[Panel discussion] The crime of aggression: legal developments and accountability efforts

04 June 2025

Starts at: 14:14h
Fee: Free
Venue: Asser Institute
Organiser: Asser Institute, IHCL Platform
Address: R.J. Schimmelpennincklaan 20-22
2517 JN The Hague
Netherlands
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In September 2023, the Asser Institute hosted a panel of experts to examine the legal case for prosecuting the crime of aggression against Ukraine. Now, at a critical moment, we return to take stock.

Russia’s full-scale invasion of Ukraine has triggered investigations and prosecutions of conflict-related crimes through a variety of national and international legal avenues. While mechanisms exist to address war crimes, crimes against humanity, and genocide, none are currently equipped to hold military and political leaders accountable for the overarching crime of breaching peace and invading Ukraine’s territory: the crime of aggression.

Given the jurisdictional barriers faced by both the International Criminal Court (ICC) and national courts, international discussions have focused on the possible creation of a dedicated tribunal. Since January 2023, an informal Core Group on the Special Tribunal for the Crime of Aggression against Ukraine has been meeting to develop a viable legal response. This work culminated in a proposal for the Council of Europe to host a Special Tribunal—a bespoke international mechanism specifically designed to prosecute the crime of aggression. After much consideration, on 9 May 2025, the Council of Europe, the European Commission, and the representatives of an international coalition of states formally endorsed the establishment of a Special Tribunal for the Crime of Aggression against Ukraine.

Meanwhile, the ICC’s limited jurisdiction over the crime of aggression has renewed calls to amend the Rome Statute and the Kampala Amendments, aiming to harmonise the jurisdictional regime for aggression with that of the other core international crimes. These proposals will be discussed at a special session of the ICC Assembly of States Parties in New York in July 2025.

Together, these developments reflect a growing international consensus that impunity for what has been called the “original crime”—the unlawful use of force that enabled further atrocity crimes—is unacceptable. They also raise complex legal and institutional questions: the applicability of personal immunities, the relationship with existing international mechanisms, and the ability of any new body to deliver credible and independent justice.

This panel will offer legal analysis on:

The long-term significance of aligning the Rome Statute’s aggression provisions with those governing genocide, crimes against humanity, and war crimes
The Council of Europe’s model for the Special Tribunal and its legal foundations
Contextual challenges, including the risk of impunity amid potential peace negotiations
The implications of current geopolitical developments, including shifts in the positions of key states

Background

While Ukraine can prosecute the crime of aggression under Article 437 of its Criminal Code, international legal norms—particularly the principle of immunity ratione personae - severely limit its ability to prosecute senior foreign officials. The ICC also lacks jurisdiction in this context, as neither Ukraine nor Russia has ratified the Rome Statute amendments on aggression, and a referral by the UN Security Council is blocked by Russia’s veto. The Special Tribunal proposed under the Council of Europe is one of several models under consideration, alongside a UN-backed international tribunal or hybrid mechanisms.

To learn more, see the Asser Institute publication: The Case for a Special Tribunal on the Crime of Aggression against Ukraine: Technical and Legal Assessment.

The role of the International Centre for the Prosecution of the Crime of Aggression against Ukraine (ICPA) in case preparation. Background While Ukraine can prosecute the crime of aggression under Article 437 of its Criminal Code, international legal norms—particularly the principle of immunity ratione personae—severely limit its ability to prosecute senior foreign officials. The ICC also lacks jurisdiction in this context, as neither Ukraine nor Russia has ratified the Rome Statute amendments on aggression, and a referral by the UN Security Council is blocked by Russia’s veto. The Special Tribunal proposed under the Council of Europe is one of several models under consideration, alongside a UN-backed international tribunal or hybrid mechanisms.

Speakers:

Prof Dr. Frank Hoffmeister, head of the legal department at European External Action Services (EEAS) and professor at the Brussels School of Governance.
Dr Kateryna Busol, associate professor at the National University of Kyiv-Mohyla Academy, and fellow at the British Institute of International and Comparative Law. [online]
Prof Dr Karolina Wierczyńska, associate professor, department of public international law, head of The Center for Research on International Criminal Law at the Polish Academy of Sciences.
Myroslava Krasnoborova, liaison prosecutor for Ukraine at Eurojust.
[TBC] Dr Anton Korynevych, ambassador-at-large at the Ministry of Foreign Affairs of Ukraine.

Moderator: Dr Gabrielė Chlevickaitė, researcher, Asser Institute

This lecture is co-organised with the IHCL platform.