Monday's article describing the use of GPS and red light cameras questions whether there is a privacy issue given that certain information, such as a license plate, is already plainly visible. The privacy violation would be minor if not for concerns not mentioned in the article: data mining, dossier building, and other tracking by those with access to the raw data.

Simply put, placing cameras at enough intersections permits the government to identify the approximate location of any car by noting where the car was last seen. By placing car sightings in a database with date and time, the track a car takes through the city can be determined quite easily and retained indefinitely. Vehicles in proximity to crimes could be identified long after the fact, whether or not they were involved. A quiet payoff by a suspicious spouse could reveal where the family car goes during the day. The city could find cars that reached one intersection too soon after passing another and issue speeding tickets, even though the traffic lights were green. Similar concerns exist with the automatic license plate reader the Boston Transportation Department is experimenting with to identify parking scofflaws, and the privacy problem quickly grows even further by combining information from all of these sources.