Chapter 5 focuses on the ICC’s relationship with the UN Security Council. Under the Rome Statute, the Council has several important roles: Article 13(b) provides that the Security Council may trigger the jurisdiction of the Court (the ‘referral power’), and under Article 16 the Council may halt any ICC investigation for twelve months at a time (the ‘deferral power’). In the 2010 Kampala Amendments, the Security Council was given a third role with respect to the Court’s jurisdiction over the crime of aggression. The first part of Chapter 5 critically examines the ways in which the Council has used Article 16 in an attempt to limit the jurisdiction of the Court. It then discusses the Article 13(b) referral power by using the Darfur and Libya situations as case studies. It argues that the legal basis for the ICC’s authority in those situations is grounded in the implied consent of Sudan and Libya to the jurisdiction of the Court by virtue of their membership of the UN. The final part of Chapter 5 considers the role of the Security Council with respect to the crime of aggression and the consequences of this for States not party to the Rome Statute.