Article 15
Consent to be bound by a treaty expressed by accession
The consent of a State or of an international organization to be bound by a treaty is expressed by
accession when:
(a) the treaty provides that such consent may be expressed by that State or that organization by means of accession;
(b) it is otherwise established that the negotiating States and negotiating organizations or, as the case may be, the negotiating organizations were agreed that such consent may be expressed by that State or that organization by means of accession; or
(c) all the parties have subsequently agreed that such consent may be expressed by that State or that organization by means of accession.
Article 16
Exchange or deposit of instruments of ratification, formal
confirmation, acceptance, approval or accession
1.Unless the treaty otherwise provides, instruments of ratification, instruments relating to an act of formal confirmation or instruments of acceptance, approval or accession establish the consent of a State or of an international organization to be bound by a treaty between one or more States and one or more international organizations upon:
(a) their exchange between the contracting States and contracting organizations;
(b) their deposit with the depositary; or
(c) their notification to the contracting States and to the contracting organizations or to the depositary, if so agreed.
2. Unless the treaty otherwise provides, instruments relating to an act of formal confirmation or instruments of acceptance, approval or accession establish the consent of an international organization to be bound by a treaty between international organizations upon:
(a) their exchange between the contracting organizations;
(b) their deposit with the depositary; or
(c) their notification to the contracting organizations or to the depositary, if so agreed.
