At Google's headquarters in Mountain View, California, Governor Jerry Brown was joined on stage by Sergey Brin to sign a new law that would allow autonomous vehicles to operate on California roads.

The bill, SB 1298, sponsored by Senator Alex Padilla (D-L.A.), establishes safety and performance standards that will be enforced by both the California Department of Motor Vehicles and the Highway Patrol. The law requires the DMV to draft regulations for autonomous vehicles by January 1, 2015, and while the vehicles can operate autonomously, a licensed driver is required to be behind the wheel if something goes awry.

California is now the third state to enact autonomous vehicle legislation, following another Google-championed bill that passed in Nevada last February, as well as a Florida law that was approved earlier this year.

The goal of Padilla's law is to keep California at the forefront of autonomous-vehicle development, and the Governor reiterated that sentiment at today's event. Google has logged more than 300,000 miles in its fleet of autonomous Toyota Prius hybrids and Lexus RX crossovers, while Stanford has worked with Volkswagen and Audi on autonomous technology in Silicon Valley.

Other automakers have announced plans to bring different forms of driver assistance that takes control of the vehicle at low speeds, including BMW, Mercedes-Benz, Ford, Volvo and Cadillac, the last of which is expected to introduce its "Super Cruise" system within the next few years.

While consumer acceptance of autonomous vehicles is still very much in question, this latest legislative move is another step towards the eventual mainstreaming of the technology.

"Anyone who gets behind the wheel of an [autonomous] car is going to be a little skittish," the Governor said at the event. "But they'll get over it."