Vienna Convention on the Law of Treaties

The Vienna Convention on the Law of Treaties (VCLT) is an international agreement governing treaties entered into between States. Part I of the VCLT provides for the scope of the Convention, which covers only international agreements concluded between States in written form and governed by international law. It provides for the conclusion and entry into force of treaties, stating that every State possesses the capacity to conclude treaties. It provides the conditions whereby a person is considered as representing a State for purpose of adopting or authenticating the text of a treaty or to express consent. It also provides for the manner by which the text of a treaty is adopted or authenticated. It likewise provides for the means of expressing consent to be bound by a treaty, including expression by signatures, by an exchange of instruments constituting a treaty, by ratification, acceptance or approval and by accession. It also provides for the formulation of reservations, and acceptance of and objection to reservations.

Significantly, the VCLT codifies the principle of pacta sunt servanda, providing that every treaty in force is binding upon the parties to it and must be performed by them in good faith. Furthermore, A treaty is void if, at the time of its conclusion, it conflicts with a peremptory norm of general international law. It further provides for the conditions under which a fundamental change of circumstances may be invoked as a ground for terminating or withdrawing from a treaty.