International law covers matters relating to the rights and responsibilities of states. In the past, only sovereign states and the Holy See were considered relevant parties in international disputes. However, today, international law also applies to corporations and individuals. Some of these entities have been recognized as relevant parties in cases involving human rights abuses.

The United Nations Charter includes the development of international law as one of its primary objectives. It is a set of rules that aims to create conditions for international justice and respect. These rules are derived from specific treaties between states. These treaties also set standards for the protection of civilians. While these treaties may not codify international law, they do serve as a foundation for international law and are used to protect civilians from war crimes.

Prior to the nineteenth century, states’ relations with each other were governed by treaties, which were not enforceable except by force. However, in the case of war, the U.S. Army and other U.S. forces enforced the Lieber Code of 1863, which is considered the first written recitation of war rules. It also led to the first ever prosecution of a war criminal, the Confederate commandant at Andersonville, Georgia.

There are several schools of international law. Some emphasize natural law while others prefer positivist approaches. Those who prefer the positivist school believe that international law is derived from state practice and normative human values.