This half-unit course examines the law relating to when it is permissible to use force (jus ad bellum). The aim of this course is to develop an understanding of the principles of international law that regulate the use of force in international society. It concentrates on the prohibition of resort to force in Article 2(4) of the United Nations Charter and the exceptions to that prohibition, namely Security Council authorisation and self-defence. It looks in detail at the right of self-defence, humanitarian intervention and the criminalization of aggression.