A. Building Judicial Consensus around the Two-Stage Approach

Until 2007, international tribunals implemented Article 15 by means of a two-stage approach, pursuant to which an equidistance line would be provisionally drawn and subsequently adjusted should special circumstances so require. The 1999 delimitation award between Eritrea and Yemen was the first judicial application of Article 15, although it contained little discussion regarding its interpretation. By means of a special agreement, Eritrea and Yemen had requested an arbitral tribunal to hand down an ‘award delimiting the maritime boundaries’ between them in the Red Sea.Footnote ¹² Both parties argued in favour of a boundary following the equidistance line.Footnote ¹³ However, while Yemen argued for an all-purpose equidistance line without distinguishing between maritime zones,Footnote ¹⁴ Eritrea argued for a boundary made of two lines based on equidistance, one for the territorial sea and one for the continental shelf and EEZ.Footnote ¹⁵ The tribunal decided that the boundary should, ‘as far as practicable, be a median line between the opposite mainland coastlines’,Footnote ¹⁶ and delimited the territorial sea by first drawing the boundary as a median line between the mainland coasts of the parties.Footnote ¹⁷ Subsequently, while constructing the equidistance line, the tribunal decided on the effect to be given to the Dahlaks, the island of al-Tayr and the al-Zubayr island group.Footnote ¹⁸ The tribunal implicitly applied Article 15 in two stages: first, it drew an equidistance line between the coasts of the parties; second, it took account of the special circumstances, namely the effect of the existing islands.Footnote ¹⁹

In Qatar v Bahrain (2001), the ICJ was called upon to apply customary international law, which, according to the Court, included LOSC Article 15.Footnote ²⁰ QatarFootnote ²¹ and BahrainFootnote ²² argued that the boundary should be delimited on the basis of equidistance. Accepting the views of the parties, the Court held that ‘[t]he most logical and widely practised approach [to delimit the territorial sea] is first to draw provisionally an equidistance line and then to consider whether that line must be adjusted in the light of the existence of special circumstances’.Footnote ²³ The Court first drew a provisional equidistance line, and subsequently considered whether certain islands present in the delimitation area constituted special circumstances warranting the adjustment of the provisional equidistance line.Footnote ²⁴ The Qatar v Bahrain judgment adopted the arbitral tribunal's reasoning in Eritrea/Yemen.Footnote ²⁵ However, it took that reasoning one step further by spelling out the two stages for the delimitation of the territorial sea under Article 15 and customary international law. The two-stage approach for territorial sea delimitation was also accepted by the dissenting judges.Footnote ²⁶

In their 2007 maritime boundary dispute, Guyana and Suriname suggested different courses for their territorial sea boundary. On one hand, Guyana argued that the boundary should follow the ‘historical equidistance line’ between the parties. If Guyana's boundary were not to be regarded as an equidistance line, ‘the conduct of the Parties since 1966 in following it would be sufficient to constitute a special circumstance justifying an adjustment to the equidistance line’.Footnote ²⁷ On the other hand, Suriname maintained that, as former colonial powers, ‘the United Kingdom and The Netherlands respected the 10° Line as the territorial sea boundary in their mutual relations from 1939 to 1965’ up to 3 nautical miles (nm) from the coast, and that such a line became the boundary between Guyana and Suriname up to 12 nm from the coast.Footnote ²⁸ In order to address Suriname's arguments, the arbitral tribunal first discussed the delimitation up to 3 nm, and then the delimitation between 3 and 12 nm. At the outset, the tribunal stated that ‘Article 15 of the Convention places primacy on the median line as the delimitation line between the territorial seas of opposite or adjacent States’.Footnote ²⁹ Concerning the delimitation up to 3 nm, the tribunal held that navigation could be a special circumstance, yet found that an agreed boundary existed up to 3 nm from the coast which followed a N10°E delimitation line starting at the land boundary terminus.Footnote ³⁰

While the result in Guyana v Suriname was a line at variance with equidistance, the tribunal reached the correct solution by finding that there had been an agreement between the parties on their maritime boundary up to 3 nm from the coast. Concerning the delimitation between 3 and 12 nm, the tribunal found that ‘a special circumstance is constituted by the very need to determine such a line from a point at sea fixed by historical arrangements of an unusual nature’, and therefore that the boundary should follow ‘a line continuing from the seaward terminus of the N10°E line at 3 nm, and drawn diagonally by the shortest distance to meet the line adopted later in this Award to delimit the Parties’ continental shelf and exclusive economic zone’.Footnote ³¹ Gao noted that ‘while giving lip-service to the equidistance method in the territorial sea delimitation, the Tribunal got rid of it almost from the outset of delimitation, since the Tribunal did not draw a provisional equidistant line as the starting point’, adding that the Guyana v Suriname award would suggest that ‘beginning the delimitation process by drawing a provisional equidistant line is not applicable for all territorial sea delimitation’.Footnote ³² However, the Guyana v Suriname tribunal upheld the two-stage approach applied by the ICJ in Qatar v Bahrain by simply making a finding, consistent with Article 15, that an agreement already existed between the parties concerning their boundary up to 3 nm. It is conceivable that, between 3 and 12 nm, the tribunal did consider a provisional equidistance line, but failed to explicitly mention it in the award on account of the first segment of the boundary being at complete variance with equidistance.

