How Much Do Automated License Plate Readers Know About You?

Civil liberties advocates argue that it may be too much.

Image
Shutterstock

The information on your license plate is public data in the most literal sense. As you drive down the road, anyone can look at it, photograph it, jot it down. You have a right to try to keep plenty of other personal numbers close to the vest – your driver's license, Social Security or cell phone digits, for starters – but this one goes on display, by design.

So what's the problem with police cameras that photograph license plates in transit all around town? Civil liberties advocates have begun to raise the question as automated license plate readers have become a standard tool of law enforcement in cities across the country. Police now rely on these sophisticated cameras mounted from squad cars or static poles to identify scofflaws or stolen cars. But in the process, plenty of other cars are photographed too, in some cases many times. And when you put all that data together, it draws a picture of personal mobility that may reveal even more about you than a surveillance camera at a single intersection can see.

"Five years ago, this was very new technology in the U.S. that only the largest departments had even started to adopt," says Peter Bibring, a senior staff attorney with the ACLU. "Today, it’s everywhere. Even very small departments."

The problem is not so much that these cameras may get a one-time snapshot of your tag.

"They're recording a single plate linked to the time and date that plate was photographed and the location of that plate," says Jennifer Lynch, a staff attorney with the Electronic Frontier Foundation. "If it were just photographed one time, that probably wouldn’t be that much information, it wouldn't be concerning to most people. It’s the fact that the data is stored, and that plates are recorded pretty frequently. That allows law enforcement to create a picture of your life, not only to find out where you've been in the past, but also to anticipate where you might be in the future."

The ACLU and the EFF recently sent public-records requests to the Los Angeles Police Department and the Los Angeles County Sheriff’s Department, looking for materials on how the agencies train officers to use the technology and how they share the data that comes from it with other departments. They also requested a week's worth of the data gathered by license plate readers around Los Angeles from 2012. The agencies declined to turn over some of their material or any of the actual data, arguing that it wasn't subject to state public records law. Now the ACLU and EFF are suing to get it in Los Angeles County Superior Court, in an effort to figure out how this data is stored and shared, and whether agencies should have tighter policies to limit what happens to those snapshots of your car once police realize you didn't steal it.

This is obviously valuable information to have about a criminal suspect (A Los Angeles County Sherrif's Department powerpoint presentation details the readers should be used to locate unregistered or stolen vehicles, vehicles associated with Amber Alerts, warrants, suspended licenses and outstanding DUIs. Also to monitor "locations of suspected narcotic or gang activity" and the motels or "large parking lots" where criminals may try to evade police) . But 7 million people driving around L.A. are under suspicion of none of these things. And, arguably, law enforcement shouldn't need to keep their data once they figure that out.

"That a ton of data being collected on people," Lynch says. "It’s not just that a patrol car scans your vehicle once and that's the end of it." A license plate reader can scan up to 14,000 plates in a daily shift, identifying even cars traveling in the opposite direction at more than 160 miles per hour. That information may also be stored indefinitely by agencies with no policies in place for when records should be discarded. And police departments share this data with each other. LA Weekly has reported that more than two-dozen law enforcement agencies in the metropolitan area collect this stamped license plate data, with police having conducted, on average, 22 scans for every one of the 7 million registered vehicles in L.A.

All of this means that your car – whether you live in L.A. or another city like it – has likely been seen by multiple agencies, at different times, in varying locations.

"It could be your doctor’s office, it could be outside a gay bar, it could be at a political rally, it could be just your house or where you work," Lynch says. "It gets to the point where it becomes pretty serious surveillance, and law enforcement has argued they don’t need any kind of legal process to get access to this kind of data."

Ironically, in this particular case, law enforcement has been arguing that it doesn't need to go through any legal process to collect the data (as police might to obtain a search warrant or gather other types of evidence) because license plate data is publicly available on the street. The agencies are withholding this collective data from a records request, though, on the grounds that it's not public.

Going forward, Bibring raises one even more troubling possibility: License plate readers and more traditional video cameras may in fact wind up compounding the privacy concerns separately raised by each technology.

Top image: Louis Caldwell/Shutterstock

About the Author

  • Emily Badger is a former staff writer at CityLab. Her work has previously appeared in Pacific StandardGOODThe Christian Science Monitor, and The New York Times. She lives in the Washington, D.C. area.