Delimitation methodology for the continental shelf beyond 200 nautical miles: Three-stage approach as a way forward?

Abstract

Delimitation of the continental shelf beyond 200 nautical miles (nm) is a relatively novel exercise by international courts and tribunals, and a question that assumes theoretical and practical importance is whether the delimitation methodology primarily developed in maritime delimitation within 200 nm can be applied to the delimitation beyond that distance. In contrast to some prevailing arguments that the delimitation methodology for the continental shelf beyond 200 nm should somewhat differ, this article examines whether the delimitation beyond 200 nm can be integrated under the three-stage approach articulated by the ICJ in the 2009 Black Sea case and discusses what methodological problems have been raised in the delimitation process. By analysing the applicability and application of the three-stage approach to the continental shelf delimitation beyond 200 nm in the jurisprudence, this article argues that substantive integration of the delimitation methodology for the continental shelf beyond 200 nm has taken place and is likely to continue. The integrated approach to the delimitation methodology adopted in the Bangladesh v. India case and the Ghana/Côte d’Ivoire case may prove to be guiding precedents that indicate a way forward in the jurisprudence.

1. Introduction

The delimitation of the continental shelf beyond 200 nm is a relatively novel exercise for international courts and tribunals, as the 2012 Bangladesh/Myanmar case marked the first decision in which the judiciary divided the continental shelf beyond 200 nm between two states.¹ Since then, an arbitral tribunal established under the 1982 United Nations Convention on the Law of the Sea (UNCLOS, or the Convention),² a special chamber of the International Tribunal for the Law of the Sea (ITLOS), as well as the International Court of Justice (ICJ, or the Court), delimited the continental shelf beyond 200 nm in the 2014 Bangladesh v. India case,³ the 2017 Ghana/Côte d’Ivoire case,⁴ and the 2021 Somalia v. Kenya case,⁵ respectively. During the same period, disputes concerning the delimitation of the continental shelf beyond 200 nm had been submitted to third-party dispute settlement procedures.⁶

A question that assumes theoretical and practical importance in the jurisprudence is whether the delimitation methodology primarily developed by international courts and tribunals in maritime delimitation within 200 nm can be applied to the delimitation beyond that distance, and, if affirmative, how the exercise is to be carried out. This question arises because the entitlement to the continental shelf beyond 200 nm under Article 76 of UNCLOS draws on geomorphological or geological elements,⁷ and is therefore different from the distance-based entitlements to the continental shelf or the exclusive economic zone (EEZ).⁸ Notwithstanding the prevailing academic view that delimitation methodology for the continental shelf beyond 200 nm should differ,⁹ the four decisions mentioned above opted for the same delimitation methodology throughout maritime delimitation within and beyond 200 nm, which is, the three-stage approach formulated by the ICJ in the Black Sea case. That methodology consists of a step-by-step exercise of maritime delimitation. First, a provisional equidistance line is drawn unless it is unfeasible or inappropriate to do so.¹⁰ Second, the provisional line is adjusted if there are circumstances particular to the case that render the provisional line inequitable.¹¹ Third, the equitableness of the boundary line is verified by the disproportionality test, which checks if there is ‘marked disproportion between the ratio of the respective coastal lengths and the ratio between the relevant maritime area of each State by reference to the delimitation line’.¹² The three-stage approach has been widely used by the ICJ and the UNCLOS tribunals in single maritime delimitation within 200 nm,¹³ and it has achieved the status of the ‘established methodology’ in the jurisprudence.¹⁴

This article sets out to examine to what extent the delimitation methodology for the continental shelf beyond 200 nm can be integrated under the three-stage approach, and what problems are raised in this process. The reflections may contribute to further refinement of the methodology articulated and practiced in the jurisprudence. Clarity of the jurisprudence concerning the continental shelf beyond 200 nm is in the interest of the states whose maritime boundaries beyond 200 nm remain undecided, especially the states whose coasts are threatened by sea-level rise resulted from climate change, as determining maritime boundaries with permanence carries an extraordinary degree of importance and urgence.¹⁵

It is submitted that methodology for delimitation beyond 200 nm does not and should not differ from that within 200 nm simply because of the different attributes of the entitlement to the continental shelf beyond 200 nm. The jurisprudence demonstrates that three-stage approach would continue to be a ‘baseline approach’ for the delimitation of the continental shelf beyond 200 nm, though a number of methodological questions remain to be clarified. Following this introduction, Section 2 discusses the applicability of the three-stage approach to the continental shelf beyond 200 nm. Section 3 explains the establishment of the entitlement to the continental shelf beyond 200 nm and its methodological implications by examining the determination of relevant coasts and relevant area in the delimitation process. Section 4 looks into each step of the application of the three-stage approach and analyses the methodological questions arising out of the jurisprudence. Section 5 concludes.

2. Applicability of the three-stage approach to the continental shelf beyond 200 nm

2.1 Challenges to the applicability of three-stage approach to delimitation beyond 200 nm

A recurring question arising out of the delimitation of the continental shelf beyond 200 nm is whether and how the entitlement to the continental shelf beyond 200 nm bears on the choice and application of delimitation methodology, and in what manners the methodology in the continental shelf beyond 200 nm departs from the methodology within that distance. The arguments challenging the applicability of the three-stage approach in delimitation beyond 200 nm can be broadly summarized in the following.

First, the different methods to establish overlapping entitlements to the continental shelf beyond 200 nm may distort the identification of relevant coasts and relevant area.¹⁶ In maritime delimitation within 200 nm, that pair of concepts reciprocally define each other in that the relevant coasts are coasts that generate overlapping projections, and the relevant area excludes any area which cannot overlap with the projections of the coast of the other party.¹⁷ They are integral to the delimitation methodology,¹⁸ because, first, ‘it is necessary to identify the relevant coasts in order to determine what constitutes in the specific context of a case the overlapping claims to these zones’,¹⁹ and, second, the disproportionality test in the final stage of the methodology relies largely on the assessment of the coastal lengths and the size of the relevant areas.²⁰ However, the changing legal bases of continental shelf beyond 200 nm entail that the area of overlapping entitlements cannot be ascertained through a geometrical exercise by reference to the distance-based projections generated by the coasts. There thus must be a re-examination of the role of relevant coasts and relevant area in the delimitation beyond 200 nm.

