How the International Criminal Court Works

Reviewed 18 September 2026. This is an evergreen explainer; case-specific legal findings should be checked against the newest authoritative source.

In short: Jurisdiction, complementarity, investigations, arrest warrants and trials at the ICC—explained without treating an accusation as a conviction.

The International Criminal Court is a permanent international criminal court created by the Rome Statute. It investigates and tries individuals, not States, and it is designed to complement rather than automatically replace national criminal justice systems.

Which crimes fall within the ICC’s mandate?

The Rome Statute covers genocide, crimes against humanity, war crimes and the crime of aggression, subject to specific legal and jurisdictional requirements. The Court does not have general authority over every serious crime committed anywhere in the world.

How can the Court obtain jurisdiction?

Jurisdiction is a threshold question. Relevant routes can include crimes committed on the territory of a State Party, crimes committed by nationals of a State Party, acceptance of jurisdiction by a non-party State for a particular situation, or a UN Security Council referral under the Rome Statute framework. Time limits also matter: the Court generally cannot prosecute conduct before its jurisdiction became applicable.

Complementarity: why national courts come first

The ICC is often described as a court of last resort. Under the principle of complementarity, a case may be inadmissible where a State with jurisdiction is genuinely investigating or prosecuting it. The legal analysis is more precise than simply asking whether a domestic case exists; the Court examines admissibility under the Statute.

Investigation, warrant, charges and trial are separate stages

An investigation gathers evidence. An arrest warrant or summons is based on the legal standard applicable at that stage. Confirmation of charges determines whether there is sufficient evidence for a case to proceed to trial. A conviction requires proof beyond a reasonable doubt. Responsible reporting should state the stage rather than using “ICC case” as if all stages were equivalent.

Why arrest warrants can remain outstanding

The ICC has no global police force. Arrest and surrender generally depend on State cooperation. A warrant can therefore remain outstanding for years if the suspect is not arrested in a place where authorities are willing and able to execute it.

What victims can do

The Rome Statute system includes roles for victims that are unusual in many international proceedings, including participation through legal representatives in certain circumstances and possible reparations after convictions. The precise rights depend on the stage and judicial decisions in the case.

Frequently asked questions

Can the ICC try someone in absentia?

The ICC generally requires the accused to be present for trial under the Rome Statute framework.

Does an arrest warrant mean guilt has been proved?

No. Guilt is determined only after a trial and the applicable criminal standard of proof.

Can countries that are not ICC members ever fall within ICC jurisdiction?

Yes, in some circumstances, including territorial jurisdiction accepted by a State or a Security Council referral.