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The Authority of Advisory Opinions in Contentious Proceedings

Published online by Cambridge University Press:  04 September 2026

Robert Christoph Stendel Open the ORCID record for Robert Christoph Stendel [Opens in a new window]  and
Alexander Wentker Open the ORCID record for Alexander Wentker [Opens in a new window]
Robert Christoph Stendel
Affiliation:
Senior Research Fellow, Max Planck Institute for Comparative Public Law and International Law, Heidelberg, Germany
Alexander Wentker*
Affiliation:
Postdoctoral Researcher, Humboldt-University, Berlin and University of Potsdam, Potsdam, Germany Senior Research Fellow, Max Planck Institute for Comparative Public Law and International Law, Heidelberg, Germany
*
Corresponding author: Alexander Wentker; Email: alexander.wentker@hu-berlin.de
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Abstract

The International Court of Justice (ICJ, the Court) increasingly addresses major regional and global conflicts and crises. In contentious proceedings, its limited jurisdiction—regarding both subject-matter and matters affecting third States—often confines the Court to examining a small portion of the actual dispute between the parties. In advisory proceedings, by contrast, the Court faces no such constraints when determining the legal positions of individual States. This article argues that legal determinations made in advisory opinions can, in principle, be relied on as ‘givens’ in subsequent contentious proceedings where the Court would otherwise be prevented from making such determinations. The Court’s advisory and contentious jurisdictions are both built on consent, which is required to protect States’ sovereignty from exercises of the Court’s authority. If the Court exercises its authority in an advisory opinion by determining the legal position of a State, it removes sovereignty concerns regarding this determination for subsequent contentious proceedings. The significant practical challenges in relying on legal determinations from advisory opinions as ‘givens’ are most likely to be overcome in relation to determinations of status, rather than for establishing specific internationally wrongful acts. ‘Givens’ from advisory opinions are thus not a general workaround to the limitations in the ICJ’s contentious jurisdiction. Still, relying on determinations from advisory opinions in subsequent contentious proceedings invites the Court to enter into an intricate dialogue between its two forms of jurisdiction, a dialogue which may further intertwine them and thereby enhance coherence in the ICJ’s exercise of its judicial function.

Keywords

International Court of Justicejurisdictionadvisory opinionscontentious proceedingsState consentindispensable third partiesMonetary Goldgivensauthority

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Type
Shorter Article
Information
International & Comparative Law Quarterly , First View , pp. 1 - 21
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2026. Published by Cambridge University Press on behalf of British Institute of International and Comparative Law

1. Introduction

In recent years, States have been increasingly willing to bring their disputes to the International Court of Justice (ICJ, the Court).Footnote 1 This trend notably includes ‘high stakes’ cases concerning major armed conflicts and other regional and global crises.Footnote 2 At the same time, the ICJ can often decide only a small part of the underlying dispute in contentious proceedings. This limitation is inherent in its jurisdiction, which is based on State consent. States may consent to the Court’s jurisdiction in different ways, but they rarely do so without limitation. Optional clause declarations are commonly accompanied by significant reservations,Footnote 3 while the compromissory clauses found in many international treaties, which are the most frequently invoked basis for the Court’s contentious jurisdiction,Footnote 4 confer jurisdiction only over disputes concerning the interpretation or application of the particular treaty in question. As a result, where jurisdiction rests on a compromissory clause, the Court’s jurisdiction is necessarily confined to that treaty’s subject-matter, such as genocide or racial discrimination. States have been creative in shoehorning their broader disputes into the narrow confines of compromissory clauses and the Court is constantly recalibrating its response to such practices. But it is clear that there are limits to this practice, as evidenced by the ongoing proceedings regarding Russia’s 2022 full-scale invasion of Ukraine: of Ukraine’s attempt to connect Russia’s war of aggression to the Genocide Convention’s compromissory clause, only the ‘reverse compliance’ claim that Ukraine has not committed genocide has survived to the merits stage of the case.Footnote 5 The consent-based nature of the ICJ’s jurisdiction also limits the Court’s capacity regarding claims in contentious proceedings that depend on the legal position of States that are not parties to the proceedings under the Monetary Gold rule, which prevents the Court from exercising jurisdiction over a dispute which would, incidentally, require the determination of the rights and obligations of a State not party to the case.Footnote 6

In parallel to the rise in contentious proceedings, the ICJ has also faced an increasing number of requests for advisory opinions. Such requests can only be made by certain United Nations (UN) organs, and the ensuing advisory proceedings have no parties on which they would be binding.Footnote 7 However, unlike in contentious proceedings, in which States’ limited consent confines the ICJ to a specific subject-matter, the Court has increasingly made findings in advisory opinions on the legal positions of individual States that it may not have been able to make in contentious proceedings. For example, in the Chagos Advisory Opinion, the Court found the United Kingdom (UK) to have engaged its international responsibility by its continued administration of the archipelago,Footnote 8 and in the Wall and Occupied Palestinian Territory Advisory Opinions, the Court found Israel in violation of international humanitarian and human rights law.Footnote 9 Due to a lack of consent to the ICJ’s exercise of its contentious jurisdiction on these questions by the UK and Israel respectively, none of these findings could have been made in a contentious case.

Considered in the broader context of the ICJ’s judicial function, there is a question as to what this feature of the Court’s advisory practice means for the exercise of its contentious jurisdiction. The relationship between the ICJ’s two types of jurisdiction, contentious and advisory, remains insufficiently understood. This article argues that the two are more intimately related than is generally appreciated and that, therefore, findings made in advisory opinions can be relied on in contentious proceedings as what the ICJ has termed ‘givens’.Footnote 10 In other words, if the ICJ has determined the legal position of a State in an advisory opinion, the Court (or indeed another international court or tribunal) can, in principle, use that determination in subsequent contentious cases where it would otherwise be prevented from making this finding, be it by virtue of a subject-matter limitation of its jurisdiction or because the State whose legal position is in question is not a party to the dispute. As a matter of scope, this article is limited to advisory opinions rendered by the ICJ and does not consider whether the argument applies to advisory opinions by other judicial bodies.

The argument flows from the very rationale for the limitations on the ICJ’s contentious jurisdiction. At its core, the principle of consent protects States’ sovereign equality from an international court or tribunal—an institution which derives its existence and jurisdiction from States—exercising its authority by determining the legal position of States. Such authority may not be exercised on a subject-matter for which States have not provided consent to have their legal position determined by an international court, or in proceedings to which they are not a party (and have thus not consented).Footnote 11 If the Court has already exercised its authority by determining a State’s legal position, subsequent references to that finding do not further infringe on sovereign equality. The consent on which the initial legal determination is based removes any sovereignty concerns regarding that finding.

Findings that determine a State’s legal position may qualify as ‘givens’ for subsequent proceedings, whether the findings were made in a contentious case to which that same State was a party or in an advisory opinion. This is so in both types of proceedings because it is the exercise of authority in determining States’ legal positions that underlies the limitations of contentious jurisdiction, not the binding force of a finding. As authority is exercised through judicial determinations of States’ legal positions, whether they are made in contentious or advisory proceedings, there is no ground for treating determinations in judgments and advisory opinions differently in this respect. Specifically, the principle of consent provides no ground for such a different treatment, for findings in advisory opinions are based on the general consent of UN Member States and the ICJ is thus justified in making determinations of individual States’ legal positions.

In practice, whether findings in advisory opinions can be relied on in subsequent contentious proceedings depends: first, on the extent to which the Court, in an advisory opinion, has actually determined the legal position of the respective State; and, second, on whether the Court has done so precisely on the legal question at issue in the subsequent contentious case at hand. These two steps present significant practical difficulties. They are more likely to be met for determinations of status, such as sovereignty over territory, statehood or maritime and land borders, than for determinations establishing responsibility for internationally wrongful acts.

The possibility of relying on legal determinations from advisory opinions as ‘givens’ should not be understood as a way to work around jurisdictional limitations in contentious proceedings. However, the potential effect of findings in advisory opinions does invite a dialogue between the Court’s advisory and contentious jurisdictions, which could help ensure coherence in the performance of its judicial function. The interpretation of advisory opinions may be relevant to determine the scope of the Court’s jurisdiction on incidental questions in contentious proceedings, while the potential implications of advisory opinions in contentious proceedings may inform how States and the Court approach advisory opinions. Shedding light on this aspect of advisory opinions’ authority and their relevance in contentious proceedings thus contributes to a more holistic understanding of the ICJ’s jurisdiction.