Second, as the area of overlapping entitlements beyond 200 nm may be defined by resorting to parameters such as the outer limits of the continental shelf, a coast-to-coast equidistance line may not properly divide the area of overlap.²¹ Whether such a scenario compels the departure from a provisional equidistance line remains unclear, because the international jurisprudence subsequent to the Black Sea case has not developed criteria on the inapplicability of a provisional equidistance line.²² In addition, the challenge to the use of equidistance in the continental shelf delimitation beyond 200 nm turns on a ‘fundamentalist’ aspect,²³ as its applicability in delimitation within 200 nm is considered to be in line with the distance-based entitlement.²⁴

Third, in recent years there is a discernible trend towards the narrowing down of the scope of relevant circumstances to be considered in the second stage, as the determination of relevant circumstances ‘has increasingly been attached to geographical considerations’.²⁵ However, a prevailing assumption about the delimitation of the continental shelf beyond 200 nm in the literature is the re-emergence of geomorphological or geological factors in the matrix of relevant circumstances.²⁶ Likewise, whether the coastal geography continues to be relevant in the delimitation beyond 200 nm also merits reconsideration, because the jurisprudence maintains that only ‘neutral criteria’ apply to the single delimitation of the continental shelf and the EEZ, which explains why geographical circumstances prevail over area-specific criteria or resource-specific criteria.²⁷ On the contrary, the delimitation of the continental shelf beyond 200 nm only concerns the seabed, and it is thus argued that ‘circumstances must be, and need only be, relevant to the seabed’.²⁸

Notwithstanding these theoretical undertakings contending deviations from the three-stage approach, the practice of international courts and tribunals demonstrates a definite move towards the integration of maritime delimitation within and beyond 200 nm. By not distinguishing delimitation methodology within and beyond 200 nm, international courts and tribunals approached the methodological questions raised by the entitlement to the continental shelf beyond 200 nm from different perspectives. Before delving into the application of the three-stage approach in delimitation beyond 200 nm, the legal bases for its applicability will be discussed first.

2.2 Legal bases for the applicability of the three-stage approach

Few explanations have been offered by the judiciary on the applicability of the three-stage approach, as the decisions either addressed the issue rather briefly, or refrained from expressing any views at all, the latter being the Somalia v. Kenya case.²⁹ Among the cases that did shed light on this issue, two major legal bases are noted, namely, Article 83(1) of UNCLOS and the concept of single continental shelf.

In the Bangladesh/Myanmar case, ITLOS observed that ‘article 83 of the Convention addresses the delimitation of the continental shelf between States with opposite or adjacent coasts without any limitation as to the area’, therefore ‘Article 83 applies equally to the delimitation of the continental shelf both within and beyond 200 nm’.³⁰ However, as rightly pointed out by Oude Elferink, Article 83(1) does not contain any delimitation methods, nor does it refer to any principles or rules to be applied to the delimitation of the continental shelf.³¹ Indeed, Article 83(1) of UNCLOS merely ‘sets a goal to be achieved, but is silent as to the method to be followed to achieve it’.³² International courts and tribunals may resort to different methods or methodologies under Article 83(1). For instance, the ICJ employed the bisector method to delimit the continental shelf and the EEZ in the Nicaragua v. Honduras case, where Article 83(1) of UNCLOS was part of the applicable law.³³

For their part, the Bangladesh v. India case and the Ghana/Côte d’Ivoire case resorted to the concept of single continental shelf to support the applicability of the same delimitation methodology in the continental shelf beyond 200 nm. In the Bangladesh v. India case, the arbitral tribunal observed that ‘there is a single continental shelf’, thus ‘the appropriate method for delimiting the continental shelf remains the same, irrespective of whether the area to be delimited lies within or beyond 200 nm’.³⁴ That observation was also accepted by the Ghana/Côte d’Ivoire case.³⁵ While it is true that Articles 76 and 77 embody a concept of single continental shelf without distinguishing the nature of the continental shelves within and beyond 200 nm, it is less obvious why the descriptive concept of single continental shelf has normative implications for the choice of delimitation methodology in the area beyond 200 nm.

The concept of single continental shelf first made its appearance in the Barbados v. Trinidad and Tobago case, though in a different context where the tribunal was ascertaining ‘the scope of the matters which constituted the dispute’ under its jurisdiction, because Barbados and Trinidad and Tobago disagreed with whether the question of ‘extended continental shelf’ formed part of the dispute.³⁶ Therefore, the statement that ‘in law only a single “continental shelf” rather than an inner continental shelf and a separate extended or outer continental shelf’ complemented the tribunal’s reasoning on the scope of jurisdiction ratione materiae.³⁷

It has been suggested that the concept of single continental shelf is incompatible with the task of single maritime delimitation, because the former cannot be applied in a simultaneous delimitation of the EEZ and the continental shelf within 200 nm.³⁸ This argument is persuasive to an extent, because in the Ghana/Côte d’Ivoire case, the special chamber excluded the relevance of oil practice in maritime delimitation within 200 nm for reasons that ‘a de facto line or modus vivendi related to oil practice cannot per se be a relevant circumstance in the delimitation of an all-purpose maritime boundary with respect to superjacent water as well as the seabed and subsoil’.³⁹ This reasoning, which is reminiscent of the ‘neutral criteria’ introduced into the language of the law of maritime delimitation by the Gulf of Maine case,⁴⁰ may create a paradox, namely, although the concept of single continental shelf tends to convey the idea that the continental shelf delimitation was part of the single maritime delimitation, practically the special chamber proceeded with a simultaneous delimitation of the EEZ and continental shelf within 200 nm by adhering to neutral criteria before turning to the delimitation beyond 200 nm.

Nevertheless, the tension between the concept of single continental shelf and single maritime delimitation is attenuated by taking into account two factors, one theoretical and the other practical. Theoretically, the neutral criteria that were deemed ‘best suited for use in a multi-purpose delimitation’,⁴¹ such as the disparities in coastal lengths, concavity, and disproportionality, were factors found relevant in earlier continental shelf delimitation cases.⁴² It is thus not the intrinsic ‘neutral character’ of these factors, but instead the courts and tribunals’ efforts that ‘neutralize’ these factors into single maritime delimitation.⁴³ Practically, the jurisprudence witnessed a trend towards the expansion of the concept of single maritime delimitation. In the Gulf of Maine case, as well as the St. Pierre and Miquelon case, single maritime delimitation was understood as ‘simultaneous delimitation of the continental shelf and the superjacent [water column]’.⁴⁴ Yet, with more states requesting international courts and tribunals to delimit their territorial sea, EEZ, and continental shelf by a single line, single maritime delimitation came to be understood as ‘to establish one uninterrupted boundary line delimiting the various – partially coincident – zones of maritime jurisdiction appertaining to them’.⁴⁵ Under the latter understanding, international courts and tribunals may still apply different methodologies for the territorial sea and for the continental shelf/EEZ.⁴⁶ Similarly, in the Ghana/Côte d’Ivoire case, the special chamber acknowledged the parties’ mutual (albeit implicit) agreement on the employment of the same delimitation methodology throughout the delimitation of the territorial sea, the EEZ, and the continental shelf, including the shelf beyond 200 nm, and decided it appropriate to do so in the entire process.⁴⁷ As a result, there were no practical obstacles against the use of the same methodology where single maritime delimitation incorporates territorial sea delimitation and the continental shelf delimitation beyond 200.

