This article explores the different moral and legal arguments used by protagonists in the debate about whether or not to conduct a humanitarian intervention in Darfur. The first section briefly outlines four moral and legal positions on whether there is (and should be) a right and/or duty of humanitarian intervention: communitarianism, restrictionist and counter-restrictionist legal positivism and liberal cosmopolitanism. The second section then provides an overview of the Security Council's debate about responding to Darfur's crisis, showing how its policy was influenced by both normative concerns and hard-nosed political calculations. The article concludes by asking what Darfur's case reveals about the legitimacy and likelihood of humanitarian intervention in such catastrophes and the role of the UN Security Council as the primary authorising body for the use of international force. The authors argue that this case demonstrates that for the cosmopolitan/counter-restrictionist case to prevail pivotal states need to put humanitarian emergencies on the global agenda and express a willingness to act without Council authorisation, though the question of how to proceed in cases where the Council is deadlocked remains vexed.