State party
A state party to a treaty is a state that has either signed and ratified or acceded to it.
To become formally bound by the terms of a treaty and thereby become a state party (also called High Contracting Party in certain treaties), a state that has signed the treaty (a signatory state) must typically ratify its signature in order to become a state party. Ratification is normally done by sending a formal letter to the depositary of the treaty, known as an instrument of ratification. States that do not or have not signed an international treaty may become party to it through the act of accession (equivalent to signature and ratification). This similarly requires a formal letter to the depositary, known as an instrument of accession.
Last updated on: 04 August 2017