in 1973, and subsequently acceded to the convention establishing the EUI. In 1992, a new convention revising the 1972 convention establishing the EUI was signed by the then 12 Community member states. It entered into force in 2007 when the last contracting state ratified the convention.

EUI contracting states must be European Union member states. As of June 2025, contracting states include all EU member states except Czech Republic, Hungary, and Lithuania.