THE CRIME OF AGGRESSION AND THE COMPLEMENTARITY IMPERATIVE

The foundation of the international criminal justice system dominated by the International Criminal Court is the notion that states, and not the ICC, should take on the primary responsibility to investigate and prosecute cases of genocide, crimes against humanity and war crimes. The ICC should in principle only step in when states are unwilling or unable to deal with the matter at hand. This is known as the principle of complementarity. Needless to say, not all states are party to the ICC. However, other enforcement regimes beyond the Rome Statute of the ICC, for instance the UN Torture Convention, the Genocide Convention and the Geneva Conventions provide for an enforcement regime based on the domestication of crimes under international law and the concomitant possibility to enforce international criminal law at the national level.

The Kampala Resolution on the Crime of Aggression adopted by the Assembly of States Parties expresses the sentiment that the crime of aggression, unlike the other core crimes, should rather not be prosecuted at the national level. There is no prohibition of national prosecutions. But there is a strong hint that there should not be any progressive domestication of the crime of aggression. Understandings 4 and 5 regarding the amendments to the Rome Statute on the crime of aggression provide that the amendments to the Rome Statute are adopted for purposes of the Rome Statute only, and not to be interpreted as limiting or prejudicing in any way existing or developing rules of international law for purposes other than the Rome Statute.

It is further understood that the amendments shall not be interpreted as creating the right or obligation to exercise domestic jurisdiction with respect to an act of aggression committed by another state. The latter Understanding is actually superfluous. The Rome Statute does not create a duty on the part of states parties to criminalise the core crimes under their domestic law. Of course, there is a duty on states parties to cooperate with the ICC, but there is no duty with respect to the implementation at national level of substantive international criminal law, safe for the modification of crimes against the administration of justice, thus including the ICC administration of justice as duly protected under domestic law as well.