B. Revisiting the Two-Stage Approach

In contrast to the three cases discussed above, the territorial sea delimitation cases since 2007 have downplayed the pre-eminence of equidistance within the two-stage approach. In the 2007 ICJ case between Nicaragua and Honduras, Article 15 was part of the applicable law.Footnote ³³ With respect to territorial sea delimitation, neither party requested an equidistance boundary. On one hand, Nicaragua requested an angle-bisector line, since the coastal instability at the mouth of the River Coco made it impossible to identify suitable base points from which to draw an equidistance line.Footnote ³⁴ On the other hand, Honduras built its argument on historical bases, arguing for an agreed boundary running due east along the 15th parallel.Footnote ³⁵ The ICJ found that no agreed boundary existed between the parties.Footnote ³⁶ Subsequently, the Court mentioned the two-stage approach used in Qatar v Bahrain with approval.Footnote ³⁷ However, the Court went on to state that ‘continued accretion at [Cape Gracias a Dios] might render any equidistance line so constructed today arbitrary and unreasonable in the near future’,Footnote ³⁸ adding that ‘geographical and geological difficulties are further exacerbated by the absence of viable base points claimed or accepted by the Parties themselves at Cape Gracias a Dios’.Footnote ³⁹ The Court finally constructed the bisector requested by Nicaragua.Footnote ⁴⁰ Crucially, the Court held that:

After having paid lip-service to Qatar v Bahrain, the Court changed its understanding of Article 15. Qatar v Bahrain stood for the proposition that Article 15 requires the drawing of an equidistance line, to be adjusted at a second stage and only if special circumstances made such a line inequitable. Nicaragua v Honduras reversed those two stages: the Court first asked whether special circumstances warranted a non-equidistant boundary, and second, given an affirmative answer, decided not to draw an equidistance line at all. Equidistance moved from being compulsory to being merely a potential method for territorial sea delimitation, its use depending on the absence of special circumstances.

In 2012, the International Tribunal for the Law of the Sea (ITLOS or the Tribunal) delivered its judgment in the delimitation dispute between Bangladesh and Myanmar. Before ITLOS, Bangladesh argued that the parties had ‘reached an agreement on their boundary in the territorial sea that satisfies the requirements of Article 15’.Footnote ⁴² Myanmar argued that there was no agreement on a territorial sea boundary, and that such a boundary should be based on equidistance, adjusted due to the presence of St. Martin's Island.Footnote ⁴³ Both Bangladesh and Myanmar appeared to construe the rule under Article 15 in the same manner as the ICJ had construed it in Qatar v Bahrain.Footnote ⁴⁴ The Tribunal found no agreement between the parties on their territorial sea boundary.Footnote ⁴⁵ Before delimiting the territorial sea, ITLOS explained that ‘[i]t follows from Article 15 of the Convention that before the equidistance principle is applied, consideration should be given to the possible existence of historic title or other special circumstances relevant to the area to be delimited’.Footnote ⁴⁶ ITLOS continued not by plotting a provisional equidistance line, but by considering whether St. Martin's Island could be a special circumstance. It concluded that the island was not a special circumstance, and should therefore be given full effect.Footnote ⁴⁷ Subsequently, the Tribunal established an equidistance line in the territorial sea.Footnote ⁴⁸ Faithful to its initial statement, ITLOS drew the equidistance line as the final product of the delimitation exercise and only after it had considered existing special circumstances. Although not explicitly, the Tribunal followed the ICJ's lead in Nicaragua v Honduras.Footnote ⁴⁹

The 2014 arbitration between Bangladesh and India is the latest case in which an international tribunal established a territorial sea boundary pursuant to Article 15. Bangladesh requested the tribunal to draw the boundary as the bisector of the lines approximating the general direction of the parties’ coasts, since, owing to coastal instability in the Bay of Bengal, it would have been impossible to select suitable base points to construct an equidistance line.Footnote ⁵⁰ Conversely, India requested that the tribunal draw an equidistance line, which it argued to be the general rule under Article 15.Footnote ⁵¹ The tribunal recalled the ICJ's decision in Qatar v Bahrain, according to which Article 15 requires the use of a two-stage method. However, the tribunal immediately continued by saying that ‘in its second sentence Article 15 of the Convention provided for the possibility of an alternative solution where this is necessary by reason of historic title … or “other special circumstances”’.Footnote ⁵² Concerning coastal instability, the tribunal found that ‘[g]iven [its] concern with the “physical reality at the time of the delimitation”, … the Tribunal need not consider whether instability could in some instances qualify as a special circumstance under Article 15’.Footnote ⁵³

The tribunal rejected the suggestion that concavity and coastal instability constituted special circumstances, and subsequently established an equidistance line.Footnote ⁵⁴ However, that equidistance line was unexpectedly provisional. After having drawn the territorial sea boundary as an equidistance line, the tribunal noted that:

Therefore, the tribunal adjusted the equidistance line because the land boundary terminus was not equidistant between the parties’ coasts. The tribunal thus considered special circumstances twice, both before and after drawing a provisional equidistance line.Footnote ⁵⁶

A. Interpreting Article 15: Text and Drafting History

Article 15 provides that, if neighbouring States have not agreed on their territorial sea boundary, neither is entitled to ‘extend its territorial sea beyond the median line every point of which is equidistant from the nearest points on the baselines from which the breadth of the territorial seas of each of the two States is measured’. Nevertheless, the equidistance line boundary does not apply ‘where it is necessary by reason of historic title or other special circumstances to delimit the territorial seas of the two States in a way which is at variance therewith’. The text of the provision suggests that special circumstances and historic title are exceptions to the general rule of equidistance.Footnote ⁵⁷ However, a merely textual reading does not clarify the raison d’être of these exceptions to equidistance. The drafting history of Article 15, discussed below, suggests that, as a general rule, the territorial sea is to be delimited by means of an equidistance line, and that it is only if special circumstances made such a boundary inequitable that it should depart from equidistance.

