More and more law enforcement agencies and even private security firms are mounting high-tech cameras atop their vehicles, scanning license plates for stolen cars.
It has become a valuable tool for Arden Fair Mall near the State Capitol: a stolen car means someone is up to no good in 80 percent of the cases. Its first "hit" led to an arrest.
"We tracked him into one of the stores here. When he was arrested, they patted them down and inside of his pants he had several pairs of shoes that he shoplifted while inside the mall," said Steve Reed, an Arden Fair Mall security guard.
Police officers and deputies have had similar success out on the streets.
But a California Watch investigation raises questions over how else the information gathered by this 21st-century tool is being used.
It found a Livermore-based company called Vigilant Video has compiled a database containing more than a half-billion license plate scans from across the country.
The California Public Interest Research Group works on privacy issues and says the database raises red flags because it shows where and when people have been, even the innocent ones.
"Whenever an individual's information is stored or compiled in one place, folks should be concerned, especially if they don't know about it," said Pedro Morillas, legislative director, Calif. Public Interest Research Group.
The investigation also raises questions about police access to the database. They're not supposed to use information from license scanning to solve other crimes, but if it's now someone else's database, it's the perfect loophole to gain access.
Vigilant Video declined an Eyewitness News request for an interview, but the firm's president told California Watch we shouldn't hinder officers from doing their jobs.
California Highway Patrol hopes the privacy issue doesn't take away a very valuable and effective tool.
"There's billions and billions of dollars that are lost in a yearly basis as far as number of vehicles stolen and the cost associated with those vehicles being stolen as far as the insurance. So that affects a lot of us," said CHP Officer Adrian Quintero.
Arden Fair Mall and CHP only share license scans only with law enforcement.
Meanwhile, critics had similar concerns with FasTrak because the company, too, had information on where customers had been once a toll was paid, but California lawmakers made it illegal two years ago to sell that data.