Definition
International law is the set of rules, treaties, and customs that regulate how states, international organizations, and increasingly individuals interact across borders. It covers matters such as the conduct of war, the rights of diplomats, the use of the seas, trade, and human rights.
Unlike domestic law, it has no single legislature, no global police force, and no court with compulsory authority over every dispute. It rests instead on agreements states choose to enter and on long-standing customary practice that states treat as binding.
Why it matters
How it works
International law develops through two main channels: treaties, which are explicit written agreements, and customary law, which forms when consistent state practice is followed out of a sense of obligation. Compliance is driven less by coercion than by reciprocity, reputation, and self-interest — states keep agreements because they want others to keep theirs. Institutions such as international courts, tribunals, and the United Nations help interpret and apply the rules, but powerful states can often evade unwelcome judgments. The system therefore mixes genuine constraint with persistent gaps in enforcement.