ICC’s Jurisdiction over the Crime of Aggression: Amending Article 5 Instead of Article 15bis (Part I)

[Terje Einarsen is Professor of International Law at the University of Bergen and Chairperson of the Norwegian Section of International Commission of Jurists]

The Assembly of State Parties special session on the review of the amendments on the crime of aggression will be held at the United Nations, New York, 7 to 9 July 2025. 

It comes with a challenging geopolitical background. The international legal order is now being threatened more than ever before since the UN Charter was enacted 80 years ago. The recent radical shift in the approach to international law by major powers, notably by the present Trump administration, seems in many ways similar to ideas shared with colonial States in the past as well as by current State leaders such as Vladimir Putin and Benjamin Netanyahu.

Although this development is disturbing to many other State leaders and peoples, a reasonable fear is that many countries and leaders will be pressured to accept policies, agreements and violations of international law that are neither in their interest nor compatible with the core values of the common international order. 

These states, whether in Europe, Latin-America, Africa, or elsewhere, should rally behind the UN Charter and core international law, including its key legal institutions. The best way to withstand pressures against individual States and their peoples, is presumably for these States to cooperate broadly and unite behind the most fundamental structures of international law, and, if possible, to strengthen rather than weaken the common system. 

Aligning the Jurisdiction over the Crime of Aggression with the Other Crimes

The call by the current and former presidents of the Assembly of States Parties of the International Criminal Court (ICC) of 27 January 2025 is a case in point. It recognizes that the ICC now faces significant threats and unlawful sanctions from states like Russia for its investigations and arrest warrants in the Ukraine situation, and from the USA for investigations and arrest orders in the Palestine situation. 

As underlined by the authors of that call, “the ICC’s mission is not political, it is about applying international law consistently and impartially to hold perpretrators of the gravest crimes accountable”. Furthermore, the call points out, by doing so “the Court affirms the principle that no one is above the law, a cornerstone of the international system of peace and security”. 

This is difficult to disagree with, if considered from within the current international order still existing. 

Of particular interest is the simultaneous call by the authors to use this moment of crisis to strengthen the ICC, notably by “aligning the Court’s jurisdiction over the crime of aggression with its jurisdiction over other core crimes”. Furthermore, “enhancing the ICC’s ability to address acts of aggression is vital for global peace and security”, and that the “upcoming ICC States Parties’ meeting in July offers a chance to advance this cause and honor the UN’s funding principles”. What has happened several places since then has just underscored the call’s urgency.

Thus, the stage is set for an important ASP meeting in New York in July (hereafter the Review Conference). To amend the Rome Statute for this end will require serious political will and a portion of courage under the circumstances. However, given that the item is now on the agenda, it is also a question of how an effective revision might look like for the purpose of aligning the Court’s jurisdiction over the crime of aggression with its jurisdiction over genocide, crimes against humanity and war crimes. 

The pros and cons of the hitherto proposed amendments of Article 15bis are first briefly explained in this Part I. Then, an alleged better option is presented and considered in Part II: Amending Article 5 instead by inserting a new paragraph 2. 

If carefully framed, an effective amendment may subsequently enter into force for any State Party from the Autumn of 2026, provided that the proposed amendment of Article 5 is adopted already at the meeting in July and subsequently ratified as rapidly as possible by a State Party.   

Amending Article 15bis – Unclear Legal Consequences

Different proposals aiming at aligning the Court’s jurisdiction over the crime of aggression with its jurisdiction over other core crimes, by means of amending Article 15bis, have been circulated among interested States. Notably, a Discussion Paper of March 2024, with two different options relating to amendment of Article 15 bis (4) and (5), was sent on 8 November 2024, to the Permanent Representatives of States Parties to the Rome Statute by ambassadors of Costa Rica, Sierra Leone, Vanuatu, Germany and Slovenia. The Discussion Paper was annexed to the Report of the Working Group on Amendment of 1 December 2024 (see Annex III).

The background for the proposals is the current special jurisdictional regime relating to the crime of aggression in the Rome Statute, installed by Articles 15bis and 15ter. 

Article 15ter concerns the referral of a situation by the Security Council. It corresponds, as pointed out also in the Discussion Paper of March 2024, to the ICCs standard regime over genocide, crimes against humanity and war crimes, cf. Article 13(b). Currently, this provision is fully operational but difficult to be set in motion in practice due to the veto powers of the permanent five Security Council members – and that problem cannot be fixed by amending the Rome Statute. 

However, Article 15bis(4) and (5) constitute important obstacles to The Court’s jurisdiction over aggression. Article 15bis(4) allows States Parties to opt-out of the ICC’s jurisdiction over the crime of aggression while Article 15bis(5) excludes ICC’s jurisdiction when the crime is committed by nationals of or on the territory of Non-States parties to the Rome Statute. 

In consequence, the ICC’s jurisdiction over the crime of aggression seems only possible when an aggressor State and a victim State have both ratified the Kampala Amendment (at present 47 States), although another, broader interpretation is that the Court will have jurisdiction if either the aggressor State or the victim State has ratified the Kampala Amendment and the aggressor State has not previously opted out of the Court’s jurisdiction. 

