By Myrto Stavridi

Abstract

In the last decades, there has been an increase in advisory opinions of the International Court of Justice (ICJ) that relate to vital political interests directly affecting the sovereignty of states. Even though advisory opinions are not binding and do not require the consent of the states involved, advisory proceedings have been increasingly and strategically used by states and international actors as contentious proceedings in disguise. Exploring the history of the advisory function of the ICJ and its predecessor, this article argues that advisory proceedings constitute a “soft” litigation strategy and a particularly useful tool for small states or non-state entities, as it has the potential to counterbalance the inherent power disparities in the process of international bargaining by adding the authoritative voice of the ICJ to the debate. This paper connects this development to a modern tendency of states to judicialize international affairs.

Introduction

Within the last 30 years, advisory proceedings before the International Court of Justice (ICJ) have addressed some of the most controversial issues in international affairs, including the independence of Kosovo (ICJ, Accordance with International Law of the Unilateral Declaration in respect of Kosovo, Advisory Opinion 2010) and the use of nuclear weapons (ICJ, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion 1996). They have also touched upon issues that directly affect vital state interests, like the legality of the Israeli West Bank barrier (ICJ, Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion 2004) and the United Kingdom’s administration of the Chagos archipelago (ICJ, Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion 2019). On the ICJ’s docket, two more highly politicized issues are pending adjudication—one relating to state obligations in respect of climate change and the other dealing with the legal consequences (for states and the UN) of the policies and practices of Israel in the Occupied Palestinian Territory, including East Jerusalem. Both pending requests for advisory opinions were brought before the ICJ by the UN General Assembly (UNGA) in 2023 and 2022 respectively.

An advisory opinion is a judicial opinion that provides guidance to natural or legal persons on a point of law (Aust 2010, 123). Advisory proceedings in domestic jurisdictions are, in essence, a dialogue between the judicial and the executive or legislative branches. Advisory proceedings are more frequent in civil-law countries compared to common-law countries, as “in common law countries there is a deep-seated objection to a court giving views on a matter that does not determine the rights of litigants in an actual dispute” (Aust 2010, 124). Typically, national advisory opinions are issued by a country’s supreme court and are non-binding unless explicitly mandated by a specific legal statute. The same idea underpins the ICJ’s advisory function: A political body requires authoritative legal advice before taking a decision (d’Argent 2019b, 275). The ICJ accepts requests for advisory opinions from the UNGA, the UN Security Council, specific international organizations, and authorized UN organs (Article 96 UN Charter, Article 65 ICJ Statute). Advisory opinions of the ICJ aim to assist other UN organs in the exercise of their activities (Kosovo Advisory Opinion 2010, para 33).

An ICJ advisory opinion is not formally binding on states. However, in advisory opinions, the ICJ exercises its power to determine the precise scope of rights and obligations of states and pronounces what international law requires a state to do or refrain from doing (Lawing Penegar 1965, 556). Seeking an authoritative pronouncement of the law by the World Court “is rarely an end in itself but a step in a broader political process” (Scott 2014, 26). Therefore, the ICJ can play a decisive role in international bargaining (ibid). For instance, in the 2019 Chagos advisory opinion, the ICJ concluded that the UK’s continued administration of the archipelago was in breach of international law, as it was unlawfully detached from the territory of Mauritius, thus rendering the latter’s decolonization incomplete. In part due to the ICJ’s conclusion, in 2022 the UK entered into negotiations with Mauritius on the exercise of sovereignty over the Chagos archipelago (Cleverly 2022).

The subject of some ICJ advisory opinions relates to vital political interests that directly address the sovereignty of states and the legality of their actions. Usually, such matters end up before an international court through contentious inter-state proceedings where the applicant and the respondent state submit their dispute to the ICJ (or other international court and tribunal) and the court functions as a third-party adjudicator with the aim to the pacific settlement of the dispute. Contentious inter-state litigation is premised on the principle of consent that underpins the foundations of modern international law. This principle is exemplified by the fact that a state is not required to submit its disputes for judicial resolution without its explicit consent (Chagos Advisory Opinion 2019, para 83). The principle of consent is not applicable in advisory proceedings as they do not constitute a form of judicial recourse for “applicant” states against other “respondent” states (Kosovo Advisory Opinion 2010, para. 33).

This article aims to show that advisory proceedings have been increasingly and strategically used by states and international actors as contentious proceedings in disguise. This state practice betrays a modern tendency to judicialize international affairs. According to Alter, Hafner-Burton, and Helfer judicialization refers to “the process by which courts and judges increasingly dominate politics and policy-making” (Alter, Hafner-Burton, and Helfer 2019, 449).  Through the strategic use of advisory proceedings before the ICJ, the court has been able to authoritatively pronounce on international issues that would typically not reach it, as the absence of state consent often serves as a procedural obstacle to any claim.  When the judicial organ of the UN pronounces on a dispute between states, states’ ability to self-assess the legality of their actions and control the narrative they present to other states and their domestic audiences is restricted as a third party that enjoys wide legitimation puts forth an authoritative interpretation of international law as applied in the specific circumstances.

The second section of the article will provide a brief overview of the advisory function in U.S. law and how advisory proceedings were envisaged in international law, specifically in the framework of the League of Nations and the United Nations. The third section will deal with how the ICJ and its predecessor, the Permanent Court of International Justice, have navigated the rocky terrain of state consent in advisory proceedings. The fourth section will examine how advisory proceedings are used by states as disguised contentious proceedings and the ICJ’s role as an inter-state dispute resolution mechanism. The fifth section argues that resorting to advisory proceedings can be considered a “soft” litigation strategy used by states. The article aims to highlight how the advisory function of the ICJ contributes to the judicialization of international relations despite states’ attempts to exclude resolution of disputes in advisory proceedings and the non-binding nature of advisory opinions.

