Gascon made his comments a day after his office filed an expanded lawsuit in San Francisco Superior Court accusing Uber of false advertising. The expanded lawsuit claims Uber failed to uncover the criminal records of 25 California drivers, including several registered sex offenders and a convicted murderer. "This is really only scratching the surface," Gascon said at a news conference.
Gascon and Los Angeles County District Attorney Jackie Lacey filed the original lawsuit in December. The lawsuit doesn't object to Uber's background checks, but it objects to the company's claim that it uses an industry-leading process to vet its drivers. Anything short of fingerprinting can't make that claim, Gascon said.
In a statement Wednesday, Uber said it disagrees with Gascon. Company spokeswoman Jessica Santillo said that no background check system is flawless and its checks are just as detailed as with taxi drivers.
Santillo said Uber ran background checks of "hundreds" of California taxi drivers and uncovered convictions for drunken driving, rape, attempted murder, child abuse and violence.
The two California district attorneys settled a similar lawsuit with Uber competitor Lyft last year. Lyft agreed to pay $250,000 and to stop claiming its background checks were among the best in the industry.
Uber and its competitors have encountered various political hurdles as they expand services.
Government entities around the globe are grappling with how to regulate and monitor ride-hailing companies. Taxi and limousine drivers and companies complain that the app makers should be subjected to the same regulations and fees they face around the world.
The ride-booking companies counter that their drivers are private contractors who use the startups' technology to find customers in need of rides.
Uber, in particular, is fighting numerous legal and regulatory battles as it aggressively expands worldwide. The San Francisco-based company says it looks "forward to resolving this issue" with the California district attorneys.
The AP contributed to this report.