This chapter focuses specifically on the Council’s contribution to the international law on the use of force (the jus ad bellum), an area of international law that is central to the Security Council’s role in the maintenance of international peace and security and the collective security system of the United Nations. The chapter addresses, first, the general state of the rules of international law on the use of force (the jus ad bellum). It then outlines the rules themselves. This is followed by sections relating directly to the Security Council: the prohibition of the use of force; the use of force by or authorized by the Council; the Council and the right of self-defence; and the Council and ‘humanitarian intervention’ and ‘responsibility to protect’.