Automated license plate reader (ALPR) cameras can help law enforcement solve crimes and locate missing people, but responsible ALPR use depends on strong policy, training, auditing, and oversight. Agencies must balance the technology’s investigative value against privacy concerns, misuse, data retention, and public trust. Clear access rules, regular audits, meaningful penalties, and transparency can help agencies reduce risk while preserving ALPR capabilities.
Drive through almost any city in America today and there’s a good chance a camera on a pole is reading your license plate, checking it against a database, and logging the time and location as you pass by. Right now, an estimated 150,000 automated license plate reader (ALPR) cameras are quietly logging traffic across the U.S. The market leader, Flock Safety, says it has placed over 120,000 cameras across more than 5,000 communities in 49 states, with no sign of slowing.
In an age when information from our use of cell phones, social media, and web searches is routinely tracked and sold to the highest bidder, ALPRs have generated an intense amount of pushback. Since early 2025, more than two dozen ALPR cameras across at least five states have been cut down, sawed apart, or hauled away. People have thrown paint on cameras in California, rammed a truck into one in Idaho, and blocked a camera’s view with a lawn chair in Florida. Two cameras in Irmo, South Carolina, were coated in spray foam just weeks after the town approved a $400,000 contract to add 22 more. Some cities have taken the official route instead, canceling contracts outright in places like Fort Collins, Eugene, and Madison.
Citizen objections vary, with some civil liberties groups calling ALPR surveillance a “warrantless search.” Every passing car gets logged, no suspicion required, and the data can be shared with local, state, or federal authorities (including ICE). To make things worse, numerous law enforcement officers have been caught using ALPR searches to track people they had no legitimate reason to investigate.
Ironically, though not surprisingly, police often use footage from vandalized cameras (or their still-working neighbors) to identify and charge the people doing the damage. And the fight isn’t close to over. Flock Safety recently announced new guardrails to crack down on misuse, while another company in the space is moving in the opposite direction, adding the ability to track phones, smartwatches, and even AirPods along with the cars they ride in.
Not Just an American Concern
The backlash against ALPRs isn’t confined just to the United States. In the United Kingdom, London’s Ultra Low Emission Zone (ULEZ) uses the same basic technology to identify and charge people driving older vehicles a daily fee in the name of preventing climate change.
In response, a loosely organized group calling itself “Blade Runners” has been cutting wires and sawing down poles by the hundreds. A political commentator was prosecuted for allegedly cheering the vandals, and a police officer was even charged (paywall) with taking a hammer to several cameras himself.
Whether the justification is fighting crime or fighting pollution, these cameras are generating pushback — at the ballot box, on social media, and on the street with hacksaws and hammers.
What ALPRs Actually Do
Strip away the controversy and the technology is straightforward. A camera photographs the license plates of passing cars, converts the tags to text, and logs them with a timestamp, location, and direction of travel. Automated processes check the data against “hot lists” of stolen vehicles, warrants, or missing persons and produce a real-time alert when a match is found.
But it’s what happens afterwards that causes the main controversy. The largest market player, Flock Safety, links roughly 120,000 cameras nationwide, so scan logs in one city can be searched by an officer in another, and the data can also be used by a variety of law enforcement agencies. Since there’s generally no expectation of privacy on a public street, there’s typically no warrant requirement to run a search — only a stated law-enforcement purpose. Retention rules vary by agency; until recently, the industry standard has been 30 days.
It’s important to note no single database ties every ALPR system in the country together. Flock’s own network is broadly interconnected, but plenty of other vendors (including DRN, described below) run separate systems that don’t share data with Flock or each other. Flock says it doesn’t sell data for non-law-enforcement purposes, and no evidence has surfaced suggesting the contrary. But not all industry actors have the same scruples.
Another ALPR company, Digital Recognition Network (DRN), operates a nationwide network of plate-scanning cameras, most of them mounted on tow trucks and flatbeds used during vehicle repossessions. DRN sells the resulting location data to auto lenders, insurers, and marketers. The company was granted summary judgment in a 2022 class-action lawsuit by California plaintiffs, a decision that was recently affirmed by California’s 4th Appellate District.
