Just as there is a law in every state that should be respected by its citizens, there are certain laws in the world that countries should respect when they deal with each other. One of the oldest examples of such laws comes from a stone tablet about 5000 years old. It records a treaty (or agreement) between two small states of Mesopotamia.
In modern times, a Dutch Jurist Hugo Grotius (1583 1645) published an important book in 1625. It was called The Laws of War and Peace. The concept was developed as the world became more civilized, and a very famous incident happened in1864. That year, many nations of the world met in Geneva (Switzerland) and agreed that wounded soldiers in war must be treated kindly. This agreement was called the Geneva Convention, and it has remained an important part of International Law. You have read that Nazi Germans and the Japanese killed and tortured many innocent citizens during the Second World War. At the end of the war in 1945, they were also tried for war crimes under the Geneva Convention. Similarly, Bosnian Serb leaders who committed crimes against the Muslim citizens of Bosnia Herzegovina in the 1990s were tried under the International Law.
Who makes International Law? The answer is everyone! International Law is based on the common principle of fairness and kindness, which is respected in every civilization. The UN, especially the World Court has also passed several laws that have been accepted by the member states, and they form part of the International Law.