Article 13 Vienna Convention on the Law of Treaties
Consent to be bound by a treaty expressed by an exchange of instruments constituting a treaty
The consent of States to be bound by a treaty constituted by instruments exchanged between them is expressed by that exchange when:
(a) the instruments provide that their exchange shall have that effect; or
(b) it is otherwise established that those States were agreed that the exchange of instruments should have that effect.
See also: Article 12 Vienna Convention on the Law of Treaties