One big issue is that most state ALPR laws were written to regulate police use, not factoring in commercial data brokers, making ALPR data yet another example of technology outpacing legislation and regulation.
“Technology doesn’t get released with built-in ethics; those boundaries get defined by a law enforcement agency’s written policies.”
The Case for the Cameras
Law enforcement agencies point to a growing list of cases where ALPR searches made the difference in solving crimes.
For example, police in Galt, California, say a Flock alert helped them track down a kidnapping suspect within five minutes of the crime. In Aurora, Colorado, officers located a stolen vehicle carrying a 14-month-old and recovered her in under 10 minutes, before an AMBER Alert could even go out. That wasn’t an isolated scenario: Colorado police agencies credit ALPR alerts with facilitating the recovery of six abducted children in a five-month stretch, including a Boulder case where investigators identified a suspect vehicle within hours of an AMBER Alert. In Tennessee, a camera match helped investigators identify a suspect and secure a confession in a case one detective said would otherwise have gone unsolved. Police in Richmond cited a 2024 homicide in which cameras helped identify suspects within 33 minutes of the killing, and Palm Springs police say camera alerts have contributed to more than 30 arrests, including multiple kidnapping cases.
Flock’s integration with the AMBER Alert system is the most obvious example of the technology’s upside. The company’s 2021 partnership with the National Center for Missing & Exploited Children broadcasts active alerts directly across its camera network, and the company reports the partnership has since contributed to more than 100 resolved missing-children cases. Among them:
- Two children recovered in Wichita after a noncustodial-parent abduction, resolved in under an hour.
- A kidnapped three-week-old newborn recovered in Canton, Ohio, after the suspect’s vehicle was identified on camera.
- A 14-year-old girl recovered in Arizona after being abducted in Casper, Wyoming, and driven across state lines.
The question isn’t whether ALPRs work. The technology is clearly successful at producing investigative leads that lead to prosecutions and recoveries. The challenge is whether the technology can be successfully managed to prevent unauthorized use. That’s the problem policy, training, and auditing should help solve.
When ALPR Tracks People, Not Just Vehicles
If public outcry against ALPRs seems to be intensifying, an emerging product suggests the backlash is about to get even more heated. A defense contractor called Leonardo has released an add-on sensor for ALPR cameras called SignalTrace that scans for Bluetooth, Wi-Fi, and RFID signals from devices like phones, smartwatches, and earbuds and associates them with a vehicle.
As with baseline ALPRs, it’s all about pattern recognition. The system looks for devices that keep appearing together and (over time) links them to license plates. This allows investigators to search by movement pattern without knowing a plate number at all. Leonardo says the system “does not identify people” and only collects signals already being broadcast. Critics point out the data gives investigators enough to work out who owns a particular device, raising the possibility someone could be targeted simply for showing up near a group being investigated. For example, such a system could conceivably be deployed around anti-government protests, which could have a chilling effect on activity protected by the First Amendment.
The unresolved question is whether government access to the data collected by this type of scanning will invoke the Fourth Amendment’s warrant requirement. In United States v. Chatrie (which we examined in our discussion on geofence warrants), the U.S. Supreme Court ruled a request for phone-location data counts as a Fourth Amendment search. It still remains to be seen what any court would say about government access to a passive collection of random Bluetooth signals, but it is likely to be similar result[1].
At this point, law enforcement doesn’t seem that interested in wading into this particular morass. But only time will tell.
Policy, Training, and Audits
Technology doesn’t get released with built-in ethics; those boundaries get defined by a law enforcement agency’s written policies. While Lexipol Policy language on ALPR use varies from state to state, it generally restricts searches to official law-enforcement purposes. Lexipol ALPR policy guidance doesn’t require reasonable suspicion before a search, but it does require officers and agencies to verify any enforcement action based on the search through a state or national telecommunications system before the lead is acted on by officers.