B. The Method for the Application of Article 15

The character of a norm as a rule and of an interrelated norm as an exception has significant implications for their interpretation.Footnote ⁹⁸ For instance, Orakhelashvili wrote that ‘[a]s soon as the context of the treaty allows the clause to be considered as an exception to primary obligations, such exception clauses will always be seen as limited in their scope and in their substantive and temporal effect’.Footnote ⁹⁹ Alland similarly stated that ‘[d]ans la plupart des systèmes juridiques, il est généralement entendu que les exceptions sont d'interprétation restrictive’.Footnote ¹⁰⁰ Commentators seem to agree that exceptions should be interpreted restrictively, entailing that they should displace general rules only in an as limited number of cases as possible. In any event, the restrictive interpretation of exceptions should always be in accordance with the object and purpose of the treaty concerned.Footnote ¹⁰¹

Such an approach to interpreting exceptions is also espoused by international tribunals,Footnote ¹⁰² and can be regarded as uncontroversial. The restrictive interpretation of exceptions is also known to the ICJ, and it has used it in law of the sea cases, such as in Qatar v Bahrain with reference to straight baselines.Footnote ¹⁰³ Moreover, in his dissenting opinion appended to the judgment in North Sea Continental Shelf, Judge Tanaka commented on Article 6 CSC, and wrote that:

Judge Tanaka added that if ‘the exceptional nature of [the special circumstances clause] is admitted, the logical consequence would be its strict interpretation’.Footnote ¹⁰⁵ As a matter of interpretation, exceptions are to be narrowly construed and are to be applied only if certain conditions set forth by the primary rule are met.

With regard to LOSC Article 15, special circumstances, as exceptions to equidistance, are to be applied only in a limited number of cases, subject to the only condition that a boundary based on equidistance would be inequitable. The exceptional character of special circumstances also suggests that a boundary determined by special circumstances should deviate from equidistance as little as feasible. This consideration justifies using the equidistance line as a provisional boundary for the territorial sea, to be adjusted only should special circumstances so require. In practice, the equitableness of an equidistance line can be assessed only by tracing such a line on a map, however provisionally. Special circumstances are the factors against which the equitableness of an equidistance line is subsequently evaluated, as well as the factors determining the eventual adjustment of such an equidistance line. The rule-exception relationship between equidistance and special circumstances and the equitable solution requirement under Article 15 indicate that, absent any agreement between the States concerned, the appropriate method to trace territorial sea boundaries involves two steps. First, a provisional equidistance line must be drawn; second, the equitableness of such a line must be evaluated by reference to special circumstances, which also determine the extent of the equidistance line's eventual adjustment.

This two-stage approach does not seem to necessarily follow from the rule-exception relationship between equidistance and special circumstances. Plausibly, the character of special circumstances as exceptions to equidistance could equally lead one to conclude that Article 15 requires international tribunals not to apply equidistance tout court if special circumstances are found to exist. This appears to be the interpretation in Nicaragua v Honduras, in Bangladesh/Myanmar and in Bangladesh v India. Nevertheless, broader considerations of predictability discourage this open-ended interpretation, which would inevitably emphasize judicial discretion to the detriment of legal certainty.Footnote ¹⁰⁶ Moreover, the equitable solution requirement emerging from UNCLOS's drafting history provides a link between the two components of Article 15, which thus operate in tandem to achieve the equitable boundary objective. Suggesting that special circumstances would displace equidistance threatens to overlook the need to achieve an equitable solution in delimiting territorial sea boundaries.Footnote ¹⁰⁷

The restrictive interpretation of special circumstances under Article 15, which suggests the application of the two-stage method, has the aim of increasing predictability and certainty in territorial sea delimitation. Certainty and predictability could be seen as corollaries of the UNCLOS's object and purpose of establishing ‘a legal order for the seas and oceans which will facilitate international communication, and will promote the peaceful uses of the seas and oceans, the equitable and efficient utilization of their resources’.Footnote ¹⁰⁸ According to the arbitral tribunal in Bangladesh v India, ‘transparency and the predictability of the delimitation process as a whole are additional objectives to be achieved in the process’.Footnote ¹⁰⁹ Similarly, in Libya/Malta the ICJ found that maritime delimitation ‘should display consistency and a degree of predictability’.Footnote ¹¹⁰ International tribunals appear to be developing a uniform law of maritime delimitation, as showed by the numerous cross-references between the decisions of the ICJ, ITLOS and arbitral tribunals.Footnote ¹¹¹ De Brabandere argued that the references by the ICJ to the maritime delimitation decisions of other international tribunals ‘may indicate a … trend towards showing that the ICJ's decision is consistent with the case law of other courts and tribunals’.Footnote ¹¹² Applying Article 15 by means of the two-stage approach could increase predictability and certainty in the law of maritime delimitation, an objective avowedly pursued by international tribunals.

