SAN FRANCISCO —  Back when liquor was outlawed during this country's Prohibition movement, Americans found clever ways to dodge police and have a drink in secrecy and safety.

Today, booze is legal — but in California restaurants and bars, cigarettes aren't. Three years ago, voters passed a ban to protect employees from second-hand smoke.

But many patrons are still lighting up at bars that secretly accommodate their habit.

"I think it's fair to say a lot of the bar owners have gone out of their way to avoid the law, to circumvent the law," said Christopher Arriola, assistant district attorney of Santa Clara County. "You do see some sort of what people might call Prohibition-era tactics."

While cops try to sniff out the worst offenders, in many cases they're butting up against organized opposition. Bartender phone trees warn each other of impending busts, powerful fans blow away tell-tale scents of "smokin' in the boys room" and tin cans double as ashtrays in case of an unexpected visit by police.

Smoker Ian Hughes said that if someone in one of those bars spots a squad car driving by, he or she will alert those puffing away — and everyone will stub out their cigarettes before they can be discovered.

While some bars are making a surreptitious end-run around the ban, others are finding mixed success in the courts, using a little-known provision in the law that allows their customers to light up.

Last week, for instance, a southern California bar won exemption from the ban because it has fewer than five employees.

Some venues get around the ban by providing smoking-only rooms.

"It's an OSHA law, so basically we kick out the employees and you're OK," said Tim Dale, general manager of Le Colonial.

Police say it's not OK when some bars comply and others don't. But until the smoking ban goes the way of Prohibition, hoppers who smoke and bars that welcome them will continue to be a perfect match.