The spread of cheap, powerful cameras capable of reading license plates has allowed police to build databases on the movements of millions of Americans over months or even years, according to an American Civil Liberties Union report released Wednesday.
The license-plate readers, which police typically mount along major roadways or on the backs of cruisers, can identify vehicles almost instantly and compare them against “hot lists” of cars that have been stolen or involved in crimes.
They are making it possible to stitch together people’s movements whether they are stuck in a commute, making tracks to the beach or up to no good.
But the systems collect records on every license plate they encounter — whether or not they are on hot lists — meaning time and location data are gathered in databases that can be searched by police.
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Some departments purge information after a few weeks, some after a few months and some never, said the report, which warns that such data could be abused by authorities and chill freedom of speech and association.
Attached to police cars, bridges or buildings — and sometimes merely as an app on an officer’s smartphone — scanners capture images of passing or parked vehicles and pinpoint their locations, uploading that information into police databases.
Over time, it’s unlikely many vehicles in a covered area escape notice. And with some of the information going into regional databases encompassing multiple jurisdictions, it’s becoming easier to build a record of where someone has been and when, over a large area.
“Using them to develop vast troves of information on where Americans travel is not an appropriate use,” said Catherine Crump, a staff attorney at the ACLU and one of the authors of the report, “You are Being Tracked: How License Plate Readers Are Being Used to Record Americans’ Movements.”
Law-enforcement officials say the scanners are strikingly efficient. The state of Maryland told the ACLU that troopers could “maintain a normal patrol stance” while capturing up to 7,000 license plate images in a single eight-hour shift.
“At a time of fiscal and budget constraints, we need better assistance for law enforcement,” said Harvey Eisenberg, assistant U.S. attorney in Maryland.
The ACLU study, based on 26,000 pages of responses from 293 police departments and state agencies across the country, found that license-plate scanners produced a small fraction of “hits,” or alerts to police that a suspicious vehicle had been found.
The ACLU of Washington said the national report reinforced its own findings about the use of automated license-plate readers in the state.
The state group has identified at least 22 city police departments and county sheriff’s offices that own the systems, including the Seattle Police Department. Few of the agencies place any “substantial restrictions” on how the information can be used, according to the state group, which also said some agencies keep the records for months or indefinitely.
“It’s time for our legislators to put regulations in place to ensure that (these) systems are not used to create large location-tracking systems of innocent people,” wrote Jamela Debelak, the ACLU of Washington’s technology and liberty director, in a news release. “Legitimate uses of the readers should be specified, and there should be no retention of location information unless it relates to suspected criminal activity. In addition, collected information should only be retained for a limited time.”
Debelak said the state group did not participate in the national report because of its own investigation.
Police and law-enforcement experts say the information can help investigators reconstruct suspects’ movements before and after armed robberies, auto thefts and other crimes. Departments typically require that information be used only for law enforcement and require audits designed to detect abuse.
But the ACLU argues that data collection by most police departments is unnecessarily broad.
While the Supreme Court ruled in 2012 that a judge’s approval is needed to use GPS to track a car, networks of plate scanners allow effective tracking of a driver’s location, sometimes several times every day, with few legal restrictions. The ACLU says the scanners are assembling a “single, high-resolution image of our lives.”
“There’s just a fundamental question of whether we’re going to live in a society where these dragnet surveillance systems become routine,” said Crump. The ACLU is proposing that police departments immediately delete any records of cars not linked to a crime.
Although less thorough than GPS tracking, plate readers can produce some of the same information, the group says, revealing whether someone is frequenting a bar, joining a protest, getting medical or mental help, being unfaithful to a spouse and much more.
In Minneapolis, for example, eight mobile and two fixed cameras captured data on 4.9 million license plates from January to August 2012, the Star Tribune reported. Among those whose movements were recorded: Mayor R.T. Rybak, whose city-owned cars were tracked at 41 locations in a year.
A Star Tribune reporter’s vehicle was tracked seven times in a year, placing him at a friend’s house three times late at night, other times going to and from work — forming a picture of the dates, times and coordinates of his daily routine. Until the city temporarily classified such data late last year, anyone could ask police for a list of when and where a car had been seen.
As the technology becomes cheaper and more widespread, even small police agencies are able to deploy more sophisticated surveillance systems. The federal government has been a willing partner, offering grants to help equip departments, in part as a tool against terrorism.
Law-enforcement officials say the technology automates a practice that’s been around for years.
The ACLU found that only five states have laws governing license plate readers. New Hampshire, for example, bans the technology except in narrow circumstances, while Maine and Arkansas limit how long plate information can be stored.
“There’s no expectation of privacy” for a vehicle driving on a public road or parked in a public place, said Lt. Bill Hedgpeth, a spokesman for the Mesquite Police Department in Texas. The department has records stretching back to 2008, although the city plans next month to begin deleting files older than two years.
In Yonkers, N.Y., just north of New York City’s Bronx, police said retaining the information indefinitely helps detectives solve future crimes. In a statement, the department said it uses license-plate readers as a “reactive investigative tool” that is only accessed if detectives are looking for a particular vehicle in connection with a crime.
“These plate readers are not intended nor used to follow the movements of members of the public,” the department said.
Even so, the records add up quickly. In Jersey City, N.J., for example, the population is 250,000, but the city collected more than 2 million plate images in a year. Because the city keeps records for five years, the ACLU estimates it has some 10 million on file, making it possible for police to plot the movements of most residents, depending upon the number and location of the scanners.