Vienna Convention on the Law of Treaties

The Vienna Convention on the Law of Treaties is an international treaty that sets out rules on how treaties between states are made, interpreted, amended and ended, and is often described as the treaty on treaties. It was drawn up by the International Law Commission of the United Nations and adopted at a conference in Vienna, and entered into force in 1980. It confirms the principle that treaties must be kept, known as pacta sunt servanda, and provides for the invalidity of treaties that conflict with peremptory norms of international law, called jus cogens. Many of its provisions are considered to reflect customary international law, and so also bind countries that are not parties to it.

Open on the timeline