final stage in this process the Tribunal will check whether the line, as adjusted, results
in any significant disproportion between the ratio of the respective coastal lengths and the ratio
of the relevant maritime areas allocated to each Party.
The three-stage approach was adopted by the ICJ, ITLOS and Annex VII Arbitral Tribunals
in subsequent cases concerning maritime delimitations.
INTERNATIONAL COURTS’ APPROACHES TO MARITIME DELIMITATIONS
Year/Case/ Type/ Configuration/ Approach
1969/ The North Sea Continental Shelf cases/ (ICJ)/ CS/ AC/ RE
1977/ The Anglo-French Continental Shelf Arbitration/ CS/ AC/OC/ CE
1982/ The Tunisia/Libya case (ICJ)/ CS/ AC/OC/ RE
1984/ The Gulf of Maine case (ICJ Chamber)/ SMB/ AC/OC/ RE/CE
1985/ The Libya/Malta case (ICJ)/ CS/ OC/ RE/CE
1985/ The Guinea/Guinea-Bissau Arbitration/ SMB/ AC/ RE
1992/ The St. Pierre and Miquelon Arbitration/ SMB/ AC/ RE
1993/ The Greenland/Jan Mayen case (ICJ)/ SMB/ OC/ CE
1999/ The Eritrea/Yemen Arbitration/ SMB/ OC/ CE
2001/ The Qatar/Bahrain case (ICJ)/ TS/SMB/ AC/OC/ CE
2002/ The Cameroon/Nigeria case (ICJ)/ TS/SMB/ AC/ CE
2006/ The Barbados/Trinidad and Tobago Arbitration/ SMB/CS/ AC/OC/ RE/CE
2007/ The Guyana/Suriname Arbitration/ TS/SMB/ AC/ CE
2007/ The Nicaragua/Honduras case (ICJ)/ TS/SMB/ AC/ RE/CE
2009 /The Black Sea case (ICJ)/ SMB/ AC/OC/ Three-stage
2012 /The Bangladesh/Myanmar case/ (ITLOS)/ TS/SMB/CS*/ AC/ Three-stage
2012/ The Nicaragua/Colombia case/ (ICJ)/ TS/SMB/ OC/ Three-stage
2014/ The Chile/Peru case (ICJ)/ TS/SMB/ AC/ Three-stage
2014/ The Bangladesh/India Arbitration/ TS/SMB/CS*/ AC/ Three-stage
2017/ The Croatia/Slovenia Arbitration/ TS/ AC/ CE
2017/The Ghana/Côte d’Ivoire case (ITLOS Chamber)/ TS/SMB/CS*/ AC/ Three-stage
2018/ The Costa Rica/Nicaragua case (ICJ)/ TS/SMB/ AC/ Three-stage
CS: continental shelf
CS*: continental shelf beyond 200 nautical miles
SMB: single maritime boundary
TS: territorial sea
AC: adjacent coast
OC: opposite coast
RE: result-orientated equity approach
CE: corrective-equity approach
Three-stage: the three-stage approach
Overall, the history of the law of maritime delimitation shows a vacillation between two
contrasting approaches to maritime delimitations: the result-orientated equity approach
which emphasises maximum flexibility and the corrective-equity approach which highlights predictability. In this sense, it may be said that the development of the law of
maritime delimitation is essentially characterised by the tension between predictability and
flexibility in the law.
Under the result-orientated equity approach, international courts and tribunals may
exercise a large measure of discretion in each case without being bound by any method.
Considering that the factors to be considered vary in each case, the merit of flexibility of
this approach is not negligible. However, because of its excessive subjectivity and the lack
of predictability, the result-orientated equity approach runs the risk of reducing the
normativity of the law of maritime delimitation.
By contrast, the important advantage of the corrective-equity approach or its variation of
the three-stage approach is that it has a certain degree of predictability by incorporating a
specific method of delimitation, i.e. the equidistance method, into the legal domain.
According to this approach, a consideration of equity may come into play at a second
stage, but only in cases in which provisionally drawn equidistance lines produce inequitable
results. To this extent, the corrective-equity or three-stage approach makes it possible
to reduce the subjectivity and unpredictability of the law of maritime delimitation. It may
be said that the corrective-equity approach would provide a better framework for balancing
predictability and flexibility.
The application of the equidistance method at the first stage of maritime delimitation is
not merely a matter of pragmatism. The application of that method is closely linked to the
legal title over marine spaces. In this regard, the ICJ, in the Libya/Malta case, was clear:
It therefore seems logical to the Court that the choice of the criterion and the method which it
is to employ in the first place to arrive at a provisional result should be made in a manner
consistent with the concepts underlying the attribution of legal title.
For the Court, ‘the legal basis of that which is to be delimited cannot be other than pertinent
to the delimitation’. Since the legal title over maritime spaces is attributed by virtue of
distance, it is logical that the method of delimitation should reflect this element. The
criterion of distance is spatial in nature. Equidistance is the only method which reflects
the spatial nature of the distance criterion, for it comes nearest to an equal division of
overlapping area by relying on the distance from the coasts. Should a method of delimitation
be combined with the distance criterion, the equidistance method should logically be
singled out. One can thus argue that the application of the equidistance method at the first
stage of maritime delimitation rests on a solid legal basis.
International jurisprudence seems to present a clear trend for the application of the threestage
approach to maritime delimitations under Articles 74(1) and 83(1) of the LOSC as well
as customary law. As ITLOS stated in the Bangladesh/Myanmar case:
International courts and tribunals have developed a body of case law on maritime delimitation
which has reduced the elements of subjectivity and uncertainty in the determination of
maritime boundaries and in the choice of methods employed to that end
. . . Over time, the
absence of a settled method of delimitation prompted increased interest in enhancing the
objectivity and predictability of the process.
However, it is not suggested that the law of maritime delimitation could acquire a sufficient
degree of predictability. In this regard, two points can be made. First, it must be noted that
at the first stage of the delimitation process, consideration of equity already comes into play
when an international court selects relevant base points for drawing a provisional equidistance
line. Yet, this blurs the distinction between the first and second stage of maritime
delimitation. Furthermore, since selection of base points by judges is not free from subjectivity,
selection of base points by judges may entail the risk of undermining the value of
predictability at the first stage of maritime delimitation. Second, under the three-stage
approach, the final delimitation line is determined by the consideration of relevant circumstances.
While an adjustment of a provisional equidistance line at the second stage of
maritime delimitation relies on a case-by-case appreciation of relevant circumstances by
international courts and tribunals, an excessively creative adjustment would run the risk of
undermining the predictability of the law of maritime delimitation. It is thus necessary to
examine the relevant circumstances in maritime delimitations.