This paper’s argument is premised on the concept of a state as a unitary actor. This conceptualization may overlook the nuances of power distribution throughout state institutions and how the political landscape shifts when governments change. However, this approach is necessary for reasons of brevity and structural coherence. This article is not an attempt to demonstrate precisely for what purpose governments have used advisory proceedings in the past. It rather builds on scholarship on when and why states resort to contentious proceedings and theorizes its application to advisory proceedings through specific examples to argue that similar motives underlie states’ decisions to resort to the advisory jurisdiction of the ICJ. This tendency is an unexpected manifestation of modern judicialization of international affairs.

Advisory Proceedings in the League of Nations and the UN and the Principle of State Consent

The Permanent Court of International Justice (PCIJ), the predecessor of the ICJ, was created by the League of Nations and functioned from 1922 until 1940. It was officially dissolved in 1946. Given the apprehension of common-law countries towards advisory opinions, it is not a surprise that a civil-law country, France, proposed the inclusion of advisory powers in the competence of the PCIJ (Hudson 1924, 986). The proposal was accepted and the Covenant of the League of Nations stipulated that the PCIJ was competent to give an advisory opinion upon any dispute or question referred to it by the Council or the Assembly. As advisory proceedings were a novelty for the PCIJ (Hudson 1924, 985), the judges responsible for drafting the rules for the functioning of the court had to deal with questions of procedure such as the publicity of the proceedings and how judges would obtain necessary information. The American judge, John Bassett Moore, submitted a vehement memorandum against the use of advisory proceedings. He considered that the advisory function “is not an appropriate function of a Court of Justice” and that the “emission, either on actual disputes or on theoretical questions, of opinions avowedly having no binding force, would tend not only to obscure but also to change the character of the Court” (PCIJ, Preparation of the Rules of Court of January 30th 1922, 397-8). He later softened his attitude and suggested that advisory proceedings should be assimilated as much as possible into normal contentious proceedings (Hudson 1924, 991) presumably to protect the interests of affected states and to preserve the judicial character of the PCIJ advisory opinions.

The advisory experiment was a success for the PCIJ. A large part of its caseload related to its advisory function. The PCIJ rendered 29 judgments on contentious matters and issued 27 advisory opinions within 18 years. However, as John Bassett Moore predicted in his memorandum, and as the drafters of the UN Charter realized, such opinions might prejudice the views or interests of states (PCIJ, Preparation of the Rules of Court of January 30th 1922, 398). While the UN Charter and ICJ Statute embrace the advisory function of the ICJ, they also try to minimize the possibility that the ICJ will render an opinion on highly political issues that affect the sovereignty of states without their consent, such as the case of the contested sovereignty over the Chagos archipelago. Thus, the relevant articles provide that the ICJ can only deal with legal questions as opposed to the PCIJ’s competency to deal with any dispute or question.

Despite this attempt to limit the World Court’s advisory function, the ICJ has never rejected a request for an advisory opinion on the ground that it encapsulates a dispute and not a legal question. The concept of dispute necessarily entails a controversy about legal rights and obligations as opposed to a legal question that is a broad concept and may encompass disputes (d’Argent 2019a, 1798). In the Legality of Nuclear Weapons advisory opinion, the United States claimed that an opinion by the World Court offering advice on what is, in many respects, a political matter, could undermine the ICJ’s authority and effectiveness (Letter dated 20 June 1995 from the Acting Legal Adviser to the Department of State, together with Written Statement of the Government of the United States of America, 6). Nevertheless, the ICJ considered that when a question is framed in terms of law and raises problems of international law, it is by its very nature susceptible to a reply based on law (Legality of Nuclear Weapons Advisory Opinion 1996, para 13). The court, therefore, proceeded to declare that while there is no customary or conventional international law that authorizes or prohibits the use of nuclear weapons, the threat or use of nuclear weapons would generally be contrary to the principles and rules of international humanitarian law. However, the Judges considered that they could not conclude whether the threat or use of nuclear weapons would be lawful or unlawful in the extreme circumstances of self-defense in which the very survival of a state is at stake. The opinion further stressed that there is an obligation upon states to act in good faith and conclude negotiations leading to nuclear disarmament.

The existence of a dispute between states is even more evident in situations that involve the territorial sovereignty of a state and the right to self-determination. In such cases, the lack of state consent plays a central role in the legal arguments of the “respondent” states. The Chagos advisory opinion is a paradigmatic case in this respect. The UNGA requested the advice of the ICJ on whether the decolonization of Mauritius had been lawfully completed when Mauritius was granted independence in 1968 and what were the consequences under international law of the continued administration of the Chagos archipelago by the UK. Before Mauritius’s independence, the local authorities had agreed with the UK that the Chagos archipelago would be detached from Mauritius to host a U.S. military base on the island of Diego Garcia (Guilfoyle 2021, 756). The ICJ found that the detachment of the Chagos Archipelago had not been based on the free and genuine expression of the will of the people concerned. As a result of the unlawful detachment of the archipelago from the territory of Mauritius, the latter’s decolonization had not been lawfully completed in 1968. Therefore, the UK’s continued administration of the archipelago was found to be in breach of international law.

Both the United Kingdom and the United States argued that if the ICJ rendered an advisory opinion on the subject-matter of the UNGA request, it would violate the fundamental principle that a state cannot be forced to submit its disputes to judicial settlement (Written Statement of the United Kingdom of Great Britain and Northern Ireland 2018, 11; Written Statement of the United States of America 2018, 12). Both states also referred to the Eastern Carelia precedent, where the PCIJ had refused to give an advisory opinion in a dispute between Finland and Russia regarding the Russian province of Eastern Carelia located near their common border (PCIJ, Status of Eastern Carelia, Advisory Opinion, 1923). At that time Russia was neither a member of the League of Nations nor was it bound by the PCIJ Statute. Some states and international lawyers have understood the Eastern Carelia principle as requiring state consent for the exercise of advisory function in cases that involve bilateral disputes (Burton 2019, 1). The ICJ clarified in 1975 that in the Eastern Carelia case the PCIJ rejected the request primarily due to the lack of sufficient material evidence resulting from Russia’s non-involvement in the proceedings. Therefore, it was “not able to arrive at a judicial conclusion upon any disputed question of fact the determination of which was necessary for it to give an opinion” (ICJ, Western Sahara, Advisory Opinion 1975, para 46).

