The Crime of Aggression and Challenges to the Exercise of International Jurisdiction: reforming the Rome Statute of the International Criminal Court and operationalizing the Special Tribunal for the Crime of Aggression against Ukraine

The crime of aggression is one the four core crimes under International Law listed in Article 5 of the Rome Statute of the International Criminal Court (ICC) of 17 July 1998. Its definition of Article 8 bis was adopted in 2010 in the framework of the Kampala Review Conference’s amendments, which was activated as of 17 July 2018. Since then, the ICC has never exercised its jurisdiction over the crime of aggression, due to the fact the amendments established a truncated jurisdictional regime on aggression under Article 15 bis of the Statute.

When the Russian Federation launched a fully-fledged war of aggression against Ukraine four years ago, a growing choir of authorities called for accountability for the crime of aggression, including via the creation of a Special Tribunal, which started to be realized through the conclusion of an agreement between the Council of Europe and Ukraine in June 2025.

In a parallel process, the Assembly of States Parties (ASP) to the Rome Statute met at a Special Session at the UN in July 2025 to discuss amendments proposed by a cross-regional group of 5 States (Costa Rica, Germany, Sierra Leone, Slovenia and Vanuatu) to harmonize the Court’s jurisdiction over the crime of aggression with the jurisdictional criteria governing war crimes, crimes against humanity and genocide. While States Parties agreed that the ICC’s jurisdiction over the crime of aggression must be strengthened, they postponed the decision-making process to a further Special Session of the ASP to be held in 2029.

Harmonizing the Court’s jurisdiction would be a vital step toward ending impunity for international crimes and ensuring that no victim is left behind simply due to jurisdictional asymmetries and legal inconsistencies. Until this can be achieved, continuing to support the operationalization of Ad Hoc Tribunals remains essential towards the effective prevention of the crime of aggression, at a time in which some of the most powerful international actors appear to consider the existing legal and jurisdictional framework irrelevant.

This event is co-organised by King’s College London and GIPA (Global Institute for the Prevention of Aggression). It is co-sponsored by MIGS (Montreal Institute for Global Security) and ELSA (European Law Students' Association).

Moderator/Chair

Dr Maria Varaki, King’s College London, Department of War Studies; Chair, War Crimes Research Group

Panelists

Dr Mark Ellis FKC, Executive Director, International Bar Association (IBA)

Dr Astrid Reisinger Coracini (Austria), Senior Scientist, Salzburg University; Member of the Steering Committee, Global Institute for the Prevention of Aggression (GIPA)

Professor Noelle Quenivet, Director of Research and Enterprise and Professor in International Law, Bristol Law School, University of West of England (UWE)

Dr David Donat Cattin (Italy), Adjunct Professor of Int. Law, NYU Center for Global Affairs; Senion Fellow, Montreal Institute for Global Security; Projects’ Coordinator & Member of the Steering Committee, GIPA