Article 20
Acceptance of and objection to reservations
1.A reservation expressly authorized by a treaty does not require any subsequent acceptance by the contracting States and contracting organizations or, as the case may be, by the contracting organizations unless the treaty so provides.
2.When it appears from the limited number of the negotiating States and negotiating organizations or, as the case may be, of the negotiating organizations and the object and purpose of a treaty that the application of the treaty in its entirety between all the parties is an essential condition of the consent of each one to be bound by the treaty, a reservation requires acceptance by all the parties.
3.When a treaty is a constituent instrument of an international organization and unless it otherwise provides, a reservation requires the acceptance of the competent organ of that organization.
4. In cases not falling under the preceding paragraphs and unless the treaty otherwise provides:
(a) acceptance of a reservation by a contracting State or by a contracting organization constitutes the reserving State or international organization a party to the treaty in relation to the accepting State or organization if or when the treaty is in force for the reserving State or organization and for the accepting State or organization;
(b) an objection by a contracting State or by a contracting organization to a reservation does not preclude the entry into force of the treaty as between the objecting State or international organization and the reserving State or organization unless a contrary intention is definitely expressed by the objecting State or organization;
(c) an act expressing the consent of a State or of an international organization to be bound by the treaty and containing a reservation is effective as soon as at least one contracting State or one contracting organization has accepted the reservation. 5. For the purposes of paragraphs 2 and 4, and unless the treaty otherwise provides, a reservation is considered to have been accepted by a State or an international organization if it shall have raised no objection to the reservation by the end of a period of twelve months after it was notified of the reservation or by the date on which it expressed its consent to be bound by the treaty, whichever is later.
Article 21
Legal effects o f reservations and of objections to reservations
1. A reservation established with regard to another party in accordance with articles 19, 20 and 23:
(a) modifies for the reserving State or international organization in its relations with that other party the provisions of the treaty to which the reservation relates to the extent of the reservation; and
(b) modifies those provisions to the same extent for that other party in its relations with the reserving State or international organization.
