In Wisconsin, where the dairy industry has long been king, suggesting margarine should replace butter always invites a messy debate.

Now, the issue is churning again.

In a one-of-a-kind debate, some legislators want to get rid of the preferential treatment that Wisconsin requires butter receive in restaurants, schools and even state prisons. They're taking aim at a decades-old law that says restaurants can't serve margarine as a substitute for butter at the table unless a customer asks for it, and that state prisons and other institutions can't do the same unless directed by a doctor.

"It's kind of silly," said Steve Snook, a chef who decided on his own to serve butter at the restaurant he co-owns, Shady Grove in Ellsworth. "A law like that needs to go away. I mean, come on ... let owners of businesses do what they want."

But butter advocates say the repeal effort would undermine and insult Wisconsin's hallmark profession: the state's dairy farmers.

"Why would you want to support a product that is a poor substitute for the real thing?" said Brad Legreid, executive director of the Wisconsin Dairy Products Association. "Our license plate says Wisconsin is America's Dairyland. That's the bottom line, and we should only pass legislation that would support it and not tarnish it."

The Professional Dairy Producers of Wisconsin say the state ranks second in the nation in butter production and supports 160,000 jobs.

Promoting dairy has been the prevailing sentiment for decades in Wisconsin. In the 1930s, the state demanded for a short time that eateries serve butter and cheese with any meal costing more than 25 cents. As late as the mid-1960s, Wisconsin residents had to get yellow margarine from bordering states because Wisconsin stores couldn't sell it.

The suburban Milwaukee lawmaker who suggested the repeal, Republican Rep. Dale Kooyenga, has declined a barrage of interview requests on the subject, a staff member in his office said. Kooyenga has told reporters that most people see the law as "a classic case of big government."

Repeal advocates say the state could also save money by serving less expensive margarine to prisoners.

While talk of changing the butter law has the industry and the Capitol buzzing, some Wisconsin restaurant owners and managers said they hadn't ever heard of the rule.

"Is this a joke?" asked one at a New Richmond eatery.

Flouting Wisconsin's butter law carries a fine of $100 to $500 and up to three months imprisonment, but enforcers at Wisconsin's Department of Agriculture, Trade and Consumer Protection haven't cited a restaurant in recent memory, said spokeswoman Donna Gilson. The department gets only one or two complaints every few years, she said, and they are usually resolved with a visit to confirm the transgression, then maybe a letter telling the restaurant to comply.

This isn't the first time a lawmaker has tried to get rid of the butter law.

Scott Jensen, a former Republican speaker of the Assembly, got a quick lesson on the power of the dairy industry when he tried a similar repeal more than a decade ago, he said.

"When I got to the floor of the Legislature, all hell broke loose on the margarine provision," Jensen said. "I was stunned."

The dairy industry doesn't need to spend much money to sway opinion at the Capitol, Jensen said, because "people are sympathetic to them from the start."

That may be why some political insiders quietly predict that Kooyenga's measure won't go very far. It's always hard to take on political sacred cows.

Pam Louwagie • 612-673-7102