Lexipol’s policies also set structural limits: Vehicle data must be transferred to the server within 30 days and must be stored only as long as the records retention schedule requires (unless tied to a specific case), and all system access must be logged and tracked. Requests that aren’t directly tied to law-enforcement activity must be routed through proper legal review.
On paper, that’s a solid framework. But as with any policy, the system only works if people are trained on it and regular audits are carried out to ensure activities comply with policy and any state laws.
Training is the first guardrail of any ALPR system. Most policies prohibit personnel from accessing ALPR data without first receiving department-approved training. Besides being taught how to access the system and perform queries, personnel should also be trained on the acceptable uses for the technology — as well as illegitimate uses and the penalties for misconduct.
Audits are the second, and arguably more important, protection because they help catch abuse of ALPR systems. Analysis of ALPR abuse shows a recurring pattern: It’s internal audits, not proactive oversight, that tend to identify cases where law enforcement personnel misuse ALPR searches. And much of that misuse is blatant in both purpose and scale.
The Problem of ALPR Misuse
As of this writing, the Institute for Justice (IJ) has tracked over 100 cases of ALPR abuse by law enforcement personnel. Many involve officers using the cameras to track romantic partners (or former partners). And many involve jaw-dropping numbers of abusive searches by individuals who should’ve known better.
In Georgia alone, at least 18 officers have been arrested for misusing ALPR data, including three Richmond County deputies charged with stalking, prohibited use of license-plate data, and violating their oath of office. All three resigned.
Some cases involve query counts that boggle the mind. For example, an Idaho sheriff searched his agency’s ALPR database hundreds of times for his wife’s vehicle; no charges were filed, but he retired two years early. One deputy in a Georgia case allegedly searched for a woman he was having an affair with more than 1,600 times over several months, and a Florida officer was charged after searching a database for his estranged wife’s vehicle more than 700 times over a two-year period.
The cases span the country and the ranks:
- A former sheriff’s deputy in Illinois was charged with stalking after allegedly using ALPR data to monitor an ex-girlfriend and her new partner.
- A Texas sergeant resigned while under investigation for using cameras to track a fellow officer with whom he’d had a relationship.
- A Kansas detective was charged with multiple crimes after allegedly tracking his estranged wife and two men he suspected were her new partners. (The investigation also led to charges for possession of child sexual abuse material.)
- A former corporal in South Carolina was fired after an internal audit revealed he’d used his department’s system to monitor a subordinate he’d previously been involved with.
- A Wisconsin officer resigned after allegedly using the network to track a romantic partner and one of her exes nearly 180 times in two months.
Not every case ends in charges and/or termination. The former police chief of Braselton, Georgia who was facing stalking and database-misuse charges was found dead before his trial could take place. In a Florida case, an officer who ran his ex-girlfriend’s plate at least 69 times (plus her parents’ plates several dozen times) received probation and a small fine rather than any serious penalty — which critics point to as evidence that consequences for misuse remain inconsistent at best.
The common thread isn’t a single bad actor — it’s how easy the system can be abused. No warrant, no supervisor sign-off, just a login and a search box. That’s precisely why audits matter more than any single training class: They’re the mechanism that catches the pattern before it becomes a criminal case. (Though you’d think over 1,600 searches for a single plate would’ve raised a red flag or two.)
Flock’s Response: New Guardrails
Under pressure from both the vandalism and the public outcry about misuse, Flock has begun tightening up its own system. After finding more than 90% of partial-plate searches happen within a week, the company is cutting its default data retention window from 30 days to seven. It’s rolling out an “Evidence Mode” feature that lets investigators move data tied to active cases into longer-term storage, and also adding mandatory audit-assistance tools to help agencies catch misuse faster. Agencies that had already adopted longer retention periods — whether through a city council vote, state law, or their own internal policy — will keep those existing settings.
These changes are welcome, but they only happened after sustained public pressure, many dozens of officer misconduct cases, and a wave of contract cancellations. Whether this is enough to rebuild trust, or just enough to slow the contract cancellations, is still an open question.