In any case the jurisdiction over the crime of aggression is substantially narrower than for the other crimes, and the current proposals seek to amend Article 15bis(4) and (5) in ways that will bring the general conditions for jurisdiction into play also for the crime of aggression. 

The first option set forth in the Working Paper deletes Article 15bis(5) and most of Article 15bis(4), keeping only part of the first sentence: “The Court may, in accordance with Article 12, exercise jurisdiction over a crime of aggression.” 

This seems like an elegant solution, but the problem with this option is that Article 121(4) on amendments will probably apply with regard to entry into force. It means that this amendment, if adopted, will enter into for force for all State Parties, but only one year after ratification by seven-eighths of them – which may never happen. 

In the communication from the Governments of Costa Rica, Germany, Sierra Leone, Slovenia and Vanuatu to the UN Secretary General on 4 April 2025, the first option is not included in the amendment proposal, while the second option remains.

This proposal is identical to the proposal by the Global Institute for the Prevention of the Crime of Aggression (GIPA) of 25 September 2023. It tries, according to the Working Paper, “to address the risks associated with adopting the amendments under Article 121(5)”. The GIPA proposal argues that Article 121(5) first sentence may apply and not the second sentence based on the Kampala Amendment’s drafting history, see GIPA proposal, para. 21. At the same time it is recognized that “the question of the proper amendment procedure” was left open, see GIPA proposal, para. 22. This question will come before the Review Conference in July 2025. 

What seems clear, then, is that there is substantial uncertainty as to which amendment rule will apply to the proposal: Article 121(4), Article 121(5) in its entirety, or Article 121(5) first sentence only. Only the latter third solution will in practice have a good chance of aligning the jurisdiction over the crime of aggression with the other crimes within a reasonable timeframe.

The matter is uncertain, first, since it is not entirely up to the Review Conference to “choose” the solution for the entry into force if one of the hitherto proposed options is adopted. This is a legal question which in the last instance may be decided by the Court based on appropriate treaty interpretation. 

Based on a textual interpretation, any amendment only to Article 15bis does not fall under Article 121(5), but Article 121(4), because the former only applies to an amendment to “Articles 5, 6, 7, and 8”, while the latter applies to all other amendments. According to Article 21(1)(a) of the Rome Statute – and Article 31 VCLT – it is the ordinary meaning of the terms of the Rome Statute provisions that carries the most weight, not prior consensus or majority views related to the Kampala process. In Kampala, there was also, in fact, an actual amendment of Article 5, deleting the second paragraph of Article 5, which supported a sui generis case for the application of Article 121(5) for the amendment package as a whole. 

According to the current proposal by Costa Rica, Germany, Sierra Leone, Slovenia and Vanuatu, there will only be an amendment to Article 15bis. Moreover, it is not consistent with the wording of Article 121(5) that the second sentence of this provision shall not apply to an amendment falling under Article 121(5). However, this might be remedied through clear preparatory statements at the Review Conference, preferably in the amendment resolution, before adopting the proposal.

Even in the latter case it is presumably difficult to say with a high degree of certainty what the Court will conclude in such a case. The provisions of the Rome Statute Article 21(1)(a), Articles 31-32 VCLT, along with the principle of legality of the Rome Statute in Article 22(1), could make it difficult for judges to accept jurisdiction over the crime of aggression in an indictment based on the entry into force under art. 121(5) first sentence only.

This means that there will remain considerable uncertainty about the legal consequences of the proposed changes in their present form. The problem is well described in a recent article by Carrie McDougall, “Expanding the ICC’s Jurisdiction Over the Crime of Aggression.”

In her view, “the stronger argument, based on the ordinary meaning of the text of the ICC Statute, is that the entry into force of any amendment to Article 15bis would be governed by Article 121(4), given that Article 121(5) is expressly stated to apply only to the amendments of Articles 5, 6, 7 and 8, and Article 122 only applies to an enumerated list of provisions of an institutional nature”. On the other hand, she also believes that “the negotiating history provides a basis on which a defensible argument can be made that further amendments of Articles 8bis, 15bis og 15ter should be governed by the first sentence of Article 121(5) for reasons of consistency”. 

In a comment to the current proposal formally submitted by Costa Rica, Germany, Sierra Leone, Slovenia and Vanuatu, Kevin Jon Heller supports the idea of the amendment, but argues that the proposal “has almost no chance of ever entering into force”. In his opinion, since “the proposal does not seek to amend Arts. 5-8 in the Rome Statute, the amendment is subject to the procedure set out in Art. 121(4)”.

Whatever would be the final outcome in a future court case before the ICC, it is not a good situation to be in for lawmakers when the legal consequences of an important amendment to the Rome Statute are unclear, as they seem to be in this instance. States Parties risk adopting an amendment that is either unworkable in practice or much less effective than intended. Thus, other alternatives ought to be considered as well.

Part II considers amending Article 5 instead.