International law is a set of rules and conventions that define acceptable behaviour between sovereign states in times of war, peace, diplomacy, trade and environmental protection. International law is a growing and evolving body of law that aims to standardise and organise international relations to attain humanity’s most important goals.

Generally, international law is based on treaties, general practice that translates into international customs and basic legal principles. A treaty is an internationally binding agreement between two or more states that is enforceable in court. A protocol is a continuing general practice that may become an international custom. International law also includes the decisions of international tribunals, as well as domestic (national) tribunals, which are considered persuasive authorities.

The Charter of the United Nations calls upon the Organization to encourage the progressive development and codification of international law. The International Law Commission, composed of 34 members representing the world’s principal legal systems, acts as an independent expert body and prepares drafts on issues of interest to international law. The Commission consults with other specialized agencies and the International Court of Justice, as necessary.

Despite the idealistic goal of establishing an international system of law, the world descended into two calamitous world wars in the first half of the twentieth century, dealing a crushing blow to the idea that international law alone could tame the human impulse for violence and conflict. The concept of state sovereignty — the principle that each country’s government is supreme and not subject to the laws of other countries or bodies — is at the heart of much of modern debate on the legitimacy and enforceability of international law.