Abstract Recent conflicts have revived interest in a subject that has remained largely untouched since the trials of war criminals after the Second World War: prosecuting individuals for the crime of aggression. Due to its restricted jurisdictional regime, the International Criminal Court has so far been unable to investigate this crime and remains barred from doing so in, for example, the context of the Ukraine situation. When exploring alternative domestic (or hybrid) venues for prosecuting aggression, discussions have come to focus on the possibility of exercising universal jurisdiction (UJ), a concept increasingly used to counteract substantive selectivity of international criminal justice. However, scholars and practitioners have expressed differing views on the extent to which the notion of UJ has come to extend to the crime of aggression under customary international law. This study contributes to the ongoing debates by providing a legal-empirical analysis of the practice and opinio juris of 126 states, as presented to the Sixth Committee of the UN General Assembly under the agenda item on the ‘scope and application of universal jurisdiction’. These empirical quantitative and qualitative insights provide a foundation for evaluating the customary status of UJ over the crime of aggression and exploring the legal challenges of prosecuting aggression under this jurisdictional title.
Nina Marie Petzel (2026) studied this question.