The California Supreme Court has rejected the argument that all license plate numbers routinely and automatically captured by roadside cameras and archived for future use by law enforcement agencies can be kept secret as “investigative” records. Instead, the license plate data must be released under the California Public Records Act if there is a way to protect the identities of the vehicles’ owners.

Yesterday’s unanimous decision in ACLU Foundation of Southern California v. Superior Court supplies a timely distinction just as surveillance technology of all kinds allows government agencies as well as corporate entities to amass and store virtually unlimited quantities of information tracking the whereabouts and activities of huge increments of the population.

While such accumulations like the Automated License Plate Reader (ALPR) network maintained by the Los Angeles Police and Sheriff’s Departments may be valuable to consult in particular investigations—TV police procedural dramas now routinely make a canvass of closed circuit video images among the earliest modes of inquiry—the court emphasized that this convenience does not make the mass of automatically captured data the record of a law enforcement investigation, because its acquisition was “not conducted as part of a targeted inquiry into any particular crime or crimes.”

If and when a specific plate number shows up in the context of a crime, however, then a search of the database to learn when and where the vehicle has been detected will be part of an investigation, and thus eligible to be withheld under the Public Records Act, the court said.

On the other hand, the court remanded the case to the trial court to determine if there is a way to strip out owner identities from the plate numbers, “anonymizing” the publicly disclosed vehicle data to protect personal privacy.

Ironically, the reason the ACLU (and Electronic Frontier Foundation) sought the information in the first place was not to find out who was driving where and when but “so that the legal and policy implications of the government’s use of ALPRs to collect vast amounts of information on almost exclusively law-abiding [citizens of Los Angeles] may be fully and fairly debated.”

Meanwhile, the bill recently noted here that would require police, sheriffs and other law enforcement agencies to present for comment and approval their surveillance technology use policies in meetings open to the public has been held without action by the Assembly Appropriations Committee under heavy opposition from the law enforcement lobby.