The cameras snap a photograph of a vehicle as it passes through an intersection that has a traffic signal. In most states using cameras, the photos are taken from behind to capture the license plate. But in California and Arizona frontal photography is mandated, giving police a view of both the driver and the vehicle's license plate. The American Civil Liberties Union does not oppose the use of the cameras, but has concerns over the use of the pictures they take. In California, if the gender and approximate age of the driver match those of the vehicle's owner, the owner is mailed a traffic ticket.
Drivers can challenge the tickets in court.