Chapter 3 analyses the prevailing theory that the ICC’s jurisdiction is based on delegation from States Parties. It provides a review of scholarship published in the years following the adoption of the Rome Statute and adopts one of the principal conclusions from this early debate: that States may lawfully delegate jurisdiction to an international court. This chapter then proceeds to undertake a conceptual analysis of what delegation of jurisdiction actually entails in the context of the ICC. It explores how the concept of delegation is understood in international institutional law, which provides a framework for understanding how international institutions receive and exercise their powers. This is directly relevant for the ICC as an international organisation. The second part of this chapter demonstrates the utility of describing jurisdiction as ‘the legal right to exercise powers’. It also provides an overview of the principles of international law under which a State may exercise jurisdiction extraterritorially and explains how these apply to the Statute’s jurisdiction regime. It argues that delegation of jurisdiction is, in theory, a sound legal basis for the ICC’s jurisdiction when either the territorial State or the State of nationality has consented to the Statute.