Vienna Convention on the Law of Treaties

The Vienna Convention on the Law of Treaties (VCLT) was adopted in Vienna on May 23, 1969 at the United Nations Conference on the law of treaties and entered into force on January 27, 1980. This Convention applies only to treaties which are concluded by states.  This Convention applies to any treaty which is the constituent instrument of an international organization and to any treaty adopted within an international organization without prejudice to any relevant rules of the organization.