Neither the United Kingdom nor the United States explicitly rejected the advisory opinion. The UK reaffirmed its position that it would return the sovereignty of the archipelago to Mauritius “once it is no longer needed for defense purposes” (Sthoeger 2023, 293). However, as noted above, three years after the issuance of the Chagos opinion, the UK commenced official negotiations with Mauritius. The United States, before the UNGA, maintained that “it unequivocally supports the sovereignty of the United Kingdom” and that the “Court did not say that today Mauritius is sovereign over the British Indian Ocean Territory, or suggest that States or international organizations must recognize it as such. Furthermore, it rejected Mauritius’s argument that the transfer of sovereign must be immediate” (UNGA 83rd Plenary Meeting 2019, 17).

In the Wall advisory proceedings, Israel also claimed that it had not consented to the adjudication of the legality of the Israeli West Bank barrier. However, the ICJ affirmed that state consent was not required in advisory proceedings even where the request related to a legal question actually pending before states. The opinion is only advisory and has no binding force. As a consequence “it follows that no State, whether a Member of the UN or not, can prevent the giving of an Advisory Opinion which the UN considers to be desirable in order to obtain enlightenment as to the course of action it should take. The Court’s Opinion is not given to the States but to the organ that is entitled to request it; the reply of the Court, itself an organ of the UN, represents its participation in the activities of the Organization, and, in principle, should not be refused” (Wall Advisory Opinion 2004, para 47).

The ICJ has accepted theoretically that it may be possible “in certain circumstances … [that] the lack of consent of an interested State may render the giving of an advisory opinion incompatible with the Court’s judicial character” (ibid). If reasons of judicial propriety require a rejection of a request for an advisory opinion, the ICJ’s discretionary power could afford sufficient legal means to ensure respect for the fundamental principle of consent (Western Sahara Advisory Opinion 1975, para 33). However, the ICJ has so far never refused to give an advisory opinion due to lack of consent by the states whose interests are at stake. Consequently, it appears that as long as a dispute, in addition to its bilateral dimension, has a multilateral character and the UN has been involved to a greater (the issue of Palestine in the Wall opinion) or a lesser degree (decolonization in the context of the Chagos opinion), the ICJ will most likely reject any claim by “respondent” states that they have not consented to the adjudication of the specific dispute.

The Use by States of Advisory Proceedings as Disguised Contentious Proceedings

While advisory proceedings before the PCIJ were envisaged as a means of contributing to the settlement of inter-state disputes (d’Argent 2019b, 272; Wagner 2018, 187), this was not the case for the ICJ’s advisory function. This flows both from the exclusion of disputes from the advisory function of the ICJ, but also from the location of the provisions related to advisory and contentious proceedings in the UN Charter. The provisions related to contentious proceedings are included in Chapter VI titled “Pacific Settlement of Disputes” while the advisory function is provided for Chapter XIV titled “The International Court of Justice.”

The ICJ also held in the Western Sahara advisory opinion, one of its earliest advisory opinions that touched upon issues of territorial sovereignty, that the UNGA’s aim in bringing the respective request to the ICJ was not so that the latter may exercise “its powers and functions for the peaceful settlement of that dispute or controversy” (Western Sahara Advisory Opinion 1975, para 39). The advisory opinion concerned the decolonization process of Western Sahara, a former Spanish colony over which two countries, Morocco and Mauritania, had competing sovereignty claims. The ICJ found that neither country had a tie of sovereignty with the nomadic tribes that lived in Western Sahara before its colonization by Spain. Therefore, the decolonization process envisaged by the UNGA—that included the right of the population of Western Sahara to determine their future political status by their own freely expressed will—had not been completed and could proceed. The same year the judgment was issued Spain relinquished its rights and concluded an agreement with Morocco and Mauritania to create a system of temporary administration by the latter two countries. The referendum that was originally envisaged in the process of decolonization of Western Sahara never took place.

That advisory proceedings can be used as contentious proceedings in disguise is implicitly recognized in the ICJ Statute and explicitly acknowledged in the Rules of the ICJ. Article 68 of the ICJ Statute allows the World Court in its exercise of advisory function to apply the Statute provisions on contentious cases to the extent that it recognizes them as applicable. The Rules of the ICJ include a provision that obliges the ICJ, when an advisory opinion is requested upon a legal question actually pending between two or more states, to apply the provisions that relate to the appointment of ad hoc judges by states in contentious proceedings (Article 102 para 3 ICJ Rules). In traditional inter-state litigation when the ICJ bench does not include a judge of the nationality of the state(s) involved in the litigation, the latter may request an ad hoc judge to replace a normal member of the bench.

The possibility of advisory proceedings functioning as disguised contentious proceedings has also been implicitly recognized by state practice. A representative example is the dispute that unfolded through four advisory proceedings and two contentious proceedings regarding Namibia’s independence. The first advisory opinion was issued in 1950 and related to the international status of South West Africa (as Namibia was known in the beginning of the 20th century). Following World War I, the League of Nations placed the former German colony under the mandate of South Africa, which had full power of administration and legislation over the territory. After the dissolution of the League of Nations, South Africa claimed that the mandate had elapsed and sought to integrate South West Africa into its territory. The ICJ opined that South Africa did not have the right to unilaterally change the status of South West Africa (ICJ, International Status of South West Africa, Advisory Opinion, 1950). Two related advisory opinions were issued in 1955 and 1956. The former dealt with procedural matters that related to the UNGA voting procedure on questions relating to reports and petitions of individuals concerning the territory (ICJ, Voting Procedure on Questions relating to Reports and Petitions concerning the Territory of South West Africa, Advisory Opinion 1955). The latter concerned the admissibility of hearing of petitioners by the UNGA’s subcommittee on South West Africa (ICJ, Admissibility of Hearings of Petitioners by the Committee on South West Africa, Advisory Opinion 1956).  

