A license plate reader mounted on D.C. police patrol car. This model, made by a U.S-based subsidiary of an Italian industrial group, scans 1,800 plates per minute.
It's natural to be slightly nervous when a police car pulls up alongside you in traffic, and even more natural to feel relieved when it drives away. But with a tool being used by the Metropolitan Police Department, an officer doesn't even need to look you up to see if you've done anything wrong — a little camera mounted on the back of their cruiser will do it for them.
D.C. police are aggressively using small cameras to scan hundreds of millions of license plates annually, storing the images in a database for two years even if the driver is not suspected of having committed any crimes.
Hailed by police officials as an invaluable tool in fighting everything from auto theft to terrorism, the growing use of the cameras — known as Automatic License Plate Readers (ALPRs or LPRs) — has provoked concern among civil libertarians, who say that they come perilously close to a massive surveillance program.
A powerful tool
The simplicity behind ALPRs belies how powerful a tool they can be for police departments.
Each camera, no larger than a hardcover book and costing between $20,000 and $25,000, scans license plates as they pass its field of vision, recording an image of the plate, the date the scan was taken and a geographic marker indicating where the scan occurred.
Those scans — up to 1,800 per minute, catching cars driving up to 100 mph — are then checked against a database known as a “hot list” that has data on cars that might be stolen or linked to criminal offenses or terrorist acts. They are also stored in a database for anywhere from 24 hours to five years, depending on the department.
The cameras are so powerful, boasted one Arizona law enforcement official, that he compared them to "fishing with dynamite."
ALPRs efficacy is evidenced by the numbers of scans produced by the units used by D.C. police. According to data obtained by WAMU 88.5 through a Freedom of Information request, in 2011 the units scanned 125,284,584 license plates. In 2012, that number rose to 204,285,053. Through September 2013, 150,206,974 tags have been scanned.
“The real value is it automates a process that officers do on a manual basis today,” explains David Roberts, a senior program manager at the Technology Center at the International Association of Chiefs of Police in Arlington, Va.
“It instantaneously notifies an officer if a vehicle in their vicinity that has been observed by the ALPR unit is on a hot list — if it’s stolen, if it’s wanted in connection with an abduction or a kidnapping or any other offense. It gives the officer a much better situational awareness,” he says.
According to a 2012 report from the Police Executive Research Forum, ALPRs have become popular among many police departments and agencies across the country. At the time of the report, 71 percent of large police agencies across the U.S. already employed ALPR, and 85 percent of those that did not said they were planning on it.
D.C. police have used ALPRs since 2009, and the department currently operates between 60 and 65 functioning ALPR units, 38 of which are posted at specific locations and the remainder on patrol cars. They were paid for through a $1 million grant from the Department of Homeland Security and $221,720 in local funds; police agencies in Virginia and Maryland were also given money to purchase the cameras, which totaled 200 across the region.
The D.C. Department of Public Works also has ALPR units on 30 vehicles ranging from pickup trucks to street sweepers; they are used to issue tickets for parking and registration violations. Hits produced by those units are made available to D.C. police.
D.C. police spokeswoman Gwendolyn Crump refused repeated requests for comment or interviews on the use of the ALPR units, but in April 2011 former Assistant Chief Alfred Durham spoke of the department’s use of ALPR at a gathering of police chiefs in Washington.
“The primary purpose of LPR is to detect wanted persons, stolen autos, and vehicles using stolen license plates in real time. It is a tool to make law enforcement more efficient and effective. The LPR technology has been helpful in numerous investigations and in the seizures of stolen autos. The technology also allows patrol officers to recover unoccupied stolen autos on their beats,” he said.
Durham said that ALPR units helped the department close out two homicide investigations in 2010, and played a key role in finding a suspect originally wanted in connection to the killing of Sue Marcum, an American University professor who lived in Glen Echo, Md.. Shortly after her killing, Marcum’s jeep was spotted by an ALPR unit in D.C.; Deandrew Hamlin, then 18, eventually pleaded guilty to stealing the vehicle, though he was not charged in relation to Marcum’s death.
A presentation by one manufacturer of ALPR units used D.C. as an example of how effective they can be: over 21 hours, five D.C. patrol cars were able to scan 59,650 plates, identify 38 stolen cars and five carjacked cars, and produce 18 arrests.
The databases fed with license plate images are also used for another purpose: fighting terrorism. As part of the Department of Homeland Security’s Urban Area Security Initiative, tens of millions of dollars have been funneled through D.C. to create a regional license plate recognition program aimed at identifying and stopping possible terrorists.
Civil liberties concerns
The power of ALPRs to quickly automate what was once left to individual police officers has provoked concerns from civil liberties advocates who say that the databases of scanned license plates could potentially serve as a means to track people who haven’t done anything wrong.
