Short answers, pulled from the story.
Jeremy Bentham coined the term international law in 1789 to replace the older concept of the law of nations. The system he described has no single sovereign power to enforce it and operates largely through the consent of sovereign states.
Some of the earliest recorded examples of international law are peace treaties between the Mesopotamian city-states of Lagash and Umma around 3100 BCE. Another early agreement was concluded in 1279 BCE between the Egyptian pharaoh Ramesses II and the Hittite king Hattusili III.
Dutch jurist Hugo Grotius, who lived from 1583 to 1645, is widely regarded as the father of international law. His seminal 1625 work, De Jure Belli ac Pacis, laid down a system of principles of natural law that bind all nations regardless of local custom or law.
The United Nations was established in 1945 to replace the League of Nations. Its aim was to maintain collective security and a more robust international legal order buttressed by institutions such as the International Court of Justice and the UN Security Council.
There are 123 state parties to the International Criminal Court, although a number of states have declared their opposition to the court. The International Criminal Court was established by the 1998 Rome Statute and is the first and only permanent international court to prosecute genocide, war crimes, crimes against humanity, and the crime of aggression.
The United Nations Convention on the Law of the Sea defined the boundaries of a nation's territorial sea as being at most 12 nautical miles from the baseline. A state can claim a contiguous zone of up to 24 nautical miles from the baseline and an exclusive economic zone stretching up to 200 nautical miles from the baseline.