Jurisdictional Displacement At The Frontiers: Aggression, Command, And The Restructuring Of Functional Immunity
Ezekiel Osei*
ABSTRACT
This article examines the competing rationales for denying functional immunity (immunity ratione materiae) to foreign state officials accused of international crimes, in light of the recent wave of domestic and international practice that has narrowed that immunity. It argues that the relationship between official immunity and international crimes is best explained by a single principle of jurisdictional displacement. According to this principle, immunity yields neither because international crimes are ‘private’ acts nor because the underlying prohibitions have a jus cogens character, but because international law has conferred a rule of criminal jurisdiction that necessarily contemplates the prosecution of state officials; the later jurisdictional rule must therefore be read as having displaced the earlier rule of immunity. The article then applies, and where necessary refines, this principle at three frontiers that recent practice has exposed. First, with regard to the crime of aggression, it demonstrates that, once displacement is uncoupled from the requirement of universal jurisdiction, the territorial jurisdiction of the victim state can displace functional immunity for this leadership crime. Secondly, it criticises the rank-based qualification that briefly entered German jurisprudence, showing that it is irreconcilable with the customary architecture of command responsibility. Thirdly, it addresses the problem of hybridity, arguing that internationalised tribunals may displace the personal immunity (immunity ratione personae) of serving leaders only where they exercise a properly international jurisdiction, and that the suspension of that immunity by the Special Tribunal for the Crime of Aggression against Ukraine is the doctrinally correct response to its territorial foundation. Drawing on the jurisprudence of the German Federal Court of Justice and the French Court of Cassation, the practice of the International Criminal Court, the draft articles adopted by the International Law Commission on second reading in 2026, and the Statute of the Special Tribunal, the article shows that these apparently distinct developments form part of a coherent structural shift in the relationship between state sovereignty and individual criminal accountability, with implications for the convention to be elaborated on the basis of the Commission’s draft articles.
Keywords: functional immunity, crime of aggression, command responsibility, hybrid criminal tribunals, ILC draft articles on immunity of State officials.
* The author is a PhD student in International Law at the Faculty of Law, University of Cambridge, and an Affiliate Researcher at the Lauterpacht Centre for International Law, University of Cambridge. He is an Adjunct Lecturer at the Faculty of Law, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, and a consultant with the Centre for Human Rights, University of Pretoria, South Africa. His research interests include Public International Law, International Trade and Investment Law, Competition Law, African Union Law, Corporate Finance and Insolvency Law, and International Human Rights Law.
