The American Civil Liberties Union (ACLU) and Electronic Frontier Foundation (EFF) are not giving up in their fight to compel greater transparency in the use of automated license plate readers (ALPR, also known as ANPR in Europe). The groups on Monday filed briefs with the California Supreme Court in their effort to overturn a lower court decision handed down last year (view ruling) denying access to a sampling of the data that police agencies in Los Angeles collect about motorists who are suspected of no wrongdoing. In May, the state Court of Appeal came to the same conclusion, to the dismay of the privacy advocates.

"This case has significant precedential impact, setting a troubling standard allowing police to keep these records and details of its surveillance of ordinary, law-abiding citizens from ever being scrutinized," EFF attorney Jennifer Lynch wrote. "The appeals court ruling may apply not only to records collected with license plate cameras, but to data collected using other forms of automatic and indiscriminate surveillance systems, from body cameras and dash cameras to public surveillance cameras and drones. Without access to these records, we can't ensure police accountability."

At issue is whether the database of license plate information extracted from the plate reading cameras constitutes a public record under state law. The statute exempts documents related to ongoing investigations from disclosure so that, for example, a career criminal cannot request a copy of his file to find out whether he is being wiretapped. ACLU and EFF are asking for a week's worth of plate records so that they can have a good idea of the extent of government surveillance of innocent drivers. The groups estimate that 99.8 percent of records are unrelated to any suspicious activity and that applying this exemption to records created by an entirely automated process is unprecedented.

"No case in California has ever before held that this kind of automatic, indiscriminate and untargeted collection of data on the public by the police constitutes an 'investigation' -- or that data collected through this kind of surveillance regime are 'records' of a police investigation," Lynch wrote. "Such a ruling appears contrary to the California Constitution, which not only mandates that the public has a constitutional right to government records but also requires that statutes and other authorities, such as the law involved in our case, 'shall be broadly construed if they further the people's right of access, and narrowly construed if they limit the right of access.'"

Each license plate reader has the capability of scanning tens of thousands of plates an hour. With the information entered into a searchable database, law enforcement can build patterns of where and when every motorist in the city travels, even creating real-time tracking alerts.

The high court has not yet decided whether it will hear the appeal.