A tax on sodas and other sugar-laden drinks, rejected by voters and courts in other parts of the country, is on the November ballots in San Francisco and Berkeley, two cities that have been open to such social-engineering initiatives in the past.
Voters in San Francisco will decide whether to make distributors pay a tax of 2 cents an ounce on sugary drinks, with the revenue used to fund programs promoting healthy eating and physical activity.
Berkeley voters will decide on a proposed tax of 1 cent an ounce, with proceeds going to the city general fund.
More than a dozen attempts elsewhere in the country to curb the sweet tooth of consumers have failed after big-spending opposition campaigns and legal battles by the $76 billion US soft-drink industry.
The California Legislature has made at least a half dozen attempts to impose some type of tax on sweetened beverages, all of which failed. In New York City, even Michael Bloomberg's clout wasn't enough to save a measure banning the sale of super-size sodas from a legal challenge.
Because no city or state has been able to get and keep a soft-drink tax, no one knows for certain whether it would actually lead to a drop in obesity or conditions such as diabetes, said initiative supporter Michael Pollan, a Berkeley resident and nationally known author who writes about food and agriculture policy.
"It's an experiment. Somewhere in America needs to give it a trial so we can see if this works," Pollan said. "If one of them works, and actually generates a lot of revenue for a municipality and ... reduces soda consumption, I think soda has a huge problem on their hands."
Soda has been under fire for years from health advocates, who say the beverages are uniquely harmful because people don't realize how much sugar they're guzzling. A 21-ounce Coke, McDonald's medium size, has 200 calories and a quarter-cup of sugar, for instance.
Berkeley and San Francisco have a record of embracing social change. Berkeley voters made the city a nuclear-free zone in the 1980s, and voters in both cities passed measures establishing benefits for domestic partners, also in the 1980s. Bans on plastic bags received support long before the state imposed its own ban this year.
So far, the California arm of the American Beverage Association has contributed $800,000 to defeat the sugar tax on the Berkeley ballot, spokesman Roger Salazar said. He declined to disclose how much opponents have contributed for the no-tax campaign in San Francisco ahead of mandatory reporting later in October.
Radio and TV ads focusing largely on the added cost to soda-drinkers started airing last month.
Supporters of the tax have raised $80,000 in Berkeley and about $200,000 in San Francisco.
The demographics of soda-drinking appear to make the measures in large part a vote on what's best for poor people. A 2011 look at soda taxes by the Chicago Federal Reserve Bank found people with less education drink more than twice as much soda as college-educated consumers, and that people living below the poverty line get 9 percent of their daily calories from sugary drinks.
Salazar contends the tax would have a "disproportionate impact on lower-income communities, punishing the very communities they purport to try to help."
For teens, sugary soft drinks and sports beverages are the single biggest calorie sources in their diet, according to a report by the Harvard School of Public Health.
Supporters of the tax in San Francisco hope it will reduce soft-drink consumption by nearly a third and generate more than $35 million in annual tax revenue for health education. Scott Wiener, a San Francisco supervisor who got the tax on the ballot, disputes claims by opponents that the tax is regressive.
"What's regressive is having an artificially cheap, disease-causing product that's being sold ... disproportionately to poor people," he said.
Opponents argue there's no evidence that a soda tax would work the same public-policy magic as tobacco taxes and bans on public smoking.
If anything, California should tax TV, which cuts into the time children spend in healthful exercises, said Liz Applegate, director of sports nutrition at the University of California, Davis.
She says consumption of sugary soft drinks by young people is already going down. At the same time, studies show that rates of diabetes have risen from 3.5 percent of Americans in 1990 to 8.3 percent in 2012.
"It's misguiding consumers to believe that that if we tax sodas" society will see resulting health gains, Applegate said.