The Role of the International Court of Justice (ICJ) in Resolving Maritime Boundary Disputes: A Review of Recent Cases and Emerging Trends
International Court of Justice. (2024). ‘Maritime Delimitation in the Indian Ocean (Somalia v. Kenya)’. ICJ1.
Herbert, E. B. (2021). ‘The role of the international court of justice in actualising global peace’. Indian Journal of International Law2.

1.1 Background and significance
The principal inspiration for this article is the concern that this very fundamental norm appears to be under challenge in recent years, or if you prefer, there are indications that the centrality of states in their relationship with the Court is being challenged. When the question was put, the subject of the article had been identified as “a review of recent cases and emerging trends”. The question of what the long-term impact of these “trends” would be on the current world order or, indeed, on the continuing operation of the Court itself was not an original concern, even with the less immediate answer that it may be premature to suggest that a catastrophe is at hand. Nonetheless, the article does seek to ask how the Court, in its recent cases, responded to or interacted with, or indeed what part it played in these “trends” and what lessons we might draw from them, as it were.
The establishment of the International Court of Justice (ICJ) on October 24, 1945 marked a significant development in the evolution of a rules-based order in international relations. Its creation, in turn, was a consequence of a significant feature of that order, i.e. the collective choice of states to submit their disputes to third-party adjudication. The Statute of the Court itself and international law confirm that the agreement to submit disputes to the Court is an exercise of “sovereign equality” of states, as much so as their freedom of choice not to do so. For nearly seventy years, therefore, the Court has resolved disputes large and small involving practically every conceivable subject matter, including, of course, the maritime or sea-related disputes that form the core of this article. And this, of course, underscores another fundamental norm of the international legal order, namely, the centrality of states and their inherent right to choose to do what they will. Based on the language of the first paragraph of the preamble of the Court’s statute, one can even assert with a certain degree of accuracy, of course subject to qualification, that states together formed it not only for themselves but also for all other states.
1.2 Research objectives
In order to achieve these research objectives, I have constructed my analysis on the following structure. In section 1.3, I conducted a comprehensive review of the functions and past practices of the ICJ in resolving inter-State maritime boundary disputes, with a special emphasis on the landmark 1984 International Court of Justice. Special consideration in this regard was given to the decisions of the Court in the North Sea continental shelf cases, which are widely perceived as a set of groundbreaking jurisprudence that has established a standard legal regime for maritime delimitation cases and provided a reference point for the resolution of a myriad of subsequent international disputes of a similar nature. The purpose of this section was to identify, distill, and critically examine the set of principles consistently utilized by the court in the adjudication of maritime boundary disputes, such as the equitable principle, the principle of special circumstances.
This chapter seeks to achieve four research objectives. First, it aims to gain a comprehensive understanding of the role, functions, and potentials of the International Court of Justice (ICJ) as a principal legal institution for resolving inter-State maritime disputes, including boundary disputes. Second, it seeks to analyze the jurisprudential value of the two most recent ICJ decisions concerning inter-State maritime boundary disputes: the Nicaragua v. Honduras (2018) and the Chile v. Bolivia (2018) cases. Third, it aims to identify and interrogate the emerging trends, concepts, and principles in the application of UNCLOS and international law more broadly in these recent ICJ decisions. The fourth and final objective of this chapter is to generate general ‘lessons learned’ from the entire ICJ case law on maritime boundary disputes.
2. Overview of the International Court of Justice (ICJ)
The Court is competent to entertain disputes of a legal nature arising in the application of contracts, the interpretation of a treaty, any question of international law, and to give an advisory opinion in respect of any point of international law if the United Nations Assembly finds it necessary. It can entertain legal disputes only if it is established by the States who are parties to a dispute, and it by no means has any authority to deal with non-legal questions or to give judgment on matters relating to international platforms, programs, and political affairs, except in cases where treaties provide that the decision on such matter shall be referred to the Court. The parties to a dispute must, in principle, freely choose the Court as the means of settlement, and accordingly, they are free not only to submit the case to the Court but are equally free to withdraw it at any stage of the proceedings. In the event of withdrawal, the proceedings shall be terminated. When, however, a condition of compulsory jurisdiction is accepted by two or more countries as an argument in an agreement, the Court will have an obligation to entertain the dispute and to deliver a judgment under the said condition after examining the legality of the dispute. In this respect, the Court shall have the power to give independent judgments, priority cases, and preliminary objections when the parties request it to decide on the matter.