Moreover, it would also be consistent with the pre-UNCLOS cases on continental shelf delimitation under Article 6 CSC. Since Article 6 CSC and Article 15 are based on the same underlying logic, the interpretation of the former should inform the interpretation of the latter. International tribunals decided three cases on continental shelf delimitation prior to UNCLOS's entry into force in 1994. First, North Sea Continental Shelf was decided under customary international law, which at the time did not include Article 6 CSC.Footnote ¹¹³ Nevertheless, in its 1969 judgment the Court stated that legal thinking on continental shelf delimitation was:

On one hand, the Court upheld the link between equitable principles and special circumstances. On the other hand, it clarified the character of special circumstances as an exception to equidistance for the cases where equidistance yields an inequitable solution.

Second, the 1977 Court of Arbitration in Continental Shelf (France/UK) implicitly applied the two-stage approach.Footnote ¹¹⁵ In delimiting the boundary around the Channel Islands, the Court of Arbitration noted that ‘[t]he existence of the Channel Islands close to the French coast, if permitted to divert the course of that mid-Channel median line, effects a radical distortion of the boundary creative of inequity’,Footnote ¹¹⁶ and only subsequently decided to enclave the Channel Islands.Footnote ¹¹⁷ The Court of Arbitration first considered that the median line proposed by the UK would have been inequitable, and then it drew an alternative boundary. The same procedure was adopted in delimiting the boundary in the Atlantic region,Footnote ¹¹⁸ in relation to which the Court of Arbitration held that it was ‘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’.Footnote ¹¹⁹ Third, in the 1993 Jan Mayen judgment the ICJ found, with respect to continental shelf delimitation, that:

The Court also underscored the direct connection between special circumstances and the ‘equitable solution’, since the ‘special circumstances of Article 6 of the 1958 Convention … are intended to enable the achievement of an equitable result’.Footnote ¹²¹ The pre-UNCLOS cases concerning Article 6 CSC all upheld the role of special circumstances as exceptions to equidistance, as well as the need for delimitation to achieve an ‘equitable solution’.

A. Reasons for Judicial Uncertainty

The text and drafting history of Article 15 suggest that the territorial sea should be delimited in two stages. However, in the last decade international tribunals have shown a degree of hesitation in applying this delimitation method. The reasons for this hesitation are not apparent, especially given the lack of any explanations in the relevant judicial decisions since Nicaragua v Honduras.

However, certain judges have commented on the use of Article 15 in their individual opinions.Footnote ¹²² In Bangladesh/Myanmar, all judges agreed on the manner in which the territorial sea was delimited, with Judge Gao briefly commenting on the issue. Discussing the adjustment of the boundary, Judge Gao wrote that:

Judge Gao referred to the ‘adjusted equidistance line’, which may entail that, in his view, the final territorial sea boundary must be based on the preliminary establishment of an equidistance line. Moreover, Judge Gao wrote of the territorial sea boundary as a line ‘every point of which is approximately equidistant from the nearest points on the baselines of the two States’, which seems to suggest that an adjusted territorial sea boundary should be as close to an equidistance line as possible. Judge Gao's comments appear to agree with the argument of this article, which raises the question of the reason why he agreed with the Tribunal's majority concerning the delimitation of the territorial sea in that case.

The individual opinions in Nicaragua v Honduras are the most interesting in the context of this article. Judge Koroma's views seem to have been strongly influenced by the parties’ arguments, as in his separate opinion he emphasized that neither State had requested a territorial sea boundary based on equidistance.Footnote ¹²⁴ However, Judge Koroma did not elaborate on his wholesale approval of the Court's approach to Article 15.Footnote ¹²⁵ By contrast, Judge ad hoc Torres Bernárdez's dissenting opinion criticized the Court's method for territorial sea delimitation. He took issue with the Court's abandonment of equidistance, since he considered the Court to be motivated by the policy aim of assimilating, in the circumstances of that case, the delimitation method used within 12 nm to the delimitation method used beyond 12 nm.Footnote ¹²⁶ Judge ad hoc Torres Bernárdez's assessment is correct. The equidistance line would presumably not have been inequitable within 12 nm, and it was feasible to construct it despite the coastal instability around Cape Gracias a Dios.Footnote ¹²⁷ Conversely, equidistance might have been less convincing as a starting point beyond 12 nm. Nevertheless, this difference did not justify abandoning equidistance in the territorial sea, especially as it is the primary delimitation method under Article 15. Judge ad hoc Torres Bernárdez considered the equidistance line to be the ‘general rule’ for territorial sea delimitation,Footnote ¹²⁸ which is a sound interpretation of Article 15.Footnote ¹²⁹ He also wrote that:

Judge ad hoc Torres Bernárdez referred to the case-by-case approach to delimitation typical of the 1980s, in which international tribunals decided which delimitation method to adopt based on the relevant circumstances of each case, as exemplified by the decisions in Tunisia/Libya and Guinea/Guinea-Bissau.Footnote ¹³¹

