The FBI made police sign a secrecy pact before they could track your phone

Cell-site simulators, commonly called Stingrays after one manufacturer's product line, work by impersonating a legitimate cell tower. Every phone in range, not just a target's, automatically connects to the fake tower, allowing the operator to locate, track, and identify devices, including bystanders with no connection to any investigation. Because the phones connect automatically, the technique requires no cooperation from a wireless carrier and, in most documented deployments, no warrant.

Before local and state police could purchase or operate this technology, the FBI required them to sign a non-disclosure agreement. When the ACLU of Arizona sued the Tucson Police Department for Stingray records, an FBI agent personally submitted a declaration in court quoting the NDA's own language directly, confirming its existence and content on the federal government's own terms rather than through a leak. The agreement states that disclosing the existence of, and the capabilities provided by, the equipment to the public would reveal sensitive technological capabilities and must be protected from disclosure.

Records obtained by the ACLU through a 2021 FOIA lawsuit, including internal FBI emails from as recently as May 2020, confirm the practice continued for FBI-provided cell-site simulators well past the technology's initial rollout, requiring personnel to read and acknowledge the NDA before deployment.

Previously released versions of the FBI's NDA required signing police departments to notify the FBI if a court appeared likely to order disclosure of Stingray use, so the government could intervene, and in documented instances, departments dropped criminal charges outright rather than reveal in open court that the technology had been used to build a case. This is not a hypothetical risk described by advocates. It is a documented pattern confirmed by the FBI's own released records and by court filings in multiple jurisdictions.

This establishes that the FBI formally required local law enforcement agencies to sign secrecy agreements as a condition of using cell-site simulator technology, that the agreement's language has been confirmed and quoted by the FBI's own agents in sworn court declarations, and that the practice of prioritizing secrecy over prosecution, up to and including dropping charges, is documented in the public record rather than alleged by outside parties.

What this does not establish is a complete list of every agency currently operating under such an agreement. The FBI has used a Glomar response, refusing to confirm or deny whether responsive records exist at all, to block a 2021 ACLU FOIA request for current NDA records, meaning the full current scope remains genuinely unknown even to the litigants actively suing to find out.