Like law enforcement agencies across the country, the police in Fairfax, Virginia, use automated license plate readers (ALPRs) to indiscriminately scan and record every passing car. The ALPRs don’t simply check for speeding, or outstanding tickets—instead, they store detailed information about the time, date, and location of each scan in a database for a year, even when they have absolutely no connection to law enforcement investigations.

The wholesale collection and storage of the public’s movements invades individuals’ privacy and free expression rights and violates a Virginia data privacy law.

As EFF explained in a friend-of-the-court brief to the Virginia Supreme Court, ALPRs collect an enormous amount of data on innocent drivers. 99.5% of cars scanned are not associated with any crime. But ALPR cameras nonetheless capture images of every license plate that comes into view, up to 3,600 plates per minute. This allows law enforcement agencies to compile enormous databases of license plate scans. And because law enforcement agencies often share the license plate information they collect with other local, state, regional, and federal agencies—and even private companies—law enforcement agencies may be able to access billions of plate scans from all over the country.

The data collected can reveal highly sensitive personal information. ALPRs record the precise time, date, and place that scans occurred, and can pinpoint where an individual’s car was at a given time in the past with even more precision than cell phone data or GPS trackers. This information opens the door to a universe of inferences about peoples’ private lives, including political, professional, religious, medical, and sexual associations.

Collecting this kind of information can chill individuals from engaging in constitutionally protected activity. In Muslim communities in the U.S. that were subject to surveillance, for example, people have been less likely to attend mosques, express religious observance in public, or engage in political activism.

And, collecting location information in a centralized database opens the door to abuse. Police can abuse ALPR information to stalk individuals or improperly keep track of vehicles at sensitive locations, such as political rallies or doctors’ offices. Sadly, the fear of abuse is far from theoretical. Among other examples we provided to the court, police have used license plate information to stalk women; to extort the owners of vehicles parked at a gay bar; and to track cars attending gun shows.

This isn’t the first time that the Virginia Supreme Court has considered the lawfulness of the ALPR system. Back in 2018, the court recognized that this ALPR collection system constitutes “sweeping randomized surveillance and collection of personal information,” and that the license plate scans allowed police to infer drivers’ past locations, as well as “personal characteristics” about the drivers. The court held that the indiscriminate collection and storage of license plate information would violate the Virginia law that regulates the government’s collection of data on private citizens if the ALPR system provides a means for police to link license plate information to the vehicles’ owners. The court then remanded the case for the lower court to decide that question.

The lower court correctly concluded that the ALPR system allows police to link license plates with individuals with just “a few clicks on the screen, all from the driver’s seat of a police cruiser.” Accordingly, the lower court held that the ALPR surveillance system does violate Virginia law. Indeed, not only do ALPR systems allow police to link license plates to specific individuals, but doing so is the core purpose of collecting and storing ALPR data. Keeping a database of individuals’ historical movements, after all, allows police to conduct expansive surveillance without needing to know in advance whether they want to follow a particular person, or when. But the Supreme Court has made clear that the Constitution does not permit police to keep track of individuals’ location histories through their cell phone records. They should not be able to do so through license plate data, either.

We hope that the Virginia Supreme Court will again recognize the immense impact ALPR tracking has on individual privacy, and make clear once and for all that indiscriminate license plate collection violates state law.