Upon closer examination, the real problem about the concept of single continental shelf is not its incompatibility with single maritime delimitation on the conceptual level; instead, it is that the reliance on the concept seeks to simplify the delimitation process to a point that deprives the delimitation methodology for the continental shelf beyond 200 nm any substance. Where there is a need to continue the boundary line throughout multiple maritime zones, it requires the judiciary to link the different segments of the boundary in a manner that pursues an overall equitable solution. As a result, whether the three-stage approach is applicable in the delimitation of the continental shelf beyond 200 nm depends upon whether it succeeds in integrating the boundary beyond 200 nm into the single line of maritime delimitation, which in turn depends upon the consideration of the appropriateness of the methodology on a substantive rather than formal level, such as by the continuous examination of relevant circumstances and by balancing-up the relative weight to the circumstances when the boundary line travels further seaward.⁴⁸

Consequently, the applicability of three-stage approach to the delimitation of the continental shelf beyond 200 nm is, eventually, measured by its appropriateness in achieving an equitable solution.⁴⁹ While some may find the conclusion objectionable for leaning towards the traditional and arguably abandoned approach of treating each maritime delimitation case as a ‘unicum’,⁵⁰ it must be stressed that the three-stage approach has never been considered to be mandatory in the jurisprudence.⁵¹ Accordingly, while the three-stage approach may serve as a ‘baseline approach’ in the delimitation of the continental shelf beyond 200 nm, its applicability depends on how each stage of the methodology contributes to the delimitation process towards an equitable solution. It is against this consideration that the application of three-stage approach in the delimitation of the continental shelf beyond 200 nm must be examined, to which the next sections will turn.

3. Stage zero: Determination of overlapping entitlements and its methodological implications

3.1 Identification of relevant coasts and relevant area in delimitation beyond 200 nm

As observed by the Ghana/Côte d’Ivoire case, ‘The first step in the construction of the provisional equidistance line is to identify the Parties’ coasts of which the seaward projection overlaps.’⁵² Due to the methodological implications of relevant coasts and relevant area, their identification is properly understood as ‘stage zero’ in the application of the three-stage approach.⁵³

The attributes of establishing the continental shelf beyond 200 nm introduce certain definitional difficulties in the identification of relevant coasts and relevant area in the delimitation beyond 200 nm. Under Article 76(1) of UNCLOS, the continental shelf beyond 200 nm extends beyond the coastal state’s territorial sea ‘throughout the natural prolongation of its land territory to the outer edge of the continental margin’. Article 76(4) further defines the establishment of the outer edge of the continental margin by reference to two formulae, one is 60-nm-distance from the foot of the continental slope (FOS), the other rests on the determination of the thickness of the sedimentary rocks. In addition, Article 76(5)-(6) set out the constrains of the maximum limits of the continental shelf, namely 350 nm from the territorial baselines and 2,500-metre-isobath plus 100 nm. As a result, coastal states’ continental shelf entitlement beyond 200 nm are loosely related to the coasts, and, unless the outer limits of the continental shelf are determined in accordance with the 350-nm constraint, the coast has no role in determining the seaward extent of such entitlement.⁵⁴ This leads to a break-up of the definitional reciprocity in determining the relevant coasts and relevant area by reference to the area of overlapping entitlements.

The judicial and arbitral practice concerning the continental shelf beyond 200 nm has not dealt with the definitional issue head-on. The relevant area defined in the Bangladesh/Myanmar case excluded a large part of the parties’ overlapping claims to the continental shelf beyond 200 nm.⁵⁵ In contrast, the Bangladesh v. India case was more explicit about the determination of relevant coasts and relevant area when it came to the delimitation beyond 200 nm. Here again, the concept of single continental shelf was resorted to as a legal device:

In keeping with its view that there is a single continental shelf … this tribunal sees no basis for distinguishing between projections within 200 nm and those beyond that point … [T]he coast is relevant, irrespective of whether that overlap occurs within 200 nm of both coasts, beyond 200 nm of both coasts, or within 200 nm of one and beyond 200 nm of the other.⁵⁶

Under this broad understanding of the relevant coasts, the arbitral tribunal included in the relevant coasts the segment on the Indian coast between Devi Point and Sandi Point, as well as the projections generated by the coast of the northern islands of the Andaman chain, even though neither party argued for the inclusion of the latter.⁵⁷ The non-distinction between coastal projections within or beyond 200 nm was endorsed by the Ghana/Côte d’Ivoire case as well.⁵⁸

While UNCLOS tribunals’ approach may be largely in line with the determination of relevant coasts and relevant area by referring to the area of overlapping entitlements, they failed to explain why the geometrically construed ‘coastal projections’, as consistently understood in the jurisprudence, should be expanded to include the geomorphologically or geologically determined continental shelf beyond 200 nm.⁵⁹ An additional definitional issue that has puzzled maritime delimitation within 200 nm is that the scope of relevant coasts may differ depending upon whether frontal or radial projections within 200 nm are employed.⁶⁰ Therefore, the delimitation of the continental shelf beyond 200 nm adds another layer of confusion in the methodological complexities inherent in the exercises of identifying relevant coasts.⁶¹ So far, the resolution seems to be found in judicial discretion. Recognizing that a radial line drawn to the north-east from a point south of Sandy Point on the India’s coast would also overlap with the projection of the coast of Bangladesh beyond 200 nm, the arbitral tribunal observed that ‘there is a margin of appreciation’ in determining the relevance of a specific segment of coasts.⁶² It is however questionable if falling back to a margin of appreciation would enhance the transparency of the application of the delimitation methodology.⁶³

3.2 Uncertainties in the scope of continental shelf entitlements

Another challenge felt in stage zero is the impact of the uncertainties of the existence or scope of the continental shelf entitlements over the accuracy of identifying relevant coasts and relevant area. Under Article 76(8), coastal states are obliged to submit information concerning their outer limits of the continental shelf to the Commission on the Limits of the Continental Shelf (CLCS), a scientific and technical body established by UNCLOS.⁶⁴ The outer limits of the continental shelf established on the basis of the recommendations of the CLCS are final and binding. The mandate of the CLCS in recommending coastal states on the outer limits of the continental shelf includes the verification of the existence of the continental shelf entitlement beyond 200 nm, which is formulated as ‘test of appurtenance’ in the CLCS Scientific and Technical Guidelines.⁶⁵ Ascertaining the existence or extent of the continental shelf entitlement can be technically and scientifically challenging for the CLCS. In its recommendations to the Cook Islands in 2016, while the CLCS found the Cook Islands passed the test of appurtenance, it was nevertheless ‘unable to recommend on the precise location of the outer limits of the continental shelf’ in a specific region involved in the submission.⁶⁶ Therefore, the existence or the scope of the continental shelf entitlement beyond 200 nm cannot be presumed.

