John Sturgeon with his hovercraft near the Yukon River in Eagle, Alaska. (Courtesy photo)

It is easy to understand why Alaska outdoorsman John Sturgeon finds a hovercraft useful in skimming across a shallow riverbed to get to his favorite moose-hunting spot in the Yukon wilderness.

But the Supreme Court seemed to find it much more difficult to decide whether the National Park Service had the authority to tell him no.

How difficult? At one point, Justice Stephen G. Breyer proposed a lengthy question that attempted to untangle the legal intricacies of federal park regulations and the special law that guides stewardship of the government’s vast landholdings in Alaska.

“Sorry,” Breyer said at the end of his question to Alaska Assistant Attorney General Ruth Botstein. “I shouldn’t have got into it. It’s too complicated. Skip the question.”

As the courtroom erupted in laughter, Chief Justice John G. Roberts Jr. interjected: “The rest of us are interested in your answer.”

Their challenge lies in the unique and complicated statutes that govern the federal government’s relationship with Alaska. As part of a 1971 settlement with Alaska Natives, the government guaranteed land to regional Native corporations and hundreds of Native village corporations.

It also set aside more than 105 million acres as a protected federal reserve and in 1980 established rules for its use in the Alaska National Interest Lands Conservation Act (ANILCA).

The separate protected ecosystems are a mix of federal, Native and private lands. The Native and private holdings must be treated differently from the federal lands, according to the act, and are not “subject to the regulations applicable solely to public lands within such units.”

Sturgeon was in such a park, the Yukon-Charley Rivers National Preserve, in 2007 when the incident that arrived Wednesday at the Supreme Court began.

He was repairing his 10-foot rubber hovercraft on a gravel shoal when three officers of the National Park Service approached. Even though he had used the craft for years, the officers told Sturgeon that the noisy hovercrafts were banned in all national parks, even in Alaska.

Sturgeon countered that the rivers in the preserves are not “federal lands” and belong to Alaska; thus, the park service’s ban on hovercrafts does not apply there.

He filed suit but has yet to find a judge who agrees with him.

A panel of the U.S. Court of Appeals for the 9th Circuit said the correct reading of the conservation act is that land not owned by the federal government is exempt only from park regulations that apply “solely” to Alaska parks.

The hovercraft is banned nationally, not just in the Alaska preserves, so the court said the law “unambiguously forecloses [Sturgeon’s] interpretation.”

Sturgeon’s attorney, Matthew T. Findley of Anchorage, said the appeals court got it backwards. The conservation act was intended to recognize that Alaska parks, with their mix of private and public lands, are different.

The rules are “specifically loosened for Alaska parks. You can camp in Alaska parks. You can hunt. You can fish. You can use snow machines. You can fly. The list goes on and on.”

Botstein agreed. “The National Park Service’s authority in other states or in other parks are not the baseline here,” she said. “The starting point is the power that Congress gave to the National Park Service and other land management agencies in regulating ANILCA parks.”

Justice Samuel A. Alito Jr. said the case may be complicated, but it seemed clear to him the appeals court was wrong. He told Assistant Solicitor General Rachel P. Kovner, defending the park service, that her brief to the court devoted one paragraph to defending the 9th Circuit decision.

“Why don’t you concede that it’s wrong?” he asked. “It’s a ridiculous interpretation, is it not?”

Kovner replied diplomatically that the government thought it had stronger defenses.

“When Congress created new park units in Alaska for the express purpose of protecting their waters, their free­-flowing rivers and their fish, it didn’t simultaneously strip the Park Service of preexisting authorities to achieve those goals by regulating navigable waters,” she said.

But it was difficult, from the justices’ questions about “usufructuary rights” and “nonpossessory use rights,” to see that they had found a way out of the legal wilderness.

The case is Sturgeon v. Frost.