Preliminary reflections on the ICJ Judgment in Question of the Delimitation of the Continental Shelf between Nicaragua and Colombia beyond 200 nautical miles from the Nicaraguan Coast (Nicaragua v. Colombia) of 13 July 2023

Almost 10 years after Nicaragua instituted a second delimitation case against Colombia, with respect to the delimitation of the continental shelf beyond 200 nm, the International Court of Justice (ICJ) issued a long-awaited (but surprising) judgment on 13 July 2023, thereby concluding the case. As one may remember, the ICJ seemed to have bifurcated the merits phase of these proceedings by an Order of 4 October 2022. In this Order, the ICJ requested the parties to limit their forthcoming oral pleadings “exclusively” to two questions posed by the Court:

• Under customary international law, may a State’s entitlement to a continental shelf beyond 200 nautical miles from the baselines from which the breadth of its territorial sea is measured extend within 200 nautical miles from the baselines of another State?
• What are the criteria under customary international law for the determination of the limit of the continental shelf beyond 200 nautical miles from the baselines from which the breadth of the territorial sea is measured and, in this regard, do paragraphs 2 to 6 of Article 76 of the United Nations Convention on the Law of the Sea reflect customary international law?

The oral pleadings were held in December 2022, and on 30 June 2023, the ICJ announced that a judgment would be delivered on 13 July 2023. It was expected that this would be a judgment on these two questions specifically, not necessarily concluding the case. Indeed, the parties had not yet had the opportunity to conduct oral pleadings on the actual requests of Nicaragua. In its oral pleadings of December 2022, Nicaragua had requested the Court to proceed to fix a timetable to hear and decide upon the outstanding requests of Nicaragua, and had “formally reserve[d] its right to complete its Final Submissions”. Surprisingly, the Judgment of the ICJ of 13 July did not just provide its conclusion with respect to the two questions posed by the Court in its Order of 4 October 2022, but also provided its final conclusions (paras 83-103) with regard to the requests made by Nicaragua in its Application Instituting Proceedings and amended in subsequent written proceedings, thereby concluding the proceedings in this case.

The Court’s findings

Ultimately, the Court determined that, “under customary international law,” a State’s entitlement to a continental shelf beyond 200 nm “may not extend within 200 [nm] from the baselines of another State” (para. 79).  It continued, “even if a State can demonstrate that it is entitled to an extended continental shelf, that entitlement may not extend within 200 nautical miles from the baselines of another State”, (para. 81) and, “regardless of the criteria that determine the outer limit of the extended continental shelf to which a State is entitled, its extended continental shelf cannot overlap with the area of continental shelf within 200 nautical miles from the baselines of another State” (para. 82). This led the Court to conclude that, “irrespective of any scientific and technical considerations, Nicaragua is not entitled to an extended continental shelf within 200 [nm] from the baselines of Colombia’s mainland coast” and that “[a]ccordingly, within 200 [nm] from the baselines of Colombia’s mainland coast, there is no area of overlapping entitlement to be delimited” (para. 86). The Court made the same conclusions with respect to the islands of San Andrés and Providencia (para. 91), and similar conclusions with respect to Serranilla and Bajo Nuevo (para. 99).

The relationship between the continental shelf within and beyond 200 nm

Although the questions posed by the Court do not explicitly refer to the relationship between the continental shelf beyond 200 nm and that within 200 nm (it merely refers to an area within 200 nm, but this could also refer to the EEZ rather than the continental shelf), the Court’s conclusion in para. 82 confirms that it is the legal regime of the continental shelf (within 200 nm) that negates the existence of an entitlement to a continental shelf beyond 200 nm of another State. In other words, an entitlement to a continental shelf within 200 nm is stronger than an entitlement to a continental shelf beyond 200 nm. A continental shelf entitlement within 200 nm of one State may overlap with a continental shelf entitlement within 200 nm of another State, but a continental shelf entitlement beyond 200 nm may not.

In any case, this Judgment upholds the idea that distance seems to be a stronger basis of entitlement to a continental shelf than natural prolongation and/or geophysical criteria. Although this is often accepted in case law and literature, it negates the genesis and foundations of the legal concept of the continental shelf, which, from its origins as an international legal concept, has been considered as the “extension of the land-mass of the coastal nation” (Truman Proclamation), the “natural prolongation of its land territory into and under the sea” (North Sea Continental Shelf Cases, para. 19) and the “extension of something already possessed” (North Sea Continental Shelf Cases, para. 43).

