Last week the Alameda Police Department initiated a field test of an automated license plate recognition system. Within 60 minutes, the officer using it reclaimed a stolen car.

“He was just literally driving down the street and got a hit, on a car stolen out of San Mateo County. We wound up recovering that vehicle,” Acting Police Chief Paul Rolleri said.

On Tuesday, Rolleri will ask the City Council for permission to seek the funding the department needs to buy a four-camera system, which would cost an estimated $22,000. He said the system would help police better perform a task they’re already doing – checking license plates in order to locate everything from stolen vehicles to missing persons and potential terrorists.

“It automates a tedious, distracting, and manual process that officers regularly complete in their daily operations, and vastly improves their efficiency and effectiveness in identifying vehicles of interest among the hundreds or thousands they observe in routine patrol,” he wrote in a report to the council.

But civil rights advocates fear the systems, which scan and store license plate and location data for guilty and innocent alike, are ripe for abuse.

“The reality is that because of the way that license plate readers work, they have the potential to collect vast amounts of information about completely innocent people,” said Nicole Ozer, technology and civil liberties policy director for the ACLU of Northern California. “The bottom line is, license plate scanners can quickly become tools for dragnet surveillance.”

Automated license plate recognition systems first came into use in the late 1970s. But they didn’t become popular until the 1990s, when the technology underpinning them improved and they became less costly. An avalanche of federal homeland security funding helped local police departments pay for the systems; according to a 2011, study, about three-quarters of the country’s police departments have one in place. Alameda police plan to request homeland security funding to purchase a system.

Rolleri said the system could be a “force multiplier” for police who are now manually checking license plates in their effort to track down stolen vehicles, missing people and crime suspects, a tool that can help police separate criminals from the thousands of innocent people who traverse Park Street every day. The system can log 1,800 cars a minute, traveling at speeds of up to 120 to 160 miles per hour, according to Rolleri’s report to council.

”It’s a huge help to your typical cop on the street who’s out on patrol,” Rolleri said. “It just gives the ability to sort of filter out cars (whose drivers) have warrants and are stolen or have lost or stolen plates on them from all of the other cars that are driving around.”

Rolleri said he didn’t have data demonstrating the success of such systems. But in the second day of the department’s field test, he said police tracked down another stolen car whose driver tossed a fake gun out the window as police gave chase. In that case, he’s convinced the system helped abort another possible crime.

“Why is a guy driving on Park Street in a stolen car … with a replica gun in his car? He’s not coming here to go to the movies or shop at one of the local stores – at least not in the traditional sense,” Rolleri said. “I would submit to you that that guy came to Alameda to commit a crime. And he didn’t.”

But the ACLU’s Ozer said that while the technology can be beneficial, few of the people surveilled by the systems are guilty of a crime and that in many cases, their privacy is needlessly being breached. In a report issued in July, the civil liberties group found that in some of the cities it studied, less than 1 percent of the license plates scanned and stored resulted in a hit on lists of stolen cars and wanted criminals.

In its report, which queries hundreds of police agencies across 38 states, the ACLU found that many police departments had lax policies or none at all governing the retention and use of the license plate data they collected and that police agencies were saving – and sharing – millions of records detailing drivers’ church, bar and doctor visits. The report cited examples where British police used the system to track an anti-war protester and New York City police tracked mosque attendees.

The report recommends that police agencies only use the data to investigate possible criminals or crimes, control access to the data and stop storing data about innocent people.

“There is no reason for law enforcement agencies to retain data on the comings and goings of innocent Americans,” the report says.

Ozer said that any city considering such a system should have a “really robust public discussion” about the implications of putting one in place.

“There need to be really strong, legally enforceable safeguards in place to make sure that this information is really being used, and the tools are being used, in a limited fashion, in a focused fashion, and not ending up as a means to target innocent people,” she said.

Rolleri conceded the city is still in the early stages of exploring the purchase of the plate readers, and that the details of any controls that might be placed on their use haven’t yet been worked out. But he said there will be limits on the storage and use of the data they collect.

Like other Bay Area departments, Alameda would feed its data into the Northern California Regional Intelligence Center, a “fusion” center that collects and shares data among participating police agencies.

He said he’d favor storing the data for a year, and would consider limiting access to specific department staff who would be required to detail their reasons for accessing any data they request. And he said there will be an audit trail showing who accessed what data, and why.

“There would be a specific policy that would dictate the usage of the license plate readers and the use of the data that we got from the license plate readers,” he said.

Rolleri said he sees the readers as a tool that will help officers conduct everyday enforcement.

“I’m not interested in singling out any person or group of people,” he said. “But I would like to know if I have 27 (stolen) cars circling my city, and the license plate reader lets me find them faster.”