Unlike international law, national law is a domestic legal system that is established by a nation. It is enforced by governmental bodies. It is generally accepted as the rule of law by the entire population of the country.
International law consists of treaties between two or more countries. These treaties often create agencies of governance and judicial bodies. Some international bodies include the United Nations and European Union. These agencies of governance can help states interpret international law.
International law can also reflect international comity. Countries cooperate with one another on military matters and other international matters. A treaty is not enforceable by force, but it can be a basis for mutual recognition.
In the 18th century, the concept of jus gentium was argued by Hugo Grotius. He argued that universal principles should govern persons and nations.
The Peace of Westphalia was a major event in international law. It established independent sovereign entities known as “nation states”. Other states subscribed to limitations on their conduct.
In the early 20th century, the naturalist school of international law gained prominence. The positivist school was also influential. The naturalist approach argues that international norms should be based on axiomatic truths. The positivist approach is based on the idea that international law should be based on general principles.
Many common law countries only enforce provisions that are directly incorporated into their own national law. However, some states do not recognize judge made laws.
The concept of international law has become more prevalent in the last two decades. Many developing world democracies support the United Nations Charter and international law at the bilateral and multilateral levels. They also often demand non-interference in their own domestic affairs.