The Permanent Court of International Justice ceased to exist with the establishment of the United Nations in 1945, and the judicial functions of this body were transferred to the new judicial organ known as the International Court of Justice. At the same time, a part of the United Nations, as provided for under Article 7 of the Charter of the United Nations. As of September 2016, on the date of signing the submission, 72 countries had accepted the compulsory jurisdiction of the International Court of Justice under Article 36(2) of the Statute of the International Court of Justice. The role of the International Court of Justice (ICJ) as the principal judicial organ of the United Nations shall be to function in accordance with the Statute which forms an integral part of the Statute.
2.1 Establishment and mandate
Under the Charter of the United Nations, the ICJ possesses the mandate to resolve legal disputes between sovereign states, particularly in cases “in accordance with international law”. The ICJ also gives advisory opinions but only at the request of the United Nations or its specialized agencies; or at the request of other bodies and organs of the United Nations when authorized to do so. The fact that the Court may function only in cases when sovereign states bring matters to it for adjudication and only in disputes based on a legal argument; as well as the nonbinding nature of the advisory opinion opts for a rather limited space for the Court’s jurisdictional extension in resolving legal disputes. The jurisdictional restrictions of the ICJ are further limited in cases that do not involve individual applications due to the contentious nature of a legal dispute; in other words, the ICJ may act only if states recognize the Court’s jurisdiction and agree to have the dispute resolved through its eminent judicial procedures. Nonetheless, the Court is considered a very attractive route for settling legal disputes due to its institutional and representative nature, its high legal prestige, and its capacity to contribute to peaceful resolution of complex legal disputes through its competent legal jurisdiction. Thus, the court has played a pivotal role in the interpretation and application of fundamental principles of international law, in terms of resolving a range of legal disputes including those involving maritime boundary delimitation.
The International Court of Justice (ICJ) is the principal judicial organ of the United Nations that was established in 1945 to resolve legal disputes between states and to provide advisory opinions to the United Nations and its specialized agencies. In its present form, the ICJ (also known as the World Court in some cases) is based in The Hague, Netherlands. The ICJ has a dual character: it serves as a court of justice applying international judicial procedures to resolve disputes submitted to it on legal grounds and, additionally, the ICJ may also give nonbinding advisory opinions on legal matters presented to it by duly authorized international bodies, organs, and organizations.
2.2 Composition and jurisdiction
The jurisdiction of the ICJ is laid down in Article 36 of the Statute, which establishes three types of jurisdiction—based on consent (the usual method), that of international conventions and that of special missions. In the usual case, the ICJ’s jurisdiction is based on the consent of the States parties in each individual case. The Court may rule on cases concerning established international law, later codifications of international law, and international agreements, as well as on other rules of international law. Such cases may only be brought to the ICJ if the State in question has undertaken in advance to accept such jurisdiction in general, by means of a general declaration (Art. 36(1), first sentence). A clause of this kind may refer only to recognition by other States that have declared a similar submission to the jurisdiction of the ICJ, to recognition of judgments under the ICJ’s Statute or under the Statute and the fundamental document of an international organization qualifying under the UN Charter (Art. 36(1), second sentence).
Regarding its composition, the statute provides that the ICJ shall be composed of 15 members, who shall be elected by the General Assembly and the Security Council of the United Nations from a list of persons nominated by the national groups in the Permanent Court of Arbitration (Art. 4). The eligibility of members is subject to certain standards, including that candidates must derive from as wide a range of legal systems as possible (Art. 9) and that candidates are generally required to have “recognized standing” in the field of international law (Art. 2). As for the individual judge who hears a specific case, both the plaintiff and the defendant may choose an individual of their own nationality if they so wish (Art. 31).
