Effort to Stem Car Thefts to Be Revived : Crime: Decals will allow police to stop vehicles. Officials say the program works but legal questions arise.

An anti-auto theft program that fizzled for lack of interest during testing in Van Nuys three years ago will be launched again across the entire San Fernando Valley later this year because police believe citizens are now more responsive to such community policing programs.

Under the Combat Auto Theft program, Los Angeles police will be able to stop any car between 1 a.m. and 5 a.m. if it has a small yellow decal in the back window that says: “Member, Operation C.A.T.--Combat Auto Theft.”

To get the decal, car owners will have to sign a form stating they do not normally drive between those hours and that police are permitted to stop the car to make sure it is not stolen.

In effect, the sticker gives the police the probable cause needed to stop a car even if nothing appears amiss, and it means the owner waives the constitutional right against unreasonable search and seizure. That aspect of the program, which was also launched earlier this month by police in West Los Angeles, is troubling to some legal experts.

But New York City police, who developed the program six years ago, say the decal has withstood challenges in court and is a highly successful deterrent to theft.

Deputy Chief Mark A. Kroeker, the highest-ranking Los Angeles police official in the Valley, said he discussed the stickers with new Chief Willie Williams last week and received the go-ahead for the program. A start-up date has not been set.

“He said, ‘I see it as a good thing.’ We will give it a try,” Kroeker said.

In 1989, police in the Van Nuys Division tried to start a pilot program but only 58 residents signed up for stickers. Sgt. Bob Shallenberger said no stickers were given out because it would have been too small a group to study.

Police sense that the social climate is right to try the program again on a wider scale, largely because community policing programs started last year have resulted in hundreds of Valley citizens becoming involved with police.

“It’s going to go Valleywide,” Shallenberger said. “I think because of our efforts at improving community involvement, we will have more people taking part.”

Kroeker said the timing is perfect.

“This is a program that depends heavily on public communication and awareness,” he said. “I think our communication and awareness have climbed to unprecedented heights.”

An average of 60 cars are stolen each day in the Valley in a crime category that has steadily risen over the past decade. Kroeker said the C.A.T. program is an effective deterrent because it makes thieves choose other cars to steal. The result may not be a decrease in overall thefts in the Valley, but it will probably safeguard the cars of participants.

In New York City, police said that one of every 15 cars will be stolen in a year. But for cars registered under the C.A.T. program, the theft rate is one in 574.

“It’s a deterrent for the person whose car has the sticker,” Kroeker said. “There are almost zero cars stolen that have the stickers. A crook just does not want to steal a car that has one of these stickers.”

Joining the program costs nothing, Kroeker said. The decals will be provided by the Auto Club of Southern California, which has also provided them to other police departments.

Despite police claims that the program is on sound legal footing, legal experts expressed doubts earlier this month when the decals were introduced in West Los Angeles. At the time, law professors from UCLA and USC said they questioned whether an owner can give a blanket waiver of rights to anyone in their car.

“You’re going to have some real questions if the owner can waive the rights of a friend who has the OK to drive the car,” USC professor Charles Whitebread said. “I think we’re going to have some fun with it.”

Times staff writer Mathis Chazanov contributed to this report.