This criticism is cogent, although possibly overstated in the light of subsequent delimitation decisions. While Judge ad hoc Torres Bernárdez's remarks were correct in the context of Nicaragua v Honduras, ITLOS and the Bangladesh v India tribunal did not apply an ad hoc delimitation method but a variant of the two-stage approach.Footnote ¹³² Moreover, Judge ad hoc Torres Bernárdez suggested that the correct manner of dealing with coastal instability was not with reference to Article 15, but by looking to LOSC Article 7 on straight baselines.Footnote ¹³³ However, this point is unpersuasive. As straight baselines connect a number of basepoints of a State whose coast is ‘deeply indented and cut into’, or ‘if there is a fringe of islands along the coast in its immediate vicinity’, they still require a State to identify such points on its coast. Coastal instability could complicate the establishment of straight baselines, in the same manner as it could complicate the selection of suitable base points for the drawing of an equidistance line. Moreover, straight baselines are established by the coastal State, and in Nicaragua v Honduras only Honduras had deposited with the UN Secretary-General the list of geographical coordinates identifying its territorial sea baseline, as required under LOSC Article 16.Footnote ¹³⁴ Therefore, using straight baselines to remedy the lack of suitable base points for the construction of an equidistance line would not have been a viable solution.

Judge Ranjeva also issued a separate opinion in Nicaragua v Honduras, discussing territorial sea delimitation under Article 15. Judge Ranjeva argued that:

Judge Ranjeva focused on whether the reasons on which the ICJ based the bisector line met the ‘necessity test’ set by Article 15 to justify establishing a boundary at variance with equidistance. He considered that ‘the notion of necessity involves an absence of solution such that no alternative can be envisaged’, concluding that ‘[t]he difficulties encountered are not of themselves sufficient to justify the necessity of abandoning the general rule’.Footnote ¹³⁶ The upshot of the Court's reasoning is to give ‘a rule-making function to the special circumstances’, which contradicts Article 15 as well as the Court's previous jurisprudence.Footnote ¹³⁷ Judge Ranjeva thus concluded that the Court had delimited the territorial sea using the wrong method. However persuasive, Judge Ranjeva's comments fail to fully elucidate the reasons that led the Court to give a ‘rule-making function’ to special circumstances.

Based on the individual opinions issued in Nicaragua v Honduras, Bangladesh/Myanmar and Bangladesh v India, it is difficult to grasp why international tribunals have recently strayed from the earlier jurisprudence. Both the judgments and the individual opinions do not convey the judges’ dissatisfaction with the two-stage approach as applied in Qatar v Bahrain. International tribunals have explicitly subscribed to this approach even in the last decade, as demonstrated by the fact that, before delimiting the territorial sea, they would explicitly cite the part of the Qatar v Bahrain judgment setting forth the two-stage approach.Footnote ¹³⁸ International tribunals simply changed their interpretation of Article 15, which shows inconsistency in the exercise of their judicial function. In Nicaragua v Honduras, the fountainhead of the change in territorial sea delimitation jurisprudence, it is plausible that the parties’ arguments played an important role in shaping the transformed interpretation of Article 15. In that case neither party requested the Court to draw the boundary as an equidistance line, which has probably influenced the Court in its judgment.Footnote ¹³⁹ Later cases have perpetuated this influence.

Remarkably, the changed understanding of Article 15 cuts across two standing tribunals, the ICJ and ITLOS, as well as an arbitral tribunal constituted under Annex VII UNCLOS. On one hand, the same approach to territorial sea delimitation in Bangladesh/Myanmar and Bangladesh v India could be explained by reference to the composition of the arbitral tribunal in the latter case. Judges Cot, Mensah and Wolfrum all sat on ITLOS when Bangladesh/Myanmar was decided, and also were three of the five arbitrators sitting on the Bangladesh v India tribunal.Footnote ¹⁴⁰ On the other hand, the adoption of the Nicaragua v Honduras approach in the Bay of Bengal cases cannot be explained by reference to the composition of ITLOS and the Bangladesh v India tribunal. However, it is significant that, as often occurs in maritime delimitation, a number of jurists were involved as legal advisers either in two or in all three of the territorial sea delimitation cases since Nicaragua v Honduras. While it is implausible that the similar interpretation of Article 15 by these different tribunals depended entirely on the same legal counsel being involved, this may have played a role. Conceivably, the ITLOS Special Chamber's forthcoming decision in Ghana/Côte d'Ivoire could lend support to the institutional connection between the ICJ and ITLOS, if the approach to the interpretation of Article 15 adopted in Nicaragua v Honduras is upheld. The ITLOS Special Chamber in Ghana/Côte d'Ivoire is composed of five judges, one of them being Judge Abraham, currently the ICJ's President and a judge at the time when the Court decided Nicaragua v Honduras. The academic literature has already credited Judge Abraham's presence on the ITLOS Special Chamber for the adoption by ITLOS of the plausibility requirement for the prescription of provisional measures under LOSC Article 290.Footnote ¹⁴¹ Therefore, Judge Abraham's potential influence on the ITLOS Special Chamber's approach to territorial sea delimitation is not wholly speculative.

It is difficult to identify the precise reasons that have led international tribunals to change their understanding of Article 15, and therefore to invert the two stages of the territorial sea delimitation method. The parties’ arguments in the cases since 2007, and especially in Nicaragua v Honduras, seem to have played a major role. A degree of institutional connection between international tribunals is also a plausible reason for judicial uncertainty since 2007, although it could not fully explain the link between the ICJ on one hand, and ITLOS and the Bangladesh v India tribunal on the other hand. It is likely that a combination of all reasons mentioned above have contributed to abandoning the earlier interpretation of Article 15 in favour of the less convincing interpretation which gives a more central role to special circumstances in territorial sea delimitation. The fact remains that there is no explicit suggestion in the case law that the two stages of the territorial sea delimitation method were inverted as a result of judicial dissatisfaction with the two-stage approach as applied in Qatar v Bahrain.

