"Cell-site simulator technology provides valuable assistance in support of important public safety objectives. Whether deployed as part of a fugitive apprehension effort, a complex narcotics investigation, or to locate or rescue a kidnapped child, cell-site simulators fulfill critical operational needs. As with any law enforcement capability, the Department must use cell-site simulators in a manner that is consistent with the requirements and protections of the Constitution, including the Fourth Amendment, and applicable statutory authorities, including the Pen Register Statute. Moreover, any information resulting from the use of cell-site simulators must be handled in a way that is consistent with the array of applicable statutes, regulations, and policies that guide law enforcement in how it may and may not collect, retain, and disclose data. As technology evolves, the Department must continue to assess its tools to ensure that practice and applicable policies reflect the Department's law enforcement and national security missions, as well as the Department's commitments to accord appropriate respect for individuals' privacy and civil liberties. This policy provides additional guidance and establishes common principles for the use of cell-site simulators across the Department. The Department's individual law enforcement components may issue additional specific guidance consistent with this policy."
Department of Justice: http://www.justice.gov/