The Iraq war was a multiple assault on the foundations and rules of the existing UN-centred world order. It called into question the adequacy of the existing institutions for articulating global norms and enforcing compliance with the demands of the international community. It was simultaneously a test of the UN’s willingness and ability to deal with brutal dictatorships and a searching scrutiny of the nature and exercise of American power. The United States has global power, soft as well as hard; the United Nations is the fount of international authority. Progress towards a world of a rules-based, civilized international order requires that US force be put to the service of lawful international authority. This book examines these major normative and structural challenges from a number of different perspectives.