The delimitation of the continental shelf beyond 200 nm by international courts and tribunals was thus far effected without all the parties having received recommendations from the CLCS, and the judiciary had employed a range of approaches to overcoming the difficulties in ascertaining the overlap of continental shelf entitlements. The Bangladesh/Myanmar case and the Bangladesh v. India case were premised on the unique situation of the Bay of Bengal, where the existence of a continental margin had been acknowledged in the course of negotiations at the Third United Nations Conference on the Law of the Sea (UNCLOS III).⁶⁷ Apparently, the factual situation in these two decisions is too unique to be generally available in other geographical or geomorphological contexts.⁶⁸

The Ghana/Côte d’Ivoire case is exceptional in that one of the parties, i.e., Ghana, had completed its procedure before the CLCS when the special chamber was deciding the boundary dispute.⁶⁹ The special chamber then recognized the existence of the entitlement for Côte d’Ivoire based on its identical geological situation with Ghana.⁷⁰ In terms of the relevant area, the special chamber determined the southern limit of the relevant area by referring to the outer limits of the continental shelf of Ghana and those of Côte d’Ivoire contained in the latter’s 2016 amended submission to the CLCS.⁷¹ As a result, the amended submission of Côte d’Ivoire was taken into account in identifying relevant coasts and relevant area, and, subsequently, in the disproportionality test.

However, the outer limits of the continental shelf claimed by Côte d’Ivoire in its 2016 amended submission were not fully approved by the CLCS. The CLCS did not accept the geological and geophysical considerations put forward by Côte d’Ivoire in supporting the eastern part of the outer limits of the continental shelf. The CLCS reiterated that the base of the continental slope region ‘should be identified based on morphological and bathymetric evidence’, while ‘[g]eological and geophysical data can be submitted by coastal States to supplement proof’ on the location of the base of the continental slope region.⁷² The working methods of the CLCS thus differ from that of the special chamber’s, which relied on the existence of identical geological structures. Moreover, after several rounds of requesting additional documentation and data, the CLCS verified six sediment thickness formula points in accordance with Article 76(4)(a)(i) of UNCLOS, whose location differed from the original seven sediment thickness points submitted by Côte d’Ivoire.⁷³ Accordingly, certain part of the continental shelf beyond 200 nm contained in Côte d’Ivoire’s amended submission, which was included in the special chamber’s identification and calculation of the relevant area, was not recommended by the CLCS to be part of Côte d’Ivoire’s continental shelf beyond 200 nm.

The contradiction between the CLCS and the special chamber over the scope of the continental shelf entitlement beyond 200 nm demonstrates that the identification of relevant area may prove to be elusive without affirmative recommendations of the CLCS. Since this initial stage is methodologically significant for international courts and tribunals to discharge their task of ‘resolving the overlapping claims by drawing a line of separation of the maritime areas concerned’,⁷⁴ the uncertainties in the scope of continental shelf entitlements may undermine the accuracy of this exercise, and, as a result, the disproportionality test as well. Although neither the calculation of the size of the maritime zones nor the disproportionality test purport to be precise,⁷⁵ the inclusion of the continental shelf beyond 200 nm into these steps still casts doubt on their methodological objectivity.

More critically, the reliance on the submissions of the parties to a dispute proves to be factually vulnerable, since the submissions of coastal states are not proof of the existence or the extent of the continental shelf entitlement beyond 200 nm.⁷⁶ Indeed, the CLCS did not verify the western segment of the outer limits of the continental shelf in Côte d’Ivoire’s submission because the Commission did not agree with the location of the foot of the continental slope points.⁷⁷ Therefore, even in a situation where one of the parties had received positive recommendations from the CLCS, judicial caution is warranted so as not to lose sight of the significant variations of the continental margin from subregion to subregion under certain circumstances.⁷⁸

On the other hand, uncertainties in the applicable law governing the establishment of the entitlement to the continental shelf beyond 200 nm may also put into question the scope of the entitlement. In the Somalia v. Kenya case, the ICJ proceeded to the delimitation beyond 200 nm on the grounds that both parties claimed a continental shelf up to 350 nm and neither of the parties challenged each other’s continental shelf claim beyond 200 nm.⁷⁹ However, in its submission to the CLCS, Kenya invoked the ‘Statement of Understanding Concerning a Specific Method to be Used in Establishing the Outer Edge of the Continental Margin’ (Statement of Understanding) to establish the outer edge of the continental margin,⁸⁰ because in Kenya’s view the application of Article 76(4) would result in inequity given the particular circumstances and characteristics of the continental margin of Kenya.⁸¹ Nonetheless, as pointed out by several commentators, it is not entirely clear if the Statement of Understanding is applicable to states outside the region of the Southern Bay of Bengal under a textual reading of the Statement of Understanding.⁸² The silence of the ICJ over the applicability of the Statement of Understanding was thus a significant omission about the legal basis of Kenya’s continental shelf claim beyond 200 nm.⁸³

Moreover, the ICJ did not examine any geomorphological or geological evidence in determining the parties’ continental shelf entitlement beyond 200 nm, even though the Court emphasized that ‘[a]n essential step in any delimitation is to determine whether there are entitlements, and whether they overlap’.⁸⁴ The deficiency in this approach was well summarized by President Donoghue:

[T]he Court has scant evidence regarding the existence, shape, extent and continuity of any outer continental shelf that might appertain to the Parties. The Court is not well positioned to identify, even approximately, any area of overlapping entitlement and thus to arrive at an equitable delimitation of any area of overlap.⁸⁵

The way that the ICJ proceeded with the delimitation beyond 200 nm in the Somalia v. Kenya case thus demonstrates a ‘minimalist approach’ to the methodology for the continental shelf beyond 200 nm, because the Court did not identify relevant coasts or relevant area in relation to the continental shelf beyond 200 nm, nor conduct the disproportionality test by taking into account the area beyond 200 nm.⁸⁶

To sum up, the uncertainty in the existence or extent of the continental shelf entitlement further complicates the exercises of identifying relevant coasts and relevant area, and, in the worst cases, may put into question the factual basis upon which the delimitation was carried out.

4. Application of the three-stage approach in the jurisprudence

As a general remark, there are two variants in the application of the three-stage approach to the delimitation of the continental shelf beyond 200 nm. One is the construction of a boundary line by applying the three-stage approach to maritime delimitation within and beyond 200 nm in a single exercise. The other consists of two separate exercises, namely, the application of the three-stage approach to maritime delimitation within 200 nm and the extension of the adjusted line to the continental shelf beyond 200 nm. While the Bangladesh v. India case and the Ghana/Côte d’Ivoire case fall within the former, the Bangladesh/Myanmar case and the Somalia v. Kenya case belong to the latter. The next sections will examine and compare the two variants by reference to the application of each step of the three-stage approach.

