(NEWSER– 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.

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