B. Implications of Judicial Uncertainty

The recent change in the jurisprudence on territorial sea delimitation could have important practical effects on future disputes. The two-stage approach under Article 15 envisages that a provisional equidistance line could be adjusted should special circumstances so require. However, no adjustment would take place if the two stages of the delimitation process were inverted, and special circumstances were appraised before plotting an equidistance line. The Qatar v Bahrain approach entails that the final outcome of delimitation is a line resembling an equidistance line. Under this approach, the choice is between a strict equidistance line, should special circumstances be absent, and a modified equidistance line, should special circumstances justify an adjustment. Under the Nicaragua v Honduras approach the final territorial sea boundary may have nothing in common with an equidistance line. Therefore, under this approach a modified equidistance line as a territorial sea boundary would be highly unlikely. Since special circumstances are assessed before an equidistance line is plotted, if they are found to exist an international tribunal would be compelled to draw a boundary according to a method at variance with equidistance. For example, such a method could be the angle-bisector, the perpendicular to the coast, a line running along a parallel of latitude, or a combination thereof.

While this was not the final outcome in either Bangladesh/Myanmar or Bangladesh v India, it was the consequence of the ICJ's findings in Nicaragua v Honduras. Having found that coastal instability constituted a special circumstance, the Court held that it could not establish an equidistance line, even provisionally, and opted to draw a bisector line instead.Footnote ¹⁴² If an international tribunal finds that special circumstances exist at the first stage of territorial sea delimitation, the logically necessary consequence is that an equidistance line cannot be drawn at the second stage of the delimitation process. However, this result is not in conformity with Article 15 as interpreted above,Footnote ¹⁴³ and contradicts the pre-2007 case law.Footnote ¹⁴⁴

A finding that special circumstances exist would give unfettered discretion to the international tribunal concerned to select any delimitation method it might deem fit in a given case. This unfettered discretion does not seem justified under Article 15, whose drafting history is permeated by the aim of limiting the freedom of international tribunals to choose the method for delimiting the territorial sea. Territorial sea delimitation also aims to achieve an ‘equitable solution’.Footnote ¹⁴⁵ In EEZ and continental shelf delimitation, the achievement of an ‘equitable solution’ is conceived as an ex post appreciation by international tribunals. By contrast, with respect to territorial sea delimitation the ILC and the UNCLOS drafters evaluated ex ante which method was capable of achieving an ‘equitable solution’, establishing that such a method is equidistance adjusted should special circumstances so require. Therefore, the ‘equitable solution’ in territorial sea delimitation is partially distinct from the ‘equitable solution’ in EEZ and continental shelf delimitation, as in the former case the ‘equitable solution’ is to be achieved within the limits of the equidistance line principle that Article 15 renders obligatory for territorial sea delimitation.

The question arises concerning whether the territorial sea delimitation methods used in Qatar v Bahrain and Nicaragua v Honduras could be reconciled. The Bangladesh v India tribunal seemed to attempt such a reconciliation by enquiring into special circumstances both before and after plotting a provisional equidistance line.Footnote ¹⁴⁶ However, this modus operandi is problematic. Under Article 15, special circumstances have the function of modifying a provisional equidistance line,Footnote ¹⁴⁷ which entails that, if any factor should be capable of determining the use of a delimitation method other than equidistance, it should belong to a category distinct from that of special circumstances. Judge Ranjeva briefly mentioned this hypothetical tertium genus of circumstances in his separate opinion in Nicaragua v Honduras. He argued that:

Judge Ranjeva's criticism might seem exaggerated. First, it is unclear whether the Court specifically intended to identify a third category of circumstances. Secondly, in the later cases neither ITLOS nor the Bangladesh v India tribunal mentioned ‘particular circumstances’ in delimiting the territorial sea, the EEZ and the continental shelf.

‘Particular circumstances’ lack any basis in positive international law, not being mentioned either under LOSC Article 15, 74 and 83. They are not mentioned in the pre-2007 case law either. Reconciling the Qatar v Bahrain and Nicaragua v Honduras approaches cannot be accomplished by introducing the category of ‘particular circumstances’, unless one accepts the possibility of overt judicial law-making.Footnote ¹⁴⁹ Moreover, Article 15 does not envisage that the equidistance could be substituted for any other delimitation method. It follows that reconciling the two approaches used in Qatar v Bahrain and in Nicaragua v Honduras does not seem viable under current international law, and that, consequently, international tribunals must choose between applying either one or the other.

