(a)(S-90) For purposes of complying with 10 U.S.C. 2465, which prohibits the DoD from “entering into a contract for the performance of firefighting or security-guard functions at any military installation or facility,” the term security guard functions should be understood to mean those functions which are the responsibility of an installation commander or stand-alone military facility commander. If there is no military commander, this prohibition shall apply to the senior DoD civilian at the location. The prohibited security guard functions include: performing or supervising protective services work that involves the protection of federally owned or leased buildings and property at the installation level or at a stand-alone military facility; protecting government equipment and material at the installation level or at a stand-alone military facility; controlling access to federal installations by employees, visitors, residents and patients; and monitoring of intrusion detection systems. The statutory prohibition on contracting for security guard functions in 10 U.S.C. 2465 does not apply to security support functions that a unit or organization performs as part of security in depth at a location or area on an installation, or performs within a stand-alone building, so long as the commander and their unit is not responsible for installation-level security or overall security at a stand-alone military facility. Contractors performing security support functions may not engage in any law enforcement functions, i.e., criminal investigative work, the preservation of peace; the prevention, detection and investigation of crimes; the arrest or apprehension of violators; and the provision of assistance to citizens in emergency situations, including the protection of civil rights, preservation of crime scenes; issuances of citations; and arrests and apprehensions of suspects.