The territorial scope of the jurisdiction of the International Criminal Court was an issue which was hotly debated prior to the adoption of the Rome Statute. Yet, in the first 10 years of the Court's operation the negotiators' concerns with regard to a jurisdictional overreach seem to have been misplaced. To date, the interpretation and application of Article 12(2)(a) of the Rome Statute – the key provision in this context – have remained uncontroversial. This practice, however, has left certain important questions untouched, and particularly the issue of jurisdiction in cases of the partial commission of a crime on State Party territory. In this context, the question is how little of an international crime should take place on State Party territory for the ICC to have jurisdiction. It is hereby suggested that in order to answer this question, the Court may have recourse to the jurisdictional rule of reason developed by Francis Mann in the context of his work on state jurisdiction and antitrust law. In this context, it is suggested that the Court would have jurisdiction over any case or situation that would have a sufficiently strong connection with the territory of a State Party. The meaning of a ‘sufficiently strong connection’ – an essential ‘reasonableness’ approach, showing the absence of an abuse of rights or arbitrariness – would then need to be specified on a case-by-case basis.