Vienna Convention on the Law of Treaties

Vienna Convention
on the Law of Treaties

Vienna Convention on the Law of Treaties   Parties   Signatories   Non-parties
Signed	23 May 1969
Location	Vienna
Effective	27 January 1980
Condition	Ratification by 35 states[1]
Signatories	45
Parties	116 (as of January 2018)[2]
Depositary	UN Secretary-General
Languages	Arabic, Chinese, English, French, Russian and Spanish[1]
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The Vienna Convention on the Law of Treaties (VCLT) is an international agreement that regulates treaties among sovereign states.

Known as the "treaty on treaties", the VCLT establishes comprehensive, operational guidelines, rules, and procedures for how treaties are drafted, defined, amended, and interpreted.^[3] An international treaty is a written agreement between countries subject to international law that stipulates their consent to the creation, alteration, or termination of their rights and obligations, as stipulated in the treaty.^[4]

The Vienna Convention on the Law of Treaties was adopted and opened to signature on 23 May 1969,^[5][1] became effective on 27 January 1980,^[1] and has been ratified by 116 sovereign states as of January 2018.^[2] Non-ratifying parties, such as the U.S., have recognized parts of the VCLT as a restatement of customary international law.^[6] In treaty law, the VCLT is the authority for resolving disputes about the interpretation of a treaty.^[7]