San Francisco, California—The Electronic Frontier Foundation (EFF) and the ACLU won a decision by the California Supreme Court that the license plate data of millions of law-abiding drivers, collected indiscriminately by police across the state, are not “investigative records” that law enforcement can keep secret.

California’s highest court ruled that the collection of license plate data isn’t targeted at any particular crime, so the records couldn’t be considered part of a police investigation.

“This is a big win for transparency in California,” attorney Peter Bibring, director of police practices at the ACLU of Southern California, which joined EFF in a lawsuit over the records. “The Supreme Court recognized that California’s sweeping public records exemption for police investigations doesn’t cover mass collection of data by police, like the automated scanning of license plates in this case. The Court also recognized that mere speculation by police on the harms that might result from releasing information can’t defeat the public’s strong interest in understanding how police surveillance impacts privacy."

The ruling sets a precedent that mass, indiscriminate data collection by the police can’t be withheld just because the information may contain some criminal data. This is important because police are increasingly using technology tools to surveil and collect data on citizens, whether it’s via body cameras, facial recognition cameras, or license plate readers.

The panel sent the case back to the trial court to determine whether the data can be made public in a redacted or anonymized form so drivers’ privacy is protected.

“The court recognized the huge privacy implications of this data collection,” said EFF Senior Staff Attorney Jennifer Lynch. “Location data like this, that’s collected on innocent drivers, reveals sensitive information about where they have been and when, whether that’s their home, their doctor’s office, or their house of worship.”

Automated License Plate Readers or ALPRs are high-speed cameras mounted on light poles and police cars that continuously scan the plates of every passing car. They collect not only the license plate number but also the time, date, and location of each plate scanned, along with a photograph of the vehicle and sometimes its occupants. The Los Angeles Police Department (LAPD) and the Los Angeles County Sheriff's Department (LASD) collect, on average, three million plate scans every week and have amassed a database of half a billion records.

EFF filed public records requests for a week’s worth of ALPR data from the agencies and, along with American Civil Liberties Union-SoCal, sued after both agencies refused to release the records.

EFF and ACLU SoCal asked the state supreme court to overturn a lower court ruling in the case that said all license plate data—collected indiscriminately and without suspicion that the vehicle or driver was involved in a crime—could be withheld from disclosure as “records of law enforcement investigations.”

EFF and the ACLU SoCal argued the ruling was tantamount to saying all drivers in Los Angeles are under criminal investigation at all times. The ruling would also have set a dangerous precedent, allowing law enforcement agencies to withhold from the public all kinds of information gathered on innocent Californians merely by claiming it was collected for investigative purposes.