Given South Africa’s persistent refusal to effectuate the ICJ’s advisory opinions, the Second Conference of Independent African States concluded “that the international obligations of the Union of South Africa concerning the Territory of South West Africa should be submitted to the International Court of Justice for adjudication in contentious proceedings” (E. A. Gross 1966, 40). The aim was to “transform a dishonored, though authoritative, Opinion into an enforceable Judgment” (E. A. Gross 1966, 40). Liberia and Ethiopia submitted applications against South Africa in 1960. These included a claim that the administrative practice of apartheid violated the duty of South Africa under the League of Nations mandate system to promote the material and moral well-being and the social progress of the inhabitants of South West Africa. Both applications were rejected by the ICJ (ICJ, South West Africa Cases (Ethiopia v. South Africa; Liberia v. South Africa), Second Phase, Judgment 1966) in a judgment heavily criticized by African and Asian states and international lawyers (Falk 1967, 4, 19; Higgins 2009, 774). Both Judge Jessup, who dissented through a lengthy opinion, and the United States expressed their support for the preceding advisory opinions and lamented the ICJ’s judgments (South West Africa Cases, dissenting opinion of Judge Jessup, 331; Falk 1967, 16).

The situation reached the ICJ one last time after a request for an advisory opinion by the UN Security Council (the only request for an advisory opinion the UN Security Council has ever submitted). By that time, the UN Security Council had issued two resolutions declaring the continued presence of South African authorities in Namibia (as South West Africa had been renamed) illegal and had called upon South Africa to withdraw its administration. The opinion was published in 1971 and confirmed that South Africa’s administration of Namibia was illegal and that UN state members are obliged to refrain from any acts implying recognition of the legality of, or lending support or assistance to, such presence and administration (ICJ, 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). The strategic and interchangeable use of advisory and contentious proceedings to achieve the same result, the withdrawal of South African authorities from Namibia, indicates that states have recognized the value of advisory proceedings as a form of disguised contentious proceedings. 

 Advisory Proceedings as a “Soft” Litigation Strategy

The boundary between contentious and advisory proceedings seems to have been blurred both in theory and in practice. Advisory proceedings can and have been used as disguised contentious proceedings in attempts to solve inter-state disputes (Crawford 2019, 704; Koskenniemi 1995, 604). The question that naturally flows then is why would states resort to advisory proceedings instead of contentious proceedings. This section will first analyze the potential motives of states in initiating advisory proceedings and how an advisory opinion can constitute “a step in a broader political process” that empowers the ICJ’s role in international bargaining (Scott 2014, 26). The section will then proceed to map the practical advantages that advisory proceedings entail compared to contentious proceedings.

Motives Behind the Initiation of Advisory Proceedings

In some cases, advisory proceedings are the only available means of judicializing international affairs issues in a world where few states have consented to the power of international courts to determine their rights and obligations under international law. While 74 states have accepted the compulsory jurisdiction of the ICJ, with the notable exceptions of France, China, Russia, and the United States, the majority of these declarations of acceptance exclude important areas of international law (i.e., nuclear disarmament - UK, deployment of armed forces abroad - Germany, territorial sovereignty - India, to name a few). Moreover, ICJ advisory proceedings may be the only available mechanism “for the settlement of disputes between recognized states and secessionist groups within those states” (Sloss 2002, 357). As non-state entities’ international legal personality is relative, they are not considered states for the purposes of litigation against states that do not recognize them. Advisory proceedings represent an attractive option when the state or non-state actor that initiates them also believes it holds the moral high ground and will likely win (Scott 2014, 30). In the Kosovo advisory opinion, Serbia’s dispute was with Kosovo, a non-state entity. Serbia was the sole sponsor of the UNGA resolution and believed they would win (Pellet 2015, 268). However, the ICJ concluded that the adoption of the declaration of independence did not violate any applicable rule of international law (Kosovo Advisory Opinion 2010).

A request for an advisory opinion may serve to level the playing field (Scott 2014, 34–35). The power imbalances that permeate international negotiations are somewhat avoided in international adjudicatory proceedings; all states and non-state entities are considered as parties that are formally equal concerning their juridical standing and their ability to make claims. The ICJ responds to all legal claims in a coherent legal manner irrespective of whether the claim was made by a non-state entity, a powerful state, or a small state. Vanuatu, an island archipelago in the South Pacific and one of the countries that will be most affected by climate change, spearheaded the pending request for an advisory opinion on climate change obligations of states. The pending request includes a specific question regarding the legal consequences of such obligations concerning states and, in particular, small island developing nations, which, due to their geographical circumstance and level of development, are particularly vulnerable to the adverse effects of climate change. One of the potential benefits of a climate change advisory opinion is that it will help bolster states’ “arguments in the international climate change negotiations or undermine the arguments of other states” (Bodansky 2022, 3). The Western Sahara case is another example of how weaker non-Western states may benefit from an advisory opinion. The Western Sahara advisory opinion brought Spain to the negotiating table to the benefit of Morocco, but to the disadvantage of the population of Western Sahara who were never allowed to exercise their right to self-determination.

Advisory proceedings are arguably not the most effective method of dispute resolution due to the lack of consent of the “respondent” state, which is usually emblematic of a general lack of voluntary will to resolve a dispute (Higgins 1974, 49). However, definitively resolving a dispute is not the only thing states may have in mind when they choose to initiate contentious or advisory proceedings against another state. An advisory opinion by the ICJ may work particularly well when the motive behind its request is to publicize the matter and gain the support of the global opinion and diplomatic momentum. The Finnish initiative behind the request submitted by the UN Security Council aimed to “expose the false legality that the South African authorities attempted to present to the world and to mobilize public opinion against apartheid” (Koskenniemi 1995, 611). The ICJ accepted the request by the UN Security Council and issued an advisory opinion (ICJ, 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).

