H.R. 4811 — Cell-Site Simulator Warrant Act of 2025

This section amends the definitions of "pen register" and "trap and trace device" in 18 U.S.C. §3127(3) and (4) to exclude any cell-site simulator, as defined in new §3119 (i.e., a device or system that transmits or receives radio signals for purposes of locating or identifying cellular devices). (As background, pen registers and trap and trace devices enable law enforcement to obtain non-content dialing, routing, addressing, or signaling information from communications providers under a court order with a relevance standard; excluding cell-site simulators—which mimic cell towers to actively collect such information from devices—subjects their use to stricter requirements.) It further adds §3119 to (1) prohibit any individual or entity from knowingly using a cell-site simulator in the United States (or an intelligence community element from using one abroad on a U.S. person), with a penalty of a fine up to $250,000; (2) bar evidence obtained from violations (except to prosecute such violations); and (3) permit use by law enforcement under a warrant from a court of competent jurisdiction—requiring demonstrations of necessity (i.e., other methods tried and failed or unlikely to succeed or too dangerous), narrowest area and time of operation, and compliance with FCC rules, for no longer than 30 days (with 30-day extensions possible), or in emergencies involving immediate danger of death or serious physical injury. (Thus, cell-site simulators may no longer be deployed under the lower-threshold pen register or trap and trace orders.)