Sobriety checkpoints are effective tools to catch more than drunken drivers, police maintain, and now the U.S. Supreme Court has upheld states' rights to erect such roadblocks.

In West Valley City, police catch impaired drivers, auto thieves and people who have thousands in dollars in outstanding warrants through the checkpoints, said traffic officer Jim Tingey.A dozen people were arrested during the last roadblock officers in the Salt Lake suburb set up in October, said Tingey, including someone wanted for auto theft.

"Our main priority is for safety - to keep people from killing each other," officer Guy Dodge, department public relations officer, said this week.

West Valley routinely operates roadblocks, and the city's cases consistently have survived court challenges, said Sgt. Kelly Davis. And officers follow stringent guidelines established long before the barricades go up.

"We wanted to alleviate the defense of witch hunting" or just going after the driver who looked as if he might be drunk, Davis said, adding, "Our procedures have become honed a whole lot better because of what we learned" in court.

The Supreme Court earlier this month let stand a California court ruling upholding the use of roadblocks to catch drunks. The justices, without comment, refused to overturn the conviction of an underage driver who was arrested for drunken driving.

Using guidelines established by the high court, officers pull over a set number of cars and check the drivers to ensure licenses and registrations are current and the operator has no outstanding warrants.

"We have a city attorney there with us to make sure we're following the correct procedure," said Tingey, who is a certified drug recognition expert trained to determine whether the driver is impaired by a substance other than alcohol.

Two weeks ago, Tingey said, a woman called to thank him for pulling her off the road. And he said many of the drivers, once officers explain the situation, are complimentary of the effort.

While the roadblocks can catch people who have outstanding warrants, both officers maintain the checkpoints are not a means to enrich city or Salt Lake County coffers. An estimated $1.5 million in warrants are outstanding in the area.

"I don't feel like the parameters (the Supreme Court has given) have hampered us any. We're not violating people's rights," Davis said, adding, "I think they're fine. I think they're good."

Part of the Supreme Court's guidelines include announcing in advance the general location and dates of potential check points. The department has not announced any plans to hold such road blocks during the holiday season due to staffing constraints, Davis said.

But West Valley officers are handing out Christmas cards this week instead of warnings or even traffic citations in some situations. The cards, which show officers, squad cars, a police dog and a motorcycle, wish recipients season's greetings and "Don't Drink & Drive, Drive Carefully."