Signature of a treaty
By signing an international treaty, a state signals its intention to become a state party to it in the future.
In most cases, signing an international treaty does not make the signatory a state party, thereby requiring it to implement the treaty’s provisions (this requires the further act of ratification).
A signatory state must not, though, undertake any action that would ‘defeat’ (i.e. frustrate or undermine) the object and purpose of the treaty. This obligation is set out in Article 18 of the 1969 Vienna Convention on the Law of Treaties, a provision that has attained the status of customary international law applicable to all states.
Last updated on: 08 August 2017