A third constraint line to the entitlement to a continental shelf beyond 200 nm

The Court’s conclusion – that a continental shelf beyond 200 nm may not extend within 200 nm of another State – has essentially created a third constraint line to a coastal State’s entitlement to a continental shelf beyond 200 nm. According to Article 76 UNCLOS, a coastal State may delineate the outer edge of its continental margin according to two scientific formulae using the foot of the continental slope. However, as part of the package deal of UNCLOS, the extent of a coastal State’s continental shelf entitlement is restricted by two constraint lines: at 350 nautical miles from the baselines, or at 100 nautical miles from the 2500 metre isobath (Article 76(5)). Delineation had always been a unilateral exercise. Much has been written about the relationship between delineation and delimitation (e.g. here and here), but it was clear that delineation referred to the unilateral procedure in which a coastal State measures the extent of its continental margin, and therefore of its entitlement to a continental shelf. In case of an overlap in entitlements, the overlapping area would then need to be delimited. With its Judgment of 13 July 2023, the ICJ essentially added a third constraint to a coastal State’s entitlement to a continental shelf beyond 200 nm, namely the extent of another State’s 200-nm limit. According to the Court’s Judgment, the delineation of a coastal State’s entitlement to a continental shelf beyond 200 nm thus now also includes a bilateral component.

State practice, opinio juris and the CLCS

The Court’s conclusion rests upon its determination that there is sufficient state practice – and opinio juris – to conclude that in customary international law, a continental shelf entitlement beyond 200 nm may not extend within 200 nm of another State. For this, it relies upon the pleadings of Colombia, which reviewed coastal States’ submissions to the Commission on the Limits of the Continental Shelf (CLCS), and the practice of submitting information up to the 200-nm limit of other coastal States. For the Court, this was sufficient state practice and apparently “indicative of opinio juris” and therefore “an expression of opinio juris”  to arrive at its conclusions, even though the Court recognized that this practice “may have been motivated in part by considerations other than a sense of legal obligation” (para. 77).

This is a striking section of the Judgment, and seems to contradict what the Court said in its well-known Judgment in the North Sea Continental Shelf Cases. According to that Judgment, a rule of customary law exists when there is “extensive and virtually uniform” State practice (para. 74), coupled with “a belief that this practice is rendered obligatory by the existence of a rule of law requiring it” (para. 77). In that same Judgment, the Court explained that “the frequency, or even habitual character of the acts is not in itself enough” (para. 77). It furthermore recognized the difficulty in determining the existence of a customary international rule when a treaty rule exists in parallel, for it remains difficult to determine whether a State acts on the basis of a treaty obligation, or whether it acts on the basis of a sense of obligation under customary international law (para. 76).

The state practice upon which the Court’s conclusion rests consists of submissions to the CLCS (as per Article 76(8) UNCLOS). These are highly technical and scientific submissions, of which only executive summaries are made to the public (available on the CLCS website). Importantly, these are not recognitions of the outer limits of a continental shelf per se. Final and binding outer limits of the continental shelf shall be established “on the basis of” recommendations of the CLCS on matters related to the establishment of the outer limits of the continental shelf (Article 76(8)). The submissions of the UK with respect to Ascension Island and that of Iceland with respect to the Reykjanes Ridge demonstrate that disagreements between the CLCS and the submitting coastal State are not uncommon. In other words, a submission to the CLCS is not the final word on the matter.

Although it is true that many coastal States do not include scientific information in relation to areas within 200 nm of other States, this may be for a variety of reasons, most notably the objection procedure established by the CLCS. The CLCS, in its Rules of Procedure, has (mis)interpreted Article 76(10) UNCLOS in such a way that it allows States to veto the consideration of a submission if there is a dispute (CLCS RoP Rule 46; Annex I). Indeed, various States have objected to the CLCS’ considerations of various submissions, leaving those situations in an impasse (as recognized by ITLOS in the Bay of Bengal case, paras 390-392). Recognizing that, due to the workload of the CLCS and the order in which it considers submissions it already takes a long time before a submission is even considered, States may want to prevent other States from objecting to the CLCS’ consideration of their submission and therefore choose (!) to exclude information from areas within 200 nautical miles of other States. Furthermore, within 200 nautical miles any form of marine scientific research is subject to the consent of the coastal State (Article 246 UNCLOS), thus potentially making it more difficult to gather the necessary data in support of a submission. It could therefore be questioned whether States thus exclude information from within 200 nm of another State because they believe they are obligated to do so (opinio juris), or whether they simply choose to do so because of strategic reasons. The CLCS submission procedure is a unique process within the law of the sea and public international law in general, and for the Court to derive a rule of customary international law from that practice with such limited explanation is surprising, to say the least.

Could these conclusions not have been reached in 2012 or 2016?

