The Special Working Group on the Crime of Aggression, whose work was aimed at completing the definition of aggression for the purposes of the Rome Statute of the International Criminal Court, discussed complementarity only briefly. That discussion suggests, correctly in the author's opinion, that the complementarity doctrine applies to this crime essentially as it does in respect of the other crimes within the jurisdiction of the International Criminal Court (‘ICC’). Aggression, however, raises acutely an issue that was glossed over in the Rome negotiations and in most of the secondary literature: does ‘a State which has jurisdiction’, as referred to in Article 17 of the Statute, include a state which asserts competence on the basis of a universal jurisdiction theory? In short, can a court, sitting neither in the aggressor state nor the victim state assert ‘able and willing’ jurisdiction such as to trump the jurisdiction of the ICC. This chapter discusses these issues and raises the question whether, under international customary law, there is jurisdiction over the crime of aggression in third-party states based on a universal jurisdiction theory. Beyond that, it seems clear that complementarity applies to prosecutions in either a victim state (which has territoriality or effects jurisdiction), or an aggressor state (where there is territoriality or nationality jurisdiction).

Introduction

Article 5 of the Rome Statute of the International Criminal Court states that ‘the crime of aggression’ is one of the four crimes within the jurisdiction of the Court. It adds that the Court shall only exercise its jurisdiction over the crime ‘once a provision is adopted in accordance with articles 121 and 123 defining the crime and setting out the conditions under which the Court shall exercise jurisdiction with respect to this crime’. Devising an appropriate ‘provision’ (or provisions) was the function of the Court's Special Working Group on the Crime of Aggression (‘SWGCA’). The Special Working Group completed its work in February 2009. Its proposals for enabling the Court to exercise jurisdiction over the crime of aggression were the main item on the agenda at the 2010 Review Conference on the Court's Statute, held in Kampala, Uganda. The Review Conference duly adopted amendments designed to activate the Court's jurisdiction over the crime of aggression, based on the SWGA's draft, but with significant developments to the parts of the draft concerned with the ‘conditions’ for exercise of jurisdiction.