A federal judge struck down a Minnesota law that prohibits wineries from making wine unless a majority of the grapes it uses are grown in Minnesota, a ruling that will divide grape growers and vineyards across the state.

Supporters of the state's "51% rule" said it undergirds an authentic local craft winemaking community. Critics, such as Nan Bailly, owner of Alexis Bailly Vineyard in Hastings and a plaintiff in the federal case, said it is "protectionism" and stifles the creativity of winemakers in the state.

"This is a huge win for the future of the wine industry and small wineries in Minnesota," Bailly said in a statement. "We are finally free to make the wines we want to make, not the wine dictated by the state legislature."

Versions of the Minnesota law are enforced in about a dozen other states. In Monday's ruling, Judge Wilhelmina Wright found the law violates the Interstate Commerce Clause of the U.S. Constitution. Her decision may have implications in other states with similar laws, such as New York, Pennsylvania and Illinois.

Jenny and Scott Ellenbecker, owners of Round Lake Winery near Worthington, said the court ruling could drive down the price of Minnesota grapes and will make it more difficult for consumers to track down the provenance of the wine they find in the state.

"I think it'll just be a little bit harder for them to know that a Minnesota winery is producing with Minnesota products," Jenny Ellenbecker said.

Some winemakers said northern grape varieties, which are grown with some difficulty in Minnesota, often produce wine that is too acidic for most consumers. Ellenbecker said that can be true, but the northern varieties are improving and there are ways to reduce the acidity of those varieties.

"We have great cold-hearty variety fruit," said Ellenbecker, the president of the Minnesota Grape Growers Association.

Round Lake Winery does not sell grapes to other wineries and does import grapes from other states for some wines. Ellenbecker said the Minnesota Department of Agriculture, which by law could strip a winery of its license for not making a majority of its wine using Minnesota fruit, has always been understanding when vintners asked for a waiver.

"I've never heard of anybody being denied," she said.

Martin Polognioli, the winemaker at Saint Croix Vineyards, said the court ruling could end up hurting Minnesota's wine industry.

"It's not good for Minnesota growers, all the growers that planted all these varieties from here," he said. "Most wineries understand that people want to try the local grapes, the local wine."

But the current law, which Judge Wright found unconstitutional, is too limiting, Bailly argues.

"Nobody knows more about growing grapes in Minnesota than I do because I've been doing it the longest," said Bailly, whose vineyard was first planted in 1973.

She said she lost 80% of her crop this year, because several of her vines are getting up in years, and she would like the freedom to import as many grapes from as many places as she wants and continue to make wine and sell it.

"The state of Minnesota for 40 years has said, 'Nope, you have to ask us first,' " she said.

This can force her to buy grapes from Minnesota growers when she would rather not.

"There's been a false economy in Minnesota," she said.

Minnesota's biggest craft beer breweries, like Summit and Surly Brewing, have been successful in part thanks to a variety of hops grown in the Pacific Northwest that flavor their signature beers.

Bailly said her business probably won't change much as a result of the ruling. But she said she was satisfied to see what she called an "arcane" law come to an end. She said she hopes the change will help more people succeed in the winemaking business in Minnesota.

"It's romantic, it's passionate, there's a culture to it," she said. "But dang, it's hard to do in Minnesota."

Adam Belz • 612-673-4405 Twitter: @adambelz