Where the Courts Stand
Case law on the ALPR debate has been surprisingly consistent — and consistently favorable to law enforcement. The U.S. Supreme Court has not directly decided on such a case[2]. Every federal circuit, along with most state appellate courts, has treated a single ALPR camera capture as no different from an officer manually jotting down a license plate on a public street: no reasonable expectation of privacy, no warrant required.
In United States v. Porter (170 F.4th 381 (5th Cir. 2026)) the 5th Circuit held that using historical ALPR data to locate a suspect didn’t implicate the Fourth Amendment at all. In Virginia, an outlier trial-court ruling that ALPR searches require a warrant (Commonwealth v. Bell) was reversed in Commonwealth v. Church (2025 WL 2908089 (unpublished opinion) (Va. Ct. App. Oct. 14, 2025)).
Curiously, several courts have sidestepped the question of whether querying an ALPR database should even be considered a “search.” For example, in United States v. Yang (958 F.3d 851 (9th Cir. 2020)) the 9th Circuit avoided the issue altogether because the defendant’s rental agreement had expired and he, therefore, lacked standing to challenge the use of ALPR data. The 11th Circuit did the same in United States v. Mapson (96 F.4th 1323 (11th Cir. 2024)), cert. denied 145 S.Ct. 344 (2024), upholding the evidence under the good-faith exception rather than deciding it on its merits. Massachusetts’s high court took a middle path in Commonwealth v. McCarthy (484 Mass. 493 (2020)), ruling the camera network in that case wasn’t big enough to raise constitutional concerns, but the court in that case hinted that a larger, denser network might get a different answer.
Schmidt v. City of Norfolk (819 F.Supp.3d 492 (E.D. Va. Jan. 27, 2026)) upheld Norfolk’s Flock network at the district court level and is now on appeal to the 4th Circuit, which would be that circuit’s first ruling on the issue. We’ve already mentioned Chatrie v. United States (609 U.S. ___,, 146 S.Ct. 2193 (2026)), in which the U.S. Supreme Court held geofence warrants to compel location data can constitute a Fourth Amendment search. It’s possible that same reasoning might eventually be applied to ALPR networks (or add-ons like SignalTrace) as deployment becomes even more widespread.
The Legal Patchwork
No comprehensive federal law currently regulates ALPR use in the United States. Roughly 16 to 18 states have passed ALPR-specific statutes, ranging from strict (New Hampshire, Maine) to moderate (California, Virginia, Minnesota). Oregon recently passed a law letting residents sue companies that misuse ALPR data; Washington’s Driver Privacy Act bars ALPR use near “sensitive locations” (like healthcare facilities, places of worship, schools, and courthouses) and requires a warrant for accessing private-vendor data.
Arizona has no ALPR-specific statute whatsoever — retention is set entirely by individual agency policy, ranging from 30 days to a year, with no statewide oversight. A 2026 bill that would have codified use standards stalled after lawmakers objected that it also would have exempted ALPR data from public records requests.
It’s also worth noting that even the more protective U.S. state laws are written almost entirely around law-enforcement use. California is a rare exception, with a statute that also governs private-sector data brokers, which was precisely the law at issue in the DRN litigation described earlier.
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What Responsible ALPR Use Looks Like
There’s definitely a “This is why we can’t have nice things” quality to the ALPR landscape today. Used appropriately, the technology is a genuine force multiplier: extra eyes on the street when a missing child or a fleeing suspect makes minutes matter. But agencies that deploy it without a comprehensive policy and effective oversight — and the individual officers who’ve turned it into a tool for surveilling wives, ex-girlfriends, and exes’ new partners — are doing more to turn public opinion against the technology than any activist campaign could. Every stalking case also degrades public trust, both for the departments that didn’t catch it and for the neighboring departments that did nothing wrong but now face an unearned black mark on their reputations.
Pulling this together, a handful of practices separate agencies that use ALPR well from agencies that end up in the news for the wrong reasons:
- A written policy with real penalties. Limits on use should be specific and enforceable, not vague boilerplate that technically permits almost anything an officer might want to do.
- Mandatory training before anyone touches the system. No exceptions, no grandfathering in veteran officers, and no informal “shadow access” for personnel who haven’t completed it.
