Glossary of Select Depositary Terms
Signature Subject to Ratification, Acceptance or Approval
Upon their adoption, treaties are open for signature for a certain period of time and at a venue explicitly specified in the treaty itself. Where the treaty provides that signature is subject to ratification, acceptance or approval, the signature does not establish the consent to be bound. However, it is a means of authentication and expresses the willingness of the signatory state to continue the treaty-making process. The signature qualifies the signatory state to proceed to ratification, acceptance or approval. It also creates an obligation to refrain, in good faith, from acts that would defeat the object and the purpose of the treaty.
[Reference: Articles.10 and 18, Vienna Convention on the Law of Treaties 1969]
Ratification defines the international act whereby a state indicates its consent to be bound to a treaty. In the case of bilateral treaties, ratification is usually accomplished by exchanging the requisite instruments, while in the case of multilateral treaties the usual procedure is for the depositary to collect the ratifications of all states, keeping all parties informed of the situation. The period of time between signature and ratification grants states the necessary opportunity to seek the required approval for the treaty on the domestic level and to enact the necessary legislation to give domestic effect to that treaty.
[Reference: Articles 2 (1) (b), 14 (1) and 16, Vienna Convention on the Law of Treaties 1969]
Acceptance or Approval
The instruments of "acceptance" or "approval" of a treaty have the same legal effect as ratification and consequently express the consent of a state to be bound by a treaty. In the practice of certain states acceptance and approval have been used instead of ratification when, at a national level, constitutional law does not require the treaty to be ratified by the head of state.
[Reference: Articles 2 (1) (b) and 14 (2), Vienna Convention on the Law of Treaties 1969]
"Accession" is the act whereby a state accepts the opportunity to become a party to a treaty which that state has not signed prior to its entry into force. Accession thus occurs after the treaty has entered into force and has the same legal effect as ratification, acceptance or approval. The conditions under which accession may occur and the procedure involved depend on the provisions of the treaty (normally found near the end of the treaty). A treaty might provide for the accession of all other states or for a limited and defined number of states. In the absence of such a provision, accession can only occur where the negotiating states had agreed or subsequently agree on it in the case of the state in question.
[Reference: Articles 2 (1) (b) and 15, Vienna Convention on the Law of Treaties 1969]
 The definitions herein are based on the Treaty Reference Guide of the United Nations Treaty Collection.