Consumer Federation of California

At a rapid pace, and mostly hidden from the public, police agencies throughout California have been accumulating millions of license-plate readings from devices placed atop patrol cars and feeding them into intelligence centers operated by local, state and federal law enforcement, the Center for Investigative Reporting has found.

With heightened concern over secret intelligence operations at the National Security Agency, the localized effort to track drivers highlights the extent to which the government has committed to collecting large amounts of data on people who have done nothing wrong.

A year ago, the Northern California Regional Intelligence Center — one of dozens of law enforcement intelligence-sharing centers set up after the terrorist attacks of Sept. 11, 2001 — signed a $340,000 agreement with the Silicon Valley firm Palantir to construct a database of license plate records flowing in from police using the devices across 14 counties, documents and interviews show. The extent of the center’s data collection has never been revealed.

Law enforcement says license-plate reading has been a boon to its efforts to spot people wanted on outstanding warrants, recover stolen cars and even arrest murder suspects.

Privacy advocates say the price is unacceptably high — millions of people who have done nothing wrong, having their movements recorded by the government.