“At the same time, police around the country have been affixing high-tech scanners to the exterior of their patrol cars, snapping a picture of every passing license plate and automatically comparing them to databases of outstanding warrants, stolen cars and wanted bank robbers. The units work by sounding an in-car alert if the scanner comes across a license plate of interest to police, whereas before, patrol officers generally needed some reason to take an interest in the vehicle, like a traffic violation. But when a license plate is scanned, the driver’s geographic location is also recorded and saved, along with the date and time, each of which amounts to a record or data point. Such data collection occurs regardless of whether the driver is a wanted criminal, and the vast majority are not.”
East Bay firm keeps log of private cars’ locations, via Mike M.