The argument proceeds as follows. Section 2 analyses the ICJ’s competence to make findings on the legal position of States in advisory opinions that it could not make in contentious proceedings for lack of consent by the State concerned. Section 3 presents the article’s core argument that determinations of States’ legal positions in advisory opinions may be relied on as ‘givens’ in subsequent contentious proceedings. Section 4 demonstrates whether and when, in practice, such invocations of findings in advisory opinions may be successful in a subsequent contentious case and how the practical challenges that States face in doing so are likely to contribute to further intertwining the two forms of the Court’s jurisdiction.

2. The ICJ’s competence to determine the legal positions of States in advisory opinions

As a matter of practical reality, the scope of the Court’s advisory jurisdiction may to some extent exceed what it can decide in contentious proceedings. In the latter, the ICJ may only decide a dispute on the merits if and to the extent that the parties to the dispute have consented to the Court’s exercise of jurisdiction (Article 36(1)–(2) of the Statute of the International Court of Justice (ICJ Statute)Footnote 12), which States tend to accept only in a limited fashion, if at all. For example, the litigation between South Africa and Israel concerning the war in Gaza is limited to violations of the Genocide Convention and can, at most, indirectly address allegations of other violations of international law in the conflict.Footnote 13 In contrast, the ICJ commented on Israel’s compliance with international humanitarian and human rights law in its Wall Footnote 14 and Occupied Palestinian Territory Advisory Opinions.Footnote 15 In the former, for example, the Court explicitly stated that ‘[t]he construction of such a wall … constitutes breaches by Israel of various of its obligations under the applicable international humanitarian law and human rights instruments’Footnote 16 and spelled out legal consequences flowing from these and other violations of international law.Footnote 17 In contentious proceedings, in the absence of Israel’s consent to the Court adjudicating on matters of international humanitarian law and human rights, the Court could not have made such observations. Along the same lines, in the Chagos Advisory Opinion, the Court found ‘that the United Kingdom’s continued administration of the Chagos Archipelago constitutes a wrongful act entailing the international responsibility of that State’,Footnote 18 although the Court would have been unable to make this determination in a contentious case absent the UK’s consent to adjudication.

Such findings in advisory opinions are neither outliers nor recent developments. More than 50 years ago, the Court determined South Africa’s position vis-à-vis Namibia, found its administration of the territory to be illegal and affirmed, inter alia, South Africa’s ‘obligation to withdraw its administration from the Territory of Namibia’ in an advisory opinion.Footnote 19 It would thus seem that the Court has indeed determined the legal rights and duties of States in advisory proceedingsFootnote 20 where the Court could not have done so in a contentious case against that State for lack of consent.

In some advisory proceedings, States have argued that determining the legal positions of States in advisory opinions circumvents the consent requirement,Footnote 21 and individual judges have shared that concern.Footnote 22 In response to such arguments, the Court has taken care to explain the apparent mismatch between the exercise of its advisory and contentious jurisdictions with institutional considerations. As the Court emphasises in almost every advisory opinion, advisory opinions ‘represent its participation in the activities of’ the UN.Footnote 23 Still, the Court will ‘decline to give an advisory opinion when such a reply “would have the effect of circumventing the principle that a State is not obliged to allow its disputes to be submitted to judicial settlement without its consent”’.Footnote 24 In practice, the Court distinguishes between cases concerning ‘only a bilateral matter’Footnote 25 and those also relevant for the requesting UN organ, such as the status of PalestineFootnote 26 or decolonisation.Footnote 27 If assisting the requesting UN organ so requires,Footnote 28 the Court will also ‘pronounce on legal issues upon which radically divergent views exist’Footnote 29 and doing so does not mean that ‘the Court is dealing with a bilateral dispute’.Footnote 30 This does, of course, leave open the possibility of indirectly resolving a bilateral dispute between States, as the Court implied in its Nuclear Weapons Advisory Opinion.Footnote 31 In essence, the Court has interpreted its advisory jurisdiction as extending to all legal questions relevant for the requesting UN organs in discharging their duties, irrespective of whether this entails pronouncing on the legal positions of States.Footnote 32

This understanding of its advisory jurisdiction is in line with its mandate. To be sure, the Court’s ability to pronounce on a State’s rights and duties in advisory proceedings, where it could not do so in a contentious case concerning that State for lack of consent, may appear as a challenge to the consent principle.Footnote 33 However, as the Court explained in Western Sahara, by ‘accept[ing] the provisions of the [UN] Charter and [ICJ] Statute [States have] thereby in general given … consent to the exercise by the Court of its advisory jurisdiction’.Footnote 34 This general consent enables the Court to render advisory opinions on topics such as the ‘decolonization of a non-self-governing territory’Footnote 35 and thereby make specific determinations on the legal positions of States.Footnote 36 While the Court has spelled out this rationale only once, it is in line with the practice of the Court’s predecessor: the Permanent Court of International Justice (PCIJ) declined to give an advisory opinion in Eastern Carelia mainlyFootnote 37 because it concerned a dispute between a Member State and a non-Member State of the League of Nations.Footnote 38 With regard to UN Member States, there is general consent to the Court’s advisory jurisdiction, ‘whether it involves … [their] disputed interests or not’.Footnote 39 In contrast to the PCIJ’s approach in Eastern Carelia,Footnote 40 the ICJ exercised its advisory jurisdiction in a situation concerning non-UN Member States in 1950.Footnote 41 Of course, scenarios involving non-UN Member States have become rather theoretical in light of the UN’s almost universal membership, but even here, the Charter of the United Nations (UN Charter)Footnote 42 and the ICJ Statute provide a sufficient basis for the Court’s exercise of advisory jurisdiction. Given that the mandate of some UN organs extends beyond UN membership—consider the Security Council’s mandate for international peace and security (e.g. Articles 24(1), 33 of the UN Charter)—it would seem that the Court’s mandate under Article 96 UN Charter and Articles 65–66 ICJ Statute is commensurate with the requesting organ’s responsibilities, if duly asked.Footnote 43 Clearly, therefore, the Court does not require any State’s consent to render an advisory opinion beyond the general consent conveyed by membership of the UN.Footnote 44

This general consent differs from the specific consent required in contentious proceedings. Yet this difference is tempered by two additional requirements unknown to contentious proceedings. Importantly, advisory proceedings are, as the Court put it, ‘not a form of judicial recourse for States but the means by which the General Assembly and the Security Council, as well as other organs of the United Nations … may obtain the Court’s opinion in order to assist them in their activities’.Footnote 45 If a State seeks an advisory opinion, it needs to secure the support of a majority vote in a UN organ.Footnote 46 The second point is closely connected to the first. The ICJ may render advice to support the requesting UN organ in discharging its duties.Footnote 47 In contentious cases, such institutional concerns are irrelevant. It should be noted, however, that the Court has interpreted this latter criterion quite leniently in the past, accepting the requesting organ’s assertion as to the usefulness of the advice at face value and declining to subject it to further scrutiny.Footnote 48

In light of these differences between advisory and contentious proceedings, the general consent to the Court’s advisory jurisdiction provided by a State’s accession to the UN Charter and the ICJ Statute forms a sufficient basis for the Court to make findings on the legal position of a State in an advisory opinion when it could not do so in a contentious case concerning that State.

3. The authority of advisory opinions and the doctrine of ‘givens’

Section 2 has shown that the ICJ can and does determine the legal position of States in advisory proceedings. These advisory findings can then play a crucial role in subsequent contentious proceedings, where they can, in principle, be relied on as ‘givens’. Two scenarios for such a use of findings from advisory opinions are particularly relevant. First, determinations of the legal position of States made in advisory opinions may enable the Court to avoid the jurisdictional obstacle posed by the so-called Monetary Gold rule (indispensable third party principle) (Section 3.1), thereby allowing it to hear contentious cases in which it might otherwise be unable to exercise its jurisdiction. Second, such findings may permit the Court to decide a dispute notwithstanding the existence of incidental issues that arise between the parties and fall outside its subject-matter jurisdiction (Section 3.2).

