Last week, a federal judge in Oklahoma ruled that querying a database of information collected by automated license plate readers (ALPRs) counts as a search under the Fourth Amendment.
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querying → rule → Amendment
As Reason's Elizabeth Nolan Brown noted, that decision was welcome news for critics who argue that warrantless access to ALPR data threatens the privacy of innocent motorists across the country.
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access → note → country
But a decision that a California judge issued the following day, which dismissed a lawsuit arguing that San Jose's ALPR network violates the state constitution, is much more typical of litigation in this area, which so far has been almost uniformly unsuccessful.
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which → issue → area
The contrast between those two decisions suggests the challenges such lawsuits face as judges grapple with the implications of Supreme Court precedents involving cellphone location data.
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judges → suggest → data
Although the relevance of those precedents might seem obvious, state and federal courts generally have perceived important differences between cellphone tracking and police use of roadside cameras that record images of passing cars.
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that → seem → cars
The Oklahoma case, United States v. Kyle, stemmed from Tulsa County Deputy Sheriff Freddie Alaniz's search of a database maintained by Flock Safety, the leading ALPR supplier.
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case → stem → Safety
Alaniz obtained historical location information for a car that had California plates, which at that point was the only grounds for suspecting the driver was involved in criminal activity.
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driver → obtain → activity
As rationales for the search, Alaniz typed "traffic violation" and "investigation," which gives you a sense of how slight the pretext for accessing ALPR data can be: When Alaniz typed those words, he had neither witnessed a traffic violation nor collected any evidence that would justify a criminal investigation.
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that → type → investigation
It did not amount to reasonable suspicion, let alone the probable cause required for a warrant.
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It → amount → warrant
In concluding that the ALPR query violated the Fourth Amendment, U.S. District Judge Sara E. Hill relied on the logic of the Supreme Court's 2018 decision in Carpenter v. United States, which involved location data collected by cell sites, and its 2026 decision in Chatrie v. United States, which involved information collected by Google's Location History feature.
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which → conclude → feature
In both cases, the Court perceived a "search" within the meaning of the Fourth Amendment and an exception to the "third party" doctrine, which says people generally do not have a reasonable expectation of privacy when they voluntarily share information with others.
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they → perceive → others
Alaniz's query generated "fifty sightings across multiple states," Hill noted.
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Hill → generate → states
Although "this is not the same fine-tuned level of detail that something like a cell phone reveals about the whole of someone's physical movements," she said, "Alaniz and other officers using these systems have access to a continuously updated location history for all vehicles caught on ALPR cameras within the network.
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Alaniz → tune → network
It is not targeted on a single individual, as in Carpenter.
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It → target → Carpenter
It is a tool that collects information about all vehicles that pass by any network-connected camera at all times, and it serves up the information to law enforcement on demand.
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it → collect → demand
As Hill saw it, ALPR networks are in that sense even more invasive than the data demand at issue in Carpenter.
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networks → see → Carpenter
"Freedom from persistent, dragnet-style surveillance while in public is not a foreign concept in our society, and it is a reasonable expectation that society already accepts," she wrote.
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she → accept → that
"This is the same expectation of privacy that the Supreme Court has continued to recognize in cases like Carpenter and Chatrie."
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Court → continue → Carpenter
Like cars, cellphones "move in public places where people can see you in plain view," Hill noted.
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Hill → move → view
"But it 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."
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enforcement → become → purpose
Last Friday in SIREN v. Joseph, Santa Clara County Superior Court Judge Jeffrey B. El-Hajj reached a starkly different conclusion about San Jose's network of Flock cameras.
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Hajj → reach → cameras
In that case, the American Civil Liberties Union (ACLU) of Northern California and the Electronic Freedom Foundation (EFF) argued that "San Jose's warrantless ALPR database searches violate the California Constitution, which guarantees the people's right to be free from unreasonable searches and seizures as well as the people's inalienable right to privacy."
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which → argue → privacy
The lawsuit, filed in November 2025, noted that San Jose "has blanketed its roads with nearly 500 ALPRs," enabling "location surveillance of all residents" that is "especially pervasive in both time and space."
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that → file → time
Citing Carpenter, the ACLU and the EFF argued that "location information reflecting people's long-term physical movements, even in public spaces, is entitled to constitutional protection under the Fourth Amendment."
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information → cite → Amendment
Since Carpenter established that people "have a reasonable expectation of privacy in the whole of their movements," they reasoned, San Jose's ALPR network violates Article I, Section 13 of the California Constitution, which likewise forbids "unreasonable seizures and searches."
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which → establish → seizures
El-Hajj disagreed.
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Hajj → disagree → ?
In the 2024 case People v. Cartwright, he noted, the 5th District California Court of Appeal held that San Diego police did not need a warrant to examine video footage collected by a street-light camera.
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police → note → camera
The appeals court said the defendant incriminated by that evidence "did not have an objectively reasonable expectation of privacy when he traversed a public right-of-way in downtown San Diego in the middle of a business day."
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he → say → day
It thought that conclusion was consistent with Carpenter, "which specifically indicated that its holding was intended to be narrow and did not extend to 'conventional surveillance techniques and tools, such as security cameras.'
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holding → think → cameras
Cartwright involved footage recorded on one afternoon by a single camera in one location, as opposed to images collected for months by many cameras scattered throughout the city, as in San Jose.
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Cartwright → involve → Jose
That network, the ACLU and the EFF noted, generated "extensive information about a driver's exact whereabouts at precise times, dozens of times a day, stretching back at least 365 days."
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ACLU → note → times
They said San Jose's system is "far more privacy invasive" than the "small number of conventional security cameras" at issue in Cartwright.
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system → say → Cartwright
El-Hajj did not think that distinction mattered.
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distinction → think → ?
"This court is bound by Cartwright," he wrote.
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he → bind → Cartwright
The plaintiffs "do not state sufficient facts" to establish a constitutional violation, he said, "because there is no reasonable expectation of privacy in license plate data collected from cameras directed solely at public streets."
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he → state → streets
El-Hajj conceded that "the scope of Defendants' system is broader than that at issue in Cartwright."
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scope → concede → Cartwright
But he thought "this case is not so factually distinguishable from Cartwright as to allow the court to disregard that binding appellate authority."
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court → think → authority
He added that "recording automobile license plate information from fixed cameras on public streets over time is less invasive than the continuous cell cite location data at issue in Carpenter."
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recording → add → Carpenter
El-Hajj's decision is not the final word on this case, since an appeals court might disagree with his analysis.
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court → disagree → analysis
And a federal lawsuit challenging San Jose's ALPR system, which the Institute for Justice filed last April, is pending in the U.S. District Court for the Northern District of California.
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Institute → challenge → California
…and 15 more, not listed.
The Aporia