- Short, defensible retention windows. Data should be kept long enough to be operationally useful but short enough to limit what’s exposed if the system is ever misused, breached, or subpoenaed.
- Regular, independent audits. Query logs must be reviewed regularly by someone outside the chain of command being audited, not treated as a one-time compliance checkbox that nobody revisits.
- Real consequences for misuse, applied consistently. A pattern of resignations and light sentences for the same underlying conduct undermines both deterrence and public confidence that the rules are actually enforced.
- Transparency with the public. Residents should be able to find out what data is collected, how long it’s kept, who can access it, and for what purposes.
- Clear rules on data sharing. Agencies should know (and be able to state publicly) whether their data can be accessed by other departments, state aggregation centers, or federal agencies, and under what conditions.
- Policy that keeps pace with the technology. Current and future uses and capabilities need to be explicitly covered by policy rather than left in the gap between what the system does today and what the rules were written to address.
ALPR technology isn’t going away, and the cases where it’s helped locate kidnapping victims or murder suspects in minutes are real. But so are the cases where the same tool became a tool for stalking with no warrant and little supervision. The tech doesn’t decide which outcome you get; the policy, training, and oversight around it does.
Getting that right isn’t something industry or law enforcement can do alone. It’s going to take both sides — vendors building better guardrails into the product, and agencies actually using and enforcing them — working together with legislators to write sensible rules, and with the public to rebuild the trust that misuse has cost. Absent that cooperation, the backlash isn’t going away either, and the technology’s long-term future in American policing is the thing actually at risk.
Editor’s Note:
As we were preparing this article for publication, information surfaced about a new product apparently in development by Flock Safety called OS Investigate. According to information discovered on Flock’s website, this tool allows law enforcement to track and identify drivers and vehicles by movement patterns alone. OS Investigate appears to link plate scan data with arrest records, 911 logs, and commercial databases, enabling law enforcement users to single out individuals and even their known associates.
Journalists from WIRED discovered complex, prewritten prompts for law enforcement users enabling queries that identify possible witnesses based on how often a vehicle appears in a neighborhood, generate dossiers on people based on their arrest histories, and rank a subject’s associates based on other plates that routinely appear in close proximity. One such prompt reportedly enables querying individuals’ movements within a defined map area based on physical description alone.
When WIRED about the tool, a Flock spokesperson said the unreleased product’s workflows may change significantly before being launched. Given that OS Investigate is a pilot, we view these details as preliminary and will be following the story as it develops.
Notes
- In Chatrie, SCOTUS reasoned that cell phone users cannot be viewed as willingly sharing private information with third parties that can then be passed along to the government. People carry cell phones so they can use the tools on them, including location history, and these devices have become an indispensable part of daily life. As a result, cell phone users’ location data, which can show where the users are even in private locations, is protected by the Fourth Amendment. A license plate, which is visible to anyone viewing a vehicle in a public place, is arguably different. It’s not the collection of data that is protected by the Fourth Amendment, but rather whether and how the data is accessed by the government. Just as the private search doctrine provides an exception to the Fourth Amendment warrant requirement, private collection of data likely only triggers constitutional complications when a government actor accesses that data. Flock and Leonardo are not government agents, and their passive collection of freely available images and device signals only comes under constitutional scrutiny when accessed by the government. Absent any legislation prohibiting them from selling it to others, the companies are likely free to do so. Providing access to the government may be a different story altogether.
- The most relevant case from the U.S. Supreme Court is New York v. Class (475 U.S. 106 (1986)) in which the Court held there was no reasonable expectation of privacy regarding a vehicle identification number (VIN) that was visible from outside the vehicle. As the Court noted, “The VIN’s mandated visibility makes it more similar to the exterior of the car than to the trunk or glove compartment. The exterior of a car, of course, is thrust into the public eye, and thus to examine it does not constitute a ‘search.’” ALPR cameras image (and, possibly, identify) vehicles on public roadways or in areas generally visible to the public. In contrast, if police want access to video from cameras in a private parking garage, they must get consent of management or request it by warrant.
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