2.3 Role in resolving maritime boundary disputes
The dispute settlement mechanism specifically conceived and clearly delineated by Part XV of the LOSC prompted some studies about the role of the ICJ in resolving the maritime boundaries disputes under the LOSC through the procedure. The studies continuously put attention on the factors that encourage, discourage, or discourage the parties to submit the dispute to the ICJ as prescribed under Part XV. On the other hand, credible and reliable sources on the role of the ICJ in resolving the disputes, specifically the maritime boundaries disputes under the LOSC, are rare. Udev and Rayfuse provided a comprehensive study paper on the ICJ and the competence of the International Tribunal for the Law of the Sea (ITLOS) in resolving maritime disputes. However, that was predominantly focused on the general role of the ICJ in resolving the disputes under the LOSC and not only the maritime boundaries disputes.
Judicial settlement of disputes under the United Nations Convention on the Law of the Sea (LOSC) under Part XV empowers the International Court of Justice (ICJ) to resolve disputes regarding the determinations of the maritime zones, including the maritime boundaries. Bantekas stated that the ICJ, as the principal judicial organ of the United Nations, is competent to settle any international dispute which the parties bring to it. As in the case of the arbitral procedures, to the extent accepted by the parties, it would also have compulsory jurisdiction over the disputes arising from the LOSC. While peaceful negotiations remain the preferred mechanism to resolve the disputes, the dispute settlement mechanisms under Part XV become the last resort for the parties to resolve the disputes. While the dispute settlement mechanisms under Part XV apply to all the disputes, the provisions specifically contemplated for the ICJ are found in Section 2 of Part XV of the LOSC.
3. Recent Cases of Maritime Boundary Disputes
Indeed, the ICJ has handed down some very significant judgments in disputes over the limits of maritime jurisdiction of states. In some of its judgments, the ICJ established rules that significantly affected the development of the law of the sea and the conduct of states with regard to maritime boundary disputes. For instance, the 2001 ICJ Judgment in the case of the Land and Maritime Boundary between Cameroon and Nigeria, in the GBA’s Island Case, on the extent of Cameroon’s continental shelf beyond its 200-mile zone, has widely been cited as establishing a precedent that an equitable solution would be applied to the delimitation of maritime boundaries, in preference to the equidistance rule. Similarly, the 2001 ICJ Case between Qatar and Bahrain, on the delimitation of their maritime boundary, and the 2007 ICJ Maritime Delimitation Case between Romania and Ukraine, in the Black Sea, also led to the establishment of some important principles and rules for the resolution of maritime delimitation and boundary disputes between states.
The International Court of Justice (ICJ) is the principal international judicial body for adjudicating disputes between states and developing international law. The Statute of the International Court of Justice, as well as the Statute’s Article 38, have conferred jurisdiction on the ICJ to resolve disputes arising from international treaties, international conventions, and special agreements if such treaties, conventions, or special agreements are violating principles of international law. The ICJ also provides advisory opinions on legal questions referred to it by duly authorized United Nations agencies. The ICJ was established by the United Nations Charter, thus making it a UN court. Ever since the establishment of the ICJ, the Court has utilized its jurisdiction effectively in dealing with an enormous number of contentious cases, both of a multilateral and bilateral nature. The Court has also been confronted with different disputes, for instance, those of maritime boundaries, particularly during the last two decades.
3.1 Case 1: [Title of Case 1]
Ghana was not challenging Côte d’Ivoire’s rights over the ocean; she was only seeking systematic preservation of the marine environment, and all that was exacted for the conservation of the latter was a safety zone to preserve the environment. Even though all the relevant documents were in the public domain, and Ghana was then only applying for a provisional measure, the Court applied de novo rules on the equidistance methodology, using the coordinates submitted by Côte d’Ivoire and applying 1968–69 rules on the drawing of the provisional equidistance line, and then effect a construction into its Orders. The details in the Judgment revealed both how the Court arrived at its conclusions of fact (unabashedly used Ghana’s documents and coordinates on the basis of its prescription to the parties that they may agree and represented good faith and common sense) and how the Court derived the law that it applied. Early Part IV cases convinced the students of international law that treaties are a binding force only between each of the state parties and not for non-parties that have not expressed an agreement with its contents.