3.1. Findings in advisory opinions and the Monetary Gold rule

Under the Monetary Gold rule, the Court cannot exercise its jurisdiction if a third State (i.e. a State that is not a party to the proceedings) is an indispensable third party.Footnote 49 This is the case if deciding on a claim would incidentally require the Court to determine the legal position of that third State (it is not enough that the third State’s interests are affected).Footnote 50 The rationale for this rule is that the Court infringes on a State’s sovereignty if it exercises its authority by determining that State’s legal position. Sovereign equality entails that an international court—which derives its existence and, crucially, its power to adjudicate from States—may only make such a determination with the consent of the State concerned.Footnote 51

There is a good case that the Monetary Gold rule does not apply where the legal position of the third State has already been determined by the Court on the relevant question, such that the Court could rely on this finding as a ‘given’.Footnote 52 Indeed, in such a case the third State would not be an indispensable third party because the Court would not need to determine the legal position of the third State itself. There would thus be no exercise of the Court’s authority on this point. Accordingly, the rationale of the Monetary Gold rule—and indeed the rationale of the consent-based character of the Court’s jurisdiction—suggests that this possibility should be accepted in principle.

At the outset, it is worth clarifying that treating determinations of a State’s legal position in advisory opinions as ‘givens’ is conceptually distinct from binding precedent, persuasive authority or res judicata. These notions are not always clearly distinguished in debates on the legal effects of advisory opinions. Two features of how the notion of ‘givens’ operates are key to the distinction from other legal effects. First, a ‘given’ is the result of an application of a rule of international law to a set of facts. Second, the Court would not be bound to treat such a determination as a ‘given’ but would merely have the faculty to do so. By contrast, treating a decision as binding precedent under a purported doctrine of stare decisis would operate at the level of the general meaning of a rule—rather than its application in a particular case—and would also mean that the Court is bound by that understanding of the rule.Footnote 53 The fact that international law has no rule of stare decisisFootnote 54 and that no decision by the ICJ, let alone an advisory opinion, formally constitutes binding precedentFootnote 55 therefore does not affect the possibility of treating certain findings in ICJ decisions as ‘givens’. Suggestions that judicial decisions constitute persuasive authority do not entail that the Court is bound by them in subsequent cases but would still operate at the level of the meaning of a rule, rather than its application to a set of facts.Footnote 56 Along similar lines, the fact that Article 38(1)(d) ICJ Statute considers judicial decisions to be ‘subsidiary means for the determination of rules of law’ is immaterial for present purposes.Footnote 57 The question here is not whether or to what extent a finding in an advisory opinion contributes to the creation or development of a particular rule of international law at a general level,Footnote 58 but simply what to make of a judicial determination as to how a rule applies to a specific set of facts in a specific case. The application of a rule to a set of facts is also what is at issue if a finding were treated as res judicata. But unlike a ‘given’, a finding that is considered res judicata would bind the Court to follow its earlier determination, not merely provide that faculty.Footnote 59 This bindingness only exists between the parties to the dispute in which the Court has made the respective determination.Footnote 60 A finding in an advisory opinion therefore cannot constitute res judicata.Footnote 61

Thus far the ICJ has not had to rule explicitly on whether and when it would rely on previous determinations of a State’s legal position as ‘givens’. In East Timor, Portugal argued that ‘the status of East Timor as a non-self-governing territory and its own capacity as the administering Power of the Territory, have already been decided by the General Assembly and the Security Council and that the determinations made by those bodies could be taken as “givens”’.Footnote 62 Portugal thus took it to be a ‘given’ that Indonesia and Australia had no power to conclude a treaty over East Timor’s continental shelf and that the Court would thus not need to determine Indonesia’s legal position de novo to decide against Australia.Footnote 63 The Court found, however, that the mere fact that the resolutions identified Portugal as the administering Power of East Timor did not entail that a third State could ‘treat exclusively with Portugal as regards the continental shelf of East Timor’.Footnote 64 The Court thus found that the resolutions did not say what Portugal claimedFootnote 65 and held ‘as a result that they cannot be regarded as “givens” which constitute a sufficient basis for determining the dispute between the Parties’.Footnote 66

While the ICJ stopped short of accepting the possibility in principle of relying on ‘givens’ in East Timor, the way it framed its reasoning suggests an openness to the possibility. The Court confirmed this openness in Nicaragua v Colombia. Footnote 67 In this case, the Court relied on a finding made in a previous judgment involving a third State, thereby implicitly accepting the notion underlying the ‘givens’ doctrine. The Court established the relevant area for maritime delimitation by referring, inter alia, to the delimitation line the Court had previously drawn in a case between Nicaragua and Honduras.Footnote 68 As a consequence of this previous judgment, the ICJ stated in Nicaragua v Colombia that ‘Nicaragua can have no rights to the north of that line and Honduras can have no rights to the south’.Footnote 69 Other international courts and tribunals have explicitly accepted the possibility of relying on previous determinations as ‘givens’.Footnote 70

If the possibility of relying on certain findings as ‘givens’ is accepted in principle, questions remain as to when a finding can be treated as a ‘given’. At the very least, determinations of a State’s legal position in decisions by the ICJ itself should qualify. Accordingly, findings in judgments can constitute potential a ‘givens’ for subsequent contentious litigation, as can findings in advisory opinions. This is so even though judgments bind the parties while advisory opinions have no parties on which they could be binding.Footnote 71 The binding nature of judgments provides no sound reason for distinguishing findings in contentious and advisory proceedings for the purposes of establishing ‘givens’. This is because the bindingness of the decision that contains the determination of a State’s legal position is not the rationale for the Monetary Gold rule and the underlying principle of consent to jurisdiction. Third States would not be bound by a decision in proceedings to which they are not a party,Footnote 72 even if that decision determines their legal position.Footnote 73 Even for judgments, the reason that consent is required is not the binding force of the eventual judgment as such.Footnote 74

Rather than the binding effect of judgments, the rationale for the Monetary Gold rule and, more broadly, the underlying principle of consent to international adjudication, is the exercise of authority by an international court or tribunal in determining a State’s legal position. In line with this logic, the arbitral tribunal in Larsen v Hawaii considered that findings in ‘authoritative’ (rather than binding) decisions could be taken as a ‘given’.Footnote 75 It is a finding’s authority that matters for present purposes. What constitutes the authority of a finding can be understood in manifold ways and the contours of authority may be elusive.Footnote 76 For present purposes, the type of authority exercised by the ICJ flows from the Court having been created by StatesFootnote 77 to reach findings as a court, i.e. an institution with a judicial function, composed of independent judges making decisions based on an impartial deliberative process with procedural guarantees and safeguards for States whose interests are at issue.Footnote 78 The ICJ exercises this authority when it determines the legal position of a State. As noted earlier in this section, sovereign equality entails that bodies created by States cannot exercise authority over a State unless it has consented to this exercise of authority.Footnote 79 This understanding of sovereign equality is reflected, for example, in the fact that the competence of human rights treaty bodies to adopt non-binding recommendations in individual complaint proceedings is contingent on the consent of the respective State.Footnote 80 Because it is the exercise of the ICJ’s authority that underpins the need for State consent—rather than the binding nature of the Court’s decisions—the Court does not require additional consent when it later treats the prior finding as a ‘given’. The infringement of sovereignty occurred when the original finding was made, in proceedings sufficiently backed by consent. As the Court does not exercise its authority again when it merely relies on a prior finding, there are no further sovereignty concerns under the Monetary Gold rule.

The exercise of authority through a judicial determination of the legal position of a State suffices for treating such a finding as a ‘given’, whether the determination is made in a contentious judgment or an advisory opinion.Footnote 81 As seen earlier in this section, authority attaches to the author of the findingsFootnote 82 and the way in which the findings are reached, namely as part of the ICJ’s judicial function:Footnote 83 legal determinations in advisory opinions are made by the same court, which is composed of the same judges (including the possibility of judges ad hoc in both contentious and advisory proceedings),Footnote 84 according to procedural rules that are not identical but apply in largely the same way,Footnote 85 with equivalent procedural guarantees and safeguards, and in a substantially comparable deliberative process.Footnote 86

In line with this reasoning, a Special Chamber of the International Tribunal for the Law of the Sea (ITLOS) in Mauritius/Maldives considered that:

judicial determinations made in advisory opinions carry no less weight and authority than those in judgments because they are made with the same rigour and scrutiny by the “principal judicial organ” of the United Nations with competence in matters of international law.Footnote 87

The Special Chamber took this reasoning to justify relying on the ICJ’s Chagos Advisory Opinion, which it read as having authoritatively determined the legal position of the UK to the effect that it had no sovereign rights over the Chagos Archipelago.Footnote 88 More specifically, the Special Chamber took the ICJ’s findings in Chagos as establishing that any dispute over sovereignty regarding the archipelago had been resolved.Footnote 89 Whether the underlying notion of a dispute accords with the ICJ’s notion thereof is beyond the scope of this article.Footnote 90 The ultimate effect of the Special Chamber’s reading of the advisory opinion as determining the UK’s legal position was equivalent, however, to taking this determination as a ‘given’:Footnote 91 the Special Chamber rejected the Maldives’ argument that the UK was an indispensable third party because its legal position regarding the Chagos Archipelago would need to be determined for deciding Mauritius’ claim.

