Article 15 Vienna Convention on the Law of Treaties
Consent to be bound by a treaty expressed by accession
The consent of a State to be bound by a treaty is expressed by accession when:
(a) the treaty provides that such consent may be expressed by that State by means of accession;
(b) it is otherwise established that the negotiating States were agreed that such consent may be expressed by that State by means of accession; or
(c) all the parties have subsequently agreed that such consent may be expressed by that State by means of accession.
See also: Article 14 Vienna Convention on the Law of Treaties
