A national debate over surveillance, privacy, and public safety is swirling around Automated License Plate Reader technology, particularly the ALPRs produced by Flock Safety. ALPRs have sparked a bipartisan moral panic, with Democrats and Republicans alike calling for investigations. Over 200 communities have vowed either to cancel or not to renew their ALPR contracts.
As a policing scholar who partners with agencies to evaluate the effectiveness of law enforcement tactics and technology, I’ve been studying ALPRs for years. In my view, the outrage is largely misguided and overblown. ALPRs, including Flock, can make a difference for public safety, and many criticisms of the technology can be addressed with stricter departmental regulations and legislation.
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ALPRs are not new. By 2009, more than one-third of all police agencies in the U.S. with more than 100 sworn officers had acquired them. As of 2020, close to two-thirds of agencies of that size were using some form of the technology.
ALPRs, which can be fixed on stationary infrastructure like utility poles or mounted on mobile police vehicles, scan the alpha-numeric license plate of every vehicle that passes to create a geocoded, time-stamped data point. ALPRs therefore add to existing information technology systems that collect vital data that can be stored, shared, analyzed, searched, and retrieved for investigative and intelligence purposes—all of which is quite useful for detectives.
Scanned license plates are instantly cross-referenced with “hot lists” in real time to alert law enforcement dispatch of stolen vehicles, drivers with active warrants, and other crimes. The technology also presents officers with the ability to live-monitor alerts in their cars and thus conduct proactive vehicle stops. Therefore, ALPRs have the potential to make an impact on both investigatory and patrol functions. Their use can make policing more efficient and evidence-based.
While not enough evaluative work has been done on the technology’s effectiveness, causal evidence indicates that the implementation of Flock ALPRs across large U.S. cities was associated with reductions in motor vehicle theft and improvements in arrest/clearance rates for such crimes. This is particularly important when considering the steep rise in motor vehicle thefts from 2020 to 2023 and the historically low clearance rate for these crimes—just 8.2 percent in 2023.
My own research in Atlantic City, New Jersey, found that non-Flock, stationary ALPRs were associated with reductions in motor vehicle theft (but not violent crime), though the city-wide, pre-post research design was unable to rule out other possible explanations for the outcomes. ALPRs also assisted police department detectives in their shooting investigations. Having access to records of specific vehicles entering or leaving the jurisdiction—at precise times and locations—helped them build cases and collect evidence in drive-by shootings and identify cars that either picked up or dropped off a shooter.
Making this happen requires a great deal of coordination. Someone in dispatch or a police department’s crime center (if one exists), or in a patrol vehicle, must be monitoring the live alerts from the ALPR scans. That person does not always transmit the information to officers out in the field, or does not do so in timely fashion, making a successful vehicle stop and interdiction much more difficult. And patrol officers are often overburdened and stretched thin, too busy responding to other service calls. Over a two-year period, the agency I worked with documented only 72 initiated vehicle stops following ALPR alerts, while it relayed 59 notifications regarding outbound ALPR alerts to neighboring police departments.
The full potential of ALPRs thus remains largely untapped. And the technology has some other problems that need ironing out.
ALPRs have had operational problems, for one. Cameras routinely malfunctioned and provided only 61 percent of active hours of traffic coverage in and out of Atlantic City’s borders over a two-year period of evaluation, leaving critical blind spots for detectives/investigators.
ALPR abuses have also been increasingly documented. These often involve officers improperly monitoring the movements of ex-partners and romantic interests on the road. But such malfeasance is not unique to ALPR data systems. A small number of officers exploit other types of law enforcement sources, including driver’s license data, for their own purposes—yet you never hear calls to ban these systems. Officers who use any data system for non-law enforcement purposes should be subject to discipline as well as possible termination and criminal charges.
Even when not being used unlawfully, ALPRs have aroused concerns about privacy and mass surveillance. But police already have access to a multitude of other types of data and recorded material: from closed-circuit television (CCTV) footage to vast networks of both public and private surveillance cameras. Singling out ALPRs as Big Brother makes little sense.
Departmental policy and supervision should limit the number and types of officers who get access to ALPR data. Historical searches must be reined in and narrowed—by both departments and vendors—for specific and articulable investigatory purposes. And state law and legislation should provide more guidance.
ALPRs can be a force-multiplier law enforcement tool that serves the public interest. We can maximize the crime-control benefits of the technology while taking tangible steps to regulate its use more effectively—thus minimizing the privacy concerns.