Furthermore, judicial decisions perform a social function; they can constitute a form of producing and recording authoritative history (Guilfoyle 2021, 752). Some advisory opinions have certainly been used by states to shift the political dialogue in a way that best suits them through attempts to “solidify [their] claims and gain political advantage by disqualifying opposing views” (d’Argent 2019b, 6). Through its use of international legal proceedings (arbitration before the UN Convention on the Law of the Sea arbitral tribunal and the Chagos advisory opinion before the ICJ), Mauritius established on the legal and historical record that its pre-independence representatives were coerced when they agreed to the separation of the Chagos archipelago from Mauritius and that the UK had implicitly recognized Mauritius sovereignty over the Chagos archipelago (Guilfoyle 2021, 761).

The Wall advisory opinion and the pending advisory request concerning the legal consequences (for states and the UN) of the policies and practices of Israel in the Occupied Palestinian Territory, including East Jerusalem, is a telling example of how multiple motives may co-exist. Advisory proceedings are the only option for Palestine, a non-state entity, to bring its claims before an international court. Palestine co-sponsored the UNGA resolution requesting the advisory opinion. In the Wall advisory opinion, the ICJ opined that the construction of the Israeli West Bank barrier was contrary to international law; Israel was under an obligation to cease the construction and to dismantle the structures already built. As a consequence of its illegal actions, Israel was also under an obligation to make reparation for all damage caused by the construction. The ICJ further considered that all states were obliged to not recognize the illegal wall and to not render aid or assistance in maintaining the situation created thereby (Wall Advisory Opinion 2004, para 163). The advisory opinion affirmed the right of Palestinian people to self-determination and the illegality of the Israeli settlements in the Occupied Palestinian Territory (Wall Advisory Opinion 2004, paras 120-2) but ultimately did not change Israeli actions in the long term.

Most Arab countries in their pleadings before the ICJ “devoted considerable attention to history” and made explicit claims about the colonial nature of Israel’s practices (Burgis 2008, 54-6). In a similar vein, in 2022, the UN Special Rapporteur Francesca Albanese, on the situation of human rights in the Palestinian territories occupied following the 1967 War, characterized the occupation as settler-colonial in nature (UN Special Rapporteur 2022, para 36). The nearly unanimous findings of the ICJ’s Wall advisory opinion were accepted by 150 states in resolution ES-10/15 (including many EU Member States) adopted by the UNGA that acknowledged the advisory opinion and demanded that Israel, as the occupying power, comply with its legal obligations mentioned in the opinion (de Blois 2015, 96). Both the United States and Israel voted against the resolution (ibid). In its written statement for the pending advisory opinion, the United States did not outright reject the ICJ’s Wall advisory opinion and even praised the ICJ’s approach in that advisory opinion (Written Statement of the United States of America to the pending advisory opinion on the legal consequences (for states and the UN) of the policies and practices of Israel in the Occupied Palestinian Territory (OTP), including East Jerusalem 2023, 19). The Wall opinion has been used as a foundational text in various UN resolutions and a frame of reference for initiatives of UN human rights bodies and civil society actors, such as the UN Register for Damage caused by the Construction of the Wall, the Russell Tribunal on Palestine, and the Boycott, Divestment, and Sanctions campaign (de Blois 2015, 97-8).

The pending request for an advisory opinion on the legal consequences arising from the policies and practices of Israel in the Occupied Palestinian Territory can be interpreted as an attempt to make the ICJ assess, in their totality, Israel’s obligations under international law and further mobilize the support of the global public opinion. Palestine’s oral pleadings before the ICJ focused on setting out the historical context in terms of the coloniality of Israel’s practices and the segregationist nature of its apartheid regime (Palestinian oral pleadings 2024, 52-55, 56, 66, 70, 82-7). In their oral pleadings to the World Court, the Palestinian counsels also referred to how the Chagos advisory opinion “led the UK to agree to negotiate with Mauritius” (ibid 61). They also stressed that only two of the 35 states that submitted written statements addressing the legality of Israel’s occupation argued that the occupation is lawful (the U.S. and Fiji) (ibid 73-4) and continued “this is not surprising. Whatever offenses against international law Israel commits, the United States comes forward to shield it from accountability” (ibid 74). They further highlighted that the advisory opinion is critical in that, if the ICJ declares the occupation illegal, it will remove the main obstacle to the realization of the two-state solution (ibid 76-7).

Practical Advantages of Advisory Proceedings

Historically, even in the limited number of cases where contentious proceedings are available, states have been reluctant to make use of them (Rovine 1976, 325). Submission of a dispute to a third-party dispute settlement procedure is risky and time-consuming (Scott 2014, 29). Litigation can also be considered as an unfriendly act by the respondent state and may influence its relationship with the applicant state (Scott 2014, 39). In the case of South Africa’s illegal administration of Namibia, Liberia and Ethiopia only initiated contentious proceedings as a last resort after an advisory opinion had already declared the illegality of South Africa’s attempt to integrate Namibia in its territory.

While resorting to traditional inter-state litigation before the ICJ is an important decision for applicant states that do not take it lightly, the “applicant” states’ involvement in the advisory function of the ICJ is more indirect and obscured. The vast majority of requests for advisory opinions is submitted by the UNGA through a resolution that requires a simple majority of states (Aust 2010). Therefore, states do not stand alone but rather as a majority block against “respondent” states and this can mitigate the inherent hostile nature of contentious litigation. As the representative of Vanuatu, the main sponsor of the UNGA request for the Climate Change advisory opinion, acknowledged “an advisory opinion is a constructive and unconfrontational route” (UNGA, 64th Plenary Meeting 2023, 2). Moreover, the ICJ has explicitly refused to assess accusations regarding political motives of states “behind” a UNGA resolution (Wall Advisory Opinion 2004, para 41; ICJ, Legality of Nuclear Weapons Advisory Opinion 1996, para 13). One could also argue that recourse to advisory proceedings carries a lower risk of political costs, as there are no winners or losers in an advisory opinion. However, this argument does not hold as evidenced by the astute title of Marko Milanovic’s blog post “ICJ Delivers Chagos Advisory Opinion, UK Loses Badly” (Milanovic 2019).