Using findings made in advisory opinions as ‘givens’ in contentious proceedings is consistent with the consent-based nature of the ICJ’s jurisdiction. Based on the above reasoning, determinations of States’ legal positions in advisory opinions qualify as ‘givens’ for future contentious cases because they constitute an exercise of the Court’s authority. It is from this exercise of authority, in turn, that the Monetary Gold principle (as an emanation of sovereign equality) protects non-consenting third States in contentious proceedings. Implicit in the argument for findings in advisory opinions as ‘givens’ is thus the notion that they are based on State consent, as otherwise the consent-based rationale of the Monetary Gold rule would indeed be circumvented.Footnote 92 But, as explained above, advisory opinions are based on the general consent of UN Member States.Footnote 93 If this consent justifies the ICJ making specific findings determining the legal position of individual States,Footnote 94 it follows that the same consent also justifies relying on those findings in subsequent proceedings and precludes sovereignty concerns in this respect.

Relying on legal determinations from advisory opinions can also accommodate concerns for due process. Due process for the State whose legal position is being determined can be provided in advisory proceedings, in which States have the right to make comments.Footnote 95 Due process can also be granted in potential subsequent contentious proceedings: if that State is a party to the case, it can ‘present evidence and arguments on questions of fact and law’ on the findings made in the advisory opinion, as the Court noted in Obligations of Israel. Footnote 96 If the State concerned is not a party to the case, it has a right to intervene pursuant to Article 62(1) ICJ Statute. The fact that the Court relies on a previous determination of the State’s legal position as a ‘given’ would surely constitute ‘an interest of a legal nature’ in the sense of that provision.Footnote 97

3.2. Findings in advisory opinions and limited subject-matter jurisdiction

Claims that concern the legal position of third States are but one instance where the Court might be invited to decide incidentally on issues that lie outside its jurisdiction. Similarly, incidental questions may arise between the parties to a contentious case, namely incidental issues falling outside the Court’s limited subject-matter jurisdiction under an otherwise applicable compromissory clause or incidental issues within subject-matter reservations to an optional clause declaration.Footnote 98 Here, the Court may rely on prior determinations of the parties’ legal positions made in advisory opinions as ‘givens’ for purposes of its subject-matter jurisdiction in the same way as it can rely on determinations of third States’ legal positions in the instances discussed in the previous sub-section. This power exists regardless of whether the requirements for applying the so-called ‘incidental questions doctrine’ are met, which allows the Court only to decide on questions that are both necessary and ancillary to the dispute before it.Footnote 99

To illustrate, in the Chagos MPA arbitration, Mauritius claimed that ‘the United Kingdom is not entitled to declare an “MPA” [“marine protected area”] or other maritime zones because it is not the “coastal State” within the meaning of inter alia Articles 2, 55, 56 and 76 of the Convention’.Footnote 100 Deciding on this claim would have required the tribunal to determine whether Mauritius or the UK held sovereign rights over the archipelago. Yet the tribunal found that making such a finding was outside its subject-matter jurisdictionFootnote 101 as provided by Article 288 of the United Nations Convention on the Law of the Sea (UNCLOS).Footnote 102 The arbitral award preceded the ICJ’s Chagos Advisory Opinion. Had the Court already rendered its advisory opinion, the tribunal arguably could have relied on findings on the UK’s legal position, just as the ITLOS Special Chamber effectively did in Mauritius/Maldives.

In such a scenario, as in the case of the Monetary Gold rule, the rationale of subject-matter constraints on jurisdiction militates in favour of using the determinations made in an advisory opinion in a subsequent contentious case. The Court cannot decide on an issue incidental to the case, over which it otherwise has jurisdiction, as the State has not consented to the determination of this issue, despite having consented to the proceedings themselves. Any authoritative determination of the legal position of a party to the contentious case would thus violate the principle of sovereign equality.Footnote 103 However, if such an authoritative determination has already been made with that State’s consent, the Court can use this finding without infringing on the State’s sovereignty. Importantly, this reasoning is limited to incidental issues, i.e. issues that arise in the context of a dispute otherwise within a court or tribunal’s jurisdiction.Footnote 104 The doctrine of ‘givens’ only complements the jurisdiction conferred on the Court in line with the principle of consent enshrined in Article 36 ICJ Statute.

To date, only once has an international tribunal engaged with a similar argument. The arbitral tribunal’s approach in Coastal State Rights is compatible with the notion of using findings in advisory opinions as ‘givens’ for incidental issues beyond an international court or tribunal’s subject-matter jurisdiction.Footnote 105 In this case, Ukraine argued that there was no territorial dispute over Crimea, inter alia, because the UN General Assembly (UNGA) had recognised Ukraine’s continued sovereigntyFootnote 106—thereby framing its claim in a manner akin to Mauritius in its case against the Maldives.Footnote 107 The tribunal doubted the soundness of Ukraine’s argument.Footnote 108 Crucially, however, this case concerned prior determinations in a UNGA resolution. UNGA resolutions differ from authoritative determinations in advisory opinions in important ways. To name but two such differences: UNGA resolutions are not the result of a judicial process, nor do they (necessarily) state or apply international law. Accordingly, UNGA resolutions do not carry the same authority as advisory opinions.

In sum, the ICJ may rely on determinations of States’ legal positions made in advisory proceedings in certain instances where the Court is otherwise unable to make this determination for a lack of consent. This is the case both where the legal position of an indispensable third party is at issue and where incidental issues fall outside the Court’s subject-matter jurisdiction. If it is accepted, in principle, that findings made in advisory opinions may be used as ‘givens’ in subsequent contentious proceedings, the key remaining question is how this can be done in practice.

4. Practical utility and limitations of relying on findings from advisory opinions in contentious proceedings

In practice, relying on findings from advisory opinions in contentious proceedings presents significant hurdles as it requires the Court to take two analytical steps. These steps ensure that the application of the doctrine of ‘givens’ remains consistent with the principle of consent as the basis of international dispute settlement. First, the advisory opinion must have made determinations that could be treated as ‘givens’. Second, these determinations must be congruent with the determinations needed to answer the incidental issue that is otherwise beyond the Court’s contentious jurisdiction, because it requires the incidental determination of the legal position of a third State or a decision on an incidental issue concerning a subject-matter outside an otherwise applicable compromissory clause or optional clause declaration. As this section will show, this two-step test is more likely to be satisfied regarding determinations of status (i.e. sovereignty over territory, statehood or maritime and land borders) than those of responsibility for specific acts or omissions. Further, to the extent that the doctrine of ‘givens’ intertwines the Court’s advisory and contentious jurisdictions, it may contribute to ensuring coherence in the exercise of the ICJ’s judicial function.

4.1. Identifying conclusive legal determinations in advisory opinions

Applying the doctrine of ‘givens’ first requires the ICJ to establish whether an advisory opinion indeed made determinations on the incidental issue that is beyond its contentious jurisdiction. The Court is in principle competent to make such determinations and has indeed done so.Footnote 109 For example, the Court found no indication of ‘any tie of territorial sovereignty between the territory of Western Sahara and the Kingdom of Morocco or the Mauritanian entity’Footnote 110 at the time of Spanish colonisation in Western Sahara. In a hypothetical case against Morocco concerning Western Sahara, the determination of Mauritania’s legal position could then be treated as a ‘given’ and could exclude the application of the indispensable third party principle in Mauritania’s favour in such a dispute, subject of course to the second step of the analysis outlined below.

By contrast, it would seem much more doubtful whether the Court made conclusive legal determinations regarding Israel’s conduct in the Occupied Palestinian Territory. If a State were to bring a case against another State for assisting the commission of violations of international humanitarian and human rights law by Israel (for example, discriminatory legislation and treatment of Palestinians in the Occupied Palestinian Territory),Footnote 111 the applicant State could argue that the Monetary Gold principle is no obstacle to the ICJ’s exercise of jurisdiction because Israel’s violations in this regard have been determined authoritatively by the Occupied Palestinian Territory Advisory Opinion and can thus be treated as ‘givens’. Whether the argument would succeed depends on the interpretation of the advisory opinion, which is a delicate exercise. The Court found:

that the régime of comprehensive restrictions imposed by Israel on Palestinians in the Occupied Palestinian Territory constitutes systemic discrimination based on, inter alia, race, religion or ethnic origin, in violation of Articles 2, paragraph 1, and 26 of the ICCPR, Article 2, paragraph 2, of the ICESCR, and Article 2 of CERD.Footnote 112

Yet the Court also stressed that it would only give a ‘legal characterization … of Israel’s policies and practices’Footnote 113 without making ‘findings of fact with regard to specific incidents allegedly in violation of international law’.Footnote 114 Read together, these passages demonstrate that it can neither be assumed nor categorically excluded that the Court made authoritative and conclusive determinations. Rather, the advisory opinion needs to be examined carefully to ascertain whether the ICJ determined Israel’s conduct conclusively.

