What is the crime of aggression?

In essence, the crime of aggression is when one country uses armed force against another country without legal justification.

While the crime of aggression was one of the four crimes listed in the Rome Statute when the treaty was adopted in 1998, the completion of the definition and provisions of jurisdiction were postponed for further negotiation. 

Three facts on the crime of aggression

It focuses on the most responsible: leaders.

It applies to individuals, not states.

It may be the fourth core crime tried at the ICC. 

How was the definition decided?

In 2010, the first Review Conference of the Rome Statute took place in Kampala, Uganda. ICC member states and non-member states alike gathered to review the implementation and impact of the Rome Statute since its entry into force in July 2002.

Several amendments to the Rome Statute were proposed at the conference, including a proposed definition for the crime of aggression (Article 8bis), as well as how and in what instances the ICC can begin exercising jurisdiction over the crime of aggression (Article 15bis and 15ter).

After weeks of lengthy and intense negotiations, both ICC member states and non-ICC member states agreed to adopt, by consensus, the Kampala Amendments, which included the crime of aggression amendments.

Read moreRead less

The crime of aggression defined

Article 8bis, paragraph 1 defines the crime of aggression as "the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations."

The act of aggression means "the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations."

These acts can include, among others, invasion, military occupation, and annexation by the use of force, blockade by the ports or coasts.

ASP Special Session – July 2025

The ICC Assembly of States Parties convened a Special Session from 7 - 9 July 2025, in order to review the Kampala Amendments on the crime of aggression.

The Special Session took place at United Nations Headquarters, in New York, USA.

DOCUMENTATION ON THE SPECIAL SESSION

Civil society addresses the Assembly of States Parties:

General debate

 

Plenary on Lessons Learnt

 

Closing plenary

Timeline: 1998 – now

1998:

  • States convened in Rome for the five-week Rome Conference from 15 June – 17 July 1998, out of which emerged the Rome Statute, the foundational document of the ICC.
  • The question of whether to include the crime of aggression, and if so, what its definition would be, sparked lively debate.
  • As part of a final compromise, the crime of aggression was included in the list of crimes under the Court’s jurisdiction, but agreement on the definition and the conditions for the exercise of jurisdiction were deferred.

 

2010:

  • The first Review Conference of the Rome Statute took place in Kampala, Uganda in 2010.  ICC member states and non-member states alike gathered to review the implementation and impact of the Rome Statute since its entry into force in July 2002.
  • Several amendments to the Statute were proposed at this time, including a proposed definition for the crime of aggression (Article 8bis), as well as how and in what instances the ICC can begin exercising jurisdiction over the crime of aggression (Article 15bis and 15ter).
  • After much discussion, both ICC member states and non-ICC member states agreed to adopt, by consensus, the Kampala Amendments on 11 June, which included the crime of aggression amendments.

 

2017:

  • After lengthy negotiations ending late after midnight on the final night of the 16th ASP session, States decided that the Court's jurisdiction over the crime of aggression would be activated as of 17 July 2018, as both conditions for the exercise of jurisdiction were met:
  • The amendments must have been ratified or accepted by at least 30 States Parties, after which one year must pass before the Court could exercise its jurisdiction
  • The ASP had to make a decision after 1 January 2017, by consensus or at least 2/3 majority, to allow the Court to begin exercising its jurisdiction.

 

2018:

  • The Court’s jurisdiction over the crime of aggression is activated on 17 July 2018, which also marked the 20th anniversary of the adoption of the Rome Statute.

 

2024:

  • At the 23rd session of the Assembly of States Parties, which took place from 2 – 6 December 2024 in The Hague, The Netherlands, the Assembly decided to hold a special session dedicated to the review of the Kampala amendments on the crime of aggression from 7 – 9 July 2025 at the United Nations Headquarters in New York, USA.
  • The Assembly allocated its Working Group on Amendments to oversee preparations for the Special Session, which would meet monthly in 2025 until the July session

 

2025:

  • The Assembly is engaging in preparatory work through its Working Group on Amendments in the lead up to the Special Session, which will take place from 7 – 9 July at the United Nations.
Read moreRead less

How is ICC jurisdiction applied over the crime of aggression?

The amendments on the crime of aggression enter into force for a state one year after its ratification or acceptance by that state. 

Even if ICC member states activate ICC jurisdiction over the crime of aggression, the option to “opt-out” of the Court’s exercise of that jurisdiction in non-UN Security Council referral situations does exist. 

The reported view held by the plurality of ICC member states is that once the two conditions (ratification by at least 30 ICC member states and the decision by the ASP) are met, the Court’s exercise of the jurisdiction over the crime of aggression applies to all ICC member states (unless an opt out declaration has been submitted), regardless of individual ratification status of the amendments.

An alternate view has also been advanced stating that the Court’s exercise of jurisdiction over the crime of aggression only applies to the ICC member states who have ratified the amendments.

Table of jurisdictional regime of the Crime of Aggression applicable to Rome Statute states parties

Three ways the ICC can currently exercise jurisdiction

The Crime of Aggression has a unique jurisdictional regime, which cannot be triggered in the same manner as with other crimes of the Rome Statute (genocide, crimes against humanity and war crimes). The Court may exercise jurisdiction over the crime either by: 

  1. An ICC member state referring a situation to the Court.

  2. The prosecutor initiating an investigation proprio motu.

  3. UN Security Council referring the situation to the Court.

Except in the case of UN Security Council referrals, non-ICC member states are excluded from the Court’s jurisdiction over the crime of aggression, regardless of victim or aggressor status.

  1. In the case of a state referral (Article 15 bis), the Court will only be allowed to exercise jurisdiction if the amendments have entered into force for at least one of the ICC member states, victim or aggressor, involved. The Prosecutor must then determine there to be a reasonable basis to proceed with an investigation. If this occurs, the Prosecutor must notify the UN Secretary-General of the situation. The Security Council itself has the authority to determine, whether an act of aggression has been committed. The Prosecutor must allow the Security Council six months to make a determination. If no such determination is made, the Prosecutor may still proceed with investigation only with authorization of the Pre-Trial Division judges.
  2. In the case of the prosecutor initiating an investigation (Article 15 bis), referred to as proprio motu, the same conditions apply as in the case of Article 15 bis state referrals.
  3. In the case of a UN Security Council referral (Article 15 ter), if the UN Security Council refers a situation, the Prosecutor has the authority to investigate any of the four core crimes, including the crime of aggression, committed in any territory by any state’s national. In this situation, the Court is able to exercise jurisdiction over crimes of aggression involving ICC member states, regardless of their individual ratification status or “opt-out” status, and non-ICC member states alike.
Read moreRead less

Resources, NGO Voices