Public international law concerns the structure and conduct of states and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond domestic legal interpretation and enforcement. Public international law has increased in use and importance vastly over the twentieth century, due all to the increase in global trade, armed conflict, environmental deterioration on a worldwide scale, awareness of human rights violations, rapid and vast increases in international transportation and a boom in global communications.
Public international law is sometimes called the "law of nations". It should not be confused with "private international law", which is concerned with the resolution of conflict of laws. In its most general sense, international law "consists of rules and principles of general application dealing with the conduct of states and of intergovernmental organizations and with their relations inter se, as well as with some of their relations with persons, whether natural or juridical.
Public international law establishes the framework and the criteria for identifying states as the principal actors in the international legal system. As the existence of a state presupposes control and jurisdiction over territory, international law deals with the acquisition of territory, state immunity and the legal responsibility of states in their conduct with each other. International law is similarly concerned with the treatment of individuals within state boundaries. There is thus a comprehensive regime dealing with group rights, the treatment of aliens, the rights of refugees, international crimes, nationality problems, and human rights generally. It further includes the important functions of the maintenance of international peace and security, arms control, the pacific settlement of disputes and the regulation of the use of force in international relations. Even when the law is not able to stop the outbreak of war, it has developed principles to govern the conduct of hostilities and the treatment of prisoners. International law is also used to govern issues relating to the global environment, the global commons such as international waters and outer space, global communications, and world trade. Written by:Abolfazl shiralizadeh
Preamble of the UN charter