Daniel and Spencer Atkin have been enjoying their shady summer retreat for half their lives.

So it was a real downer, literally, when they learned the government was evicting them from their treehouse high up in the old willow tree.But Daniel, 14, and Spencer, 11, are not giving up without a fight, even if it is against City Hall.

On Friday, their lawyer, Blake S. Atkin, who also happens to be their father, filed a lawsuit to stop Salt Lake City from depriving them of the "quiet enjoyment" of their property.

According to the 3rd District Court suit, the treehouse was built more than 40 years ago in a willow tree on the edge of an urban farm at 1812 S. West Temple. The Atkins bought the 2.5-acre property about six years ago, and the two boys took possession of the treehouse.

In 1995, the city bought the property south of the Atkins for the construction of housing that had been displaced by the development of Franklin Quest Field. The housing project provoked a boundary dispute that was ultimately settled with an agreement that included the preservation of the treehouse and willow tree.

"That agreement was reaffirmed with the current owner of the lot into which the willow tree and treehouse portion of the plaintiff's property extends," the suit said.

But then last February, the city's zoning enforcement office informed Atkin that the treehouse failed to comply with certain zoning ordinances and would have to go.

According to the lawsuit, one city official told Atkin the zoning ordinance applied because the treehouse was an "accessory building."

"The treehouse is not a `building' under the Salt Lake City Code," the lawsuit argues. The applicable code "defines building to be `a structure with a roof, intended for shelter or enclosure.' Structure is defined as `anything constructed or erected with a fixed location on the ground or in/over the water bodies in the city.' "

Atkin said he thought he had persuaded the city to adopt this line of reasoning and drop the threat of zoning noncompliance. But then in May, another official said the city would not back off and that Atkin would not be given a hearing on his appeal.

Comply, the Atkins were warned, or pay a penalty of $150 a day, which is about what a cabin at a mountain resort would cost. Atkin said when he refused to comply, the city "conjured up" other zoning violations on his property and threatened to hit him with those as well.

City Attorney Roger Cutler said he saw the lawsuit for the first time Friday and couldn't comment on its specific allegations. He said he asked his staff to look into the dispute and find out why it had reached the point of litigation.

Atkin said even he doesn't know why.

"I've asked them (the city) to explain their objections to the tree-house, and no one seems able to tell me. I've negotiated until I'm blue in the face," Atkin said. "If someone has complained about it, I wish they would tell me because I'm a reasonable person, and I think we can work it out."

Atkin remains optimistic that the dispute can be resolved out of court. But if it can't, he will ask a judge to issue an injunction stopping the city "from interfering with plaintiff and his family's quiet enjoyment of the property, including the treehouse."

The lawsuit added, "The threatened injury to plaintiff from loss of a treehouse that has been on his property for over 40 years substantially outweighs any injury that might occur to the (city)."

It also said the injunction would be in the public interest because it would "prevent city officials from attempting to expand the reach of zoning ordinances through interpretation."

Atkin said he filed the suit not only to save his boys' treehouse but also because he wants them to feel that their rights are "protected and important."