“The ACLU does not oppose the use of license plate readers, but we do have concerns when police departments not only check plates to see if they’re stolen, but then store information on all innocent people for months and even years at a time,” says Catherine Crump, a staff attorney for the ACLU and author of the group’s July report on the use of ALPRs, “You Are Being Tracked: How License Plate Readers Are Being Used To Record Americans’ Movements.” (Crump is not related to the D.C. police spokeswoman of the same last name.)
According to department regulations, D.C. police retain license plate images for two years, keeping them for longer if part of an investigation. But data obtained by WAMU 88.5 shows that the overwhelming majority of the plates scanned are of people who have committed no crimes: of the 204 million license plates scanned and stored in 2012, for example, 22,655 were linked to specific offenses — a hit rate of .01 percent.
D.C. police spokeswoman Gwendolyn Crump refused to detail what types of crimes those were, saying only that the units are used to identify stolen cars. A Freedom of Information request for further information on arrests stemming from the use of ALPR units received no response.
The ACLU’s Crump says that repeated scans of individuals license plates at different locations can give police a detailed and troubling picture of a person’s habits.
“What business is it of law enforcement agencies to be stockpiling all of this information about our daily movements? Where people go can be tremendously sensitive, and it can reveal the pattern of their daily life: where they work, who their friends are, where they go to the doctor,” she says.
That can lead to profiling and abuse, says Crump. In October, the Virginia chapter of the civil liberties group reported that Virginia State Police had used ALPRs during the 2008 presidential campaign to log visitors to political rallies and to track every visitor crossing from the commonwealth into D.C. for President Obama’s inauguration.
Cynthia Lum, an associate professor of criminology at George Mason University and author of a landmark 2010 survey of the use of ALPRs by police departments across the country, says that aside from civil liberties concerns, the oft-cited benefits of ALPRs to police remain largely untested.
“That’s the interesting thing about technology: we know that it’s faster, we know that LPR is more efficient in terms of scanning plates as opposed to the old-fashioned way. But does it actually reduce crime, does it prevent crime, does it lead to crime clearance? These are uncertain, we don’t know the answers to these,” she says.
As part of a $550,000 grant from the Department of Justice, Lum and a group of academics will be embarking on such a study next year.
A balanced approach?
Roberts, of the International Association of Chiefs of Police, says that one way that police departments can help assuage concerns over the use of ALPRs is to be open about it and lay out specific policies governing their use — primarily when it comes to how long images if license plates are kept on file.
“If you don’t have any policy dealing with data retention and who can access it and for what purposes, you’re going to be in trouble. You have to have a policy,” he says.
Lum agrees, and says that police departments should speak more openly about how and why they use the technology. “Ultimately, we all want the same thing — we want the community to be safer. And sometimes we can achieve that just from people knowing what kinds of things are being done to secure their communities,” she says.
But for Crump of the ACLU, it’ll take more than simply being open about ALPR use to assuage the civil liberties concerns the organization has raised.
“Transparency is a good start, but it’s not enough. The ACLU believes that if law enforcement has reason to believe that a particular license plate is associated with wrongdoing, it’s OK to keep that information for the duration of the investigation. But… the vast number of people whose plate data is stored in these systems are completely innocent,” she says.
A better solution, she says, is for police departments to drastically limit the time they can keep license plate images not linked to any crimes. In Minnesota, state police delete non-hit license plate images after 48 hours, while in Ohio non-hit images are deleted immediately. Locally, police in Takoma Park and Gaithersburg keep images for 30 days; Montgomery County for one year.
Since 2010 D.C. police have operated LPR units under a general order mandating who can use the cameras, how long images will be kept, and how to verify license plates identified as suspicious. The order also limits their use to officers who have been specifically trained — in 2012, 52 officers took a class on ALPRs offered at the department’s academy. But for the ACLU, more limits are needed on how long images can be kept and who can access them.
The group's local affiliate, the ACLU of the Nation’s Capital, testified before the D.C. Council in March 2012 on possible legislation that would limit the scope of the LPR program and increase oversight. Fritz Mulhauser, a staff attorney with the group, specifically asked that non-hit plates be more quickly deleted from the database and that rules governing who can access the database and for what purpose be tightened up.
Whether or not that happens, though, Lum believes that the aggressive use of LPRs by D.C. police will continue to spur debate over the balance between criminal investigations and civil liberties.
“It’s the classic tug of war in the American justice system: protecting individual rights and privacy and also figuring out ways to control and prevent crime. LPR really gets to the heart of that particular, very unique aspect of the American criminal justice system,” she says.
MPD LPR Presentation