4.1 Construction of a provisional equidistance line

In the Bangladesh/Myanmar case, applying the three-stage approach to the delimitation of the EEZ and continental shelf within 200 nm, ITLOS chose four basepoints on Myanmar’s coast and two basepoints on Bangladesh’s coast, which created a provisional equidistance line that was to be connected through four turning points.⁸⁷ Afterwards, ITLOS proceeded to consider the relevant circumstances and adjusted the provisional equidistance line accordingly.⁸⁸ After that, ITLOS did not describe a provisional equidistance for the continental shelf beyond 200 nm. Rather, it proceeded to ‘re-examine the question of relevant circumstances’ and decided to extend the adjusted line in the same direction beyond 200 nm.⁸⁹ In the Somalia v. Kenya case, the ICJ applied all three steps in the three-stage approach to maritime delimitation within 200 nm and then extended the adjusted boundary line within 200 nm to delimit the continental shelf beyond 200 nm without offering any reasoning.⁹⁰

The reason why ITLOS separated the delimitation process may be explained by the arguments of the parties in that case. Myanmar argued for the use of equidistance to delimit the maritime boundary, and, as a result of this method, no question of delimitation beyond 200 nm would arise because the boundary line would terminate well before reaching the 200 nm limits of the two parties.⁹¹ Bangladesh, on the other hand, denied that Myanmar had a continental shelf entitlement beyond 200 nm.⁹² The fact that both parties requested ITLOS to delimit the boundary line in a manner that would leave the entire continental shelf beyond 200 nm under dispute to that party alone may have had a bearing upon the structure of the judgment, as ITLOS addressed the jurisdictional and admissibility issues concerning the continental shelf beyond 200 nm after having delimited the boundary line within 200 nm.⁹³ However, in the Somalia v. Kenya case, both parties requested the ICJ to delimit maritime zones within and beyond 200 nm in a single line that extends to the outer limits of the continental shelf. While Somalia proposed an equidistance line, Kenya argued for a boundary that follows a certain parallel of latitude.⁹⁴ That the ICJ confined the application of the three-stage approach to maritime delimitation within 200 nm further attests to its ‘minimalist approach’ towards the continental shelf delimitation beyond 200 nm.

On the contrary, both the Bangladesh v. India case and the Ghana/Côte d’Ivoire case constructed a complete equidistance line within and beyond 200 nm. Although both tribunals drafted the delimitation within 200 nm and that beyond 200 nm in separate sections, the delimitation process was de facto integrated. In the Bangladesh v. India case, some of the basepoints chosen for constructing a provisional equidistance line continued to affect the equidistance line beyond 200 nm, and an additional basepoint was selected when the tribunal applied the first step of the three-stage approach to the continental shelf beyond 200 nm.⁹⁵ The special chamber in the Ghana/Côte d’Ivoire case observed that the basepoints set out in maritime delimitation within 200 nm ‘are sufficient to establish the provisional equidistance line until it reaches the outer limits of the continental shelf beyond 200 nm’.⁹⁶

It is arguable that the integrated approach to the construction of a provisional equidistance line within and beyond 200 nm is more faithful representation of applying the three-stage approach to the continental shelf beyond 200 nm. In fact, the extension of an already adjusted line to the continental shelf beyond 200 nm displaces the application of the first stage of the three-stage approach. As observed by Judge Cot in the Bangladesh/Myanmar case, ITLOS merely drew an initial segment of the provisional equidistance line and then replaced it with an azimuth line after some 30 nm.⁹⁷ That was, in his view, a departure from applying the three-stage approach ‘judiciously and in a manner true to both its letter and spirit’.⁹⁸

By displacing the first stage of the methodology in the delimitation beyond 200 nm, the judiciary also avoided to consider the appropriateness or feasibility of a provisional equidistance line, which was however key to the choice of the delimitation methodology, since ‘it will not be appropriate in every case to begin with a provisional equidistance/median line’.⁹⁹ The omission was accentuated because a coast-to-coast equidistance line may not always arrive at a proper division of the area of overlap beyond 200 nm. Oude Elferink observed that, in the Bangladesh/Myanmar case, a strict equidistance line would not have any relation to the area of overlapping entitlements beyond 200 nm, and the provisional equidistance line drawn by ITLOS was located in the north western corner of the part of the relevant area beyond 200 nm.¹⁰⁰ Had ITLOS proceeded with the usual sequence of identifying relevant coasts and relevant area and constructed a complete equidistance line, it would have to justify the drawing of an equidistant line in delimitation beyond 200 nm. Lack of this step inevitably undermined the objectivity of the three-stage approach, as the primary value of the equidistance method is deemed to be its contribution to the objectivity and certainty of the delimitation process.¹⁰¹

Moreover, the absence of a complete equidistance line beyond 200 nm would also have a collateral effect over the second stage of the methodology, namely, the consideration of relevant circumstances. Without depicting the provisional equidistance line against the relevant area – a step lacking in both the Bangladesh/Myanmar case and the Somalia v. Kenya case, the effect of the provisional line in dividing the area of overlapping entitlements in the light of the coastal relationship is obscured, thus rendering the examination of relevant circumstances less transparent. This problem will be elaborated further below.

4.2 Examination of relevant circumstances

4.2.1 Continuing relevance of coastal geography in the delimitation beyond 200 nm

Cut-off effect resulting from the concavity of the coastal configuration is, among others, one relevant geographical circumstance firmly established under the law of maritime delimitation,¹⁰² and its continuing relevance in the delimitation beyond 200 nm has been recognized by all four decisions that delimited the continental shelf beyond 200 nm. Both the Bangladesh/Myanmar case and the Bangladesh v. India case recognized the severe cut-off effect resulted from the concavity of the Bangladesh coast in the delimitation beyond 200 nm.¹⁰³ Although the Ghana/Côte d’Ivoire case did not adjust the provisional line for considerations of cut-off effect, the special chamber did accept that the coast of Côte d’Ivoire was concave, and analysed the cut-off effect produced by the provisional equidistance line to the projections of Côte d’Ivoire’s coasts both within and beyond 200 nm.¹⁰⁴ The ICJ, for its part, decided to accord weight to ‘the consideration of the concavity of a coastline in a broader geographical configuration’ by observing the coasts of Somalia, Kenya, and Tanzania (a third party to the proceedings) as a whole, which provoked criticism.¹⁰⁵ Without specifically tending to its relevance for the continental shelf delimitation beyond 200 nm, the Court extended the adjusted line to the continental shelf beyond 200 nm, thus giving weight to the cut-off effect that may be felt in the disputed areas beyond 200 nm.

