The ACLU Is Arming Lawyers to Expose State Surveillance Secrets

The American Civil Liberties Union of Massachusetts says it’s releasing an online toolkit this week for criminal defense attorneys designed to uncover whether police used surveillance technologies —facial recognition, automatic license plate readers, gunshot detection systems, and more—to build the cases against their clients in secret.

The toolkit, which the group describes as the first of its kind, is built around handcrafted legal motions that, when granted by a judge, will force prosecutors to reveal whether surveillance technology was used against a defendant. It covers an array of technologies, from “stingray” phone trackers and location data sold by commercial brokers to AI-drafted police reports and forensic tools that crack phones and siphon data from car infotainment systems.

It also includes preservation motions—demands that surveillance data be saved before it is deleted automatically—aimed at government agencies and private vendors alike. The filings rest on a bedrock rule of American criminal law, established in 1963, that prosecutors are required to turn over all evidence that could help the defense. The motions will be distributed through a password-protected library, the ACLU of Massachusetts says, available only to verified defense attorneys.

The group is fighting a war against unregulated surveillance tools on two fronts, says Jennifer Herrmann, a staff attorney at the ACLU of Massachusetts and one of the toolkit’s authors. One front is pressuring cities to drop tools like Flock , the license plate reader network, and ShotSpotter , the gunshot detection system, outright. The other is arming defense lawyers to expose the surveillance in court.

“The amount of time that it can take for that initial use of technology and investigation to actually get to a court and constitutional challenge is long,” Herrmann says—so the motions give attorneys a way to “challenge what has already happened in the past,” building a record that carries over to whatever tool comes next.

The project responds to what its authors describe as a chronic lag between the moment police adopt a new surveillance tool and the moment courts finally decide whether using it is legal. Most Americans carried cell phones by the late 1990s, but the United States Supreme Court did not require police to get a warrant for cell phone location records until 2018 . The lag isn’t just the result of slow-moving courts. The technologies with the worst disclosure records have faced the fewest court rulings precisely because a defendant cannot challenge a tool they were never told about.

In materials accompanying the launch, the ACLU of Massachusetts says police deploy these tools “sometimes without even disclosing their use to the prosecutors handling the case.” For years, the FBI required local police departments to sign secrecy agreements before using cell-site simulators—suitcase-sized devices, commonly called stingrays, that impersonate cell towers to secretly locate phones. In Baltimore, one such agreement instructed prosecutors to drop criminal cases entirely rather than reveal the device in court, even as the city’s police used it more than 4,300 times between 2007 and 2015. FBI records later obtained by the ACLU show the agreements persisted until at least 2020 .