SAN FRANCISCO — California First Lady Maria Shriver may be the only California driver to be caught on video thrice yapping on her handheld phone by celebrity gossip website TMZ. But she certainly isn't alone.

Every month, thousands of motorists flout the state's ban on talking on handheld cellphones while driving. They do it speeding along the highway and puttering through city streets. Drivers text at stoplights or check e-mails while keeping one hand on the wheel.

Ms. Shriver, who was caught on video talking while driving even after Gov. Arnold Schwarzenegger pledged she would quit breaking the law Tuesday, has apologized. She is donating her handheld phone to a program that provides mobile phones to abused women.

But Shriver's cellphone saga has raised questions about how many Californians are actually heeding the ban on talking while driving.

Some say that Californians followed the law when the ban first came into effect in July 2008, but have now slackened off.

Last month, the California Highway Patrol issued 12,277 cellphone citations. That's 4,498 more than the department handed out in July 2008. In total, highway patrol officers have written 150,497 tickets for mobile phone violations since last year, not counting local police departments or the parks service.

"My theory about the hands-free driving law is that Californians obeyed it for a while because it required us to do something we love even more than driving: buy new stuff," wrote Meghan Daum in Thursday's Los Angeles Times. "A subset of that group actually installed speakerphones and earpiece holders in their cars and made use of them, until the batteries ran down and they couldn't find the chargers, or they took a call from their doctor about a nasty rash with other people in the car. At that point, they craved the sensation of phone-on-ear the way a baby craves a pacifier."

But the state senator who wrote the law says it's working. In the first six month after it went in effect, says California Sen. Joe Simitian (R), the state saw about 6,000 fewer highway collisions and 360 fewer fatalities. While there's nothing to prove the law caused the drop in numbers, the figures certainly suggest the ban is helping, he says.

The reason many people notice others chatting away on their mobile phones is because "it's the exception, not the rule," he adds.

The Insurance Institute for Highway Safety also says the increasing number of bans taking effect across the country are working. In an October report, the group found that laws in the District of Columbia, Connecticut, and New York have cut drivers' use of cellphones.

Still, Senator Simitian agrees there's room for improvement. "This is one of those things where continued enforcement and education is needed ... just like seat belt use," he says.

Highway patrol has been conducting several "zero-tolerance" crackdowns in an effort to catch violators. The fines for breaking the law start at $20 and can go up to as much as $300.

Says one highway patrol officer who spoke with the San Jose Mercury News: "People seem to be ignoring it now.... That is why if I see them and can get to them, I give them tickets."