Third State Intervention at the International Court of Justice: Expanding Participation in International Adjudication

Written by Jomart Joldoshev as part of the International Courts Reporter Series

The growing number of third-state interventions before the International Court of Justice (“ICJ” or “Court”) has become one of the more notable procedural developments in contemporary international adjudication. Although intervention under Articles 62 and 63 of the Statute of the International Court of Justice has existed for decades, recent practice shows a broader and increasingly strategic use of these mechanisms. This trend is particularly visible in disputes involving multilateral conventions and issues of wider international concern. Traditionally, intervention played only a limited procedural role in contentious proceedings. Recent cases, however, suggest that states now view intervention as more than a technical procedural option. Increasingly, states use intervention as a legal and diplomatic tool to participate in the interpretation and development of international law without becoming principal parties to the dispute.

Historically, contentious proceedings before the ICJ have been understood primarily as bilateral disputes between sovereign states. The Court’s jurisdiction reflects this traditional understanding. Under Article 59 of the ICJ Statute, the Court’s judgments are binding only on the parties to the particular case and only in respect of that dispute. For much of its history, the Court largely operated within this bilateral framework. Interventions by third states remained relatively uncommon and were generally limited to disputes in which states could demonstrate a direct legal interest affected by the proceedings. As a result, intervention was often viewed as an exceptional procedural mechanism rather than a regular feature of international litigation before the Court.

Articles 62 and 63 of the ICJ Statute provide two distinct legal bases for intervention. Article 62 permits a state to request permission to intervene when it considers that it has “an interest of a legal nature which may be affected by the decision in the case.” The Court retains discretion to determine whether the legal interest asserted by the requesting state justifies intervention. Article 63 operates differently. It applies when the interpretation of a multilateral convention is at issue. In such situations, every state party to the convention has the right to intervene for purposes related to treaty interpretation. The distinction between these provisions is important. Article 62 interventions generally require a more direct legal connection to the dispute, whereas Article 63 reflects the broader principle that all state parties to a treaty may have an interest in how the Court interprets that treaty.

Recent proceedings before the ICJ, particularly those involving the interpretation of the Genocide Convention, have shown a growing willingness among states to intervene. Cases such as The Gambia v. Myanmar, Ukraine v. Russian Federation, and South Africa v. Israel have attracted an unprecedented number of declarations of intervention from third states. In many of these proceedings, states sought to participate not because they were directly affected by the underlying dispute, but because of the broader significance of the legal questions before the Court. This development reflects the changing nature of many disputes brought before international courts. Cases involving allegations of genocide, environmental obligations, or human rights protections often carry political, legal, and diplomatic implications that extend beyond the immediate parties to the proceedings.

In these disputes, states increasingly view intervention as an appropriate means to express legal positions on treaty interpretation and broader questions of international responsibility. As a result, contentious proceedings before the ICJ are no longer seen as strictly limited to the original applicant and respondent states. In practice, some proceedings now serve as broader forums for legal participation by multiple states interested in the interpretation and application of international law. Although intervening states do not generally become parties to the dispute itself, their participation still contributes to the proceedings’ broader legal and institutional significance.

The growing use of intervention also raises important procedural and institutional questions for the Court. Greater state participation may strengthen the legitimacy of the Court’s interpretation of multilateral treaties, particularly in disputes involving conventions with widespread international participation. Allowing additional states to present legal views may also contribute to broader acceptance of the Court’s reasoning within the international community. At the same time, increased intervention practice may pose practical challenges for the Court. Proceedings involving multiple intervening states may become more complex, require additional written and oral submissions, and potentially prolong already lengthy litigation. Politically sensitive disputes may also become more difficult to manage as more states seek to participate directly or indirectly in the proceedings.

The expanding role of intervention also reflects a broader development within international law. Many contemporary disputes involve obligations increasingly viewed as collective rather than purely bilateral. Questions concerning genocide prevention, environmental protection, human rights obligations, and the interpretation of multilateral treaties often affect a broader range of states beyond those directly involved in the dispute. Intervention is therefore increasingly used not only to protect immediate legal interests but also to participate in the broader interpretation and development of international legal norms. This trend demonstrates that modern international adjudication continues to adapt to the interconnected nature of global legal disputes.

Importantly, the expansion of intervention practice does not formally alter the consensual foundation of ICJ jurisdiction. The Court remains a judicial body whose jurisdiction depends on state consent, and intervening states generally do not become full parties to the proceedings unless specific jurisdictional conditions are met. Nevertheless, recent practice suggests a broader understanding of participation before the Court, particularly in disputes involving multilateral conventions and obligations of wider international concern. While the ICJ formally continues to resolve disputes between sovereign states, the growing participation of third states through intervention indicates that contentious proceedings are also playing a broader role in shaping the interpretation and development of international law in the contemporary international legal order.