This legislation, known as the Cell-Site Simulator Warrant Act of 2025, aims to significantly regulate the use of cell-site simulators by amending title 18 of the United States Code. It establishes a general prohibition against the knowing use of these devices by any individual or entity in the United States, and by the intelligence community against U.S. persons abroad. A cell-site simulator is defined as any device that mimics a base station to identify, locate, or intercept transmissions from cellular devices for purposes other than ordinary commercial mobile services.

The primary exception to this prohibition is the use of a cell-site simulator by a law enforcement agency under a court-issued warrant. To obtain such a warrant, agencies must demonstrate that other investigative procedures have failed or are unlikely to succeed, specify the narrowest possible area and time of effect, and certify compliance with FCC regulations. Courts must weigh the government's need against potential negative side effects and public safety risks, with warrants limited to 30 days and subject to extensions.

An exception for emergency use is also provided, requiring an immediate danger of death, serious injury, organized crime, or national security threat, and necessitating a warrant application within 48 hours. All warrant applications must disclose potential disruptions to emergency calls (like 9-1-1), certify third-party inspection of the device, and detail methods to minimize disruption. Furthermore, notice of cell-site simulator use must generally be provided to affected individuals within 90 days, detailing whether their device information, location, or communications were obtained.

The bill stipulates that information or evidence acquired in violation of the prohibition is generally inadmissible in court proceedings. It also mandates that the Attorney General adopt and publish specific minimization procedures to limit the acquisition, retention, and dissemination of information pertaining to non-target individuals. Any information introduced into evidence must be disclosed to the defendant.

The scope of collection is limited to identifying nearby electronic devices and their transmission strength and direction, with additional requirements for wiretapping or tracking. The legislation also creates a civil action for individuals subjected to unlawful cell-site simulator operations and provides for administrative discipline against officers who willfully violate the act. Annual reports from various Inspectors General are required to detail compliance, usage statistics, and the number of targeted and non-targeted devices.

The bill also amends the Foreign Intelligence Surveillance Act of 1978 (FISA) to incorporate similar requirements for cell-site simulator use in foreign intelligence surveillance. The Federal Communications Commission (FCC) is directed to initiate proceedings to promulgate or modify regulations to implement the Act. Most provisions will take effect two years after enactment, with a potential three-year extension for existing cell-site simulator models if certified by the Attorney General.