High-tech cameras that capture the date, time and location of vehicles are used in some capacity by about 600 local and state police departments and other state and federal agencies, according to the American Civil Liberties Union. Private business, such as repossession companies and vehicle insurance companies, also use the technology, which can capture about 1,800 images per minute.
The technology is not without flaws. Conditions that include bad weather, poor lighting, dirt on plates, and even background colors can result in false matches.
Critics say use of the scanners amounts to warrantless searches.