This story was first published in Technical.ly.
The Baltimore Police Department purchased more than 200 Axon Enterprise automated license plate readers, public records show.
In May, the Board of Estimates approved a 10-year, $153 million no-bid contract with Axon, a major police technology company, covering everything from body cameras and Tasers to other public safety equipment. Nestled within that deal lies Axon’s automated license plate reader (ALPR) technology, known as Axon Outpost and Axon Fleet.
ALPRs scan passing license plates, recording where a car was and when it was there. Fixed units, like Axon Outpost, are installed on poles, buildings or trees, while mobile units, like Axon Fleet, operate from inside police vehicles.
The purchase could expand the Baltimore Police Department’s (BPD) existing ALPR system, which sits at around 120 mobile and fixed units. Experts told Technical.ly that an increased camera capacity heightens privacy risks for the public.
Across the country, people are pushing back against Axon competitor Flock Safety’s ALPR technology. Legal scholars like University of Maryland (UMD) law professor Chaz Arnett say they’ll want to see the data showing that surveillance technology actually makes communities safer.
“We’re in this period where there have been significant efforts to try to tie together notions of digital surveillance and safety,” Arnett said, “without the studies to back it up.”
The BPD acquired the ALPR cameras through a bundle deal from Axon rather than selecting them intentionally, according to a department spokesperson.
BPD has not yet started operating the cameras. The department did not specify when or even whether it plans to deploy the technology in the future.
Mayor Brandon Scott voted to approve the Axon contract as a member of the Board of Estimates. ALPRs are part of Baltimore Mayor Brandon Scott’s longer-term budget plans for the city.
Scott released a 10-year financial plan in December. It included modernizing traffic control and parking enforcement using ALPR technology, though it didn’t mention using the cameras for other policing purposes. The new Axon deal could be a significant boost of BPD’s existing license plate reader technology. More than a quarter of Maryland’s one billion ALPR scans in 2024 happened in the city.
The BPD currently uses Italian defense contractor Leonardo’s ALPR technology. The department prioritizes using the cameras for violent crime reduction, according to its policy. Unlike Leonardo, Axon’s ALPRs can also livestream, but the BPD can choose its data retention and external sharing policies for either system.
While research shows plate readers are associated with lower rates of auto theft and other property crime — though not necessarily a direct cause — it did not find ALPR expansion to be effective in reducing violent crime.
Neither Axon nor the mayor’s office replied to Technical.ly’s requests for comment.
ALPRs face growing legal scrutiny
Baltimore’s purchase comes as jurisdictions across the country cancel contracts with controversial ALPR vendor Flock Safety, an Atlanta-based startup, over privacy concerns.
In August alone, 90 cities and towns canceled deals with Flock. But several municipalities, including cities in Colorado and Upstate New York, are swapping out their Flock ALPR system for Axon’s.
As the pushback continues, maintaining a large ALPR network could face legal hurdles, according to UMD law professor Ben Yelin.
“Within the city of Baltimore, you’re still going to have a large network of ALPRs that can theoretically track the whole of a person’s movement,” Yelin said, “and that’s going to create Fourth Amendment problems.”
For example, residents of Norfolk, Virginia, sued Flock Safety under the Fourth Amendment, which protects against warrantless searches. While a federal judge ruled that the cameras do not constitute an invasion of privacy, he noted that could change as the technology expands.
A recent Supreme Court ruling could accelerate that shift, Yelin said.
Building on prior rulings on cellphone location, the court held that individuals retain a reasonable expectation of privacy in location history data, and that even a brief window of surveillance requires a search warrant.
The stakes of data retention
Axon may be trying to capitalize on Flock Safety’s stumbles, pitching its ALPR hardware to departments struggling with camera vandalism and public scrutiny.
In a recently deleted webinar, one officer went so far as to ask if Axon could alter its camera designs to avoid being confused with Flock’s. Customers like BPD are now including Axon’s Outpost vandalism warranty in contracts, helping cover the cost of potential damage.
While Axon’s cameras work much like Flock’s — capturing passing license plates and storing the data — there is a key difference in how that data is shared. Axon does not automatically make records searchable across a nationwide network, a feature that became a central flashpoint for Flock.
Law enforcement agencies using Axon cannot search camera data from outside jurisdictions by default, though they can manually share information with other agencies.
Howard County offers one example of how that can play out. The police department operates 27 Axon ALPR cameras, according to its website. While the department does not share its license plate data with outside agencies, it does retain recorded data for up to one year. A department representative declined to share statistics with Technical.ly on how the technology has assisted policing efforts.
That makes data retention one of the more consequential questions surrounding Axon’s system. The company’s standard default is 30 days, but it does not impose a hard limit on how long departments can store plate data. Flock recently lowered its recommended default retention period to seven days.
Under current protocol, the BPD retains license plate data on its servers for 18 months.
Critics argue that prolonged data retention increases the risk of misuse or unauthorized access, such as tracking patients seeking abortions or sharing information with federal immigration authorities.
Neither the Supreme Court nor lower courts have established a specific limit on how long law enforcement can store location data. But UMD professor Yelin said that longer retention periods could increase the risk of legal challenges.
“I think the longer not only the surveillance takes place, but the longer the retention period is,” Yelin said, “the more you might trigger judicial scrutiny.”