A quirky Wisconsin law intended to protect the state's dairy industry by making it illegal for restaurants to serve margarine as a replacement for butter is being targeted for repeal.

The 44-year-old law that's little known to most diners is celebrated by some as a colorful part of the Dairy State's past, even inspiring the state Historical Society to sell T-shirts reprinting the language of the law on a yellowish, buttered-colored background.

But the law, so marginalized that the National Association of Margarine Manufacturers doesn't even refer to it in a timeline of significant action affecting the industry, has a loophole: Restaurants can abide by it simply by serving both butter and margarine.

"I literally Googled 'stupid Wisconsin laws' and this one came up as No. 1," said Republican state Rep. Dale Kooyenga, a 32-year-old accountant from Brookfield who wants to undo law he calls silly, antiquated and anti-free market.

Most restaurant owners are aware of the law, but it's not something that the industry talks about, said Pete Hanson, director of government relations for the Wisconsin Restaurant Association. It's simply not an issue, he said.

"Restaurant owners are in business and are successful because they give customers what they want and in Wisconsin that's generally butter," Hanson said. "I don't think there necessarily needs to be a law requiring butter to be on the table. I think most patrons in Wisconsin prefer butter."

The battle over margarine's place in the country was seriously debated after its invention in 1870. The agricultural community, led by Wisconsin's strong dairy interests, saw the artificially produced margarine as an intruder on the market and the rural way of life.

In 1895, just 47 years after it became a state, Wisconsin passed its ban on the sale or use of margarine colored to imitate butter. The pressure to repeal that ban grew in the 1960s as Wisconsin was left as the only state with the prohibition. Residents were getting around the law by buying margarine in neighboring states just across the border.

Then state-Sen. Martin Schreiber, a 26-year-old Democrat who went on to serve as acting governor in the 1970s, proposed doing away with the ban in 1965 but he said rural Republicans bottled it up. So he came up with a creative way to make his case: a blind taste test.

One of butter's most ardent supporters, Republican Sen. Gordon Roseleip, happily took the taste test and promptly chose margarine as better tasting. His flub made national news.

"That was the beginning of the end," Schreiber said.

It wasn't until after his death in 1989 that Roseleip's family members said they had been secretly going to Iowa for years to buy margarine where it was legal to feed it to Roseleip instead of butter out of concerns for his health.

In 1967, two years after the taste test, the state's ban on margarine sales was repealed but the restrictions that Kooyenga hopes to undo were passed.

"Our laws are important and should be respected," Kooyenga said in a letter to lawmakers earlier this month asking for their support. "Silly laws erode citizens' respect for the overall rule of law in our state."

Only one or two complaints about restaurants violating the law come in a year to the state Department of Agriculture, Trade and Consumer Protection, said spokeswoman Donna Gilson. It issues warning letters, she said.

"We're not out there looking for this," Gilson said.

The law Kooyenga seeks to replace also requires that butter be served to students, patients and inmates at state institutions, except as necessary for the health of the person. In accordance with the law, butter is served to the roughly 21,000 inmates in Wisconsin's prisons.

"It's pretty much butter across the board," said Department of Corrections spokeswoman Linda Eggert.

Kooyenga argues that changing the law would save the state money since margarine is typically a third of the cost of butter.

Breaking the law is punishable by up to three months in jail, but Kooyenga said it's never enforced.

No one is registered as lobbying either in support or opposition to the bill and Kooyenga said he does not think, unlike in past battles over butter, that there will be much fervor one way or the other this time around.

It doesn't appear his idea for change is spreading too quickly in the Legislature. So far, only 11 other lawmakers out of 132 have signed on as co-sponsors.