For the complete documentation index, see llms.txt.
Skip to main content
New
20% · 1/5
Lesson 12 min 20 XP

The Complementarity Principle

How the ICC's relationship with national courts works and why complementarity is both the Court's greatest strength and limitation.

Last Resort, Not First Resort

Complementarity is the foundational principle governing the ICC's relationship with national courts. Under Articles 17 and 20 of the Rome Statute, the ICC can only exercise jurisdiction when national courts are 'unwilling or unable genuinely' to investigate and prosecute. This makes the ICC a court of last resort: it does not replace national justice systems but steps in only when they fail.

Unwillingness is assessed by examining whether national proceedings are designed to shield the person from criminal responsibility, whether there has been an unjustified delay inconsistent with intent to bring the person to justice, or whether proceedings are not conducted independently or impartially. Inability exists when a state's judicial system has substantially collapsed or is unavailable due to conflict or institutional dysfunction.