Advisory proceedings are fairly easily accessible as the main requirement is to lobby the UNGA. They do not require state consent and advisory opinions are issued within a couple of years after the UNGA request. The ICJ is obliged to invite states that are somehow affected by the advisory proceedings to act as participants. This obligation extends to other states or non-state entities that are likely to be able to furnish information on the question under consideration (Article 66 of the ICJ Statute). Therefore, states and non-state entities enjoy many of the procedural rights they would have enjoyed in contentious proceedings, such as submission of arguments within specific time-limits and the ability of one participant to respond to the other (Paulus 2019, 1827–28), written and oral proceedings with both legal and factual arguments (Thirlway 2016, 117), a say in the composition of the bench, etc. Advisory proceedings also entail fewer financial costs compared to contentious proceedings (Higgins 2009, 763). In contrast to traditional inter-state litigation where applicant and respondent states have to produce all relevant material, in advisory proceedings the main file with all necessary factual and legal arguments is transmitted to the World Court by the Secretary-General of the UN in accordance with Rule 104 of the Rules of the ICJ (Paulus 2019, 1824–25). In addition, the burden of proof, unlike contentious proceedings, is not primarily upon the participant who raised the specific argument (Western Sahara Advisory Opinion 1975, para 46).

Consequently, advisory proceedings, when they are pursued as disguised contentious proceedings, can be considered a “soft” litigation strategy as “applicant” states and non-state entities enjoy their basic rights as litigants. Thus, they benefit from such litigation in a similar manner to traditional inter-state adjudication while at the same time advisory proceedings entail less social and financial costs for them. It can also be argued that advisory opinions constitute a “soft” litigation strategy due to their non-binding effect. However, the lack of binding effect is mitigated by the fact that advisory opinions constitute an authoritative pronouncement of international law by the ICJ. It is also clear from the fact that the ICJ itself cites its advisory opinions in its contentious judgments, demonstrating that advisory opinions are considered as valid precedent. In addition, through intra-judicial dialogue, advisory opinions are taken into consideration and possibly given effect by other national or international courts. The International Tribunal for the Law of the Sea in a case between the Maldives and Mauritius rejected two objections of the former that were premised on the existence of a dispute between Mauritius and the UK over the sovereignty of the Chagos Islands. For the Tribunal, the Chagos advisory opinion had resolved the dispute in favor of Mauritius (Lanzoni 2022, 298).

Conclusion

From 1948 until 2023, the ICJ has only rendered 27 advisory opinions (the same number of advisory opinions the PCIJ issued in the 18 years of its operation) and more than 100 judgments in contentious proceedings. Of the 27 advisory opinions the ICJ has published, 20 arguably relate to procedural and/or administrative issues of UN organs, such as the powers of the UNGA in the admission of a state to the UN, reparation for injuries suffered in the service of the UN, effects of awards of compensation made by the UN Administrative Tribunal, applications for reviews of judgment of the latter tribunal, and the interpretation of agreements made between UN organizations and states. The subject-matter of some of these opinions may have been of particular importance for some states, such as the interpretation of treaties between international organizations and host states; however, none of these cases affected vital state interests nor did they have a serious impact on international affairs.

Within the first 40 years of its operation, the ICJ only rendered three opinions (two were requested by the UNGA and one was requested by the UN Security Council) that directly related to vital state interests and politically controversial issues. These include the two opinions related to the independence of Namibia from South Africa and one opinion touched upon the decolonization of Western Sahara. However, from the mid-90s onwards there has been an increase in this type of advisory opinions. The ICJ has issued four opinions on matters that essentially and directly affect vital state interests and/or territorial sovereignty and two equally important requests for advisory opinions are pending. All requests were submitted by the UNGA. The pending advisory opinions are likely to be issued within the next couple of years as advisory opinions are published fairly quickly after the submission of the request; it does not look like they will be rejected given the ICJ’s persistent reluctance to refuse requests for advisory opinions. As a result, well before the completion of the last 40 years of its operation, the ICJ will most likely have issued six advisory opinions that directly affect vital state interests, including their territorial sovereignty.

This article aims to show that the increased use of advisory opinions by states through the UNGA tends to judicialize international affairs issues that would not normally be reviewed by a judicial body as lack of state consent would have acted as a procedural barrier. Even in the exercise of its advisory function, the ICJ offers a potential venue for judicializing politics following the criteria set by Alter, Hafner-Burton, and Helfer  (Alter, Hafner-Burton, and Helfer 2019, 451). The ICJ decides concrete legal disputes between contesting parties even if it denies doing so. The judges are formally independent and do not represent states. They apply pre-existing rules and procedures to the disputes that arise. They have the power to authoritatively declare violations or not of international law and they can suggest actions that the “losing” party must take to remedy legal violations and prevent their recurrence. While the lack of binding force undercuts the criterion that relates to the ICJ’s ability to remedy a legal violation, judicialization of international relations is potentially important when the adjudication contributes to a shift in political dialogue over which states once had primary control (Alter, Hafner-Burton, and Helfer 2019, 458). As a Judge of the ICJ noted with respect to advisory proceedings “it is striking to note to what extent the political debate shifted from within the United Nations to the Peace Palace in the Hague” (Bennouna 2013, 96).

