CrimeBeat Q&A is a weekly feature where police reporter Julie Johnson answers readers’ questions about local crimes and the law.

Why do police publicize DUI checkpoints beforehand?

- C.L.

Advance publicity is key to the strategy.

Sobriety checkpoints may appear to be aimed at nabbing drunken drivers on the road, but the main goal is to stop people before they drink and drive, Santa Rosa Police Sgt. Ryan Corcoran said.

“We put it out there so that everyone in Santa Rosa is thinking, ‘If there’s a checkpoint, I should make some decisions, make a plan for how I will get home so I don’t end up in a checkpoint,’” Corcoran said.

Although it’s not required in California, most Sonoma County law enforcement agencies give advance notice about sobriety checkpoints because it’s believed to discourage people from driving drunk.

There is research backing up that belief. States with highly visible and publicized checkpoints reported reductions — between 11 percent and 20 percent — in deadly crashes involving alcohol, while states with lower levels of publicity and enforcement did not, according to a 2008 analysis by the Centers for Disease Control and Prevention.

Corcoran said publicity is part of what’s called the “Ingersoll Eight,” a set of guidelines for lawful DUI checkpoints laid out in a 1987 California Supreme Court decision, Ingersoll v. Palmer. The court instructed law enforcement agencies to ensure neutrality in checkpoint locations and strategies, such as choosing high traffic intersections and checking every third vehicle.

The court also said checkpoints should be highly visible with signs, flashing lights, marked police vehicles and uniformed officers to reassure drivers of the official nature of the roadblock.

In Santa Rosa, officers hand out fliers about the risks of drunken driving to each vehicle passing through a checkpoint. The department announces the checkpoint on radio, in print and through social media.

The effort, including overtime pay for extra officers, is paid for by grants. The California Office of Traffic Safety handed out nearly $23 million in federal grants last year to local agencies, including Santa Rosa police, for alcohol-impaired driving prevention programs like checkpoints.

“It’s hard to say how many people didn’t drive drunk that night because they were educated,” Corcoran said. “The fliers, the publicity, the word of mouth, people talking at the bars, a bartender saying, ‘Hey, I saw a checkpoint on College Avenue.’ How do you put that into a dollar figure as to whether it’s not worthwhile?”

Submit your questions about crime, safety and criminal justice to Staff Writer Julie Johnson at julie.johnson@pressdemocrat.com. On Twitter @jjpressdem.