A Tale of Two Nationalities: Dual Nationality and Jurisdiction Ratione Personae in Investment Treaty Arbitration

Abstract

Dual nationality poses complex challenges in public international law, particularly in international investment law. In this context, nationality plays a key role: serving as a determining factor to establish who qualifies for protection under a treaty regime and acting as a ratione personae criterion to establish jurisdiction in dispute resolution forums. This study provides a doctrinal and policy-oriented analysis to understand how international investment tribunals approach the issue of dual nationality when determining the jurisdiction ratione personae and what interpretative trends emerge across different arbitration frameworks. The analysis introduces a threefold typology of interpretative approaches and is tested against the case Alicia Grace v. Mexico, which illustrates how recent tribunals navigate and balance the existent tensions. By examining the treatment of dual nationality across the ICSID and non-ICSID awards and analyzing the interpretative methodologies employed in addressing treaty silence, the study identifies an emerging pattern of convergence across different arbitration fora: in recent awards, tribunals apply functionalist tools when faced with treaty silence which leads to restrictive outcomes, i.e., excluding dual nationals from access to arbitration. This ultimately signals increasing sensitivity to the integrity of the arbitration system against abuse, such as treaty shopping or strategic structuring of nationality.