Despite the problems discussed above, evaluating special circumstances as a first step in territorial sea delimitation could increase transparency with respect to the selection of base points for constructing the equidistance line. Base points could be located on islands, which entails that international tribunals may decide at the first stage of the delimitation process the effect of the islands on which base points are to be located. Selecting base points on islands could amount to evaluating special circumstances sub rosa at the first stage of the delimitation process. Black Sea exemplifies this practice, although with respect to the EEZ and continental shelf. In that case, the ICJ had jurisdiction to delimit only the continental shelf and EEZ,Footnote ¹⁵⁰ and applied the three-stage approach envisaging the evaluation of relevant circumstances after the establishment of a provisional equidistance line.Footnote ¹⁵¹ Before drawing the equidistance line, the Court held that it could not place a base point on Serpents’ Island. Therefore, its decision seemingly amounted to a surreptitious finding on Serpents’ Island's effect before the second stage of delimitation.Footnote ¹⁵²

Inverting the two stages of the territorial sea delimitation method could avoid doubtful decisions on the effect of islands comparable to Black Sea. In Bangladesh/Myanmar, ITLOS evaluated special circumstances before establishing an equidistance line. ITLOS discussed whether St. Martin's Island should have been considered a special circumstance, and, as a consequence, whether it should have been awarded no effect in delimiting the territorial sea. The Tribunal concluded that St. Martin's Island was not a special circumstance, and gave it full effect in territorial sea delimitation by using it as a base point.Footnote ¹⁵³ ITLOS did not decide the effect of St. Martin's Island sub rosa, since it had explicitly stated that it would consider special circumstances before drawing the equidistance line. Considering special circumstances at the first step of delimitation would thus avoid surreptitiously evaluating the effect of islands before drawing an equidistance line. However, inverting the two stages of territorial sea delimitation is not an appropriate interpretation of Article 15, and, accordingly, another means should be found to avoid determining the effect of islands sub rosa at the first stage of the delimitation process.

The post-2007 jurisprudence on territorial sea delimitation could have consequences for the delimitation of the EEZ and continental shelf. Delimitation beyond 12 nm is effected by means of a three-stage approach, identical to the two-stage approach to territorial sea delimitation but for the addition of a third stage concerning proportionality. The two-stage approach under Article 15 was inspired by the two-stage approach under Article 6 CSC, as both provisions are based on the same underlying logic.Footnote ¹⁵⁴ Similarly, a change in the understanding of Article 15 could lead to a comparable change in the approach to delimitation beyond 12 nm, emphasizing the role of relevant circumstances in the selection of methods alternative to equidistance. In Nicaragua v Honduras, the ICJ rejected the use of an equidistance line for delimitation beyond 12 nm based on the same reasons that had led it to not draw an equidistance line in the territorial sea. The Court's reasoning on equidistance seemed to embrace all maritime zones, as the judgment makes no clear distinction between delimitation within and beyond 12 nm. The Court only reasoned on the basis of Article 15, decided for a bisector line, and simply extended that line up to the boundary's end-point situated at 200 nm from the States' coasts. This lack of clarity is regrettable.

Some individual opinions in post-2007 cases show that it is far from implausible that the reasoning in Nicaragua v Honduras might be extended to delimitation beyond 12 nm. In his separate opinion in the 2012 Nicaragua v Colombia judgment, Judge Abraham criticized the ICJ for having used the equidistance-based three-stage approach. He noted there were ‘circonstances particulières justifiant d'ajuster la ligne médiane provisoire’.Footnote ¹⁵⁵ Judge Abraham referred to ‘particular circumstances’ as a means to adjust a provisional equidistance line, and not as reasons to draw a boundary at complete variance with equidistance. Nevertheless, his use of the expression ‘particular circumstances’ is reminiscent of the Court's judgment in Nicaragua v Honduras, as well as of Judge Ranjeva's criticism against it. Similarly to Judge Abraham, Judge Gao also mentioned ‘particular circumstances’ in his separate opinion in Bangladesh/Myanmar. Judge Gao explicitly cited with approval the ICJ's statement at paragraph 272 of the Nicaragua v Honduras judgment, in which the Court held that ‘in particular circumstances, there may be factors which make the application of the equidistance method inappropriate’.Footnote ¹⁵⁶ Although the ICJ's statement mainly applied to territorial sea delimitation, Judge Gao referred to it in the context of delimitation beyond 12 nm. Judge Gao's would seemingly favour resorting to ‘particular circumstances’ to justify the abandonment of equidistance in delimitation beyond 12 nm. This would extend the Nicaragua v Honduras judgment to delimitation beyond the territorial sea. Based on Judge Abraham's and Judge Gao's views, extending the reach of ‘particular circumstances’ from territorial sea delimitation to delimitation beyond 12 nm does not seem entirely implausible. However, this extension raises strong concerns for predictability and certainty in continental shelf and EEZ delimitation.

The Nicaragua v Honduras approach could also influence delimitation beyond 12 nm due to the vagueness of LOSC Articles 74 and 83, which only require that delimitation must achieve an ‘equitable solution’. Those provisions make no mention of a compulsory method for delimiting the EEZ and the continental shelf, which in principle emphasizes the discretion of international tribunals in choosing how to delimit boundaries beyond 12 nm.Footnote ¹⁵⁷ With regard to continental shelf and EEZ delimitation, the only bastion against a case-by-case approach is the quest for consistency with previous judicial decisions, which is not a matter of binding positive law but only of good judicial policy.

