SAN JOSE, Calif. — California drivers squawked, they talked, and one or two even balked at having cellphones ripped from their hands when the state law forbidding the use of hand-held phones on the road went into effect in 2008. But according to a study announced Monday by the state Office of Traffic Safety, since that time the total number of traffic deaths in California declined by 22 percent. With fewer drivers yakking into hand-held phones, the death-by-cellphone rate dropped an even more stunning 47 percent.

“Those are huge numbers,” said state Sen. Joe Simitian, D-Palo Alto, author of the bill whose outcome the study tracked, while taking a (hands-free) victory lap after the announcement. Simitian submitted a version of the bill for five consecutive years and was rebuffed each time, before the Legislature finally relented in 2006.

The year after the law was implemented, the CHP reported 700 fewer fatal accidents, and that there were 75,000 to 100,000 fewer collisions. “The drop in collisions was the biggest single year-to-year drop in the history of the state since the CHP began keeping the data,” Simitian said.

The report examined state crash records two years before and two years after the hand-held ban went into effect.

Though the base fine for being caught driving with a phone in your hand is still only $20 — Gov. Jerry Brown vetoed Simitian’s attempt to have it increased last year — the law here is viewed as more effective than other states’ because it is strictly enforced.

“California is one of the few states that has been very aggressively enforcing its cellphone law,” said Barbara Harsha, executive director of the Governors Highway Safety Association in Washington, D.C. “That’s a big drop. We were surprised by the numbers. It shows that enforcement works, that other states should look at what California has done and follow its lead.”

The study used a statewide census of police-reported traffic crashes, crunching the numbers and the fenders to produce the first analysis of its kind in the nation. Its findings were restricted to accidents caused specifically by drivers using hand-held cellphones, and came to conclusions that were less grandiose than Simitian’s — only 70-80 lives saved and about 5,000 injuries prevented in the first two years of the law.

Critics of the law also point to distractions other than talking on the phone — eating a sandwich, applying makeup, changing the radio station — as the cause of accidents. Asked if the 22 percent decline in traffic deaths traced to implementation of the hands-free phone law was too specific, David Ragland, the study’s author, said, “It is.”

The state agency that produced the study is already at work on expanding the distracted driver data. “The subject of distracted driving and cellphone use is so new that there hasn’t been a lot of statistical studying done,” said Chris Cochran, spokesman for Office of Traffic Safety. “We’re in favor of not talking at all — hand-held, hands-free, nothing. Because it’s actually the talking that’s more of a problem than the holding. Even though the law only covers half of the problem, it’s affecting both holding and hands-free. It’s doing good overall. But the whole realm is in need of a lot more research.”