2 The Rome Statute provided, in Article 5 (1), that the crime of aggression is one of the four crimes over which the Court ‘has jurisdiction’, along with the crime of genocide, crimes against humanity, and war crimes. But the ‘exercise’ of aggression jurisdiction was postponed. Article 5 (2) provided that:
3 Article 5 (2) foresaw two future tasks, ‘defining the crime’, and ‘setting out the conditions’ for the ‘exercise’ of jurisdiction over it. ‘Defining’ was necessary because earlier efforts at making the crime concrete, notably the Charters of the Nuremberg and Tokyo Tribunals (International Military Tribunals), had been rudimentary at best. While most participants in Rome were of the opinion that the crime existed under international customary law, there was significant disagreement about its parameters. The principle of legality (Nulla poena nullum crimen sine lege) dictated that definition of its substantive, criminal law elements was fundamental to prosecuting the crime under the Statute.
4 ‘Conditions’ was itself ambiguous. It was ultimately required to carry significant freight concerning how much the procedural structure for the crime of aggression could differ from the structure the Statute applied to the other three crimes. This included, in particular, the role of the United Nations Security Council (‘Security Council’; United Nations, Security Council) in relation to this crime. It also implicated the (non-)application of the Statute to the nationals of States that are not party to the Statute, and the extent to which it would even be applicable to all States Parties to the Statute.
5 Article 5 (1) is about the subject-matter of the Court’s jurisdiction, the four crimes over which it has competence. Article 5 (2)’s words ‘exercise of jurisdiction’ relate, inter alia, to other aspects of jurisdictional competence than subject-matter jurisdiction.
7 Second, the phrase ‘exercise of jurisdiction’ in Article 5 echoes Article 12 of the Statute, titled ‘Preconditions to the exercise of jurisdiction’. Article 12 (1) provides that a State which becomes a party to the Statute thereby accepts the jurisdiction of the Court with respect to the four crimes referred to in Article 5. Article 12 (2) provides that, in the case of referrals to the Prosecutor by a State Party, or in the case where the Prosecutor exercises his or her proprio motu power to commence proceedings, the Court may exercise its jurisdiction if one or more relevant States have accepted the jurisdiction of the Court. These are ‘(a) the State on the territory of which the conduct in question occurred or, if the crime was committed on board a vessel or aircraft, the State of registration of that vessel or aircraft’, or ‘(b) the State of which the person accused is a national’. It is striking that, in the case of a referral by the Security Council (Art 13 (b) Rome Statute), there is no requirement that the territorial State or the State of nationality of the accused be a party to the Statute. Article 13 (b) is a form of universal jurisdiction.
8 Article 12 is thus about jurisdiction over persons, jurisdiction ratione personae—in respect of whom may the Court take adjudicative power? The Court has jurisdiction only over natural persons (Art 25 (1) Rome Statute) but, in the absence of a Security Council referral, those persons must fit one of the categories delineated in Article 12. They must act within the territorial jurisdiction of a State Party, or be a national of a State Party to the Statute.
9 As we shall see below (paras 27–31, 41, 44–45), the Statute also speaks to ‘exercise of jurisdiction’ in one of its amendment provisions, Article 121 (5), which likewise refers to jurisdiction over persons.
10 ‘Exercise of jurisdiction’ in Article 5 (2) Rome Statute, then, implied that attention needed to be paid, in negotiating a ‘provision’ on aggression, to the trigger mechanism, to jurisdiction ratione personae, and perhaps to amendment modalities.
11 To complete the background from Rome: Resolution F of the Final Act of the Rome Conference established a Preparatory Commission to facilitate the entry into force of the Statute. Among its tasks was to ‘prepare proposals for a provision on aggression, including the definition and Elements of Crimes of Aggression and the conditions under which the International Criminal Court shall exercise its jurisdiction with respect to this crime’ (Resolution F). The Resolution contemplated submission of the ‘provision’ to a Review Conference to be convened seven years after the Statute came into force. Aggression was, indeed, the main business of the Review Conference held in Kampala, Uganda, in 2010. ‘A provision’ in Article 5 (2) and Resolution F was an understatement of the task, as the Amendments required new articles to be added to the Statute, alterations to others, a set of Elements of Crimes (‘Elements’), and a group of Understandings (Crime of aggression, RC/Res.6; and, generally, Barriga and Kress, 2012, passim).