A central and defining feature of international relations is the condition of anarchy, a term that means the lack of world government. Without an overarching supranational force to constrain the behaviour of states and individuals, the anarchic system is inherently conflict prone. Since reordering the international system in an effort to avoid anarchy is highly unlikely, states promote order and clarity in world politics by developing and maintaining rules of behaviour. International laws have been developed in virtually every area of international relations, ranging from trade to diplomatic immunity, air space to the law of the sea. An area of consistent concern and of utmost importance to countries is war. As a result, a significant amount of time and energy have been devoted to drafting international laws that regulate armed conflict. This chapter seeks to explain efforts by the international community to eliminate, mitigate, or reduce the destructive behaviour of states towards one another and towards their own citizens through the adoption and application of international law. Attention is divided into three main areas: the laws that regulate the use of force, human rights laws that protect individuals from repressive treatment, and the institutions that are used to enforce these standards. Contemporary developments, including the concept of Responsibility to Protect (R2P) and the International Criminal Court (ICC), are considered helpful stepping stones.