Expanding the Jurisdictional Reach of the ICJ and the Evolving Scope of Indirect Expropriation in Investor State Disputes: A Public International Law Perspective

This Comment explores the evolving intersection between diplomatic protection, international investment law, and the jurisdiction of the International Court of Justice (“ICJ”), with a particular focus on whether and how the ICJ may adjudicate inter-state claims arising from investment disputes. Against the backdrop of increasing investor-state arbitration under Bilateral Investment Treaties (“BITs”) and multilateral frameworks such as the ICSID Convention, the Comment examines the legal foundations, practical tensions, and jurisdictional boundaries involved when States seek to espouse the claims of their investors before the ICJ. This Comment examines the potential role of the ICJ in investment dispute resolution, highlighting its practical significance beyond mere legal possibility. ICJ jurisdiction over investor-state claims becomes particularly relevant when arbitration is unavailable, unsuitable, or insufficient. Such circumstances include situations where investors are unable or unwilling to arbitrate, disputes involve state-owned enterprises or sovereign funds with mixed commercial and regulatory elements, or systemic interpretive issues emerge across multiple treaties, including questions of fair and equitable treatment or indirect expropriation. In these contexts, ICJ adjudication not only provides a forum for resolving inter-state investment disputes but also contributes to doctrinal coherence and reasserts sovereign control over treaty interpretation, positioning the Court as a complementary mechanism within the broader architecture of international investment law. Ultimately, this Comment argues that the modern mechanism of inter- state espousal at the ICJ represents a partial return to the pre-BIT era of diplomatic protection, where States exercised full control over the dispute process on behalf of their nationals. This revival of state-led dispute resolution, now operating through international judicial channels rather than purely diplomatic ones, reflects a broader trend of state re- intermediation in investment disputes. By allowing home States to bring claims before the ICJ, inter-state espousal reinforces the Court’s role as a generalist adjudicator of public international law and ensures that state consent remains central to the adjudicatory framework. Yet, it simultaneously curtails investor autonomy, as claims are reframed through the home State’s diplomatic and political considerations. In this sense, inter-state espousal embodies a reassertion of sovereignty-based control within a pluralist system of international adjudication, coexisting uneasily with the individualized and investor-centric model of modern investment arbitration.