The earliest conventions of international law were probably laid down during the medieval period, with states reaching a mutual understanding between themselves of how they should behave towards each other. However, the first time the idea of an official international law that applied only to states appeared was in the works of the philosopher Jeremy Bentham in the 18th century.
The United Nations, as the world's governing body, has not surprisingly been one of the main bodies where the topic of international law enforcement has been debated and the conclusions been implemented. However, it does not directly play much of a role in enforcing international law as it comes up with resolutions rather than binding statements. International law enforcement between states is instead left to the United Nations Security Council and the International Court of Justice (ICJ). For cases involving non-state actors committing international crimes then international agencies such as Interpol and Europol would be responsible for enforcing international law.
The key body in international law enforcement is the International Criminal Court or ICC. It is a permanent court set up to prosecute individuals for crimes of genocide, crimes against humanity or war crimes. It was set up by the Rome Statute of the International Criminal Court in 2002. Its official headquarters is in The Hague in the Netherlands, but judicial proceedings can take place anywhere around the world. There are 115 members of the ICC, with a 116th, Tunisia, joining as of September 2011. Unlike the International Court of Justice, the ICC is independent of the UN. Article 13 of the United Nations Security Council does allow it to refer situations to the ICC if needed, which it used in relation to the Darfur genocide.
The United Nations Security Council is tasked with preventing wars taking place between nations. It was founded in January 1946 after the end of World War II, with the winning powers of the war having permanent seats on the council, those being the United States, the United Kingdom, Russia, France and China. The aim of the United Nations Security Council is to intervene in situations where international conflict may occur. The United Nations Security Council can also refer cases to the International Criminal Court which would normally lie outside of its jurisdiction.
For non-state actors, Interpol, or to use its full title the International Criminal Police Organization, aims to facilitate police cooperation internationally in order to solve international criminal investigations and bring to justice those criminals who operate across borders. It was founded in 1923 under the name of the International Criminal Police Commission. In 1956 it changed its name to its current title, Interpol. Interpol currently has 188 member countries and it is the world's second largest intergovernmental organization, ranked only behind the United Nations.
Interpol aims to maintain political neutrality and its constitution does not allow it to become involved in any political, racial, military or religious crimes. Instead, Interpol focuses on solving crimes that could potentially affect the public's safety. These include: terrorism, organized crime, genocide, environmental crimes, the production of and trafficking illegal drugs, money laundering, weapons smuggling, piracy, human trafficking, child pornography, intellectual property theft and corruption.
Although Interpol was officially created in 1923, the initial discussions to create an international body to help national police forces work together actually started in 1914 when representatives from fourteen countries met in Monaco to discuss arrest procedures, extradition proceedings, identification techniques and the creation of an international criminal recording system. Unsurprisingly these attempts were delayed by the outbreak of World War I and it was only at the Second International Police Congress in Vienna in 1923 that the first formulation of Interpol was created. The founding members of Interpol were Austria, Belgium, China, Egypt, France, Germany, Greece, Hungary, Italy, the Netherlands, Romania, Sweden, Switzerland and Yugoslavia. The United States, which at that point had an isolationist international policy, did not join until 1938.
As a result of the Nazi invasion of Austria, Interpol was actually under the auspices of the Nazis until 1945. Its leaders during this period were all generals in the SS. After the Nazi's defeat, Interpol moved its headquarters to Saint-Cloud near Paris, and then in 1989 relocated to Lyons with Khoo Boon Hui from Singapore as president. International law enforcement was also helped by the end of the cold war as the West and the East were able to work together more freely due an end in tensions between the U.S. and USSR