This transition of the political debate to the ICJ has not been welcomed by everyone. States’ objections have focused on how the principle of consent to the adjudicatory jurisdiction of the ICJ is circumvented and how negotiations may be impeded (Written Statement of the United States of America to the pending advisory opinion on the legal consequences (for states and the UN) of the policies and practices of Israel in the Occupied Palestinian Territory (OTP), including East Jerusalem 2023, 23). Bodansky has claimed in the context of the pending request on climate change that states may be unwilling to make further compromises in the United Nations Framework Convention on Climate Change negotiations because they fear that this would undercut their legal position before the ICJ and that the request itself may be viewed as an attempt to circumvent the negotiations and make the whole process “more adversarial and acrimonious” (Bodansky 2022, 4). Another potentially crucial disadvantage is the difficulties of establishing and assessing all relevant facts for the final advisory opinion to be considered credible by the international community (Wall Advisory Opinion, dissenting opinion of Judge Buergenthal, 240-1). This can be problematic when the “respondent” state does not participate in the proceedings, as in the case of Israel in the Wall advisory opinion.

In conclusion, advisory proceedings as a “soft” litigation strategy are a particularly useful tool for small states or non-state entities as they have the potential to counterbalance the inherent power disparities between powerful and weaker states in the process of international bargaining by adding the authoritative voice of the ICJ to the debate. This tool can only be legitimately used with respect to disputes that pertain to the interests of the global community, such as the catastrophic effects of climate change or nuclear weapons, or when the principle of self-determination or violations of human rights and humanitarian law are at play. However, the non-participation of “respondent” states can, unfortunately, undercut the legitimacy of the advisory opinions through claims of factual deficiencies of the advisory opinions.

*This article was edited by Alexandra Huggins (John's Hopkins University) and Jennifer Williams (Princeton University) 

About the Author

Myrto Stavridi is a lawyer licensed in Greece who specializes in public international law and European and international human rights law. She is a graduate student at the Geneva Graduate Institute in the Master in International Law program.  She holds an LLB and an LLM in Public International Law (with honors) from the National and Kapodistrian University of Athens. She works as the Coordinator of the Refugee and Migration Studies Hub of the same university and as a research assistant to Yusra Suedi, Lecturer in International Law at the University of Manchester.

Acknowledgments

This paper was drafted in the context of the course Politics of International Adjudication taught by Professor Fuad Zarbiyev at the Geneva Graduate Institute. Myrto would like to extend her heartfelt gratitude to Professor Zarbiyev for his inspiring classes and his insightful feedback. Myrto is also grateful to Yusra Suedi for her encouragement and thoughtful comments and to the JPIA editing team, Alexandra Huggins and Jennifer Williams for their invaluable assistance.

References

1.  Case-law

ICJ

Accordance with International Law of the Unilateral Declaration in respect of Kosovo, Advisory Opinion, 2010 ICJ Rep 403

Admissibility of Hearings of Petitioners by the Committee on South West Africa, Advisory Opinion, 1956 ICJ Rep 23

International Status of South West Africa, Advisory Opinion, 1950 ICJ Rep 128

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

Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, 2004 ICJ Rep 136

Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion, 2019 ICJ Rep 95

Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 ICJ Rep 226

South West Africa Cases (Ethiopia v. South Africa; Liberia v. South Africa), Second Phase, Judgment, ICJ Reports, 1966 ICJ Rep 6

Voting Procedure on Questions relating to Reports and Petitions concerning the Territory of South West Africa, Advisory Opinion, 1955 ICJ Rep 67

Western Sahara, Advisory Opinion, 1975 ICJ Rep 12

PCIJ

Status of Eastern Carelia, Advisory Opinion, 1923 Series B No. 5

U.S. Supreme Court

Aetna Life Insurance Co. v. Haworth 300 U.S. 227 (1937)

2.  Other documents related to states and international organizations

Documents related to PCIJ

Preparation of the Rules of Court of January 30th 1922

State submissions to ICJ

Related to Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965 Advisory Opinion (2019)

 Written Statement of the United Kingdom of Great Britain and Northern Ireland (2018)

 Written Statement of the United States of America (2018)

Related to Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion (1996)

Letter dated 20 June 1995 from the Acting Legal Adviser to the Department of State, together with Written Statement of the Government of the United States of America

Related to the pending advisory request on the Legal Consequences arising from the Policies and Practices of Israel in the Occupied Palestinian Territory, including East Jerusalem

Verbatim Record of Public sitting held on Monday 19 February 2024 (CR 2024/4)

Written Statement of the United States of America (2023)

UN documents

UNGA. 83rd Plenary Meeting (22 May 2019). UN Doc A/73/PV.83.

UNGA. 64th Plenary Meeting (29 March 2023). UN Doc A/77/PV.84.

UN Special Rapporteur on the situation of human rights in the Palestinian territories occupied since 1967. Report on the situation of human rights in the Palestinian territories occupied since 1967. UN Doc A/77/356 (21 September 2022) (by Francesca Albanese). 

3.  Statements by states

Cleverly, James. 2022. “Statement on British Indian Ocean Territory/Chagos Archipelago” (Statement of 3 November 2022 UIN HCWS354). https://questions-statements.parliament.uk/written-statements/detail/2022-11-03/hcws354

4.  Literature

Alter, Karen J, Emilie M Hafner-Burton, and Laurence R Helfer. 2019. “Theorizing the Judicialization of International Relations.” International Studies Quarterly 63 (3): 449–63. https://doi.org/10.1093/isq/sqz019.

d’ Argent, Pierre. 2019a. “Article 65.” In The Statute of the International Court of Justice: A Commentary, edited by Andreas Zimmermann, Christian J. Tams, Karin Oellers-Frahm, and Christian Tomuschat, 3rd edition, 1787–1811. Oxford Commentaries on International Law. Oxford, U.K.: Oxford University Press.

———. 2019b. “Article 96 UN Charter.” In The Statute of the International Court of Justice: A Commentary, edited by Andreas Zimmermann, Christian J. Tams, Karin Oellers-Frahm, and Christian Tomuschat, 3rd edition, 269-275. Oxford Commentaries on International Law. Oxford, United Kingdom: Oxford University Press.