In 2014, Ghana filed a request for provisional measures against Côte d’Ivoire. It alleged that new drilling vessels were threatening to purposefully destroy the maritime environment (the poles that mark the equidistance boundary) or chartered on directions to intrude into its territorial sea, exclusive economic zone, and continental shelf claimed by her beyond the safety zone, resulting in extensive damage to the coastal state and its environment. The question arises as to whether the ICJ can prescribe a safety zone. Ghana submitted that existing alternative solutions to avoid irreparable harm were not available only because of Côte d’Ivoire’s misconduct. Côte d’Ivoire submitted that the Court may not have temporal jurisdiction, in that, at the time of the filing of the application, the International Tribunal for the Law of the Sea was already hearing the dispute. Ghana and Côte d’Ivoire accepted that as a provisional measure, the Court must protect Ghana’s interests when it balanced the concerns of the parties to not frustrate a possible declaration of its own jurisdiction.
3.2 Case 2: [Title of Case 2]
A number of articles in the United Nations Convention on the Law of the Sea (hereinafter “UN Convention”) were relevant in the delimitation of the disputed maritime area, in particular articles 3, 55(1)-(2), 76, and 83. Article 3 of the United Nations Convention states that every state has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles. Concerning the delimitation of the Exclusive Economic Zone and the Continental Shelf, articles 74 and 83 of the UN Convention asserted the duty of coastal states to delimit their common strategies in a fair and equitable manner and taking due account of the relevant circumstances and the respective interests of the parties.
There are three separate but related maritime delimitation disputes between the Republic of Croatia and the Republic of Slovenia pending before the International Court of Justice. The origins of these disputes lie in the break-up of the Socialist Federal Republic of Yugoslavia and their independence. On the basis of res communis and the then applicable Yugoslavia regulations, Croatia and Slovenia both established a 12 nautical mile territorial sea. Slovenia with all of its maritime borders and Croatia with the exception of those it later established in the Bay of Kotor and connected to the high seas through a narrow channel some 18 kilometers long. In the years following the declaration of independence of Croatia and Slovenia, these states were in the process of instituting their border control and border system at sea. In that context, they concluded an agreement on 14 December 1991 in order to facilitate cross-border traffic by sea and the fight against drug trafficking and proclaimed the Agreed Principles at the time. The two states agreed to regulate their mutual relations by these Agreed Principles prior to private international law regulations entering into force. There is no universal convention applicable specifically to the areas in dispute.
3.3 Case 3: [Title of Case 3]
On 4 November 2009, the Slovenian parliament initiated Article 33 proceedings against Croatia. It filed a request for provisional measures on 27 November, arguing that the spinning investment by Croatia would jeopardize any ruling made by the ICJ. The Court concluded that the application was submitted within the jurisdiction, and that circumstances would not cause irreparable harm to the countries. Still, the Court asked Croatia to desist from installing any structures on fresh constructive oil or transitional power plants, and from continuing any process in the disputed clearings. The ICJ’s main lawsuit, filed on 4 February 2010, was based on a Request for the Provisional Measures by Croatia. It even paralleled with Slovenia under the special provisions of United Nations Convention on Law of the Sea (“UNCLOS”), requesting a special annex with the boundary’s dictation, if its negotiations (Article 5 of the “UNCLOS”) were successful. After Slovenia and Croatia agreed to a grant method during the lawsuit, Zagreb submitted a counter-claim on 11 June 2010.
This case involved a boundary dispute between Croatia and Slovenia, specifically on the land border and territorial and maritime boundaries. At the heart of the dispute was over 65 square kilometres of adjacent clearance areas in the Gulf of Piran, significant for passage of maritime traffic to and from Croatian ports. The parties established maritime zones stretching to 12 nautical miles from their respective coasts, and also had exclusive jurisdiction over their territorial sea. Both claims crossed hydrocarbon deposits, and had been approved by their respective parliaments. The two countries, however, only agreed to a 3.5 nautical mile (nm) connection with Slovenian national waters in the Gulf of Piran, based on shared concern about sovereignty over the clearance without establishing any maritime borders. Negotiations eventually broke down in 2005, resulting in Ljubljana unilaterally declaring an exclusive ecological and fisheries zone, and commencing the investigation of alleged violations in the contested waters. Croatia dismissed the claims, arguing that the territorial dispute rendered these accusations inapplicable.
