Automated License Plate Readers: Frequently Asked Questions

What are Automated License Plate Reader Systems (ALPRs) and what data do they collect?

ALPRs are computer-controlled, high-speed camera systems—generally mounted on police cars or fixed objects such as light poles—that automatically capture an image of every license plate that comes into view. ALPRs can detect when a license plate enters the camera’s field, capture an image of the car and its surroundings (including the plate), and convert the image of the license plate into alphanumeric data—in effect “reading” the plate. ALPRs record data on each plate they scan, including not only the plate number but also the precise time, date and place it was encountered. The cameras can scan up to 1,800 license plates per minute, day or night, allowing one squad car to record more than 14,000 plates during the course of a single shift. We learned through litigation that the Los Angeles Sheriff’s and Police Departments are able to collect data on about 3 million vehicles every week.  We’ve estimated that these two agencies alone may have amassed a database as large as a half billion datapoints.

How many law enforcement agencies use ALPRs?

Police use of ALPRs has exploded in recent years. A September 2009 survey reported that out of 305 randomly selected police departments nationwide, 70 (or 23%) used ALPRs. A 2011 Police Executive Research Forum survey of more than 70 of its member police departments showed that 71% used ALPR technology and 85% expected to acquire or increase use in the next five years.

How much do ALPR systems cost, and how are law enforcement agencies paying for them?

The cost of ALPRs varies depending on a lot of factors. A glance at the government purchase order database SmartProcure shows that:

  • The city of Laguna Beach, CA approved $87,000 to purchase 10 ALPR cameras in 2014.
  • The city of Austin, TX spent $36,934.00 on its ALPR technology.  $23,920.00 was for one car-mounted ALPR camera.
  • Rancho Cucamonga, CA, paid $223, 970 for 10 mobile ALPRs.

Cities also pay maintenance fees, software agreement fees, and data maintenance fees that range from $300 to $1100 for maintenance per camera for a 6 camera system.

  Some cities are undoubtedly paying for ALPRs with local taxpayer dollars. But much of this funding is coming from the Justice Assistance Grant Program and the Homeland Security Grant Program.[1]  And the ACLU learned through a Freedom of Information Act request that “The National Highway Traffic Safety Administration has granted hundreds of thousands of dollars to local and state law enforcement agencies for the procurement of automatic license plate reader systems.”

Are there any laws regulating ALPRs?

Yes. Although there is no federal legislation regulating ALPRs, some states have passed laws, and in 2015 ALPR statutes were introduced or pending in 18 states. The state legislation mainly focuses on exempting ALPR data from public records acts, creating audit and other control processes, and creating retention limits. Some of the legislation also places limits on when ALPRs and ALPR data can be used—a good precaution against abuse. The following states have established statutes:

Arkansas: Arkansas limits the use of ALPRs to law enforcement, parking enforcement, and for controlling access to secure areas, and it creates a 150 day limit on retention.

California: The California ALPR legislation applies only to the California Highway Patrol. It creates a 60 day retention limit on ALPR data, unless the data is being used as evidence in felony cases. IT also prohibits the sale or sharing of ALPR data with non-law enforcement officers or agencies, and creates an annual or more frequent report on ALPR use to the California legislature.

Colorado: This bill originally had a much shorter limit for retention of ALPR data. After amendments, Colorado ended up with a bill that limits access to ALPR data to one year from the date of capture, and requires that it be destroyed after three years.

Florida: The Florida ALPR legislation exempts ALPR data from public records act requests for everyone except the registered owner of a vehicle and the police. The registered vehicle owner can’t access data that is “active criminal intelligence information or active criminal investigative information.” The “criminal intelligence information” exemption could be used to deny nearly anyone access.

Maine: The Maine legislation limits law enforcement use of ALPRs to investigations “based on specific and articulable facts.” It also allows ALPR use for commercial vehicle inspection and highway safety purposes, and  limits retention of data not actively being used for an investigation to 21 days. It also exempts the data from public records act requests.

Maryland: The Maryland legislation limits the use of ALPR data to “legitimate law enforcement purposes,” and makes it a misdemeanor to violate that limitation. The law also requires law enforcement agencies to create basic minimum procedures governing access to ALPR data. The law requires an annual report on the use of ALPRs in the state, including numbers that look at efficacy and potential privacy violations. The legislation exempts ALPR data totally from public records act requests—including a requestor’s own data.

Minnesota: The Minnesota ALPR law requires that data not related to an active criminal investigation be destroyed after 60 days.

New Hampshire: This legislation is one of the strongest. It bans police and private companies from using license plate readers except in narrowly limited circumstances, including a specific investigation or one of 9 places listed in the law. And even where it authorizes use of ALPRs, it limits how long ALPR data can be retained. 

Tennessee: The Tennessee legislation requires that any data not being retained in connection with an active investigation or criminal action be destroyed after 90 days.

Utah: The Utah legislation exempts ALPR data from Utah’s public records statute and has a 30 day for private entities and 9 months for governmental entities retention limit.       

Vermont: The Vermont statute originally expired on July 1, 2015, but has been extended through July 1, 2016. It creates an 18 month retention limit, limits sharing of ALPR data, and requires annual report on the use of ALPRs.   