This is especially so when the Court’s findings in an advisory opinion are mainly general observations, as was the case in its three most recent advisory opinions. In the two recent advisory opinions concerning the Occupied Palestinian Territory, namely Occupied Palestinian Territory and Obligations of Israel, the Court either assessed Israel’s conduct in rather general termsFootnote 115 or simply laid out Israel’s duties, deliberately avoiding a conclusive determination of Israel’s compliance with them.Footnote 116 The Court showed even more restraint in its Climate Change Advisory Opinion, where it stressed that ‘it has been requested to address legal consequences in a general manner, and that it is not called upon to identify the legal responsibility of any particular State or group of States’.Footnote 117 The Court explained that it could not decide on the ‘responsibility of individual States or groups of States’ because doing so ‘requires an in concreto assessment that must be undertaken on a case-by-case basis’.Footnote 118

The Court’s approach in these advisory opinions points to three crucial factors that determine whether an advisory opinion may conclusively determine the legal position of a State. First, the formulation of the questions put to it determines the kinds of findings the Court may make, as it clarified in Obligations of Israel. It noted that only if the requesting organ asked ‘the Court to determine the “legal consequences” of any breach of these [i.e. Israel’s] obligations’ (quod non) would the Court indeed consider itself competent to make such determinations.Footnote 119 Second, the ICJ’s interpretation of the particular question must be considered. The ICJ has interpreted the ambit of the questions put to it more narrowly in some advisory opinions than in others.Footnote 120 The extent to which the Court will answer a question is closely linked to the role the Court ascribes to advisory opinions. There may never have been one settled approach within the Court on this broader issue, and its advisory opinions may reflect a certain compromise prevailing at a specific point in time. Since 1950, individual judges have suggested limiting the ICJ’s pronouncements in advisory opinions to general observations and excluding concrete assessments of the behaviour of States.Footnote 121 Yet the majority has repeatedly found that assisting UN organsFootnote 122 through advisory opinions also warrants quite specific findings on the legal positions of States, as seen, for example, in Namibia and Western Sahara. Footnote 123 Third, the Court has clarified that it may make determinations regarding the legal positions of States in advisory opinions only when it has sufficient evidence at hand, and would refrain from doing so when establishing the relevant facts would require hearing all States concerned.Footnote 124 The question of evidence may, in part, explain why the Court made highly specific legal determinations in Chagos,Footnote 125 while confining itself to more general observations in the recent advisory opinions on Climate Change and Occupied Palestinian Territory. The latter two concerned questions of international responsibility requiring detailed factual assessments, while the former concerned a question of status in respect of which the ICJ may more readily have felt that it possessed the necessary facts to make a determination.Footnote 126

4.2. Congruence between the legal determinations in an advisory opinion and the incidental questions in a contentious case

If an advisory opinion did in fact make determinations relevant to an incidental issue in a contentious case, the Court would then need to satisfy itself of the extent to which such a finding answers the incidental issue in the claim before it. To illustrate, consider a State asserting ‘coastal State’ status under UNCLOS on the basis of the ‘givens’ doctrine in a case brought under the compromissory clause in Article 288(1) UNCLOS. In order to succeed, that State would have to show that the advisory opinion relied upon determined its status as the sovereign over the relevant piece of territory. Essentially, ITLOS in Mauritius/Maldives found that this was the case with regard to the Chagos Advisory Opinion.Footnote 127 Upon closer inspection, this conclusion is quite a stretch with respect to what the ICJ actually said in Chagos. While the Court found that ‘the United Kingdom is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible, thereby enabling Mauritius to complete the decolonization of its territory in a manner consistent with the right of peoples to self-determination’,Footnote 128 unambiguous determinations of the archipelago’s current status are conspicuously absent from the advisory opinion. It is likely that the Court carefully avoided any such determination.Footnote 129 It may be possible to read this silence as the ITLOS Special Chamber did. However, it may also be read as Judge Donoghue suggested, as requiring the UK ‘to relinquish sovereignty to Mauritius’,Footnote 130 which would imply that Mauritius is not (yet) the sovereign over the archipelago.Footnote 131 By its own admission, the ITLOS Special Chamber only ‘inferred’Footnote 132 Mauritius’ sovereignty and thus it may be doubted whether this satisfies the requirements of the ‘givens’ doctrine.Footnote 133 The point here is not to settle this issue, but to stress the nuanced interpretive exercise that is involved in applying the ‘givens’ doctrine to a specific case.

It is perhaps no coincidence that the doctrine of ‘givens’ was first invoked before the ICJ in East Timor on a question of status, and that the ICJ’s reliance on a prior judgment concerning a third State in Nicaragua v Colombia concerned (maritime) boundaries.Footnote 134 Indeed, the second step for successfully invoking the doctrine of ‘givens’ is also most likely to be satisfied by determinations of the legal status of a particular territory or entity. This is so because the doctrine of ‘givens’ rests on the assumption that the Court does not have to take a fresh decision if it can rely on a ‘given’ in a subsequent contentious case.Footnote 135 Consider a determination by the ICJ of sovereignty over a certain territory, as ITLOS believed was the case in Chagos:Footnote 136 relying on such a finding in a contentious case does not involve a new legal determination because international law presumes continuity in questions of territory and status.Footnote 137

By contrast, no such presumption exists for establishing an internationally wrongful act. Therefore, the distinction between specific past internationally wrongful acts and continuing wrongful conduct may prove decisive when invoking ‘givens’ in relation to State responsibility. In this respect, the finding referred to above on Israel’s (non-)compliance with international human rights law in the Occupied Palestinian Territory could be taken as an example, leaving aside for a moment the doubts as to whether these findings indeed contain conclusive determinations of Israel’s legal position in the first place.Footnote 138 Relying on such a ‘given’ in a case against a third State for complicity in Israel’s non-compliance may hinge upon the continuity of such non-compliance. Here, this continuity can hardly be presumed. Accordingly, the determination made by the ICJ in the advisory opinion is not coextensive with the finding required in the contentious case. Of course, a contentious case may build on a specific internationally wrongful act committed by a third State in the past, which has been established in an advisory opinion. In that case, relying on this determination would not require the Court to draw on any presumptions of continuity. Such scenarios do not, however, necessarily lend themselves to requests by competent UN organs. These requests, after all, require a majority of Member States to take an interest in such a determination. Moreover, establishing the relevant facts for a specific act in the past may prove to be challenging for the ICJ without hearing all States concerned.Footnote 139 In sum, these factors may explain why the Court’s determinations of States’ legal positions in advisory opinions have frequently concerned questions of status.Footnote 140

Overall, the practical scope for relying on determinations from advisory opinions as ‘givens’ in contentious cases is thus more modest than it may appear at first sight. It cannot operate as a general tool to overcome jurisdictional limitations in contentious proceedings. Still, the possibility of relying on determinations from advisory opinions may have wider implications for the interplay of the two forms of the ICJ’s jurisdiction. As discerning the exact content of advisory opinions can be crucial to contentious proceedings as a result of the doctrine of ‘givens’, States may well invite the ICJ to bring its two forms of jurisdiction into an intricate internal dialogue and interpret its own advisory opinions in subsequent judgments. In turn, the possibility of ‘givens’ provides a reason for the Court to anticipate potential subsequent contentious cases when issuing its advisory opinions and carefully reflect on what it determines and what it does not.Footnote 141 In this way, the doctrine of ‘givens’ may further intertwine the Court’s exercise of its advisory and contentious jurisdictions in a manner that ensures coherence, preventing the Court from having to disregard a determination made in an advisory opinion when deciding a contentious case.