This was not the first case in which the ICJ was requested to delimit the continental shelf beyond 200 nm between Nicaragua and Colombia – it was already part of the dispute in Territorial and Maritime Dispute. There, Nicaragua had requested the Court to “determine the course of the single maritime boundary” between the areas of continental shelf and EEZ appertaining to Nicaragua and Colombia and asserted an entitlement to a continental shelf beyond 200 nm. Colombia denied the existence of such an entitlement and argued that Article 76 UNCLOS “does not enable States by means of outer continental shelf submissions […] to encroach on other States’ 200-mile limits.” (para. 123) The ICJ, however, eventually concluded that it could not proceed with the delimitation of the continental shelf beyond 200 nm because Nicaragua had not yet made a full submission (only preliminary information) to the CLCS subject to its obligation in Article 76(8) of UNCLOS – a treaty to which Nicaragua is a party, although Colombia is not (see here). Specifically, the Court concluded that since Nicaragua had not “established that it has a continental margin that extends far enough to overlap with Colombia’s 200-nautical-mile entitlement to the continental shelf”, the Court was not in a position to delimit the continental shelf boundary (para. 129). This Judgment implied that if Nicaragua had made a full submission (instead of only submitting preliminary information), the Court would have proceeded with the delimitation. Indeed, the Court summarized its own conclusion in a subsequent Judgment precisely so: “Nicaragua had to submit such information as a prerequisite for the delimitation” of the continental shelf beyond 200 nm by the Court” (para. 105).

So, after having made a full submission to the CLCS on 24 June 2013, on 16 September 2013,  Nicaragua instituted the second delimitation case against Colombia. It asked the Court to adjudge and declare the “precise course of the maritime boundary” of the continental shelf between Nicaragua and Colombia. Colombia took issue with the jurisdiction of the Court – not the least because Colombia had since withdrawn from the Pact of Bogotá and thus its compromissory clause recognizing the jurisdiction of the ICJ – and the admissibility of the case. It claimed that Nicaragua’s request to adjudge and declare the precise course of the maritime boundary should be considered inadmissible because of the lack of a recommendation of the CLCS (see here). The Court considered Colombia’s arguments in detail, but eventually rejected this objection (by a split vote, with the President’s casting vote), and considered the case to be admissible.

However, at no point did the Court conclude that the case should be inadmissible because there was in fact no area of overlapping entitlements (a conclusion it eventually reached in its Judgment of 13 July 2023). This is not necessarily surprising per se. To determine whether an entitlement to a continental shelf beyond 200 nm exists, one would need to assess scientific and technical information, which is an issue that would certainly belong in a merits phase of a dispute. However, in the current case, the ICJ did not assess such information. The first of the two questions posed by the Court was also not a question applied to the facts of the case. Rather, it was a question about law: whether or not – in general – an entitlement to a continental shelf beyond 200 nm could extend within another State’s entitlement to a continental shelf/EEZ within 200 nm. It is this question the Court has concluded in the negative, therefore concluding that, in the present case, there is no area of overlapping entitlements between the two parties, and that it is therefore unable to uphold Nicaragua’s requests. This is surprising. For the Court can be expected to know the law, and to know the law at the time of the 2012 Judgment, or at the 2016 Judgment on Preliminary Objections. If indeed, as the Court concludes, an entitlement to a continental shelf beyond 200 nm may not extend within another State’s entitlement within 200 nautical miles (thus creating the situation in which there is no overlap in entitlements), why did the Court consider the case to be admissible in 2016? Why did the Court, in 2012, not simply deny any possible entitlement of Nicaragua’s continental shelf beyond 200 nm within 200 nm of Colombia instead of deciding it could not proceed with delimitation due to the status of Nicaragua’s CLCS submission (especially considering the fact that Colombia raised that precise argument)? It would be hard to imagine that in 2012 and in 2016 no such rule of customary international law existed, but that suddenly in 2023 this had become customary international law. It is truly unfortunate the ICJ’s Judgment is so short, as it does not provide any clarification in this regard.

Questions, so many questions!

Rather than concluding that one entitlement (within 200 nm) trumps another entitlement (beyond 200 nm) in the delimitation process (with a possible “equitable solution” then being a delimitation at the 200-nm mark), the Court concluded that there is no overlap in entitlements in the first place. We have yet to see what the possible far-reaching ramifications of this conclusion are. What will this mean for the existence and indeed the legal validity of grey areas? How does this conclusion impact a coastal State’s delineation process? It would now be obliged to exclude from its entitlement any areas falling within 200 nautical miles of another State, including that of islands. Can a coastal State delineate the outer edge of its continental margin according to submarine features and scientific data collected from within a 200-nm radius surrounding islands abutting on the same continental margin? And, how does this conclusion affect the concept of a “single continental shelf” so religiously upheld by the case law and scholarly literature?

We are left with so many questions, and in that respect it is a shame the Court has not elaborated its findings with more detail. The dissenting and separate opinions in this regard provide some consolidation. Furthermore, those of us who were hoping to finally see a continental shelf beyond 200 nm with opposite coasts delimited before an international court or tribunal (and an authoritative statement on the applicable law in such cases) will be disappointed and will have to wait until a new situation arises: one in which one continental shelf entitlement beyond 200 nm overlaps with another continental shelf entitlement beyond 200 nm, or perhaps (although unlikely?) one in which an entitlement beyond 200 nm overlaps with an entitlement within 200 nm but which is governed by treaty law rather than customary international law (for it is now unclear whether treaty law still allows the entitlement of a continental shelf beyond 200 nm to extend within 200 nm of another State).