The continuing relevance of cut-off effect in delimitation beyond 200 nm is not, however, unpredictable under the law of maritime delimitation, because it was pointed out, as early as the North Sea cases, that ‘in the case of concave or convex coastlines that if the equidistance method is employed, then the greater the irregularity and the further from the coastline the area to be delimited, the more unreasonable are the results produced’.¹⁰⁶ Moreover, as the maritime zones within and beyond 200 nm are delimited by a single line, the practical need for continuity also warrants a continuing assessment of the relationship between the boundary line in relation to the coasts of the parties. According to the tribunal of the Barbados v. Trinidad and Tobago, ‘what governs the delimitation essentially are the geographical elements which are at its origin, close to land, and not at its end’, and ‘the continuity of the line is the inevitable expression of the principle that the “land dominates the sea”’.¹⁰⁷

A number of analytical problems, however, arise out of assessing the cut-off effect in the delimitation of the continental shelf beyond 200 nm. The Bangladesh/Myanmar case and the Somalia v. Kenya case shed little light on measuring the cut-off effect beyond 200 nm. In the Bangladesh/Myanmar case, Bangladesh contended that the use of a strict equidistance line would result in cutting off Bangladesh entirely from its entitlement to the continental shelf beyond 200 nm, which should warrant the choice of a different method.¹⁰⁸ ITLOS did not respond to this argument specifically, thus it remained unclear if cutting off a coastal state’s access to its entitlement to the continental shelf beyond 200 nm should be a factor that compels the departure from using equidistance in the first stage. Moreover, by not drawing a complete equidistance line to the continental shelf beyond 200 nm, there was no demonstration of the cut-off effect produced by the provisional equidistance line, and hence no illustration of to what extent the adjusted line did address such cut-off effect beyond 200 nm. ITLOS merely observed that the three-stage approach ‘can, and does in this case, permit resolution also beyond 200 nm of the problem of the cut-off effect’.¹⁰⁹

Similarly, in the Somalia v. Kenya case, Kenya argued that the cut-off effect produced by an equidistance line would be severely exacerbated past the 200-nm-limit, especially to the point that Kenya would be completely cut off from the outer limit of the continental shelf.¹¹⁰ It is virtually unclear whether the ICJ took into account this argument, since the Court did not examine relevant circumstances in the delimitation beyond 200 nm. The absence of reasoning on this point was especially problematic, because, in response to Kenya’s argument, Somalia contended that, however severe any cut-off would be, it was solely the result of the delimitation agreements between Kenya and Tanzania in 1976 and 2009,¹¹¹ which were res inter alios acta and hence not a relevant circumstance.¹¹² The Court did not address this contention either. However, sketch-map No.13 on the course of the maritime boundary produced by the ICJ demonstrates that a measure of cut-off effect for Somalia begins to materialize to the end of the boundary line where it reaches the 200-nm-limit, which, although not shown by the sketch-map, will be magnified as the boundary line travels to the 350 nm-limit. By not examining the relevance of the cut-off effect beyond 200 nm, the ICJ also refrained from considering whether the extension of the adjusted line ‘allows the adjacent coasts of the Parties to produce their effects, in terms of maritime entitlements, in a reasonable and mutually balanced way’.¹¹³ Hence the second stage of examining relevant circumstances in the delimitation beyond 200 nm was limited and partial given the incomplete exercise of drawing a provisional equidistance line.

Another problem relating to the assessment of cut-off effect in delimitation beyond 200 nm is the lack of coherence between distance-based coastal projections and geomorphology-based continental shelf entitlements in the analysis of the cut-off effect. In maritime delimitation within 200 nm, international courts and tribunals evaluate the severity of cut-off effect by looking at the effects of the provisional line over the coastal projections of the parties.¹¹⁴ Since the entitlement and overlapping entitlements to the continental shelf beyond 200 nm are not always distance-bound, it may require an analytical shift in the examination of cut-off effect in the delimitation beyond 200 nm. The arbitral tribunal in the Bangladesh v. India case attempted to formulate two criteria to assess cut-off effect where a provisional equidistance line was employed, namely:

First, the line must prevent a coastal State from extending its maritime boundary as far seaward as international law permits. Second, the line must be such that – if not adjusted – it would fail to achieve the equitable solution required by articles 74 and 83 of the Convention. This requires an assessment of where the disadvantage of the cut-off materializes and of its seriousness.¹¹⁵

In that case, the arbitral tribunal examined the cut-off effect by taking into account the whole area where the parties’ overlapping claims met, including the continental shelves beyond 200 nm.¹¹⁶ As the arbitral tribunal saw it, ‘The effect is even more pronounced in respect of the southward projection of the south-facing coast of Bangladesh … as far as the area beyond 200 nm is concerned.’¹¹⁷ Accordingly, the arbitral tribunal examined the cut-off effect within and beyond 200 nm in an integrated manner, which seemed only natural following a complete equidistance line throughout these maritime areas.¹¹⁸ Proceeding with the two criteria thus formulated, the arbitral tribunal noted that the provisional line prevented Bangladesh from reaching its seaward limits permitted by international law, that was, the outer limits of the continental shelf beyond 200 nm.¹¹⁹ Intriguingly, the arbitral tribunal went beyond a geometric analysis of cut-off effect by looking at the parties’ coastal projections, and measured the cut-off effect by comparing the area attributed to each party and the area of overlapping claims. The arbitral tribunal observed that ‘the area attributed to Bangladesh in the area beyond 200 nm is limited in scope in comparison to the area in which the entitlements of the Parties overlap’.¹²⁰ Nonetheless, the area beyond 200 nm remained to be limited for Bangladesh even after the arbitral tribunal adjusted the provisional equidistance line. That may be explained by the arbitral tribunal’s integrated approach to delimitation as well, since it emphasized that ‘the entitlement of a State to reach the continental shelf beyond 200 nm is not the only relevant consideration. The Tribunal must examine the geographic situation as a whole’.¹²¹

Summing up, the jurisprudence has not been entirely consistent with respect to measuring the cut-off effect beyond 200 nm, despite the recognition of the continuing relevance of coastal geography. Nevertheless, an integrated approach to examining relevant circumstances within and beyond 200 nm tends to ‘adequately meeting the test of transparency, certainty and predictability’ in the adjustment of a provisional equidistance line,¹²² while the extension of adjusted lines within 200 nm to the continental shelf beyond 200 nm significantly limits the scope of the court and tribunal’s examination of relevant circumstances in the delimitation beyond 200 nm.