5. Conclusion

As States increasingly leverage proceedings in high-stakes cases before the ICJ, both contentious and advisory, to address major international conflicts and crises, a more fine-grained understanding of the relationship between the two forms of the Court’s jurisdiction becomes ever more crucial. Contentious proceedings and advisory opinions differ in many respects, including the ways in which they are initiated, the manner in which they are based on State consent, the legal status of the participants and the binding force of the decision. However, they share the possibility of the Court exercising its authority to determine States’ legal positions. Backed by State consent, these determinations can, in principle, be used in subsequent proceedings.

The practical challenges inherent in this possibility remain significant. In practice, these challenges may be overcome in relation to certain questions concerning the determination of status, but the possibility of relying on ‘givens’ from advisory opinions does not present a general workaround to jurisdictional limitations in contentious proceedings. Still, the interpretation of advisory opinions may well play an increasingly important role in contentious proceedings. The potential subsequent relevance of its advisory opinions is also likely to begin to shape how the Court deliberates and the pronouncements it makes in such decisions. This process may further intertwine the Court’s contentious and advisory practice and contribute to the coherence of the exercise of its judicial function.

Acknowledgments

We are grateful to Freya Baetens, Michael Becker, Fabian Eichberger, Valentin Schatz, Tobias Thienel and Antonios Tzanakopoulos as well as to the anonymous reviewers for thoughtful comments. Earlier versions of this article were presented at the Annual Conference of the European Society of International Law at Freie Universität Berlin in September 2025 (Pre-Conference Workshop of the Interest Group on International Courts and Tribunals) and at a workshop on ‘Responses by Non-Injured States to Violations of International Law’ convened by Dapo Akande, Miles Jackson and Priya Urs at All Souls College and St John’s College, Oxford, in March 2026. The article has greatly benefitted from the discussions with participants of these events. Part of the research for this article was carried out under a Postdoc Network Brandenburg Fellowship, funded by the Ministry of Science, Research and Culture of the State of Brandenburg.

References

1 R Jennings, R Higgins and P Tomka, ‘General Introduction’ in A Zimmermann and C Tams (eds), The Statute of the International Court of Justice (3rd edn, OUP 2019) 3, paras 139, 164, 191; Z Vermeer and D Akande, ‘Prior Consent by States to the Jurisdiction of International Courts and Tribunals in Inter-State Disputes’ (Oxford Institute for Ethics, Law and Armed Conflict, Report, November 2019) 6 <https://www.elac.ox.ac.uk/wp-content/uploads/2023/10/PriorConsent_Final_Report.pdf>.

2 J Bendel and Y Suedi, ‘Introduction’ in J Bendel and Y Suedi (eds), Public Interest Litigation in International Law (Routledge 2024) 1, 1–2; C Tams, ‘Strindberg, Fried und Tomuschat: Internationale Gerichte und bewaffnete Konflikte’ (2020) 93 Friedens-Warte 347, 360ff; A Wentker, ‘Krieg und Frieden vor dem Internationalen Gerichtshof’ (2024) 79 JZ 1067, 1069ff.

3 See for the texts of all optional clause declarations that are currently in force <https://www.icj-cij.org/declarations>.

4 ‘Speech of HE Judge Joan E. Donoghue, President of the International Court of Justice, to the Sixth Committee of the General Assembly’ (25 October 2023) Doc No 000-20231025-STA-01-00-EN, 2 <https://www.icj-cij.org/sites/default/files/press-releases/0/000-20231025-sta-01-00-en.pdf>.

5 Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v Russian Federation) (Preliminary Objections) [2024] ICJ Rep 360, paras 144ff.

6 Monetary Gold Removed from Rome in 1943 (Italy v France, UK and US) (Judgment) [1954] ICJ Rep 19, 33.

7 See Section 2.

8 Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965 (Advisory Opinion) [2019] ICJ Rep 95, 138, para 177.

9 Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136, 193, para 137; Legal Consequences arising from the Policies and Practices of Israel in the Occupied Palestinian Territory, including East Jerusalem (Advisory Opinion) [2024] ICJ Rep 753, para 267ff.

10 East Timor (Portugal v Australia) (Judgment) [1995] ICJ Rep 90, 104, para 32.

11 D Akande, ‘Introduction to the Symposium on Zachary Mollengarden & Noam Zamir “The Monetary Gold Principle: Back to Basics”’ (2021) 115 AJIL Unbound 140, 141–42.

12 Statute of the International Court of Justice (adopted 26 June 1945, entered into force 24 October 1945) XV UNCIO 355.

13 Application of the Convention on the Prevention and Punishment of the Crime of Genocide in the Gaza Strip (South Africa v Israel) (General List No 192) <https://www.icj-cij.org/case/192>.

14 Wall (n 9).

15 Occupied Palestinian Territory (n 9).

16 Wall (n 9) 193–194, para 137.

17 ibid 197ff, para 150ff; Occupied Palestinian Territory (n 9) para 267ff.

18 Chagos (n 8) 138, para 177.

19 Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) Notwithstanding Security Council Resolution 276 (1970) (Advisory Opinion) [1971] ICJ Rep 16, 54, para 118.

20 J Collier and V Lowe, The Settlement of Disputes in International Law (OUP 1999) 185; see also A Gros, ‘Concerning the Advisory Role of the ICJ’ in W Friedmann, L Henkin and O Lissitzyn (eds), Transnational Law in a Changing Society: Essays in Honour of Philip C. Jessup (Columbia University Press 1972) 313, 315; T Sparks, ‘Reassessing State Consent to Jurisdiction’ (2022) 91 NordJIL 216, 223.

21 See, e.g. Chagos (n 8) 116ff, para 83ff.

22 Chagos (n 8) Dissenting Opinion of Judge Donoghue, para 21 (‘The delivery of this Advisory Opinion is a circumvention of the absence of consent’).

23 Interpretation of Peace Treaties with Bulgaria, Hungary and Romania (Advisory Opinion) [1950] ICJ Rep 65, 71; Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion) [1996] ICJ Rep 226, 235, para 14; Wall (n 9) 156, para 44; Accordance with International Law of the Unilateral Declaration of Independence in Respect of Kosovo (Advisory Opinion) [2010] ICJ Rep 403, 416, para 30.

24 Chagos (n 8) 117, para 85, citing Western Sahara (Advisory Opinion) [1975] ICJ Rep 12, 25, para 33; see also Status of Eastern Carelia (Advisory Opinion) [1923] PCIJ Ser B No 5, 28.

25 Wall (n 9) 159, para 49; Occupied Palestinian Territory (n 9) para 35.

26 See, e.g. Wall (n 9) 159, para 49–50 Occupied Palestinian Territory (n 9) para 35.

27 See Western Sahara (n 24) 24, para 30; Chagos (n 8) 118, para 87–88; see also Namibia (n 19).

28 Reservations to the Convention on Genocide (Advisory Opinion) [1951] ICJ Rep 15, 19; Namibia (n 19) 25, para 35; Nuclear Weapons (n 23) 236, para 15; similarly Kosovo (n 23) 421, para 44 (‘However, the purpose of the advisory jurisdiction is to enable organs of the United Nations and other authorised bodies to obtain opinions from the Court which will assist them in the future exercise of their functions’).

29 Namibia (n 19) 24, para 34 (concerning a dispute between the UN and South Africa); similarly Occupied Palestinian Territory (n 9) para 34.

30 Chagos (n 8) 118, para 89.

31 Nuclear Weapons (n 23) 236, para 15 (‘The purpose of the advisory function is not to settle – at least directly – disputes between States, but to offer legal advice to the organs and institutions requesting the opinion’).

32 See recently Obligations of Israel in Relation to the Presence and Activities of the United Nations, Other International Organizations and Third States in and in Relation to the Occupied Palestinian Territory (Advisory Opinion) (General List No 196, 22 October 2025) para 77.

33 For a critique of the Court’s practice, see, e.g. MN Shaw, Rosenne’s Law and Practice of the International Court, 1920–2015 (5th edn, Brill Nijhoff 2016) 1003ff.

34 Western Sahara (n 24) 24, para 30; see also Namibia (n 19) 23, para 31, where the Court distinguishes Eastern Carelia and Namibia on the ground of South Africa’s membership of the UN; for an argument that consent is irrelevant to the Court’s advisory function, see M Lando, ‘Advisory Opinions of the International Court of Justice in Respect of Disputes’ (2023) 61 ColumJTransnatlL 67, 101ff.

35 Western Sahara (n 24) 24, para 30.

36 ibid 68, para 162.

