The California Highway Patrol does not yet have figures to show whether banning cell phone use while driving has reduced accidents.
But Gary Dominguez, head of the CHP in San Diego, says since the law went into effect, officers have ticketed thousands of drivers statewide for talking on their cells or texting while driving.
"One of the banes of our existence in enforcing driving traffic right now is that cell phone," Dominguez said. " We wrote about 135,000 cell phone tickets last year and we are going to increase our enforcement effort in citing people for illegally using the phone for texting."
The CHP says 29,000 accidents statewide in 2008 were caused by inattention - and a thousand of those drivers admitted they were on their cell phones.
The agency says national statistics show 28% of accidents were caused by inattention due to cell phone use.