The Law and Practice as to Treaties The Vienna Convention on the Law of Treaties
The Vienna Convention on the Law of Treaties (VCLT) is an international agreement regulating treaties between states.[3] Known as the "treaty on treaties", it establishes comprehensive rules, procedures, and guidelines for how treaties are defined, drafted, amended, interpreted, and generally operate.[4] The VCLT is considered a codification of customary international law and state practice concerning treaties.[5]
The Convention was adopted and opened to signature on 23 May 1969,[6][1] and entered into force on 27 January 1980.[1] It has been ratified by 116 states as of January 2018.[2] Some non-ratifying parties, such as the United States, recognize parts of it as a restatement of customary law and binding upon them as such.[7]
The VCLT is regarded as one of the most important instruments in treaty law, and remains an authoritative guide in disputes over treaty interpretation.
