Intervening for the community?—The law and politics of third-party intervention before the International Court of Justice

Abstract This article explains why states intervene before the International Court of Justice (ICJ) and how they choose between Articles 62 and 63 of the ICJ Statute. Against accounts of a general turn from bilateralism to community interests, it offers a comprehensive mapping of all interventions and classifies them as ‘community interest’ or ‘self-interest intervention’ by reference to the rights invoked, the submissions made and the overall context of the interventions. Of 87 Article 63 interventions, about 77% advance community interests, whereas only 35% of Article 62 applications do so. Read through a ‘costs and commitments’ lens, the pattern coheres: Article 63 is comparatively low-cost and low-commitment and has become the principal vehicle for advancing community interests; Article 62 is higher-cost and is used mainly to pursue particularized rights and outcome-driven aims. Yet, the utility of Article 63 is constrained by its interpretive scope, which limits practical effect in contentious proceedings. The article therefore assesses whether existing avenues match contemporary practice and considers reform options. Two policy paths are outlined. One would maintain generous admissibility under Article 63 and recognize that obligations erga omnes and erga omnes partes may satisfy the legal interest threshold of Article 62. The other would conserve resources by policing the scope of Article 63 more strictly and clarifying that obligations erga omnes and erga omnes partes alone do not meet the threshold of Article 62, paired with the introduction of amicus curiae submissions for states in contentious cases. Together, the analysis shows both greater recent willingness by states to intervene for community interests and the need to recalibrate procedures to that practice.