A recent Supreme Court decision restricting warrantless access to cell phone location history could have consequences well beyond Big Tech geofence requests, according to legal scholars and privacy advocates who say the ruling strengthens the case against warrantless use of automated license plate readers (ALPRs).
The case, Chatrie v. United States, was the first major Fourth Amendment ruling from the court in eight years. It addressed whether police can obtain geofence data from companies like Google without a warrant to identify which phones were near a crime scene during a given time window. The court sided with the defendant, finding that even short-term location history can expose visits to sensitive places such as psychiatric offices, abortion clinics, or by-the-hour motels, and therefore warrants Fourth Amendment protection.
Legal experts say the reasoning could extend to ALPR networks, which capture and store license plate data on a massive scale. Flock Safety, the leading vendor in the space, says it has roughly 90,000 to 100,000 cameras deployed on public roads and collects data on about 20 billion license plates monthly. Police increasingly rely on this data to identify suspects and reconstruct movements.
Similar Concerns, Different Technology
Michael Soyfer, an attorney at the Institute for Justice, said the Supreme Court’s emphasis on the “retrospective and indiscriminate” nature of location tracking applies just as easily to ALPR data. He noted the justices focused on what police could access across an entire database, not just what they used in a specific case, a framing that could matter significantly for ALPR litigation.
Andrew Guthrie Ferguson, a law professor at George Washington University, said ALPR systems function as an entry point into much larger networks of personal data, including social media activity, drone and dashcam footage, gunshot detection sensors, and other surveillance feeds that police link together to build detailed profiles of individuals’ movements and habits.
Flock Safety Pushes Back
A Flock Safety spokesperson said the ruling does not apply to its technology, arguing that Google location history draws from a person’s own device and reveals movement across both public and private spaces, while ALPR technology only captures point-in-time images of vehicles already in public view. The company said courts have consistently treated ALPR data differently from cell site location information and argued that a footnote in the opinion may reinforce a distinction based on whether tracking occurs on public roads.
Whether that distinction holds up in future litigation remains to be seen, but legal observers say Chatrie has opened the door to renewed challenges over how police access and store ALPR data without judicial oversight.