Useful to know in the context of TPP and copyright treaties:
What is the difference between signing, ratification and accession of UN treaties?
“The United Nations Treaty Collection website provides a Glossary of terms relating to Treaty actions.
This text is taken from that Glossary:
Signature ad Referendum
A representative may sign a treaty “ad referendum”, i.e., under the condition that the signature is confirmed by his state. In this case, the signature becomes definitive once it is confirmed by the responsible organ.
[Art.12 (2) (b), Vienna Convention on the Law of Treaties 1969]
Signature Subject to Ratification, Acceptance or Approval
Where the 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.
[Arts.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 if the parties intended to show their consent by such an act. 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 institution of ratification grants states the necessary time-frame 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.
[Arts.2 (1) (b), 14 (1) and 16, Vienna Convention on the Law of Treaties 1969]
“Accession” is the act whereby a state accepts the offer or the opportunity to become a party to a treaty already negotiated and signed by other states. It has the same legal effect as ratification. Accession usually occurs after the treaty has entered into force. The Secretary-General of the United Nations, in his function as depositary, has also accepted accessions to some conventions before their entry into force. The conditions under which accession may occur and the procedure involved depend on the provisions 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 were agreed or subsequently agree on it in the case of the state in question.
[Arts.2 (1) (b) and 15, Vienna Convention on the Law of Treaties 1969]
For more glossary terms, visit the UN Treaty Collection’s Glossary of terms relating to Treaty actions. The UN Treaty Collection also has a page with Definition of key terms used in the UN Treaty Collection.
Disclaimer: Questions are answered by Library staff. Answers are current at the time published and as complete as our resources allow. Links and references to third-party resources do not imply endorsement by the United Nations.”