Originally focusing on wartime laws, international law has grown to encompass all aspects of human activity. As with national law, international law is a set of rules and normative guidelines that guide international actors. It provides a common conceptual framework for states, covering many areas, including economics, international non-state groups, and the law of war. It also serves as a framework for international organizations, such as the United Nations.

A variety of sources contribute to the development of international law, including customs, state practice, and judicial decisions. In addition to international treaties, the International Court of Justice (ICJ) plays a significant role. The ICJ gives advisory opinions on legal questions referred to it by authorized international organs.

During the 19th century, positivism became more prevalent. As international organizations emerged, the influence of positivism declined. However, natural rights continued to be influential in international politics during the republican revolutions in the United States.

The United Nations is the main deliberative body for international law. It has a General Assembly that consists of representatives from all UN Member States. It also has a Security Council that authorizes the use of force and approves peacekeeping missions.

The International Court of Justice (ICJ) is the principal judicial organ of the United Nations. It has 18 judges who are elected by state parties for nine-year terms. The ICJ does not have supreme executive authority. Nevertheless, the court has the ability to prosecute national leaders for serious human rights violations.