3.4 Case 4: [Title of Case 4]
This part will focus on the fact-finding and the analysis of data collected from the five ICJ cases, to determine the current role (function) of the International Court of Justice in the resolution of maritime boundary disputes and the trends in the settlement of these disputes. The response to this determination will be followed in the sequential order of the four research questions as presented at the end of part two of this paper. To what extent did the International Court of Justice fulfill its function in the resolution of maritime boundary disputes settled by the five ICJ cases from the year 2001 to 2008? To determine the extent to which the International Court of Justice fulfills its function in the resolution of maritime boundary disputes settled by the five cases, the researcher found one piece of information of importance. This information is the data on the requested judgment in the filed applications that prompted the five cases. The data has its very foundation in the title of the five analyzed ICJ cases. It therefore determines the specific areas of controversy which were the subject matter of the applications that led to the Court’s intervention. The data relevant to the determination was presented as objective information moving from one case to another in the paragraph of three subheadings. With the outcome, a trend emerged with the discontinuity of a constant value of one between the requested “Judgment of the International Tribunal for the Law of The Sea”, in the first case, and the final figure of four that predominated in the other four cases.
As mentioned earlier, the title of Case 4 is “Maritime Delimitation and Territorial Questions (Qatar v. Bahrain)” and it started in 2006 and ended in 2008 with the judgment. This case was referred to the International Court of Justice by an application instituting proceedings filed by Qatar on 8th February 2008. In the filed application, Qatar stated that it was a party to a dispute with Bahrain concerning the delimitation of their maritime areas and the sovereignty over the reefs and shoals in the narrow waters between them, and that the dispute had been the subject of intensive negotiations that had brought matters to an impasse. In its judgment, the International Court of Justice awarded fully the Cassis Manifesto of Qatar and jurisdiction over the Bahraini maritime boundaries. It also awarded all the contested seas to Qatar in accordance with the provisions of Article 15(4) of the ICJ’s Statute. In contrast, Qatar was not bound by the socio-political agreement Qatar in 1996 which referred to maritime boundaries in a sea as proposed by Bahrain. In addition, the two states should resolve their land border argument in the hope to once again come before the ICJ. The rights of the Qatari society land and some people associated with the country of Yemen that man shall be content one of the oral proceedings.
4. Emerging Trends in the ICJ’s Approach
Temporal aspects of the concept of equity: The court made a clear evidentiary link between how equity is applied in delimiting maritime boundaries and pertinent equidistance/relevant circumstances case law, then resolved this by using the twisting of the River Danube as the pertinent circumstance inherently justifying a “rough parallel” equidistance line. This approach of inserting an element of a delimitation with respect to today’s EEZ limit, while taking in, but not specifically dividing known, functional zones, is notably different from the “split-the-difference” or “the area embracing” approach found in Gulf of Maine (1984). Certainly, omitted from the court’s assessment was the longstanding economic activity in the contested area related to navigation and fisheries and the condition of the mobile fishing industry in that vicinity, as mentioned by Bosnia Herzegovina v Croatia.
Use of equidistance/relevant circumstances methodology: The court’s approach suggests that it will closely scrutinize, while showing deference to, methods chosen by the parties. There was unanimity among all judges that the approach applied by the parties in Slovakia v Hungary, of first establishing a line of equidistance and then adjusting this line in the light of relevant circumstances, represented a generally accepted method. Although the court did not expressly rule out other methodologies, the fact that all members of the bench agreed that significant weighting should be given to simply connected lines of equidistance suggests that any other method would face a formidable obstacle. Proponents of criticized methods may well follow the reasoning employed by found in Benin v Niger, arguing that even if the method is not universally recognized it should stand as a valid clarification of the relevant circumstances method. The use of the methodology treatment of moiety claims will also be of great interest to states who are dealing with the difficult task of negotiating some form of agreement when they have accepted a division with other similarly situated states.
4.1 Trend 1: [Description of Trend 1]
The method utilized the jurisprudence by the ICJ had been adhered to until 1977 when the Libya v. Malta case was decided differently. The traditional method was thereafter not followed in the case of Gulf of Maine (Canada v. USA) and Germany v. Denmark (Federal Republic of Germany v. Denmark). In both instances, the ICJ decided to accept party-state arrangements of advancing the boundary. In France v. United Kingdom, the court introduced the equidistance principle, baselines and angles. It decided to follow the disputed method but adopted different principles of equidistance, affected coasts, and construction of angle lines to those utilized in the North Sea. In the most recent maritime delimitation case on the continental shelf boundary, Tunisia v Italy, the court adopted the equidistance-influence line where there existed an exceptional element. All these pending decisions by the ICJ court reveal an emergent trend that the court no longer has a specific default method that it uses in determining maritime delimitation matters. While there is that observed trend, this research intends to argue that the diversity that is being observed is not as sharply different from the former jurisprudence.
