Automatic license plate readers – those cameras on police cars and light poles that capture plate numbers – have been in widespread use since the 1990s. But some argue regulations for how and how long police can use and store that information hasn’t kept up with the technology.
ALPRs can vary widely in appearance and are usually mounted at an odd angle toward the street. When a license plate enters the camera’s field, it takes a photo of the car, its plate and limited surroundings, then converts the image into alphanumeric data.
They record plate information, plus the time, date and place it was captured. 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, according to the Electronic Frontier Foundation.
This week on 90.5 WESA’s Criminal Injustice podcast, University of Pittsburgh law professor and host David Harris talks to American Civil Liberties Union attorney Nathan Freed Wessler, who says automatic plate readers are great for spotting stolen cars or wanted drivers, but they’re also watching the rest of us.
Their conversation has been edited for length and clarity.
DAVID HARRIS: Listeners to Criminal Injustice will know right away there's nothing private about a license plate number. So police photographing license plate numbers in public, they haven't broken any laws, have they?
NATHAN FREED WESSLER: If police are photographing or just looking at individual license plates as they go by and checking them against the list of wanted criminals or stolen vehicles, that's just fine under the Fourth Amendment. The problem comes when police start aggregating that information into humongous databases. They can start to show where all of our cars were going at multiple times a day over the course of weeks and months and years, and that holding that data for later use. That kind of aggregation raises serious concerns.
HARRIS: How many plates are we talking about? Is it thousands? Is it millions? Are the police targeting certain ones or are they just taking pictures of all of them?
FREED WESSLER: We're talking about billions of scans and databases now across the country. In many places you have police cars that are equipped to these as they drive around, and ALPR devices mounted on light poles and utility poles taking pictures of every car that goes by. Now sometimes they will alert the police when that license plate matches a wanted vehicle, and that's generally OK. But when they are starting to save all of those plates of all of the millions of innocent drivers who are going by in databases that have millions or even billions of plate hits, that paint a very detailed and sensitive picture of our lives. And that's why it's really crucial that state legislatures and city councils adopt strict limits on how long that information can be retained in order to prevent police from creating essentially dossiers on our movements over time that allow them to go back in time and see whether a person went to the doctor or a lover's house or an AA meeting or other sensitive locations.
HARRIS: There are police agencies in Pennsylvania that use these devices – the Pennsylvania State Police and the Pittsburgh Parking Authority. It's all completely legal, but should we be worried in any way?
FREED WESSLER: Yes, there's a lot of reason for concern. The crucial question is whether those police departments have appropriate policies that limit the amount of time they can save the information and who else has access to it. And to provide transparency to the public about what their policies are, how much data they're collecting and what they use it for. Without that kind of transparency, the public can't know whether this is a really troubling privacy violation or whether it's a relatively limited piece of good police work.
HARRIS: Is there any oversight in Pennsylvania or here in Pittsburgh?
FREED WESSLER: I don't know of any city council rules or state legislation. We do know that, for example, the Pittsburgh Parking Authority, as of a few years ago when we did a public records request, had a 30-day retention limitation on that data. That's relatively good. That's in the neighborhood that we would like to see government agencies using elsewhere. We found that most police departments across the country don't have policies that impose good limitation requirements. Sometimes they barely have a policy at all.
**UPDATED: 5:25 p.m. Tuesday, June 13, 2017. An earlier version of this story said the Port Authority of Allegheny County also used automatic license plate readers. Spokesman Adam Brandolph reports they do not.
Criminal Injustice is recorded at the studios of 90.5 WESA. Find more at criminalinjusticepodcast.com.