In a legal challenge with possible national ramifications, St. Croix County, Wis., is pushing back against a Hudson family that wants the right to sell or develop prime — and protected — St. Croix River property as they choose.

The county's attorneys argue that allowing the Murr family an exception to laws that protect the "already threatened" riverfront area would weaken the government's ability to guard against erosion and pollution anywhere on the St. Croix, according to a response filed Friday with the U.S. Supreme Court.

Despite the family's apparent surprise at zoning restrictions put in place in 1975, their claim of being treated unfairly compared with their neighbors is false, attorneys for St. Croix County wrote.

"What would be truly unfair would be to single out [the Murrs] for special treatment — exempting them from generally applicable sale and development restrictions — while allowing [them] to enjoy the increased property values that have resulted from those very same restrictions on other landowners," the county's attorneys wrote.

In April, four of the six children of William and Margaret Murr filed an appeal to the nation's high court contending that St. Croix County wrongly blocked them from selling a vacant waterfront parcel. The Murrs said they wanted to sell the 1.25-acre lot to finance improvements to their family summer home, built soon after the parents bought the property in 1960 on an adjoining lot south of Hudson.

St. Croix County argues that regulations governing the St. Croix prohibit such land use, but the Murrs allege the county's denial of the sale violated the Fifth Amendment's "takings clause" because it amounts to a taking of private property for public use without just compensation.

"Our property rights have been violated and our family legacy has been stolen from us," family spokeswoman Donna Murr said recently at the summer home.

Issue of adjoining parcels

The Murrs' attorney, John Groen, said the case "is now poised to potentially set national precedent" by resolving a recurrent issue in property rights law. Groen represents the Pacific Legal Foundation, a national property rights watchdog organization that took the case for free.

"It's a much larger issue than helping the Murrs," said Michael Murr, one of the siblings who brought the suit. "There are literally thousands of people in the country who have multiple parcels of property that adjoin each other that might be affected by this decision."

But the county's attorneys said that neither of the Murrs' parcels have sufficient "buildable acreage" because of a 130-foot cliff that intersects them.

Only if the Murrs combined the properties — either to expand their existing home or to sell — could they meet zoning ordinances that conform with state and federal regulations written to protect the St. Croix from erosion and pollution, attorneys Remzy Bitar, Matteo Reginato and Richard J. Lazarus wrote in their filing.

"The problems with petitioners' land for development are so great that petitioners still fall short of the one buildable acre minimum requirement even after combining the total buildable acreage available on both lots," they said.

Groen said the Murrs' parents bought the vacant parcel as an investment to supply income to their family in later years, and that the family has always paid property taxes on each parcel. "Our position for the Murrs is that these two parcels have always been separate, discrete, independent, legally identified parcels, and the takings clause protects each parcel independently," Groen said. The county's attorneys wrote that the Murr family "enjoyed the two lots in combination since becoming owners," using the vacant parcel for swimming, camping, parking and volleyball. "Neither they nor the parents ever treated them as distinct parcels in their day-to-day use of the lots," the attorneys wrote.

'A beautiful building site'

The county's attorneys also noted that the Murrs have options, including constructing a summer home that straddles both parcels.

But Groen said "they want to sell the investment parcel to have the proceeds to take care of the recreational parcel." He described the investment parcel as "a beautiful building site with great views up on top."

The Murr case, he said, isn't about rules that govern the St. Croix, a federally protected river, but about conflicting views of how the Constitution protects private property.

"Certainly the government attorneys will say a lot about how important the river is and that's fine, we don't disagree," Groen said at a news conference at the summer home.

"The Murr family is here because they love the river and they love the environment and they're great stewards of their property. But that's not what this case is about."

Bitar, however, said recently that "circumstances of this case may vary greatly" if the land in dispute was outside riverway boundaries.

The Supreme Court is scheduled to hear oral arguments in October.