Sacramento, Calif. ? Having already laid down the law for his two teenage daughters, Gov. Arnold Schwarzenegger signed legislation Thursday that will prohibit the rest of Californians younger than 18 from using cell phones, text message devices and laptop computers while driving.

The new law, which takes effect July 1, 2008, addresses a leading cause of traffic accidents resulting in deaths and injuries, the governor said during a signing ceremony at Sequoia High School in Redwood City.

“This is to eliminate a major distraction for our young, inexperienced drivers and to make our roadways safer for everybody,” Schwarzenegger said.

He volunteered that he has barred his two teenage daughters from using cell phones while driving. Katherine has been driving for a year, and Christina is about to start driving.

“I’m one of those parents, like anybody else that when your teenage child leaves in the car, you worry until they get home,” Schwarzenegger said.

“I told my daughters: ‘I give you the car. I give you the cell phone, but if I see you one time using both at the same time, both of them are gone,'” he said. “‘The car will be gone for a long time, and the phone will be gone for a long time. You go to school with the bus.’ They know that.”

The governor added: “And I sometimes spy on them. They also know that.”

Motor vehicle crashes are the leading cause of death among 16- to 20-year-olds, said Teresa Becher, chief of the Golden Gate Division of the California Highway Patrol.

“A person’s first year of driving is the most dangerous of their life,” Becher said.

The new law also prohibits under-18 drivers from using hands-free cell phone devices. Violators will face a possible $20 fine for a first offense, and $50 for subsequent offenses.

Starting next July, adult drivers in California will be required to use hands-free equipment if talking on the phone while driving.