18 U.S.C. § 3125: Emergency pen register and trap and trace device installation

immediate danger of death or serious bodily injury to any person; conspiratorial activities characteristic of organized crime; an immediate threat to a national security interest; or an ongoing attack on a protected computer (as defined in section 1030) that constitutes a crime punishable by a term of imprisonment greater than one year; there are grounds upon which an order could be entered under this chapter to authorize such installation and use; In the absence of an authorizing order, such use shall immediately terminate when the information sought is obtained, when the application for the order is denied or when forty-eight hours have lapsed since the installation of the pen register or trap and trace device, whichever is earlier. The knowing installation or use by any investigative or law enforcement officer of a pen register or trap and trace device pursuant to subsection (a) without application for the authorizing order within forty-eight hours of the installation shall constitute a violation of this chapter. A provider of a wire or electronic service, landlord, custodian, or other person who furnished facilities or technical assistance pursuant to this section shall be reasonably compensated for such reasonable expenses incurred in providing such facilities and assistance.