- International courts do not have the resources or the powers to prosecute all perpetrators of international crimes.
- Various treaties impose obligations on states to extradite or prosecute a person found in their territory who is suspected of certain specific offences. This obligation is known as aut dedere aut judicare.
- For the 'core crimes' of genocide, war crimes and crimes against humanity, there is a treaty-based obligation aut dedere aut judicare only for grave breaches of the Geneva Conventions and Additional Protocol I. For the other core crimes it is questionable whether customary international law imposes such an obligation.
- The obligation aut dedere aut judicare is distinct from the principle of universal jurisdiction, which provides a basis for prosecution but does not, in itself, imply any obligation to extradite or prosecute.
- Immunity of state officials, which acts as an obstacle to the exercise by a state of its jurisdiction, could, in practice, preclude the effective application of the obligation to extradite or prosecute.
- For the core crimes of genocide, war crimes and crimes against humanity a treaty imposing an international obligation on states to extradite or prosecute would help to bring perpetrators to justice.