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A "License Plate Reader" or LPR, one of two mounted on the trunk of a Metropolotian Police Department(MPD) is seen on a police car in Washington, DC, December 1, 2011.
Two privacy rights groups questioning law enforcement's use of automated license plate readers asked a judge Monday to order the Los Angeles Police Department and Los Angeles County Sheriff's Department to provide more details on how they use the technology.
The American Civil Liberties Union Foundation of Southern California and the Electronic Frontier Foundation filed a writ against the city, county and its law enforcement departments after waiting more than eight months for a complete response to public records requests.
The groups are seeking one week of data collected by the readers, which are usually mounted on police cars and scan thousands of license plates per officer shift. The readers — which collect the license plate scanned, the time, date, GPS location and a photo — alert law enforcement to stolen and wanted vehicles.
Privacy advocates say the readers create a database that tracks movements of innocent people.
Neither department responded to a request for more details on the program or a response to the legal action.
In the LAPD's response to the public records request, the department said the records could not be provided because they contain "official information" and referred to them as "investigatory files" that need to remain confidential.
The Sheriff's Department's also wrote in its response that it would not provide the data out of a concern for protecting "investigatory or security files."
"The public interest served by not disclosing the record clearly outweighs the public interest served by disclosure of the record," the department wrote.
A Sheriff's Department PowerPoint presentation, which was provided in response to the public records request, seems to indicate that individuals searching their database for a specific license plate can also link over and search the servers of more than a dozen other law enforcement jurisdictions.
Investigators can check the whereabouts of a vehicle after a crime has occurred to determine where it has been, essentially mapping its location over time. They can also identify witnesses in the area where a crime has occurred.
The automated reader can scan more than 14,000 license plates during an officer's shift, reading a plate coming in the opposite direction at up to 160 mph even in poor lighting, according to the PowerPoint presentation.
Peter Bibring, a senior staff attorney for the ACLU of Southern California said the legal action is an effort to determine how many plates are being collected in a week and also whether the databases, likely taken from areas with higher policing rates, may be more skewed to blacks and Latinos.
Though there is a limit to how long the departments retain the information, there are no clear legal guidelines limiting how the information is used, Bibring said.
"Our concern is they've got this technology that collects information on law abiding residents, and they're saying they can't disclose even a narrow slice of it," Bibring said. But providing such information "would help the public gauge how intrusive it is."