There is no evidence of a central, Federal database recording your every road trip. That said, many local law enforcement agencies–and even private organizations–use automated license plate reading (ALPR) technology to record where and when you drive. There is almost no regulation of what they can do with this data and how long they can keep it, causing major concerns for some civil liberties activists. This is Part Three of my series on ALPR technology. Read how ALPR systems work, or continue scrolling to find out how the government uses them.

Where are automatic license plate scanners deployed?

An increasingly common surveillance technology is the automatic license plate reader system. It includes cameras that scan passing vehicles and a computer that identifies the license plate number of these vehicles. These systems are mounted statically on bridges and intersections. They are also increasingly common on police cars—and even private vehicles.

An early application of ALPR technology was to identify vehicles passing through toll booths. This allows traffic to cross bridges like the San Francisco’s Golden Gate without slowing down, knowing the bridge operator will simply mail them a bill.

Many towns saw an opportunity and began to install these systems at intersections or along the town’s borders. These systems scan passing traffic and warn authorities of vehicles of interest—according to the Wall Street Journal.

Smaller systems allowed police to mount them on a cruiser and monitor traffic wherever they wanted. Finally, authorities leveraged mobile systems to identify every parked car on a street. These systems were first mounted on parking enforcement vehicles and are now becoming common on garbage trucks.

Who gets the data from license plate scanning equipment?

Anyone willing to invest in an ALPR system is entitled to the data it collects. Most states have no regulations on how long they can keep this data or who they can share it with. This is a concern for some civil liberties activists, such as the ACLU.

Data from one ALPR scan include the license plate of a car, the registered owner, and its location at a given time. But data from many scans can include the driving habits or specific trips taken by thousands of drivers.

Some police departments which choose to keep all their ALPR data have begun to pool it in regional databases. If they are investigating any driver, they can search back through previously recorded trips with no warrant.

Because many of the manufacturers of ALPR equipment keep the data from all their equipment, they have some of the largest databases. For example, a city garbage truck could scan all the license plates on a street. Then the scanner’s manufacturer could give or sell this data to a repo agent interested in the driving habits of the owner of one of those cars—even if they were doing nothing illegal at the time.

What happens to data from scanned license plates?

With no federal regulation of automatic license plate readers’ data, what happens to this information varies by police force. The Minnesota State Patrol collects ALPR data and deletes it after 48 hours. But cities such as Milpitas, CA, and Grapevine, TX collect their own ALPR data, which they appear to be keeping forever.

One of the largest ALPR manufacturers is Vigilant (owned by Motorola). This company advertises a private database which includes over nine billion individual plate scans. That includes 30 scans, on average, for every registered car.

Dave Maas, director of investigations at Electronic Frontier Foundation, put it bluntly when speaking with the Wall Street Journal:

“They are collecting data on everyone regardless of whether there is connection to a crime..and they are storing that data for long periods of time….License-plate readers are mass surveillance technology.”

Dave Maas, EFF

There’s a very good chance that the next time you go for a drive—or just park your car on a public street—some electronic eye will take note of your trip.

Next, learn how police stop crime with ALPR or hear concerns about storing this data in the video below: