When Anne Arundel County Police announced in August that their crime rates had dropped since the beginning of the year, they attributed it in part to the technology at their fingertips, including automated license plate readers.
Police departments across Maryland and the country have employed these cameras in the past few decades to assist in investigating traffic violations, finding stolen vehicles and locating missing people. But experts and critics alike warn that, as they grow in use, these license plate readers could be more of a cause for concern than a solution.
David Jaros, a professor of law at the University of Baltimore, said this issue has become “increasingly complicated” in recent years.
“As technology has become more sophisticated, the ability of the government to track our movements has started to raise really important privacy issues,” he said.
What are automated license plate readers?
Automated license plate readers consist of high-speed cameras and computers that are able to take the data from images of vehicles and compare them against a database of images.
Jaros, who is also faculty director of the school’s Center for Criminal Justice Reform, said the cameras can be in fixed positions, on mobile units or affixed to police vehicles.
“So that as the police are going through a neighborhood or driving on a highway, they are constantly recording the license plates of cars that go by them,” he said.
The data from these images, including time and location, is stored on a server, Jaros said.
According to the Maryland Coordination and Analysis Center’s 2025 audit report on license plate readers in the state, 20 law enforcement agencies in Maryland used their own license plate reader storage server in 2024. This includes Baltimore Police, Baltimore County Police, Howard County Police, Anne Arundel County Police and the Harford County Sheriff’s Office.
Among the 18 agencies that the center tracks, 1.01 billion license plates were recorded by license plate readers in 2024. Anne Arundel County Police’s license plate readers recorded 71.3 million of those plates.
Lt. Brian Carney, commander of the Anne Arundel County Police Department’s Real-Time Information Center, said the county has 176 license plate readers set up on 88 sites across the county.
In a document detailing its program, the Anne Arundel County Police Department says it uses license plate readers for “legitimate law enforcement purposes only.”
This purposes are defined as:
- The investigation, detection or analysis of a crime
- The investigation of a vehicle law violation
- The investigation or location of persons known to be terrorists or wanted
- The investigation, location and searching of missing or endangered persons
The definition is taken from the state’s law on license plate readers, which also says the data cannot be sold by a law enforcement agency or contracted vendor and cannot be accessed by a vendor unless authorized by the law enforcement agency.
Carney said license plate readers have been “instrumental” in recovering stolen vehicles and has helped in finding missing people, including those with Alzheimer’s or people in a mental health crisis.
Marc Limansky, a spokesperson for the police department, said the department purchased the majority of its license plate readers for a total cost of $650,000. He said the department spends roughly $646,000 annually on storage, troubleshooting and maintenance of the license plate reader systems.
How automated license plate readers assist police
During the past week, Anne Arundel County Police used license plate readers to find a stolen vehicle in Brooklyn Park. Limansky said the assistance of these cameras in the investigation led to an arrest.
University of Maryland assistant professor Zubin Jelveh, who works in the school’s Department of Criminology and Criminal Justice as well as its College of Information, said studies show that these cameras are helping solve crimes, particularly vehicle theft cases.
According to data from Anne Arundel County Police, the department has used license plate readers in 567 investigations so far this year. The department says it has used data from the cameras this year to help find 10 missing people — up 100% from this time last year — and recover 126 stolen vehicles, up 137% from this time last year.
Concerns with automated license plate readers
It was October 2024 when software engineer Will Freeman, who lives in Boulder, Colorado, started to notice black cameras with “giant black solar panels” popping up on streets. When he learned what they were — “untargeted surveillance that’s recording absolutely everyone,” he said — it didn’t sit right with him.
Freeman created DeFlock, a website that tracks the number of license plate readers in the country and where they are located. He said DeFlock has tracked roughly 50,000 of these cameras in the U.S. But, based on public audits, he estimates there are closer to 100,000 of them.
“It’s a very powerful tool,” Freeman said about the license plate readers. “But it’s a powerful tool that deliberately bypasses Fourth Amendment protections,” which protects against unreasonable searches and seizures.
The University of Baltimore’s Jaros said that as the number of these cameras has grown, so has the ability of the government to track people’s movements. He said Maryland’s law on license plate readers doesn’t require probable cause for police to look at the data.
If police could walk into anyone’s house without a warrant, it’s possible they’d find evidence they might not otherwise have found, he said. But he said the country has made “certain decisions” to limit the government’s involvement in and knowledge of a citizen’s private life.
According to Anne Arundel County Police, license plate readers are not a GPS or live-feed camera that acts as general government surveillance. Carney said they aren’t used for immigration enforcement either.
“It simply creates a record of a vehicle passing a specific point, much like a digital toll booth,” the department said in an email. “It does not know who is driving, and it cannot follow that vehicle to its next destination.”
Last month, the Court of Appeals of Virginia reversed a lower court ruling that Norfolk Police need a warrant to access license plate reader data. The Court of Appeals ruled that police access to the data is not a violation of the Fourth Amendment and Virginia police do not need a warrant before accessing it.
Jelveh, of the University of Maryland, said that although Maryland is one of the leading states when it comes to regulating license plate readers, there is no strict retention policy that details how long data can be stored before it is deleted.
“In theory we could be creating these large stores of innocent people moving around the state, and do we want that?” Jelveh asked. “That’s a potential serious privacy concern.”
Although state law doesn’t say data must be deleted after so many days, Anne Arundel County Police say they delete their license plate reader data after 30 days unless it’s evidence in a specific case.
Carney said this means there is no way for the department to “build a detailed, historical database of people’s movements.”
Carney said he thinks the general population in Anne Arundel County is “pretty good” with the department’s use of these cameras. He said he wants those with concerns about the cameras to know that state law has a “strong framework” that addresses its potential misuse.
“This technology is a proven asset for solving serious crime, but it’s only effective if the community trusts it,” he said. “That’s why the Anne Arundel County Police Department has embraced a ‘privacy-by-design’ approach. We don’t just use the technology; we govern it.”
Have a news tip? Contact Maggie Trovato at mtrovato@baltsun.com, 443-890-0601 or on X @MaggieTrovato.
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