4.2.2 Irrelevance of geomorphological or geological circumstances

The judicial and arbitral practice so far has not given weight to any factors of geomorphology or geology in the examination of relevant circumstances. In the Bangladesh/Myanmar case, Bangladesh, basing on an extensive study of the geological evolution of the Bay of Bengal, contended that a fundamental geological discontinuity existed in the Bay of Bengal, which prevented Myanmar from having a continental shelf beyond 200 nm but allowed Bangladesh to have the most natural prolongation into the Bay of Bengal.¹²³ That argument, in effect, is resonant of the doctrine of identification of separate natural prolongations as a method of delimitation, which was passionately argued by the parties and, eventually, rejected by the ICJ in the Tunisia/Libya and the Libya/Malta cases.¹²⁴ ITLOS considered ‘the most natural prolongation’ argument to be irrelevant in the Bangladesh/Myanmar case, because, having found that both parties’ entitlements to the continental shelf beyond 200 nm overlap in the present case, Bangladesh cannot claim a larger portion of the disputed area by reference to the geological discontinuity of the Bay of Bengal.¹²⁵ Bangladesh subsequently withdrew ‘the most natural prolongation’ argument from the proceedings of the Bangladesh v. India case,¹²⁶ and no state made similar arguments in subsequent cases concerning the continental shelf delimitation beyond 200 nm.

It is likely that excluding geomorphological or geological circumstances from the consideration of relevant circumstances will contribute to the substantive integration of maritime delimitation within and beyond 200 nm. While a number of scholars are sceptical of the Bangladesh/Myanmar case setting a precedent,¹²⁷ it is submitted that arguments invoking identification of separate natural prolongations as a method of delimitation or as a relevant circumstance in the delimitation process can hardly be successful in judicial or arbitral proceedings. A fact of particular importance is that the judiciary has never accorded weight to geomorphological or geological submarine features in the continental shelf delimitation cases, thus there are essentially no guiding precedents to appreciate the legal relevance of these factors.¹²⁸ Even in the Tunisia/Libya case, where the ICJ examined the scientific evidence submitted by both parties and concluded that no fundamental discontinuity could be discerned in the disputed area, the Court cautioned that:

It would be a mistake to suppose that it will in all cases, or even in the majority of them, be possible or appropriate to establish that the natural prolongation of one State extends, in relation to the natural prolongation of another State, just so far and no farther, so that the two prolongations meet along an easily defined line.¹²⁹

Moreover, to determine maritime boundaries through identifying separate natural prolongations, which involves an exercise of searching ‘marked disruption or discontinuance of the sea-bed as to constitute an indisputable indication of the limits of two separate continental shelves’,¹³⁰ would be fundamentally incompatible with the precondition to maritime delimitation, namely, the existence of overlapping entitlements.¹³¹ If the continental shelves were separate as a matter of geomorphological or geological fact, there would be two continental shelves instead of one common continental shelf, and the task at issue would be one of ascertaining the outer limits of the continental shelf rather than that of delimitation where the separate continental shelves were claimed by two different parties.¹³²

Nor is it tenable that the legal criteria under Article 76 of UNCLOS provide a legal basis for comparing the relative strength of the continental shelf entitlement so that a delimitation can be based on the differentiation of the ‘naturalness’ of the continental shelves.¹³³ It is because the formulae under Article 76(4) and the constraints under Article 76(5)-(6) of UNCLOS are to be flexibly employed by coastal states to maximize their continental shelf entitlement beyond 200 nm.¹³⁴ The distinction between the rule of entitlement and the rule of delimitation is of paramount significance. As highlighted by the ICJ, ‘the appurtenance of a given area, considered as an entity, in no way governs the precise delimitation of its boundaries’.¹³⁵

An additional, yet crucial consideration is the unwillingness of the judiciary to base a delimitation decision on prior assessment of scientific and technical data. That concern has been expressed by Judges ad hoc Mensah and Oxman in the Bangladesh/Myanmar case, who, commenting on Bangladesh’s ‘the most natural prolongation’ argument, observed that ‘[a]cceptance of this idea would, in our view, introduce a new element of difficulty and uncertainty into the process of maritime delimitation in this case’.¹³⁶ The unwillingness of the judiciary to reach definite conclusions on contested scientific or technical matters is neither new,¹³⁷ nor confined to the field of maritime delimitation.¹³⁸ In the recent Mauritius/Maldives case, the special chamber considered that ‘there is a fundamental disagreement between the Parties on a number of scientific and technical issues’,¹³⁹ and that there was significant uncertainty as to some arguments advanced by Mauritius to prove its entitlement to the continental shelf beyond 200 nm.¹⁴⁰ Instead of rejecting Mauritius’ claim to the continental shelf beyond 200 nm, the special chamber rather decided that it ‘was not in a position to determine the entitlement of Mauritius’.¹⁴¹ Although that decision was reached not in relation to the delimitation exercise of the continental shelf beyond 200 nm as such,¹⁴² it once again shows, through a decision not to decide, the reluctance of the judiciary to rule on contested technical data or choose between conflicting scientific explanations.¹⁴³

Consequently, once the existence and overlap of the entitlements to the continental shelf beyond 200 nm have been established in accordance with Article 76 of UNCLOS, geomorphological or geological circumstances are unlikely to be taken into account in the second stage of the application of the three-stage approach.¹⁴⁴ This is not to deny the conceptual relationship between entitlement and delimitation, which, in the words of the ICJ, means that ‘[t]he legal basis of that which is to be delimited, and of entitlement to it, cannot be other than pertinent to that delimitation’.¹⁴⁵ Instead, it is submitted that the judiciary are unlikely to take into account argumentation based on the ‘naturalness’ of certain geophysical submarine features. As elaborated above, there are virtually no applicable legal criteria that appreciate the relative ‘naturalness’ of geomorphological or geological factors. A fundamental consideration in this respect is that delimitation is, by nature, a legal-political exercise that differs from a search for natural boundaries.¹⁴⁶ The irrelevance of geomorphological or geological circumstances with the delimitation of the continental shelf beyond 200 nm shall be confined, however, to the context of legal proceedings before international courts and tribunals. States are free to give weight to submarine features as long as they reach agreement in their delimitation practice.¹⁴⁷

4.3 The disproportionality test

The conduct of the disproportionality test in the delimitation of the continental shelf beyond 200 nm was largely in line with the two variants identified at the outset of this section.