Aust, Anthony. 2010. “Advisory Opinions.” Journal of International Dispute Settlement 1 (1): 123–51. https://doi.org/10.1093/jnlids/idp005.

Bennouna, Mohamed. 2013. “The Advisory Function of the International Court of Justice in the Light of Recent Developments.” In THE GLOBAL COMMUNITY YEARBOOK OF INTERNATIONAL LAW AND JURISPRUDENCE: Global Trends: Law, Policy & Justice Essays in Honour of Professor Giuliana Ziccardi Capaldo, edited by M. Cherif Bassiouni, Gomula Joanna, Paolo Mengozzi, John G. Merrills, Rafael Nieto Navia, Anna Oriolo, William Schabas, and Anna Vigorito, 95–100. Oxford University Press. https://doi.org/10.1093/acprof:osobl/9780199332304.003.0006.

de Blois, Matthijs. 2015. “Bad Law and a Hard Case? The Impact of the Wall Advisory Opinion of the ICJ.” In What's Wrong with International Law? Liber Amicorum A.H.A. Soons edited by Cedric Ryngaert, Erik J Molenaar, Sarah Nouwen, 93-113. Leiden: Brill.

Bodansky, Daniel. 2022. “An ICJ Advisory Opinion on Climate Change: Ten Questions and Answers” Center for Climate and Energy Solutions https://www.c2es.org/wp-content/uploads/2022/10/an-icj-advisory-opinion-on-climate-change-ten-questions-and-answers.pdf 

Burgis, Michelle. 2008. “Discourses of Division: Law, Politics and the Advisory Opinion on the Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory” Chinese Journal of International Law 7(1): 33-63.

Burton, Philip. 2019. “Searching for the Eastern Carelia Principle.” ESIL Reflection 8 (1).

Crawford, James. 2019. Brownlie’s Principles of Public International Law. 9th edition. Oxford: Oxford University Press.

Falk, Richard A. 1967. “The South West Africa Cases: An Appraisal.” International Organizations 21(1): 1-23

Gross, Ernest A. 1966. “The South West Africa Case: What Happened?” Foreign Affairs 45 (1): 36–48. https://doi.org/10.2307/20039211.

Guilfoyle, Douglas. 2021. “The Chagos Archipelago before International Tribunals: Strategic Litigation and the Production of Historical Knowledge.” Melbourne Journal of International Law 21 (3): 749–71.

Higgins, Rosalyn. 1974. “The Desirability of Third-Party Adjudication: Conventional Wisdom or Continuing Truth?” In International Organization: Law in Movement, edited by Rosalyn Higgins and James Fawcett. Oxford: Oxford University Press.

———. 2009. Themes and Theories. Oxford: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780198262350.001.0001. 

Hudson, Manley O. 1924. “Advisory Opinions of National and International Courts.” Harvard Law Review 37 (8): 970. https://doi.org/10.2307/1329024. 

Kannan, Phillip M. 1998. “Advisory Opinions by Federal Courts.” University of Richmond Law Review 32 (3): 769–98.

Koskenniemi, Martti. 1995. “Advisory Opinions of the International Court of Justice as an Instrument of Preventive Diplomacy.” In International Legal Issues Arising under the United Nations Decade of International Law edited by Najeed Al-Nauimi and Richard Meese, 599-619. The Hague/Boston/London: Martinus Nijhoff Publishers.

Lanzoni, Niccolò. 2022. “The Authority of ICJ Advisory Opinions as Precedents: The Mauritius/Maldives Case.” The Italian Review of International and Comparative Law 2 (2): 296–322. https://doi.org/10.1163/27725650-02020005.

Lawing Penegar, Kenneth. 1965. “Relationship of Advisory Opinions of the International Court of Justice to the Maintenance of World Minimum Order.” University of Pennsylvania Law Review 113 (4): 529–61.

Milanovic, Marko. 2019. “ICJ Delivers Chagos Advisory Opinion, UK Loses Badly.” EJIL:Talk! (blog). https://www.ejiltalk.org/icj-delivers-chagos-advisory-opinion-uk-loses-badly/. 

Paulus, Andreas. 2019. “Article 66.” In The Statute of the International Court of Justice: A Commentary, edited by Andreas Zimmermann, Christian J. Tams, Karin Oellers-Frahm, and Christian Tomuschat, 3rd edition, 1812-1834. Oxford Commentaries on International Law. Oxford: Oxford University Press.

Pellet, Alain. 2015. “Kosovo—The Questions Not Asked.” In The Law and Politics of the Kosovo Advisory Opinion, edited by Marko Milanovic and Michael Wood, 268–79. Oxford: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780198717515.003.0013. 

Rovine, Arthur W. 1976. “The National Interest and the World Court.” In The Future of the International Court of Justice, edited by Leo Gross, 313–35. New York: Oceana Publications, Inc.

Scott, Shirley V. 2014. “Litigation Versus Dispute Resolution Through Political Processes.” In Litigating International Law Disputes, edited by Natalie Klein, 1st edition, 24–41. Cambridge: Cambridge University Press. https://doi.org/10.1017/CBO9781139062008.004. 

Sloss, David. 2002. “Using International Court of Justice Advisory Opinions to Adjudicate Secessionist Claims.” Santa Clara Law Review 42: 357–89.

Sthoeger, Eran. 2023. “How Do States React to Advisory Opinions? Rejections, Implementation, and What Lies in Between.” AJIL Unbound 117: 292-297.

Thirlway, Hugh. 2016. The International Court of Justice. Oxford: Oxford University Press.

Wagner, Julia. 2018. “The Chagos Request and the Role of the Consent Principle in the ICJ’s Advisory Jurisdiction, or: What to Do When Opportunity Knocks.” Questions of International Law, Zoom-out 55, 177–89. https://doi.org/10.2139/ssrn.3326122.