You know about speed cameras and red-light cameras. But did you know about plate-reading cameras? Few people do, and that's a worry for the ACLU, which says the cameras are infringing on our civil liberties. Unlike the speed and red-light cameras, which are activated only when someone violates a traffic law, plate cameras photograph every license plate that goes by. Vehicles are instantly IDed then checked against cars associated with crimes, the Washington Post reports. The problem, says the ACLU, is that the license plate info is being stored, creating huge databases of motorists and where they travel—even though more than 99% of those recorded are innocent. ACLU privacy lawyer Catherine Crump calls the cameras "the most pervasive system of location tracking that people haven't heard of," per NBC News.
Despite the massive amounts of data, authorities rarely record a "hit," according to an ACLU review of 600 local and state police departments. Maryland, for instance, collected data on 85 million plates last year, but only one in 500 matched with a criminal offense, and 97% of those were for minor violations (say, an emissions test violation). Just 47 per million were potentially serious crimes. But "those are 47 cases that may not otherwise have every been resolved," says an International Association of Chiefs of Police spokesperson. "If you can make 47 apprehensions, keep those 47 dangerous people off the street, that has real value." The ACLU doesn't see it that way. "We just think innocent people shouldn't end up in a database," says Crump. The Post notes that some departments wipe the records after a few weeks or months; some never purge them.