A member of the Royal Navy Regulating Branch, the Royal Marines Police, the Royal Military Police, or the Royal Air Force Police. They have many of the functions of civilian police but are members of the armed forces with no constabulary powers. This means that service police cannot exercise statutory powers conferred on constables; any powers they require must be specifically applied to them. Prior to the Armed Forces Act 2001, powers, which might need to be exercised by a service policeman during the investigation of offences allegedly committed by members of the armed forces (or other persons who are subject to the service discipline Acts) were exercised on the authority of the commanding officer under his inherent powers. However, the 2001 Act provides the service police with statutory powers of entry, search, and seizure based on those available to the civilian police. By virtue of the Police and Criminal Evidence Act 1984 (Application to the Armed Forces) Order 2006 (SI 2006/2015), the relevant provisions of the Police and Criminal Evidence Act 1984 apply to the investigation of offences conducted by a service policeman and to persons held in arrest in connection with such an investigation.
The Armed Forces Act 2006 defines the powers of arrest in relation to service offences, powers to search arrested persons, to stop and search persons and vehicles, and to enter premises for the purpose of search and seizure. It also sets out the regime governing the holding in custody (before or after charge) of a person arrested by a service policeman and covers such matters as time limits for custody and review of custody. The requirements include review of that custody by a judge advocate. See also service law.