This article highlights the main achievement of the Report of the International Commission on Intervention and State Sovereignty (ICISS): the establishment of the foundations for a new normative and operational consensus on the role of military intervention for humanitarian purposes. Most significantly, the report moves beyond the political debates and conceptual histories surrounding the polarized notions of military intervention and state sovereignty, and introduces the concept of the ‘responsibility to protect’ to bridge the polemical–political divide. This concept encapsulates the growing necessity for the norm of non-intervention to yield to the principle of international responsibility to protect foreign populations under threat of mass killings and ethnic cleansing, where these populations’ governments are either complicit or ineffectual. The ideas contained in the report are based on a spectrum of philosophical principles relevant to different actors, from the more general principles of the responsibility to prevent conflict and to rebuild peace, to the more specific threshold criteria and cautionary principles – right authority and due process – to ensure the ethical legitimacy of intervention on the basis of the responsibility to protect. The article concludes with some reflections on the role of the UN and leading powers in the implementation of this framework, and the usefulness of the precautionary principle to avoid irreversible humanitarian atrocities.