Additionally, the State Attorney Generals of both Virginia and New Jersey have provided guidance on ALPRs can be used. The New Jersey guidance allows ALPR data to be retained for 5 years,  and places limitations on "hot lists" (lists of vehicles with alerts attached to the plate number). The Virginia guidance states that ALPR collection by the Virginia fusion center is allowable, and when it's done for an active investigation is exempt from the Virginia Data Act.

Who are the main manufacturers of ALPRs and how have they aided the rapid proliferation of ALPRs?

A review of purchase orders in the Smart Procure database shows that Vigilant and 3M are the largest vendors of ALPR technology. Vigilant has been especially involved in lobbying for the adoption of ALPR technology. The company has attended city council meetings to lobby for adoption of the technology, spoken against regulations in state legislatures, and published op-eds.  But that’s not all. The company has gone so far as to sue both Utah and Arkansas to prevent the states from regulating ALPRs. Vigilant also has lobby firms working in DC.

Are private companies using ALPRs?

Yes. There are currently two main companies, DRN and MVTrac, that hire contractors to collect license plate data from cars all across the United States. DRN is a subsidiary of Vigilant. DRN’s database contains over 2 billion records, and MVTrac said in 2012 that it has data on a “large majority” of the vehicles in the United States. We have no idea how long these companies retain their data, and they have both lobbied and litigated vigorously against any statutory limits.

What are these companies doing with their ALPR data?

DRN and MVTrac share their data with banks, insurance companies, credit reporting agencies, and “auto recovery”(repo) companies and assert that their data can help these companies find fraud and identity theft. DRN’s parent company is Vigilant Solutions, which provides ALPR tools to law enforcement—and it also shares its vast database of privately-collected data with the cops.

What are the privacy implications of ALPRs?

ALPR data is not targeted to specific criminal activity or suspects but is gathered indiscriminately from any vehicle that comes within range of the devices. This means that the systems are collecting data on millions of ordinary people. The ACLU has estimated that fewer than 0.2% of plate scans are ever linked to vehicle registration issues or criminal activity.

Most law enforcement agencies that collect ALPR data retain it for years. Over time, the accumulated location data creates a history of drivers’ movements that can provide private and intimate details on people’s lives, like where they work, where they live, where they go throughout their day, and who they associate with. ALPRs can be used to scan and record vehicles at a lawful protest or house of worship; track all movement in and out of an area; gather information about certain neighborhoods; or organizations; or place political activists on hot lists so that their movements trigger alerts. And by analyzing this data, ALPR systems can even anticipate where a person might be at a given time in the future.

The cameras also may collect images of people getting in or out of a vehicle.

How has ALPR data been treated under public records laws?

As noted above, some states are moving towards exempting ALPR data from public records laws, with some leaving exceptions for individual’s to request their own data. While this may have the effect of protecting the privacy of individuals from outside parties, it does nothing to protect their privacy from the law enforcement agencies collecting the data in the first place—and it ensures that the full extent of ALPR use will be hidden.

EFF, along with the ACLU of Southern California, continue to fight this trend in our public records act case against the Los Angeles Police and Sheriff’s Departments.  seeking a week’s worth of ALPR data. The trial and appellate courts ruled that the data was exempt under California’s public records act. But as we pointed out, the court didn’t decide that location information is too private and too sensitive to release to the public. Instead, the court held that the ALPR data qualifies as the kind of investigative record police can keep secret and that the harm to law enforcement investigations from disclosing data outweighs the value to the public of seeing what data police collect on them. The California Supreme Court will be reviewing the case later this year.

Other places in California, including Oakland, have released ALPR data. In 2013, the Boston police “ inadvertently released to the [Boston] Globe the license plate numbers of more than 68,000 vehicles that had tripped alarms on automated license plate readers over a six-month period.” Minnesota has classified ALPR data as non-public, after a reporter published a story showing that ALPR data allowed the Minneapolis mayor’s movements. The classification expires on August 1, 2015.

What are these companies doing with their ALPR data?

DRN and MVTrac share their data with banks, insurance companies, credit reporting agencies, and “auto recovery”(repo) companies and assert that their data can help these companies find fraud and identity theft. DRN’s parent company is Vigilant Solutions, which provides ALPR tools to law enforcement, so it also shares its vast database of privately-collected data with the cops.

Can I prevent ALPR capture?

Preventing ALPR capture requires obscuring your license plate in some way, which is illegal in most states. For example, California requires that license plates be mounted in a particular way, visible and illuminated at night.  The science show Mythbusters tested methods for trying to beat speed cameras, including special license plate covers and other products, and showed that they don’t work. 

Covering a license plate while a car is parked in a driveway may be legal. You should check your state’s laws.

My city/county is considering adopting ALPR technology. What can I do?

We’ve created talking points for activists who want to oppose ALPR technology in their community. We also encourage you to file a public records act request on ALPR data in your community and email sls@eff.org with the results.

How do law enforcement agencies use ALPRs?

Most law enforcement agencies also store the plate data in a database for many years and share it with other law enforcement agencies throughout the region. For example, in the greater Los Angeles area, nearly 30 individual law enforcement agencies pool their license plate data.  Agencies also share data across the state and even with federal agencies. Police can then search these massive amounts of accumulated data in future investigations.

For camera systems mounted on patrol cars, ALPR systems immediately send that data to a display monitor and computer system in the car. The system automatically compares the newly collected ALPR data against a “hotlist” of plates associated with wanted vehicles and alerts the officer in the car if there’s a match. The officer can then search a DMV database to learn the name and identifying information of the owner of the vehicle.

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