a) By consensus
In the same way as States can conclude treaties, they can also terminate them by mutual consent. Their consent can be expressed either in the treaty itself which they had originally concluded (expiry date, denunciation clause) or thereafter (article 54), in particular through the conclusion of a later treaty aiming at achieving this very purpose (Article 59, explicit termination), or through the conclusion of a treaty relating to the same subject-matter (see Article 30 (3), implicit termination). The same rules apply for the termination as well as for the suspension of treaties (Article 57 and 59 (2)).
With regard to multlateral treaties, the
Vienna Convention authorizes two or more parties to suspend the operation of treaty provisions
- temporarily and
- as between themselves alone,
as long as this does not entail a limitation of rights or obligations of the other parties (Article 58 (1); applicaton of the principle "
pacta tertiis nec nocent nec prosunt").
Unless the treaty otherwise provides, the parties in question have to notify the other parties of their intention to conclude the agreement and of those provisions of the treaty the operation of which they intend to suspend (Article 58 (2)).
As a matter of course, where a treaty contains a denunciation clause, the parties can avail themselves of the possibility offered by it and withdraw from the treaty. The unilateral denunciation is not in contradiction to the principle of
free consent, since the possibility of such a denunciation had been agreed upon by the parties in the treaty.