37 See also, for such a reading of Eastern Carelia: Namibia (n 19) 23, para 31; Interpretation of Peace Treaties (n 23) Dissenting Opinion of Judge Zoričić, 102ff; Collier and Lowe (n 20) 183ff; but see Western Sahara (n 24) 28, para 45, emphasising that the factual difficulties were the main reason to decline the request for an advisory opinion; P d’Argent, ‘Art. 65’ in A Zimmermann et al (eds), The Statute of the International Court of Justice: A Commentary (3rd edn, OUP 2019) 1783, 1804, para 43.

38 Eastern Carelia (n 24) 29.

39 H Lauterpacht, The Development of International Law by the International Court (Stevens & Sons 1958) 357.

40 The Court itself distinguished Eastern Carelia as relating to substance and not (solely) to procedure: Interpretation of Peace Treaties (n 23) 72; see also Collier and Lowe (n 20) 184; but see Lauterpacht (n 39) 353–54.

41 Interpretation of Peace Treaties (n 23) 71 (‘no State, whether a Member of the United Nations or not, can prevent the giving of an Advisory Opinion which the United Nations considers to be desirable in order to obtain enlightenment as to the course of action it should take’). Note that this passage has rarely been cited by the Court (but see Applicability of Article VI, Section 22, of the Convention on the Privileges and Immunities of the United Nations (Advisory Opinion) [1989] ICJ Rep 177, 189, para 31) and then only concerning UN members to emphasise that the Court does not need an interested State’s consent to this specific advisory proceeding. Thus, the Court seems to have returned to its predecessor’s position in Eastern Carelia when giving the Western Sahara Advisory Opinion: d’Argent (n 37) para 45.

42 Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) XV UNCIO 335.

43 R Kolb, The International Court of Justice (Hart 2013) 1076.

44 See also G Hernández, The International Court of Justice and the Judicial Function (OUP 2014) 81; H Thirlway, The Law and Procedure of the International Court of Justice: Fifty Years of Jurisprudence (OUP 2013) vol I, 824–25; J Wagner, ‘The Chagos Request and the Role of the Consent Principle in the ICJ’s Advisory Jurisdiction, or: What to Do when Opportunity Knocks’ (2018) 55 QIL 177, 182; though see Sparks (n 20) 235–38 (arguing that the Court does not require even this general consent for its advisory jurisdiction).

45 Kosovo (n 23) 417, para 33.

46 See A Kulick, ‘Between Advice and Miracle’ (2025) 27 ICLR 33, 37, 46.

47 Kosovo (n 23) 417, para 33; see also Kulick (n 46) 46.

48 Nuclear Weapons (n 23) 237, para 16; Chagos (n 8) 115, para 76; Occupied Palestinian Territory (n 9) para 37.

49 Monetary Gold (n 6) 33; East Timor (n 10) 104, para 33.

50 For a detailed discussion of the contours of the indispensable third party principle, see R Stendel and A Wentker, ‘Monetary Gold in the Age of Public Interest Litigation’ (2025) 36 EJIL 559, 564–66.

51 Akande (n 11) 141ff; for scepticism see Sparks (n 20) 246 (‘Consent … cannot explain Monetary Gold’).

52 See generally T Thienel, Drittstaaten und die Jurisdiktion des Internationalen Gerichtshofs – Die Monetary Gold-Doktrin (Duncker & Humblot 2016) 329; V Rezadoost, ‘Unveiling the “Author” of International Law’ (2024) 15 JIDS 506, 523ff.

53 For an argument that considering findings in advisory opinions as ‘givens’ would amount to ascribing them value as precedent, see JA Tilloy, ‘The Unprecedented Legal Effect of a Precedent: the Chagos Advisory Opinion in Light of the Mauritius/Maldives Judgment’ (2023) 26 Max Planck UNYB 502, 525–27; N Lanzoni, ‘The Authority of ICJ Advisory Opinions as Precedents: The Mauritius/Maldives Case’ (2022) 2 The Italian Review of International and Comparative Law 296; see similarly FS Eichberger, ‘The Legal Effect of ICJ Advisory Opinions Redefined? The Mauritius/Maldives Delimitation Case: Judgment on Preliminary Objections’ (2021) 22 MJIL 383, 397; for the ICJ’s claim of adherence to findings of law in its previous decisions, see Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Croatia v Serbia) (Preliminary Objections) [2008] ICJ Rep 412, 428, para 53.

54 For a detailed assessment of the doctrine of precedent in relation to ICJ decisions, see Hernández (n 44) 156ff.

55 D Pratap, The Advisory Jurisdiction of the International Court (Clarendon Press 1972) 228.

56 For an argument that advisory opinions can become legally relevant in subsequent proceedings by virtue of their persuasive value and an exploration of the factors determining their persuasiveness, see Kulick (n 46) 56–60.

57 Though see Tilloy (n 53) 525; Eichberger (n 53) 398; for the inclusion of advisory opinions in the term ‘decisions’ under ICJ Statute (n 12) art 38(1)(d), see ILC, ‘Draft Conclusions on Identification of Customary International Law’ (2018) UN Doc A/73/10, 150, para 5; C Jalloh, ‘First Report on Subsidiary Means for the Determination of Rules of International Law’ (2023) UN Doc A/CN.4/760, 93–94, para 280.

58 On the law-making function of advisory opinions, see generally K Oellers-Frahm, ‘Lawmaking through Advisory Opinions?’ (2011) 12 GLJ 1033.

59 Kolb (n 43) 1055–56.

60 Croatia v Serbia (n 53) 428, para 53.

61 Pratap (n 55) 228; Kolb (n 43) 1094–97, 1116.

62 East Timor (n 10) 103, para 30.

63 ibid 102, paras 28–29.

64 ibid 104, para 32.

65 ibid 103, para 31.

66 ibid 104, para 32.

67 Territorial and Maritime Dispute (Nicaragua v Colombia) (Judgment) [2012] ICJ Rep 624, 685.

68 Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean Sea (Nicaragua v Honduras) (Judgment) [2007] ICJ Rep 659.

69 Nicaragua v Colombia (n 67) para 162.

70 Larsen v Kingdom of Hawaii [2001] PCA Case No 1999-01, para 11.24; Delimitation of the Maritime Boundary between Mauritius and Maldives in the Indian Ocean (Mauritius/Maldives) [2021] ITLOS Case No 28, para 246ff; see also Dispute Concerning Coastal State Rights in the Black Sea, Sea of Azov, and Kerch Strait (Ukraine v Russian Federation) [2020] PCA Case No 2017-06, paras 171–77.

71 Interpretation of Peace Treaties (n 23) 71; Privileges and Immunities of the UN (n 41) 188–89, para 31.

72 See ICJ Statute (n 12) art 59.

73 See Sparks (n 20) 233.

74 Stendel and Wentker (n 50) 567–68; see similarly Sparks (n 20) 240–41 (pointing to the binding force of provisional measures, which can be ordered when consent to jurisdiction is established merely prima facie, as evidence that States do not need to consent to being bound).

75 Larsen (n 70) para 11.24.

76 On the notion of authority in political theory, see J Raz (ed), Authority (NYU Press 1990); for the different usages of the concept in international law, see B Çalı, ‘Authority’ in J d’Aspremont and S Singh (eds), Concepts for International Law: Contributions to Disciplinary Thought (Edward Elgar 2019) 39; on different approaches to the authority of international courts and tribunals, see generally K Alter, LR Helfer and MR Madsen, ‘International Court Authority in a Complex World’ in K Alter, LR Helfer and MR Madsen (eds), International Court Authority (OUP 2018) 3; on the authority of the ICJ’s judicial decisions, see Hernández (n 44) 96ff, 183ff; for a distinction between formal and normative authority with respect to decisions of the ICJ, see Lanzoni (n 53) 300.

77 Akande (n 11) 141.

78 Hernández (n 44) 17ff, 41ff, 96, 158; d’Argent (n 37) para 49; Rezadoost (n 52) 516.

79 Akande (n 11) 141–42; see also C Warbrick, ‘The Principle of Sovereign Equality’ in V Lowe and C Warbrick (eds), The United Nations and the Principles of International Law: Essays in Memory of Michael Akehurst (Routledge 1994) 204, 209.

80 See, e.g. Optional Protocol to the International Covenant on Civil and Political Rights (adopted 16 December 1966, entered into force 23 March 1976) 999 UNTS 302, art 1; International Convention on the Elimination of All Forms of Racial Discrimination (adopted 21 December 1965, entered into force 4 January 1969) 660 UNTS 195, art 14(1); Optional Protocol to the Convention on the Elimination of All Forms of Discrimination against Women (adopted 6 October 1999, entered into force 22 December 2000) 2131 UNTS 83, art 3.

