The present document describes the implementation of a Lawful Interception interface in a TETRA system. It provides the requirements and specification of the interface within a TETRA system for the purpose of providing data to Law Enforcement Agencies (LEAs) in the area of Lawful Interception (LI) of communications. The provision of a Lawful Interception interface for TETRA is a national option, however where it is provided it shall be provided as described in the present document.