California officials reported today one of the first significant results of a national citizens' campaign against intoxicated drivers--a 43 percent drop in New Year's holiday traffic deaths in the state as stringent new drunken driving laws went into effect.

Federal and state officials said the new package of California laws, which took effect at midnight Thursday, appears to have brought about a new caution in many drivers. They said the development may help accelerate a stiffening throughout the country of laws against drunken driving, which was involved in an estimated half of the 51,000 U.S. traffic deaths in 1980.

California Highway Patrol spokesman Ernest J. Garcia said the drop in traffic deaths from 47 a year ago to 27 in the three-day holiday period--the lowest New Year's death toll in 20 years--appears to be the direct result of the changes in state law and widespread publicity about them. There was so much preliminary news coverage warning of the new laws, which include mandatory jail terms and license suspensions, that Christmas holiday traffic deaths also dropped sharply, from 64 to 31, Garcia said.

"I've talked to many people, both as an officer and a citizen," Garcia said. "Most people say, 'The law has teeth now; it looks like you can't get off with a fine or going to school. This might mean a jail term and I don't want to go to jail.' "

Al Lauersdorf, a spokesman for the National Safety Council in Chicago, said bad weather and the poor economy also may have helped cut the highway death rate in recent months, but the citizen campaign against drunken driving was crucial and produced more concern about the issue than he had seen in 15 years in traffic safety work.

Month-by-month figures provided by the National Highway Traffic Safety Administration show traffic deaths across the nation from 1 to 11 percent below 1980 levels from May through November.

The impact of the new California laws is particularly significant because the state has been the base of one of the most active citizen groups, Mothers Against Drunk Driving (MADD). The group's leader, Candy Lightner, began a concerted lobbying effort in Sacramento, now expanded to about a dozen other states, including Maryland and Virginia, after her 13-year-old daughter was struck and fatally injured by a car whose driver had been drinking.

Efforts to toughen drunken driving penalties have been resisted in the past by judges who feel mandatory sentences are too inflexible, by prosecutors who feel juries would be unwilling to impose them and by defense attorneys who argue that such laws would just make jails more crowded and hurt rehabilitation efforts. Citizen lobbying last year, however, resulted in California's unusually tough laws and in less far-reaching changes in other states, including Maryland, where the blood alcohol level requirements have been stiffened.

Law enforcement efforts also have been increased, as in Maryland, where roadblocks were set up to check drivers during the New Year's holiday.

John Moulden, a research psychologist for the National Highway Traffic Safety Administration, said the role of citizen groups like MADD and Remove Intoxicated Drivers (RID) "has been absolutely critical." Moulden said the initial California results show drivers responding to the threat of penalties, but he advised a close look at how rigorously judges and prosecutors apply the laws when cases begin to come to court in two weeks.

Reducing drunken driving, Moulden said, "appears to be a political and not a technical problem." Most states have harsh penalties on their books that are rarely invoked, he said.

Many of the changes in California law involve subtle distinctions and technicalities such as a new statute making a .10 percent blood alcohol level absolute evidence, and not just a presumption, that the driver is under the influence of alcohol. Maryland last year also stiffened its blood alcohol level requirements, resulting in a sharp increases in arrests for drunken driving. But Maryland, Virginia and the District have not yet instituted the kind of penalties for drunken drivers now in effect in California.

But MADD chapters are working on it. Susan Midgett of Norfolk, the Virginia state representative for MADD, said her group is pushing for law changes that will be "a whole lot" like those California has, "except there are a lot of loopholes here we also want to plug." Maryland's MADD chapter is headed by Tom and Dorothy Sexton of Bowie.

Under the new California law, every conviction for driving under the influence of alcohol requires a jail sentence of at least 48 hours, with one exception. If the case is a misdemeanor first offense, the judge may substitute a fine, require attendance at drinking drivers' school and a 90-day license suspension including permission to drive only to and from work.

A mandatory minimum fine of $375 for every driving-under-the-influence conviction has been instituted, and $20 of each fine will be directed to a victims' indemnity fund to help pay accident damages.

On a second drunken driving conviction, a judge may require the driver to attend an alcoholic treatment program for one year and add further jail time if he or she fails to attend. If a judge dismisses a drunken driving charge or reduces one to a lesser offense, he must read into the record his reasons for doing so, and this summary must remain on his personal record, the California law provides.