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day of the dalek [soylentnews.org] writes:

As per an article from The Hill [thehill.com], a federal judge in Tulsa County, Oklahoma ruled that an officer's warrantless search of ALPR data may violate the Fourth Amendment because it was done without probable cause:

The ruling concerned ALPRs’ role in a Tulsa County deputy sheriff’s traffic stop that resulted in a drug arrest. In this case, the deputy began following a driver after noticing she had an out-of-state license plate and ran her vehicle through an AI-powered camera database — allegedly before the officer had identified any traffic violation or other criminal activity

The officer had access to both Flock and VehicleManager systems, according to the judge’s ruling, and his search turned up over 50 sightings of the woman’s vehicle across several states. The deputy sheriff eventually observed an infraction and pulled over the driver.

The judge’s ruling does not label the use of Flock data to aid in arrests as illegal, rather, it clarifies that the officer in this case did not have probable cause to “intruded on her reasonable expectation of privacy” with the technology — setting stricter precedent for when law enforcement may employ extensive ALPR databases during investigations.

This case involves a police officer who had access to data from both Flock and VehicleManager, the latter of which is owned by Motorola Solutions. An article from TechCrunch [techcrunch.com] provides more details:

In this case, Judge Sara Hill said the deputy should have obtained a warrant before searching the Flock database for the woman’s license plate, as he had “no apparent reason” for the search “other than the fact that [the woman’s vehicle] had a California license plate.”

The deputy then used the woman’s travel history in Flock as part of the justification for searching her car, where he allegedly discovered 91 pounds of meth. But Judge Hill wrote that all evidence obtained after the Flock search “must be suppressed as the fruit of a poisonous tree.”

Judge Hill also took broader aim at warrantless searches of the Flock database, writing that tracking people’s location — even when they’re in public places — becomes “constitutionally problematic when law enforcement can indiscriminately and passively catalog your whereabouts over an extended period of time and then use that information for any purpose whenever convenient.”

Police generally access data from Flock and similar ALPR cameras in at least three different ways. One is that the police department can flag license plates on various hotlists and get alerts. As long as the hotlist isn't abused to add vehicles not associated with criminal activity, this is generally accepted as legal. The second is that police can search for all vehicles with certain characteristics detected by one or more cameras within a particular window of time. This is analogous to the geofence warrants that were the subject of Chatrie v. United States (2026) [scotusblog.com]. It also has similar elements to searching cell tower logs, which was also ruled a search under the Fourth Amendment in Carpenter v. United States (2018) [gwlr.org]. These precedents strongly suggest that geofence-like Flock searches will also be ruled as searches under the Fourth Amendment and be heavily restricted.

This case involves a third use of ALPR cameras, where police can enter a license plate number and obtain a history of where a vehicle has been detected. By default, Flock retains data for 30 days, meaning that many details of a person's travels during that period are shown to a police officer searching for the license plate. Other vendors may have different data retention policies, so it's entirely possible that a person's travel over a longer window of time could be searched. The problem in this case is the lack of a warrant or probable cause, and that merely having an out-of-state license plate is not grounds to search a vehicle's travel history.

It is worth asking what actually provides probable cause to conduct an ALPR search. For example, if the officer had pulled over a vehicle with a California plate for a traffic infraction in Oklahoma, does that traffic infraction provide probable cause for such a search? It seems like a mere traffic infraction should not be probable cause, and that there must at least be compelling reason to suspect actual criminal activity before conducting a search. The bigger picture is that I don't believe it should be legal for the government to allow third-parties like Flock and Motorola Solutions to install ALPR cameras, record vehicles that pass those cameras in a database, and then purchase access to search the database. This case deals with a different aspect of ALPR searches than the geofence-like functionality, but it reaches the same conclusion that this is an unreasonable intrusion into people's private lives, even when they're traveling on public roads.

Original Submission