81 On the authority of advisory opinions, see E Hambro, ‘The Authority of the Advisory Opinions of the International Court of Justice’ (1954) 3 ICLQ 2; G Abi-Saab, Les exceptions préliminaires dans la procédure de la Cour Internationale (Pedone 1967) 84; d’Argent (n 37) para 49; R Falk, ‘Toward Authoritativeness: The ICJ Ruling on Israel’s Security Wall’ (2005) 99 AJIL 42, 48.

82 See also Rezadoost (n 52) 507.

83 On the judicial character of advisory proceedings and the implications for the authority of advisory opinions, see also Hernández (n 44) 74ff; d’Argent (n 37) para 49.

84 Rules of Court art 102(3) (‘When an advisory opinion is requested upon a legal question actually pending between two or more States, Article 31 of the Statute shall apply, as also the provisions of these Rules concerning the application of that Article’); for the Court’s application of this provision, see PH Kooijmans and FL Bordin, ‘Article 31’ in A Zimmermann et al (eds), The Statute of the International Court of Justice: A Commentary (3rd edn, OUP 2019) 604, paras 32–36; see also Hambro (n 81) 7ff.

85 ICJ Statute (n 12) art 68.

86 See generally Kolb (n 43) 1021, 1102ff, 1111; Hambro (n 81); Lanzoni (n 53) 301–02.

87 Mauritius/Maldives (n 70) para 203.

88 ibid para 247.

89 ibid paras 243–45; for criticism, see Mauritius/Maldives (n 70) Separate and Dissenting Opinion of Judge ad hoc Oxman, para 32.

90 See Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v Russian Federation) (Preliminary Objections) [2011] ICJ Rep 70, 84, para 30.

91 See similarly Eichberger (n 53) 399.

92 For this concern, see HP Aust, Complicity and the Law of State Responsibility (CUP 2011) 309; Lanzoni (n 53) 316.

93 See Section 2.

94 ibid.

95 ICJ Statute (n 12) art 66.

96 Obligations of Israel (n 32) para 30.

97 On this criterion, see Sovereignty over the Sapodilla Cayes/Cayos Zapotillos (Belize v Honduras) (Application by Guatemala for Permission to Intervene) (General List No 185, 19 March 2026) paras 26–30, 35–46.

98 On the concept of incidental issues, see FS Eichberger, ‘Give a Court an Inch and It Will Take a Yard? The Exercise of Jurisdiction over Incidental Issues’ (2021) 81 ZaöRV/HJIL 235; JG Devaney and H Cho, ‘The Proper Role of the Doctrine of Incidental Questions in International Adjudication’ (2025) 16 JIDS 1; see also the contributions to the AJIL Unbound Symposium on Incidental Jurisdiction: (2022) 116 AJIL Unbound 160–90.

99 See Devaney and Cho (n 98) 15–18; see similarly Eichberger (n 98) 251–52, 254–56, 262–63 (for necessity and the nature of the incidental issue as requirements).

100 Chagos Marine Protected Area Arbitration (Mauritius v United Kingdom) [2015] PCA Case No 2011-03, para 163.

101 ibid para 221; Coastal State Rights (n 70) paras 155–61; see also South China Sea Arbitration (Philippines v China) [2015] PCA Case No 2013-19, para 153.

102 United Nations Convention on the Law of the Sea (adopted 10 December 1982, entered into force 16 November 1994) 1833 UNTS 3.

103 See Section 3.1.

104 See, for such an understanding of incidental issues, Devaney and Cho (n 98) 4.

105 See also VJ Schatz, ‘The Status of Crimea and the Sea of Azov as a Jurisdictional Hurdle in Ukraine v Russia’ (2021) 46 RCEEL 400, 414–15; but see Mauritius/Maldives (n 70) Separate and Dissenting Opinion of Judge ad hoc Oxman, para 29 suggesting that Mauritius/Maldives should have been decided along the lines of Coastal State Rights and X Qi, ‘Reviving the Monetary Gold Principle? A Case Note on the Judgment of Preliminary Objections in the Mauritius/Maldives Case’ (2023) 54 ODIL 1, 15.

106 Coastal State Rights (n 70) para 171; see, for Ukraine’s argument in detail, ‘Written Observations and Submissions of Ukraine on Jurisdiction in the Dispute Concerning Coastal State Rights’ (2018) paras 27–33 <https://pca-cpa.org/en/cases/149/>.

107 See Section 3.1.

108 See Coastal State Rights (n 70) para 176 (‘if the Arbitral Tribunal were to accept Ukraine’s interpretation of those UNGA resolutions as correct, it would ipso facto imply that the Arbitral Tribunal finds that Crimea is part of Ukraine’s territory. However, it has no jurisdiction to do so.’). These considerations were, however, obiter dicta, as the tribunal rejected Ukraine’s argument on the facts: see ibid paras 172–78.

109 See Section 2.

110 Western Sahara (n 24) 68, para 162.

111 See, for a similar claim brought by Nicaragua against Germany concerning the war in the Gaza Strip, Alleged Breaches of Certain International Obligations in respect of the Occupied Palestinian Territory (Nicaragua v Germany) (General List No 193) <https://www.icj-cij.org/case/193>.

112 Occupied Palestinian Territory (n 9) para 223.

113 ibid para 77.

114 ibid.

115 ibid.

116 See, e.g. Obligations of Israel (n 32) paras 145, 162.

117 Obligations of States in Respect of Climate Change (Advisory Opinion) (General List No 187, 23 July 2025) paras 106, 406.

118 ibid para 106.

119 Obligations of Israel (n 32) para 77.

120 See, e.g. Kosovo (n 23) 425–26, para 56; H Hannum, ‘The Advisory Opinion on Kosovo: An Opportunity Lost, or a Poisoned Chalice Refused?’ (2011) 24 LJIL 155; but see D Müller, ‘The Question Question’ in M Milanovic and M Wood (eds), The Law and Politics of the Kosovo Advisory Opinion (OUP 2015) 118; see more recently Climate Change (n 117) para 106; for different lines of criticism from within the Court itself on the ICJ’s narrowing of the questions put to it by the UNGA, see Climate Change (n 117) Separate Opinion of Judge Yusuf, paras 4–10; Declaration of Judge Nolte, paras 15–17.

121 See Interpretation of Peace Treaties (n 23) Separate Opinion of Judge Azevedo, 85, para 13; see more recently Occupied Palestinian Territory (n 9) Separate Opinion of Judge Nolte, paras 4–6.

122 On the institutional dimension of the Court’s advisory jurisdiction, see Section 2.

123 See Section 2.

124 Western Sahara (n 24) 28–29, paras 45–47; Wall (n 9) 161, para 56.

125 See Section 2.

126 See Obligations of Israel (n 32) para 77 on the one hand, and Chagos (n 8) 114–15, paras 73–74, on the other.

127 Mauritius/Maldives (n 70) paras 173–74, 246.

128 Chagos (n 8) 139, para 178.

129 See also Eichberger (n 53) 394.

130 Chagos (n 8) Dissenting Opinion of Judge Donoghue, para 19; see, for a contextualised discussion on that passage, Eichberger (n 53) 395.

131 See, on the ambiguity of the Advisory Opinion, S Thin, ‘The Curious Case of the “Legal Effect” of ICJ Advisory Opinions in the Mauritius/Maldives Maritime Boundary Dispute’ (EJIL:Talk!, 5 February 2021) <https://www.ejiltalk.org/the-curious-case-of-the-legal-effect-of-icj-advisory-opinions-in-the-mauritius-maldives-maritime-boundary-dispute/>; see also Qi (n 105) 16; Eichberger (n 53) 394.

132 Mauritius/Maldives (n 70) para 246.

133 For such an argument, see Qi (n 105) 16.

134 See Section 3.1.

135 ibid.

136 Mauritius/Maldives (n 70) para 246.

137 On the presumption against the extinction of States, see J Crawford, The Creation of States in International Law (2nd edn, OUP 2007) 700; Climate Change (n 117) para 363; on the continuity of maritime entitlements, see ILC, ‘Final Report of the Study Group on Sea-Level Rise in relation to International Law’ (2025) UN Doc A/80/10, 7–10, paras 25–34.

138 See on this point Section 4.1.

139 ibid.

140 Chagos (n 8) 138–39, paras 177–78; Western Sahara (n 24) 68, para 162; Namibia (n 19) 54, para 118.

141 See Rezadoost (n 52) 529–31.