Vienna Convention on the Law of Treaties

The 1969 Vienna Convention on the Law of Treaties (or VCLT) codified the pre-existing customary international law on treaties, with some necessary gap-filling and clarifications. The Convention entered into force on January 27, 1980. 108 states have ratified the VCLT (May, 2007); those that have not may still recognize it as binding upon them in as much as it is a restatement of customary law.
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