A Historic Chance Missed: Harmonization of the ICC’s Jurisdiction over the Crime of Aggression Delayed Once More

[Arne Bardelle is a senior legal advisor at the European Center for Constitutional and Human Rights (ECCHR). ECCHR has supported the reform process and is among the over 80 co-signatories of the Joint Civil Society Statement calling for harmonization of the ICC’s jurisdiction over the crime of aggression with that of the other three core crimes.]

The commendable efforts to enable the International Criminal Court (ICC) to effectively prosecute the crime of aggression have, for now, stalled. On 9 July 2025, during a Special Session in New York, States Parties to the Rome Statute decided by consensus to postpone consideration of an amendment proposal, aimed at closing existing jurisdictional gaps, until 2029. The proposal, put forward by a cross-regional Group of Friends, was fiercely opposed by a vocal minority of states – most prominently France, the UK, Canada, New Zealand and Japan – and ultimately failed to be adopted. 

For victims of aggression, this is a blow; for aggressors, it means continued impunity. Nonetheless, the adopted resolution offers a modest victory: States Parties committed to revisiting the issue in four years and reaffirmed the majority`s intention to strengthen the Court’s jurisdiction over the crime of aggression.

A Unique Opportunity to Fill the Gaps 

The Special Session was a long-awaited opportunity to strengthen accountability for the crime of aggression. Already in 2010, at the Review Conference in Kampala, States Parties agreed that the ICC’s aggression provisions would be reviewed seven years after the Court’s jurisdiction over them was activated – a step that was decided in 2017 to take effect as of July 2018. The glaring gaps in the ICC’s jurisdiction over the crime of aggression are well known and have become painfully visible – not only in light of Russia’s full-scale invasion of Ukraine (see, e.g., Haßfurther; Kreß/Hobe/Nußberger; McDougall; Trahan). 

Because of the compromise reached in Kampala (for details, see Kreß/von Holtzendorff), the ICC cannot prosecute acts of aggression committed by or on the territory of countries that are not States Parties to the Court – unless the case is referred to the Court by the UN Security Council This applies even when such acts are committed against a State Party or a country that has accepted the Court’s authority on an ad hoc basis. Moreover, even States Parties can opt out of the Court’s jurisdiction. These limitations, enshrined in Article 15bis(4) and (5) of the Rome Statute, represent an unjustified deviation from the Court’s jurisdictional regime for the other three core crimes. They have led to a fragmentation of justice mechanisms, as evidenced by the need for a special tribunal to prosecute the crime of aggression against Ukraine. At a time when acts of aggression are on the rise, it is imperative to enable the ICC – as the only permanent international criminal court – to effectively fulfil its mandate.

At the Special Session on the Review of the Aggression Amendments, States Parties had the opportunity to fix the loopholes in the Court’s jurisdiction. The necessary tools were on the table: a legally sound amendment proposal was submitted by a cross-regional group of states in April 2025, and a draft resolution by Liechtenstein from June 2025 (here in Annex I) convincingly clarified the relationship between the proposed harmonization amendment and the earlier Kampala amendments. Together, they would have harmonized the Court’s jurisdiction over the crime of aggression with its jurisdiction over the other three core crimes (see Reisinger Coracini/Kreß). Seven meetings of the Working Group on Amendments provided ample opportunity for discussion. With the necessary political will (see Grzebyk), the amendment proposal could have been adopted during the Special Session. 

However, even in the run-up to the session, opposition from some States was fierce. It quickly became clear that consensus would be difficult to reach, with France, Canada, Japan, the UK, and New Zealand among the most vocal opponents. Seemingly aiming to delay harmonization indefinitely, they submitted an alternative draft resolution proposing that harmonization be considered only after two-thirds of States Parties have ratified the Kampala amendments (here in Annex II). With two competing draft resolutions in hand, States Parties entered the Special Session held from 7 to 9 July. Moreover, the United States attempted to deter any expansion of the Court’s jurisdiction through issuing a threatening statement to all States Parties ahead of the session, reiterating this position on the second day through a high-level representative of the State Department. 