C. Judicial Uncertainty, Coastal Instability and Special Circumstances

In Nicaragua v Honduras, the ICJ established a non-equidistant territorial sea boundary due to the lack of suitable base points for the construction of an equidistance line. The Court could not identify such base points due to the high coastal instability at the mouth of the River Coco. The Court found that ‘whatever base points would be used for the drawing of an equidistance line, the configuration and unstable nature of the relevant coasts, including the disputed islands formed in the mouth of the River Coco, would make these base points … uncertain within a short period of time’.Footnote ¹⁵⁸ Building on the ICJ's findings, Bangladesh made the same argument in the dispute against India, which the arbitral tribunal ultimately rejected.Footnote ¹⁵⁹

This argument suggests that it is inappropriate to draw an equidistance line using base points which could disappear in the future owing to the high degree of coastal instability in the area to be delimited. Nicaragua v Honduras and Bangladesh v India raise the question concerning whether Article 15 allows an international tribunal not to draw an equidistance line as a first step in territorial sea delimitation if suitable base points are lacking for reasons of coastal instability. According to Rothwell and Stephens, the Nicaragua v Honduras judgment ‘indicates that while equidistance or median line is the starting point for territorial sea delimitation, it is not necessarily conclusive and may be displaced by the special circumstances of the case’.Footnote ¹⁶⁰ However, it could not be said that coastal instability is a special circumstance. Special circumstances are only the means to adjust an already-drawn equidistance line. Drawing an equidistance line necessitates the prior identification of suitable base points, which entails that the lack of such base points cannot be seen as a special circumstance.

In the ILC's work preceding the 1958 Geneva Conventions, the subject of coastal instability was hardly ever mentioned, and was not seen as a special circumstance within the meaning of Article 12 TSC or Article 6 CSC. The 1952 Report of the Special Rapporteur contained a Draft Article 12 on the delimitation of the territorial sea at the mouth of a river, whose second paragraph provided that ‘[i]f the river flows into an estuary, the rules applicable to bays apply to the estuary’.Footnote ¹⁶¹ The commentary to that provision stated that the Draft Article was:

Although the commentary mentioned the ‘nature of the coastline and alluvial deposits’, such factors were seen as relevant to determine what an estuary was for the purpose of the application of the legal provision on bays, and not to delimit the territorial sea in the presence of an estuary. At the ILC's 320th meeting, Mr. Salamanca remarked on the formation of new strips of land at the estuary of the River Plate, adding that Argentina and Uruguay ‘had agreed not to attempt any demarcation because of the constantly changing contour of the land’.Footnote ¹⁶³ However, Mr. Salamanca's comments concerned the definition of an estuary, and not territorial sea delimitation.Footnote ¹⁶⁴ The precursors of Article 15 were not drafted with the intention of allowing departures from equidistance based on coastal instability.Footnote ¹⁶⁵

The argument that it is inappropriate to draw an equidistance line by using base points which are more or less likely to disappear in the future is linked to the issue of the stability of international boundaries. Generally, once a boundary has been established, whether on land or at sea, it will remain unchanged,Footnote ¹⁶⁶ unless the States concerned agree on a new boundary. In Nicaragua v Honduras, the Court seemed to reject this principle by stating that ‘continued accretion at the Cape might render any equidistance line so constructed today arbitrary and unreasonable in the near future’.Footnote ¹⁶⁷ However, the Court's approach is unsound. An international tribunal could not possibly be expected to predict the evolution of coastal geography, as countless variables would render that exercise purely speculative. An international tribunal seised of a delimitation dispute must decide the case in the light of the geographical facts prevailing at the time of the delimitation. The ICJ implicitly changed the view it had previously expressed in Nicaragua v Honduras. In Black Sea, the Court found that ‘the delimitation exercise leads it to use as base points those which the geography of the coast identifies as a physical reality at the time of the delimitation’.Footnote ¹⁶⁸ The arbitral tribunal in Bangladesh v India expanded on the ICJ's statement in Black Sea. The arbitral tribunal held that it ‘must … choose base points that are appropriate in reference to the time of the delimitation, i.e. the date of its Award’.Footnote ¹⁶⁹ Therefore, the tribunal ‘need not address the issue of the future instability of the coastline’,Footnote ¹⁷⁰ and would ‘determine the appropriate base points by reference to the physical geography at the time of the delimitation and to the low-water line of the relevant coasts’.Footnote ¹⁷¹ In other words:

A concern of the ICJ in Nicaragua v Honduras was that a possible equidistance line would be constructed using only two base points, which could result in a distortion of the maritime boundary the further the line would protrude into the sea. The Court held that:

However, the Court's concerns were ill-founded. Subsequent cases have shown that an equidistance line can be constructed using a limited number of base points located in the close proximity of the land boundary terminus. In Black Sea, the Court identified two base points on the delta of the Danube, one on the Sulina Dyke on the Romanian side and one on Tsyganka Island on the Ukrainian side, which controlled the course of the equidistance line up to point 3 of the boundary, lying further than 30 nm from the coast.Footnote ¹⁷⁴ Moreover, in Bangladesh/Myanmar ITLOS chose base points ß1 on Bangladesh's side and μ1 and μ2 on Myanmar's side, which controlled the course of the equidistance line up to point 10 on the boundary, located further than 25 nm from the coast.Footnote ¹⁷⁵

In these two cases, the base points identified close to the land boundary terminus determined the course of the equidistance line beyond the outer limit of the territorial sea. Therefore, it is also possible that base points having similar characteristics could have been used in Nicaragua v Honduras to delimit the territorial sea boundary, without that boundary being necessarily inequitable. As the ICJ found in North Sea Continental Shelf: