Automated License Plate Readers: Are We Sacrificing Privacy For Security?

As there are more automated license plate readers, questions about who has access to that data need to be raised.
Marcia Wendorf

After a day at work, you pull into the parking lot of your apartment complex and someone knows you've arrived home. Your trip to the grocery store is also noted, and if you grab a friend and drive to the beach for a weekend of sun and surf, someone knows about that as well.

Welcome to the world of Automated License Plate Readers, or ALPRs. ALPRs use optical character recognition (OCR) to identify your car's license plate, and it then stores that information, along with the date, time and location where the plate was read, in a database.

Who has access to the databases of stored information is the question since location databases contain according to a recent New York Times article, "a record of people visiting drug treatment centers, strip clubs, casinos, abortion clinics ... churches and synagogues, ... counseling sessions and chemotherapy treatments."

ALPR cameras can be mounted on utility poles, streetlights, road signs, overpasses or on police cars, and they can photograph every passing license plate. Software advances allow ALPR systems to run on PCs or laptop computers, which can be within police vehicles.

ALPRs capture around 2,000 plates a minute, on vehicles traveling up to 120 miles per hour. Manufacturers in the ALRP space include PlateSmart Technologies, 3M, OpenALPR Software Solutions LLC, Jenoptik, Inex Technologies, Pelco, Cyber Vision, Signatur ITS, Senstar Corporation, DTK Software, NDI Recognition Systems, Neurosoft Sp. z o.o, ARH Inc, Rekor Recognition Systems, Inc, PIPS Technology, ACTi Corporation, and Avigilon.

OpenALPR offers its software for free on Github, and that software can allow an ordinary, internet-connected surveillance camera to capture license plates across a four-lane highway with 99% accuracy. While the software may be free, OpenALPR charges between $39 and $995 a month for cloud-based storage and analysis.

ALPR's history

It's not surprising given their extensive use of closed-circuit cameras, that ALPRs got their start in the UK during the early 1980s. The first ALPR systems were deployed on the A1 road and the Dartford Tunnel. During the 1990s, ALPR systems really took off.

In 2002, license plates in the Netherlands were changed to increase their optical character recognition. The Dutch introduced small gaps in some letters, such as the P and the R, to make them more readable by ALPR systems.

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Netherlands OCR modification
Netherlands OCR modification Source: Achim Raschka/Wikimedia Commons

On November 26, 2019, in Baltimore, Maryland, which regularly appears on lists of America's most dangerous cities, the Police Department informed the City Council of its plan to deploy ALPRs at 15 sites around the city by the end of the year. These new ALPRs will join the 20 already deployed.

On December 3, 2019, the Palm Beach Florida Board of County Commissioners approved ALPRs to be placed on poles and other structures along county roads. In the city of Delray Beach, the data from ALPRs is uploaded in real-time to servers housed within the Police Department.


The system allows officers to follow a specific car as it passes multiple ALRP cameras. To prevent possible abuse of privacy, Delray Beach's system will log officers who have searched for plates.

On December 4, 2019, the Reno, Nevada City Council approved the use of a federal grant of $117,000 to buy 6 fixed and 2 mobile ALPRs. A spokesperson for the Reno police told the Reno Gazette Journal that the information collected by the devices wouldn't be shared with outside agencies.

However, an investigation by the University of Nevada Reno’s Reynolds School of Journalism showed that license plate data was indeed being shared with outside agencies, including Immigration and Customs Enforcement (ICE).

On December 16, 2019, the Abilene, Texas City Council heard a request from its police department for 2 mobile automatic license plate readers, and one fixed in a trailer to analyze interstate traffic.

A cause for concern

In March 2019, an investigation by the American Civil Liberties Union (ACU) showed that the license plate reader company, Vigilant Solutions, shared the data collected by local and state law enforcement agencies, private businesses and parking lots with Immigration and Customs Enforcement (ICE).

Vigilant draws license plate information from the 50 most populous metropolitan areas in the U.S., which together account for almost 60% of the U.S. population.

According to the ACLU, the Vigilant database contains over 5 billion license plate scans and adds "an average of 150 - 200 million unique" license plate scans each month.

ALPR is increasingly in private hands, and it is being used for security and "business intelligence" such as allowing retailers to track who drives into their parking lots. Homeowners associations, neighborhood watch groups, and property managers are increasingly using the systems.

ALPRs could be used to track journalists as they visit their sources. It could be used to determine who has attended a political meeting or protest. There have even been cases of law enforcement officers looking up and then stalking women.

Only 16 states have statutes on how ALPR data can be used: Arkansas, California, Colorado, Florida, Georgia, Maine, Maryland, Minnesota, Montana, Nebraska, New Hampshire, North Carolina, Oklahoma, Tennessee, Utah, and Vermont.

Currently, nothing prevents ALPR companies from selling the data they have collected. The New York Times article says, "The price of participating in modern society cannot be turning our lives into open books, diaries of all travels and relationships and wants and desires ... Americans need to know how their information is being gathered, and whether it is being used to manipulate them. They deserve the freedom to choose a life without surveillance."

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