Until recently, Boulder shared license plate data on a national network accessed by ICE

This story was updated on Aug. 21 to add new information about data sharing with U.S. Border Patrol.

For more than three years, the Boulder Police Department shared license plate data with a national network accessible to agencies working with U.S. Immigration and Customs Enforcement. In June 2025, after criticism from privacy advocates, the city limited its sharing to a Colorado state network.

Boulder contracts with Flock Safety, an Atlanta-based surveillance company that operates automatic license plate readers. These cameras, positioned at some of Boulder’s busiest intersections — such as Canyon Boulevard and Broadway, 30th Street and Arapahoe Avenue, and 28th Street and Valmont Road — capture license plate numbers and other vehicle information.

Until June, Boulder’s data was searchable by thousands of law enforcement agencies across the country via Flock’s national network. That included agencies known to collaborate with ICE. Records show that on Jan. 1, 2025 alone, Boulder’s system was included in 5,438 database queries. As part of a Flock search, police must provide a reason they are conducting a search. Between June 1, 2024 and May 5, 2025, the national system logged more than 4,000 searches citing “immigration” as the reason, according to records obtained by researchers and reported by 404 Media.

But those records identify only the agencies making the searches, not which local camera systems returned results, so it’s unclear whether any immigration-related searches involved data from Boulder’s cameras. Public records reviewed by Boulder Reporting Lab, however, show that Boulder was included in more than 100 searches of the network by U.S. Border Patrol before the city cut off national sharing.

The shift to a more limited sharing arrangement came only after months of scrutiny and questioning from Boulder resident Will Freeman, founder of the advocacy group Deflock. While the city now limits access to about 90 Colorado law enforcement agencies, Freeman and other privacy advocates say the change doesn’t go far enough to address privacy concerns.

Flock operates cameras for over 5,000 law enforcement agencies in 49 states. Its technology enables participating law enforcement agencies to search a national database for any license plate that passed a Flock camera in the past 30 days. The system functions somewhat like an internet search: An officer enters a license plate number and a reason, and the database instantly returns a list of times and locations where that vehicle was spotted.

Although Boulder has pulled back from the national system, it still shares surveillance data with over 90 Colorado law enforcement agencies. That includes the Loveland Police Department, which recently admitted to giving the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) access to its Flock account for ICE-related searches, according to a 9News investigation. After those revelations, Denver cut off Loveland’s access to its own Flock system.

Federal access has taken different forms. Instead of informal back-door arrangements like Loveland’s, Flock gave U.S. Border Patrol its own account, letting federal agents formally request access from local police departments, 9News also reported. 

Privacy advocates, including the ACLU and the Electronic Frontier Foundation, have long raised concerns about Flock’s potential to facilitate unconstitutional surveillance. Freeman, a software engineer, began investigating Flock after noticing a camera at a local intersection. He argues that tracking residents each time they pass a Flock camera amounts to warrantless surveillance and violates the Fourth Amendment, which protects against unreasonable searches and seizures.

Assurances from Boulder police, but national sharing continued

In January, Freeman spoke at a Boulder City Council meeting, prompting questions from several councilmembers. In a Feb. 20 email, Boulder Police Chief Stephen Redfearn told them that Boulder used the system only for legitimate investigations, adding that city policy prohibits its data from being used for immigration enforcement. But officials later acknowledged Boulder had no way of knowing whether the thousands of agencies with access nationwide were complying with that policy.

“We could not then, and cannot now, speak for any other agency or how they do/don’t/did/didn’t use Flock,” police spokesperson Dionne Waugh wrote to Boulder Reporting Lab in response to questions. 

Waugh also confirmed that “before June 2025, the Boulder Police Department had the national lookup feature activated. As such, any other agency using Flock with this feature enabled could have searched for a specific license plate within our database, assuming they could articulate a law enforcement purpose.” She added that the department does not maintain a list of which agencies actually used Boulder’s data. She directed Boulder Reporting Lab to Flock Safety for further information; the company did not respond to a request for comment.

During Freeman’s comments to city council, he claimed that Montgomery County, Texas, had requested access to Boulder’s data shortly after Roe v. Wade was overturned. This raised concerns among advocates because some Texas localities have restricted abortion access across state lines, and at least one has used Flock to track a woman who had a self-administered abortion. Councilmember Mark Wallach asked how Boulder responded to that request from Montgomery County.

Redfearn told councilmembers he couldn’t determine whether Boulder police had granted access. Records requests obtained by Freeman show that Montgomery County tapped the national Flock network more than 600 times in a single month while Boulder was still sharing its data. 

“I felt a really strong responsibility to share [what Flock does] with everyone,” Freeman told Boulder Reporting Lab. 

