Article 42 Vienna Convention on the Law of Treaties
Validity and continuance in force of treaties
1. The validity of a treaty or of the consent of a State to be bound by a treaty may be impeached only through the application of the present Convention.
2. The termination of a treaty, its denunciation or the withdrawal of a party, may take place only as a result of the application of the provisions of the treaty or of the present Convention. The same rule applies to suspension of the operation of a treaty.
See also: Article 41 Vienna Convention on the Law of Treaties