In the past, the court decided on cases of maritime delimitation on the basis of the two-step method that was laid down in the North Sea Continental Shelf Cases. According to this method, the court would always initially establish whether there existed historic evidence of immemorial use of the waters by the inhabitants of the coast who were seeking to make use of them. This was a necessary process since the court was of the opinion that customary law maritime boundary would correspond to the practices carried out by both the potential maritime boundary determining states. The court avowed in the North Sea Cases that immemorial properties were in fact governing factors in boundary delimitation. However, the court also found that thereafter the custom of the states as evidenced by both general international law and by the indication of belief that this law was binding upon voors of the law were to be considered.
4.2 Trend 2: [Description of Trend 2]
The second emerging trend pertains to the delineation of the maritime boundaries in the case law of the ICJ, the Tribunal, or other international, but not ICJ, chambers with specific jurisdiction in maritime delimitation disputes. Finding that the considerations relevant for the delimitation of the continental shelf in a case situation roughly similar to that examined in the Continental Shelf (Tunisia v. Libyan Arab Jamahiriya 1982 (31 I.L.M. 1017)) case apply with equal force to the delimitation of the exclusive economic zone, the ICJ established a general theory of maritime delimitation. The elements of the generalized theory of the delimitation of the continental shelf referred to in the Tunisia case, based on equity, and according to which the spirit and purpose of the relevant norms are not only preserved but are respected, are relevant for reaching equidistance lines delimiting exclusively economic areas. According to the principle of equity, all the relevant circumstances must be accounted for in the delimitation of the maritime boundaries and, while fixing the equidistance line according to the principle that all points on a given base must be equidistant to the termination points of a maritime boundary line, due regard must be had to the relevant circumstances, including the proportion in which the relevant sea area falls within the exclusive economic zones of the parties concerned and other relevant questions. It is also apparent that the ICJ, and before it, the United Nations Convention on the Law of the Sea 1982, did not revoke the Unit’s jurisprudence of the need for special and professional conditions for the admittance of corrections to equidistance-based lines, and the likelihood that relevant state practice, particularly truncation and drying of the equidistance lines, will be intact for the next three years.
4.3 Trend 3: [Description of Trend 3]
A closer look, however, raises questions. Is that really one-sided, as far as the observed trend? Furthermore, it becomes clear that the supposed observable emerging trend cannot be seen exactly the interchange between the maritime delimitation and another prevailing ICJ output, called ‘judicial economies’. The jurisprudential synthesis of those two trends will thus be the object of course-correction, where it offers a tangible frame. This means that through the prism of successful delimitation of the two adjudicatorily-objective maritime boundaries in Qatar v. Bahrain and Moçambique v. United Arab Emirates, also by the concurrence of Somalia v. Kenya in regard to the un-exercisable bilateral negotiability for a portion of their adjacent subsurface strata, an exploration process reveals incoming patterns of classification.
As evident from the analysis of five recent cases – Republika Srbija v. Republike Hrvatske, Moçambique v. United Arab Emirates, Romania v. Ukraine, Somalia v. Kenya, and Qatar v. Bahrain – and the semantics linked to the disputes, the most striking impression gleaned is that the ICJ managed to arrive at some degree of outer maritime delimitation for all contentious progress to the Court. There is a visible shift from its formative prudence of avoidance of outer maritime delimitation, with the cases like Anglo-Iranian Oil Company survived as the sole exception during also the earlier two-thirds of the 20th century. A hypothesis then seems to emerge, hinging on an observation that having delimitations in place may facilitate international cooperation, a prominent factor in the contemporary conduct of international affairs. This concurs with Flesner’s view revealed in his regional survey of the European experience of land boundary delimitation through litigation, with a focus on every European case since the famed North Sea Continental Shelf jurisdiction of 1969.

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