City scales back, but stops short of ending sharing

The decision to limit access to about 90 Colorado police departments followed repeated inquiries from Freeman and an internal audit.

In a written statement, Waugh said the department changed its Flock settings after realizing other agencies were using the system in ways that conflicted with Boulder’s values. 

“Over time, between early 2025 and mid-2025, our national political landscape shifted, and we became aware of ways that other agencies could search for information that was not aligned with our policies and values,” she wrote. She added that Chief Redfearn then directed the department to adjust its sharing settings. Waugh also said that Flock “has recently begun automatically blocking any search that lists a reason related to immigration.”

Privacy advocates say those steps don’t do enough to address their broader concerns about the Fourth Amendment or ICE.

Boulder still shares surveillance data with many Colorado law enforcement agencies. Freeman is concerned that nothing prevents an officer from entering one reason for a search and then using the data for another. In Kansas, for example, a police officer entered reasons like “test” and “investigation” 164 times to track his ex-girlfriend, according to the Wichita Eagle. It was the second case in that city where an officer misused Flock technology to stalk an ex. Flock training videos show that a user need only enter a reason for the search – and in some cases a case number – to run a query.

Freeman argues that with statewide data sharing, Boulder would need to oversee not only its own officers but also those in more than 90 Colorado police departments, a level of auditing he says isn’t practical.

“If you want to build a really extensive system to audit [Boulder’s system], you can, but the best way is just to treat it like a Fourth Amendment search and get a warrant,” he said. 

Extent of surveillance

Flock cameras don’t just capture license plate numbers. They also log a car’s make, model, color, plate state and more than 20 other identifying details, including roof racks and bumper stickers. Freeman has mapped about 40 of these cameras around Boulder, many at busy intersections such as Canyon and Broadway, 30th and Arapahoe and 28th and Valmont. Thirty are operated by Boulder Police, while others belong to CU Police or private businesses. 

Map courtesy of Deflock

“When you have them placed at such strategic locations and you have so many of them all around the city, you can basically track where anyone’s been,” he said. 

To illustrate, Freeman described a test in which an out-of-state resident gave him Flock license plate data he had requested for his own car. Within minutes, Freeman said, he was able to figure out where the person lived, worked and what time he usually came home, “just from a couple minutes talking to ChatGPT or writing a Python script,” he said. “So I’m pretty sure the police could do a lot more than that.”

Boulder Police denied records requests from Boulder Reporting Lab for a reporter’s license plate data, saying responding to the request would require them to run a search of the system, something they said they can only do for “a legitimate law enforcement purpose (i.e. a criminal investigation or a missing person case).” 

National legal challenges

Flock’s technology is facing legal scrutiny. In Norfolk, Virginia, a lawsuit argues the city’s use of Flock violates residents’ Fourth Amendment rights. The case cites the U.S. Supreme Court’s 2018 decision in Carpenter v. United States, which found that “individuals have a reasonable expectation of privacy in the whole of their physical movements.” That decision also points to a concurring opinion in United States v. Jones, which held that “society’s expectation has been that law enforcement agents and others would not — and indeed, in the main, simply could not — secretly monitor and catalogue every single movement of an individual’s car for a very long period.”

Jennifer Ciplet, a city communications manager, told Boulder Reporting Lab that Flock does not obtain or share anyone’s name, address, date of birth or other personal identifying information, and that its terms and conditions allow the company to restrict or suspend users’ access if they search the system for anything other than a “legitimate public safety and/or business purpose.” 

Asked how those rules are enforced, the police department referred questions to Flock. The company did not respond.

Police, meanwhile, emphasize the system’s value in fighting crime.

“This license plate reader system has helped us dramatically reduce auto theft in our community, among other crimes,” Ciplet said. Since Boulder began using license plate readers in January 2022, the department reports a 34.5% decline in vehicle thefts compared with the previous five-year average.

She also pointed to high-profile cases. “Flock was one of the ways we were able to very quickly — exceedingly more quickly than without Flock — locate the car of the suspect in the June 1 antisemitic terror attack on the Pearl Street Mall,” she said. “The car did have other explosives in it, and Flock was also able to help us see if there were any additional cars involved, and to see if the suspect’s car had been casing other locations to potentially attack additional sites.”

Police say the technology has been used to investigate mail fraud, felony menacing, assault and a hit-and-run crash.

The Denver City Council recently voted not to renew the city’s contract with Flock out of concerns over mass surveillance and ICE access to the system. The cameras remain operational for a few more months, though with Loveland’s access now cut off. The City of Boulder’s contract with Flock is up for renewal in March 2026.