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States Begin Restricting, Prohibiting Police License Plate Readers

Critics say the now-popular technology needs to be regulated, but cops worry too much regulation will hurt their ability to fight crime.

Police have a new set of eyes called automated license plate readers, and they're growing in popularity -- and controversy.

Automated license plate readers are mounted either on a police car or a fixed position like a bridge. As their name suggests, they read the numbers and letters on license plates -- even when vehicles are moving at high speeds -- and tag the time and location. Then another program compares the data with a list of license plates associated with criminal activity.

The entire process takes just seconds and can automatically check tens of thousands of plates in just one hour. That’s why cops love them, said David Roberts, senior program manager for the International Association of Chiefs of Police (IACP).

“The old practice involved driving around and checking license plate numbers on suspicious cars against a hotlist typed on sheets of paper. [Automated license plate readers] can do in minutes what it took a cop to do in an entire shift,” he said.

The technology not only makes police more efficient, it's been shown to increase arrests of car thieves and deter auto theft, according to a 2010 study of large and small police departments across the U.S.

In 2007, 17 percent of America's police departments had automated license plate readers, according to the Rand Corporation. By 2012, that number had jumped to 71 percent.

Meanwhile, the cost of the technology has dropped. Today, installing the readers in every police car costs departments between $10,000 and $25,000. But hardware and software costs are only a portion of the overall expense. Police departments sometimes overlook the labor costs associated with running one of these systems. Depending on its size, the technology can require one -- if not more -- full-time administrators to maintain and repair the cameras, update the lists of stolen and suspect vehicles, and upgrade the software.

Despite their benefits, automated license plate readers aren't technologically flawless.

Bad weather, poor lighting, the speed of the vehicles, dirt on plates and even background colors can affect how well a camera “reads” a license plate. Under good conditions, the technology can accurately read over 90 percent of the plates they scan. But when conditions are less than ideal, performance can drop -- below 80 percent, according to some reports -- potentially triggering false matches. In 2009, for example, police detained a person in San Francisco after her car was mistakenly identified as stolen because the system misread her license plate. The driver later sued the police department, according to the San Francisco Chronicle.

But the biggest issue with the readers is privacy. Some worry that police will use the technology to track just about anyone who drives a car.

In 2013, the American Civil Liberties Union (ACLU) studied 600 state and local police departments' use of automated license plate readers. The ACLU acknowledged the technology has a legitimate law enforcement purpose but was alarmed at the lack of rules about its use. According to the ACLU, departments keep the records anywhere from 48 hours in Minnesota to five years in New Jersey. "Too many police departments are storing millions of records about innocent drivers," the organization concluded. 

Proponents of the readers, however, argue that they don't collect personal information about drivers and aren't used to track people in real-time.

Nevertheless, growing concerns about possible abuse have led six states (Arkansas, Maine, Maryland, New Hampshire, Utah and Vermont) to enact laws that restrict or prohibit the technology, according to Pam Greenberg of the National Conference of State Legislatures. In June, Louisiana Gov. Bobby Jindal (who's vying for the Republican nomination for president) vetoed a bill that would have let the state start using automated license plate readers. The technology, he said, poses “a fundamental risk to personal privacy and create large pools of information belonging to law-abiding citizens that unfortunately can be extremely vulnerable to theft or misuse.”


Louisiana Gov. Bobby Jindal (Olivier Douliery/Abaca Press/TNS)

State efforts to regulate the readers worry the law enforcement community so much that they've asked Congress not to restrict the use of the technology, arguing any further limits would significantly impact their ability to investigate crimes.

At the same time, however, the police realize they need to set comprehensive privacy and data retention policies. In other words, if a police department is using the technology to identify parking scofflaws, then there’s no need to retain the data for more than a few days, said IACP's Roberts. But if the data is gathered for more complicated criminal investigations and needs to be kept for a longer period, then the policy should explain that and have empirical evidence to support it.

The police should also define what constitutes authorized use of the data it's captured, whether that data can be shared and under what circumstances, according to IACP’s guidelines. Finally, the use of the license plate data should be regularly audited to show it's being properly used and stored so as not to violate the privacy of innocent drivers.

This story was originally published by Governing.

With more than 20 years of experience covering state and local government, Tod previously was the editor of Public CIO, e.Republic’s award-winning publication for information technology executives in the public sector. He is now a senior editor for Government Technology and a columnist at Governing magazine.