The Bangladesh/Myanmar case determined the relevant area only in connection with the disproportionality test, after ITLOS extended the adjusted line to the continental shelf beyond 200 nm.¹⁴⁸ As that exercise excluded almost all the area of the overlapping continental shelf beyond 200 nm claimed by the parties,¹⁴⁹ it was unclear if ITLOS intended to include the area beyond 200 nm into the relevant area. The ICJ, in the Somalia v. Kenya case, on the other hand, conducted a disproportionality test solely for maritime delimitation within 200 nm.¹⁵⁰ Therefore, in these two decisions there was no or, in the case of the Bangladesh/Myanmar, highly limited application of the disproportionality test that took into account the continental shelf beyond 200 nm. On the contrary, both the Bangladesh v. India case and the Ghana/Côte d’Ivoire case incorporated the continental shelf beyond 200 nm into the final stage of the disproportionality test after having delimited the maritime zones within and beyond 200 nm.¹⁵¹ As mentioned earlier, both cases relied on the submissions of the parties to the CLCS to define the geographical scope of the relevant area in preparation for the disproportionality test.¹⁵²

The methodological problems raised by the application of the disproportionality test in the delimitation beyond 200 nm to a considerable extent derive from the initial stage of identifying relevant coasts and relevant area. Where the judiciary refrained from identifying relevant areas that included a continental shelf beyond 200 nm, such as in the Somalia v. Kenya case, it is practically impossible to verify whether the boundary line beyond 200 nm led to marked disproportionality. On the other hand, where the judiciary determined the relevant area with precision by referring to the submissions of the parties to the CLCS, the uncertainties in the scope of the overlapping entitlements of the parties would undermine the objective basis for the disproportionality test.¹⁵³

Nevertheless, to put the application of the disproportionality test in the delimitation beyond 200 nm into perspective, it should be recalled that even in single maritime delimitation within 200 nm, the disproportionality test is not free from conceptual or operational difficulties. It is pointedly observed that the exercise of the disproportionality test is largely formalistic, as in no case did a court or tribunal find the test unfulfilled.¹⁵⁴ The ‘impressionistic’ application of the disproportionality test is most acute where ‘broad assessment of disproportionality’ was deemed sufficient without any figures of the coastal lengths or the size of relevant areas being presented.¹⁵⁵ As elucidated by Tanaka, the disproportionality test as part of the three-stage approach is open to question particularly because of the lack of objective criteria to calculate coastal lengths and maritime areas and of objective criteria to measure what amounts to ‘significant’ or ‘marked’ disproportion.¹⁵⁶ The critique thus leads to robust suggestions of limiting the application of the disproportionality test to certain clearly defined situations,¹⁵⁷ if not denying the use of the disproportionality test all together.¹⁵⁸

For the purpose of the present study, suffice it to say that disproportionality test is another element in the application of the three-stage approach to delimitation beyond 200 nm that is in want of further refinement, for the inclusion of the area of the continental shelf beyond 200 nm without being verified by the CLCS also shakes the foundation of that test. However, the real problem lies in the disproportionality test as a stand-alone step in the three-stage approach rather than its application to the continental shelf beyond 200 nm.

5. Concluding remarks

The examination of the jurisprudence concerning the continental shelf delimitation beyond 200 nm exposes a trend towards the integration of maritime delimitation within and beyond 200 nm under the three-stage approach. The integration takes place not only in the formal level, namely, the choice of the same delimitation methodology for the continental shelf beyond 200 nm, but also in the substantive level. Drawing a complete provisional equidistance line and adjusting the provisional line within and beyond 200 nm in a single exercise, as practiced in the Bangladesh v. India case and the Ghana/Côte d’Ivoire case, illustrates the point. In particular, the recognition of the continuing relevance of coastal geography and the exclusion of geomorphological or geological circumstances from relevant circumstances contribute to the essentially common process of maritime boundary-making by the judiciary.

It may be further considered, after having identified, examined, and compared the two variants of applying the three-stage approach in the jurisprudence, whether consequential differences would ensue under the two variants. It seems unlikely that the delimitation results would differ, because even where the judiciary applied different methodologies in a single maritime delimitation that divided multiple maritime zones, it would be unimaginable that the judiciary completely separated the two segments of the boundary lines without considering how to link them in a single line. It is useful to recall the observation in the Qatar v. Bahrain case, where the delimitation for the territorial sea and that for the EEZ and the continental shelf were carried out separately:¹⁵⁹

When carrying out that part of its task, the Court has to apply first and foremost the principles and rules of international customary law which refer to the delimitation of the territorial sea, while taking into account that its ultimate task is to draw a single maritime boundary that serves other purposes as well.¹⁶⁰

Nevertheless, the two variants of applying the three-stage approach do have an impact on the ‘transparency and the predictability of the delimitation process’, if the advantage of the three-stage approach ‘lies in the fact that it clearly separates the steps to be taken and is thus more transparent’.¹⁶¹ As elaborated in connection with the application of each step of the three-stage approach, extension of an adjusted provisional line to delimit the continental shelf beyond 200 nm displaces the construction of a provisional equidistance line and renders the examination of relevant circumstances partial and limited. Therefore, an integrated approach to the delimitation of the continental shelf beyond 200 nm, which was adopted by the Bangladesh v. India case and the Ghana/Côte d’Ivoire case, is preferable.

Notwithstanding the trend of integration of the delimitation of the continental shelf beyond 200 nm under the three-stage approach, it must be stressed that the practice is still limited, as it has been confined to a single geographical context, namely, between two adjacent coasts. If, however, the continental shelf beyond 200 nm between two opposite coasts is to be delimited, the application of the three-stage approach might be subject to more complexities, depending on how the area of overlapping entitlements in this geographical context is to be identified.¹⁶² On the other hand, if two opposite states share a common continental margin, as between Norway and Russia in the Loop Hole,¹⁶³ a provisional equidistance line retains its ‘equitable nature’ of dividing equally the area of overlap.¹⁶⁴ Moreover, examination of relevant circumstances may draw on the judicial and arbitral practice concerning opposite states.¹⁶⁵ Therefore, the three-stage approach may continue to be a ‘baseline approach’ to be employed by the judiciary to delimit the continental shelf beyond 200 nm between two opposite coasts.

Taken together, it is plausible that the trend of integration of the delimitation of the continental shelf beyond 200 nm under the three-stage approach will continue. What remains to be clarified in the jurisprudence is, first and foremost, the factors that compel a departure from a provisional equidistance line. For example, if a provisional equidistance line between the two coasts of the parties was not located in the area of overlap beyond 200 nm, would that constitute a circumstance calling for a different method? Or, would that merely imply to draw a provisional equidistance line by reference to different parameters, such as the approximate outer limits of the continental shelf of the respective parties? Additionally, where the parties to the dispute have not received affirmative recommendations from the CLCS and where the parties’ entitlements to the continental shelf beyond 200 nm remain uncertain, how the judiciary overcome the difficulties in determining relevant coasts and relevant areas and in applying the disproportionality test would continue to trouble the general applicability of the three-stage approach. These questions are likely to be raised (again) in the future, and it is in these aspects that the merit of the ‘established methodology’ in the jurisprudence remains to be tested.