The law is even stricter for drivers under 18; they aren't allowed to use a cell phone at all, hands free or otherwise. Violators will be fined $20 for a first offense and $50 for subsequent offenses.
Sending text messages, dialing and using a speaker phone are still allowed, but there's a caveat: An officer can pull over anyone who, in his or her opinion, is distracted and therefore not driving safely.
"Texting" behind the wheel could be the next thing to go. Last Thursday the Palo Alto senator who originally introduced the cell phone bill, Joseph Simitian, introduced a similar bill that would ban text messaging while driving.
Police in Danville and Alamo will begin enforcing the cell phone law immediately after it goes into effect, they said.
"If I'm driving down the roadway and somebody's not paying attention, and I look over and they're talking on their cell phone, yes, I'm going to pull them over," said Alamo Deputy Elmer Glasser. But he added, "I'd much rather educate the public than go out and write as many tickets as I can."
Glasser and Danville Police Chief Chris Wenzel compared the new law to the "click it or ticket" seatbelt campaign.
"It's a discretionary thing whether the officer writes a citation or even pulls them over," said Wenzel.
Adults can be pulled over solely for violating the new rule, but teens under 18 can only be ticketed for talking on a cell phone if they're already stopped for something else, the law states.
Simitian introduced the bill several years ago with the hope of making the roads safer. Gov. Arnold Schwarzenegger finally signed off on it in September 2006. While the bill crawled its way through the legislature, controversy brewed over whether banning "driving while chatting" was a good idea, and the past several years have seen a slew of studies on the topic.
One frequently referenced study, done in 2002 by the Harvard Center for Risk Analysis, estimated that cell phone use while driving accounts for 5 percent of accidents and causes about 2,600 deaths per year.
A 2006 study by psychologists at the University of Utah attracted media attention when it concluded that driving while talking on the phone was as hazardous as driving with a .08 percent blood-alcohol level, i.e. legally drunk. But that group also found that subjects' ability to drive was equally impaired if they were using a hands-free or handheld phone. The danger is in the cognitive attention it takes to hold a conversation, not the physical attention needed to hold the wheel, the study concluded.
According to preliminary data from the California Highway Patrol, there were 1,327 accidents in the state last year in which cell phone use contributed to the cause of the collision. Seven were fatal.
In Danville, cell phone use contributed to two out of 178 collisions in 2007, according to the same data. Both collisions resulted in property damage only; there were no injuries.
CHP Spokeswoman Jaime Coffee said the numbers are probably low since people rarely want to admit having been on the phone at the time of an accident.
"It's a matter of what the drivers told the officer for the report," she said.
She also said that cell phone use was the No. 1 cause of inattention reported by drivers. Other factors that distract attention include children or pets in the car, playing with the radio, lighting a cigarette, putting on makeup or eating.
State Assemblyman Bill Maze (R., District 34) recently introduced a bill that would ban drivers from having pets in their laps. The bill passed in the Assembly and now heads to the Senate.
California joins Connecticut, New Jersey, New York, Washington state and Washington, D.C., in banning cell phones behind the wheel.
A citation for driving while talking on the phone will not count as a point on the offender's driver's license but will show up on his or her driving record. The law makes exceptions for emergency calls to police, fire or medical officials.
For more information on the new cell phone law, visit www.dmv.ca.gov/cellularphonelaws/