Momentum Meets Resistance

Unsurprisingly, the divide among States Parties over harmonization remained evident during the Special Session, despite many delegations emphasizing the importance of unity in the face of unprecedented attacks on the Court and its personnel. During the plenary meetings, a considerable number of States spoke out in favor of the reform. Germany delivered a joint statement on behalf of 34 members of the Group of Friends, calling for harmonization. In addition to many European countries, the endorsing states included Chile, Sierra Leone, the State of Palestine, Timor-Leste, Vanuatu, and Zambia. Several other delegations voiced their support in individual statements, including a number of African and Latin American States Parties, such as the Democratic Republic of the Congo (DRC), Ghana, Senegal, Nigeria, as well as Uruguay, Mexico, and Peru. A positive sign was Ukraine’s clear endorsement of the reform, following its previous silence on the matter. 

On the other side, a smaller but vocal group of states expressed hesitancy, scepticism or outright rejection of the proposed harmonization. France, Canada, the UK, Japan, New Zealand, Brazil, Australia, Mali, and Uganda were among them. While many of these States emphasized the importance of consensus, this emphasis – at least in some cases – arguably reflected underlying concerns about potentially exposing their own leadership to the Court’s jurisdiction if the reform were to be adopted. Participating as observer States, the United States (as noted above) and China also opposed the proposed reform – with China arguing that only the Security Council has the authority to determine acts of aggression.

Throughout the session, civil society actors repeatedly emphasized what should already have been beyond dispute: the crime of aggression must not go unpunished. It is a matter of life and death for the victims of illegal wars – entire populations and the communities within them, such as those in Ukraine or the eastern DRC. In the lead-up to the session, more than 80 civil society organizations had called for harmonization (see Haßfurther). 

The Outcome: A Lukewarm Compromise     

Following short, but intense negotiations, it became clear that the proposed amendment could not be adopted at the Special Session. With more than 20 States Parties absent, reaching the two-thirds majority required for adoption under Article 121(3) of the Rome Statute would have been difficult. In addition, many States Parties were unwilling to break consensus. Nonetheless, the resolution adopted during the final plenary meeting includes several elements that can be considered a significant step towards harmonization – especially when compared to the earlier draft resolution introduced by France and others, which seemed to be aimed at indefinitely stalling the process (see above).

First, the Assembly of States Parties committed “itself to the aim of strengthening the jurisdiction of the Court over the crime of aggression”. Second, the resolution maintains momentum by keeping the crime of aggression on the agenda: States Parties agreed to convene another Special Session in 2029 to reconsider the harmonization proposal, which was annexed to the resolution. Third, interim steps are planned to sustain dialogue, including the establishment of a subgroup within the Working Group on Amendments and the convening of an intersessional meeting in 2027.

However, as the representative of the State of Palestine rightly pointed out at the very end of the Special Session, some of the compromise language is difficult to accept. Notably, there was no consensus to objectively acknowledge that a gap in jurisdiction exists. Instead, the resolution merely states that “many States Parties take the view” that such a gap exists. But, ignoring it will not make the gap disappear. 

Failing Survivors’ Expectations, Perpetuating Double Standards 

It is not without irony that 80 years after the first indictment for crimes against peace at Nuremberg, the four Allied powers now stand – albeit in different ways – among the strongest opponents of enabling the effective prosecution of the crime of aggression. But one need not look far back in history to observe such double standards. While opposing harmonization of the Rome Statute, France, the UK, and Canada have been important advocates for a Special Tribunal for the Crime of Aggression Against Ukraine, aimed at addressing the accountability gap left by the ICC’s limited jurisdiction. Yet in other situations – particularly where Western powers see little strategic or political benefit – support for such a tribunal remains extremely unlikely.

Still, it is important to highlight positive developments. Thanks to the tireless efforts of the Group of Friends and many other states, the long-overdue amendment was at least seriously debated. In the course of the process, Timor-Leste and Seychelles ratified the Kampala amendments, committing to the legal framework and increasing the number of ratifications to 49. Crucially, civil society played a central role – advocating for reform, amplifying the voices of victims and survivors of aggression, and providing technical expertise (see here and here).

Political leaders must be judged by the consequences of their decisions. Those obstructing harmonization must ask themselves: Have their actions made the world a safer and more just place? The answer, certainly, is no. Yet there is hope: As civil society continues to demand reform, a growing number of States are joining the call for harmonization – bringing us closer to the equal application of the law and stronger protection against illegal wars.

I would like to thank my colleague Andreas Schüller for his valuable comments and suggestions.