Protocol Concerning Frontier Controls and Policing Co-operation in Criminal Justice Public Safety and Mutual Assistance Relating to the Channel Fixed Link [Sangatte Protocol] – France-UK Border Research

Governments of the UK and France (1991)

Also online: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/273137/2366.pdf

(The Channel Tunnel (International Arrangements) Order 1993 brought the protocol into effect. Also see the Additional Protocol to this protocol and the amendments to that additional protocol.)