LOS ANGELES — Police don’t have to disclose license plate records that advocacy groups sought to gauge how high-tech surveillance was being used, a California appeals court ruled Wednesday, May 6.

The unanimous ruling by the 2nd District Court of Appeal rejected a California Public Records Act request for data compiled by the Los Angeles police and sheriff’s departments.

Law enforcement departments across the country are increasingly using automated license plate readers mounted on patrol cars and fixed locations to check plate numbers against a “hot list” of vehicles associated with crimes, such as stolen cars, child abductions or arrest warrants.

Police can store the data for years to use in future investigations and Los Angeles police said they had used the information to identify a vehicle linked to a homicide and another at the location of an armed robbery.

The American Civil Liberties Union and Electronic Frontier Foundation contended the records were not for specific investigations, but data collected indiscriminately that could be used to track anyone, such as political activists.

They sought a week of records from August 2012 to assess the scope of government surveillance.

The 3-0 ruling sided with a Los Angeles County Superior Court judge who said the records were exempt from disclosure because they related to law enforcement investigations.

The court noted that technology had made the case different from previous challenges.

“To be sure, the automated nature of the … system, with its capacity to capture and record millions of plate scans throughout Los Angeles city and county, sets it apart from the traditional investigatory techniques that courts have considered in earlier cases addressing the scope of the investigative records exemption,” Acting Presiding Justice Patti Kitching wrote.

“But that distinction is irrelevant to the question of whether the ALPR system’s core function is to … investigate suspected crimes.”

Attorney Jennifer Lynch of the EFF said the group was disappointed and weighing its appeal options.