Public international law deals with the structure and conduct of states and intergovernmental organizations. Public international law may also affect multinational corporations and individuals. Public international law has increased in use and importance tremendously during the 20th century due to increase in global trade, armed conflict, environmental deterioration, human rights violations, international transportation, and a boom in global communications. Within public international law, there are two main branches. These are the law of nations and international agreements and conventions. In public international law, the framework and criteria for acknowledging states as the main actors in a legal system that goes beyond borders is established. These laws delve into areas such as acquisition of territory, state immunity, and the interaction between states and international laws. Public international law also has jurisdiction over matters such as group rights, the treatment of aliens, the rights of refugees, international crimes, nationality problems, and human rights.
Furthermore, public international law also covers grounds such as global environment, the global commons such as international waters, outer space, global communications, and world trade. Within public international law, all states are sovereign thus considered equal.
Public international law has a great deal of grey areas as there is no established legal and judicial system for the mediation of disputes, nor is there a strict penal code it is a difficult task for lawyers to carry out their tasks. Initially, states and the Holy See were the main subjects of international law. However, with the increase in international organizations over the last century, international human rights law, international humanitarian law, and international trade laws have also made its way into public international law.
In public international law, there has been a history of tension between sovereign states and the law. Majority of people view the state as the final say in international affairs and they should be given the right to voluntarily enter into treaties of international law while also being able to maintain the right of seeking and following their own counsel. Furthermore, each nation has its own interpretations on laws based on their customs, traditions, and political situations. The final say in these matters belong to the courts who will decide what the laws mean, and in certain cases where the courts do not have a say, it is the responsibility of the states to interpret the law for themselves.
Since international law exists in a legal environment without an overarching state, some ignore certain aspects of public international law, therefore it is difficult to enforce anything. In the United Nations, there has been a movement called “Uniting for Peace” and it is a resolution that called for nation states to agree to public international law and do their level best to adhere to the guidelines.
Public international law is extremely important, therefore many aspects have been taken from it and have manifested itself in the form of customary law, and other laws that the International Court of Justice upholds.