Explore How Cops Are Collecting and Sharing Our Travel Patterns Using Automated License Plate Readers

EFF and MuckRock have filed hundreds of public records requests with law enforcement agencies around the country to reveal how data collected from automated license plate readers (ALPR) is used to track the travel patterns of drivers. We focused exclusively on departments that contract with surveillance vendor Vigilant Solutions to share data between their ALPR systems.

We have released records obtained from 200 agencies, accounting for more than 2.5 -billion license plate scans in 2016 and 2017. This data is collected regardless of whether the vehicle or its owner or driver are suspected of being involved in a crime. In fact, the information shows that 99.5% of the license plates scanned were not under suspicion at the time the vehicles’ plates were collected.

On average, agencies are sharing data with a minimum of 160 other agencies through Vigilant Solutions’ LEARN system, though many agencies are sharing data with over 800 separate entities.

In my town, south of Boston, a working class suburb of Boston, permanent installations of what are ostensibly fixed radar speed warnings.  Set for the legal speed for that street, they flash if you are going above that speed.  They flash a lot.  But that’s not all that they are doing.  According to recent articles published by privacy advocates, they have optical license plate readers incorporated into their design.  All being paid for by the Federal Government.

Ditto for the new highway billboards that have the distance to the next exit and the digital readouts of the estimated times to reach those points at the (legal) speed limit.  Has anyone driving by those signs ever wondered how the estimated time between exits are known so exactly?  By scanning all the license plates of all the cars traveling on that road, and getting the real-time travel times between exits, an accurate estimate of travel time is easy to calculate.   The hidden tool: automated license plate readers (ALPR).

At its core, ALPR is a simple technology. These systems are a combination of high-speed cameras and optical character recognition technology that can identify license plates and turn them into machine-readable text. What makes ALPR so powerful is that drivers are required by law to install license plates on their vehicles. In essence, our license plates have become tracking beacons.

ALPR systems can be affixed to stationary locations, such as highway overpasses and street lights, to capture the license plate of every vehicle that passes. The cameras can also be mounted on police cars (or other vehicles, such as tow trucks) to passively collect license plate scans during routine patrols or to surveil specific communities by driving systematically through targeted neighborhoods.

After the plate data is collected, the ALPR systems upload the information to a central a database along with the time, date, and GPS coordinates. Cops can search these databases to see where drivers have traveled or to identify vehicles that visited certain locations. Police can also add license plates under suspicion to “hot lists,” allowing for real-time alerts when a vehicle is spotted by an ALPR network.

It is crucial to remember that ALPR is a mass surveillance technology that spies on every driver on the road, and logs their location, regardless of whether they are suspected of being involved in a crime. In fact, as the California Supreme Court noted in a 2017 opinion, “The scans are conducted with an expectation that the vast majority of the data collected will prove irrelevant for law enforcement purposes.”

Past behavior shows that the police can be very lazy at times.  The first suspect they get pointed at usually has to hope that they can ‘Prove their innocence’ to the police, or otherwise have a very good lawyer.  So maybe that liquor store that got robbed is one that your car drove by, while the actual thief walked there.  So all the police have initially is you.

How Law Enforcement Uses ALPRs

ALPR data is gathered indiscriminately, collecting information on millions of ordinary people. By plotting vehicle times and locations and tracing past movements, police can use stored data to paint a very specific portrait of drivers’ lives, determining past patterns of behavior and possibly even predicting future ones—in spite of the fact that the vast majority of people whose license plate data is collected and stored have not even been accused of a crime. Without ALPR technology, law enforcement officers must collect license plates by hand. This creates practical limitations on the amount of data that can be collected and means officers must make choices about which vehicles they are going to track. ALPR technology removes those limitations and allows officers to track everyone, allowing for faster and broader collection of license plates with far reduced staffing requirements.Law enforcement has two general purposes for using license plate readers.

Real-time investigations

By adding a license plate to a “hot list,” officers can use ALPR to automatically identify or track particular vehicles in real time. Licenses plates are often added to hot lists because the vehicle is stolen or associated with an outstanding warrant. Officers may also add a plate number to the list if the vehicle has been seen at the scene of a crime, the owner is a suspect in a crime, or the vehicle is believed to be associated with a gang. Hot lists often include low-level offenses, too.

Historical investigations

Since ALPRs typically collect information on everyone—not just hot-listed vehicles—officers can use a plate, a partial plate, or a physical address to search and analyze historical data. For example, an officer may enter the location of a convenience store to identify vehicles seen nearby at the time of a robbery. The officer can then look up those plate numbers to find other locations that plate has been captured.

Training materials, policies and laws in some jurisdictions instruct officers that a hot-list alert on its own may not be enough to warrant a stop. Officers are instructed to visually confirm that a plate number is a match. Failure to manually confirm, combined with machine error, has caused wrongful stops.

Law enforcement claims that ALPR data has been used to, for example, recover stolen cars or find abducted children. However, police have also used ALPR data for mass enforcement of less serious offenses, such as searching for uninsured drivers or tracking down individuals with overdue court fees.

The length of time that ALPR data is retained varies from agency to agency, from as short as mere days to as long as several years, although some entities—including private companies—may retain the data indefinitely.

Of course, commercial interest in the data will also be keen.  And how many jurisdictions will farm out the implementation and collection of the data to private corporations.  And to

If the data shows that you drive by a area in which certain nationwide chains have stores, then you can be targeted with ads; print, mailed, or robocalls.  Worse, drive over to visit your girlfriend every Friday night and Thursday you get a flurry of different ads in every medium for flowers, wine and condoms.  Explain that to your wife.

The debasement of privacy in this country, already extreme, would soon make the concept of personal privacy meaningless.