A trail run that began years ago in the desert of Utah has brought outdoor retailer Patagonia to an unexpected – and considerably less scenic – crossroads, at a federal courthouse in Washington DC.

The company filed a complaint on Wednesday accusing Donald Trump of exceeding the powers of his office earlier this week when he ordered that Bears Ears national monument be reduced in size by 85%.

The president framed the action as a correction of earlier federal overreach. Barack Obama established the monument at 1.3m acres one year ago, in a move Republicans in Utah’s legislature compared at the time to “the unilateral tyranny exercised by the King of England against the American colonies two and a half centuries ago”.

But Patagonia’s lawsuit asserts that Trump is the one playing king, by enacting the largest removal of protection from federal lands in history.

The complaint, which was joined by a coalition of conservation groups, was filed in parallel with a separate lawsuit joined by five Native American tribes who say the president’s move endangers sacred sites.

Obama established Bears Ears following a request from the inter-tribal coalition that cited increasing thefts and vandalism at more than 100,000 native cultural sites in the area.

While it’s not unheard of for corporations to sue the government, it’s also not an obvious business play. But anyone who doubted Patagonia’s willingness to swap backpack for briefcase in the long-running battle over Bears Ears and other public lands had their answer on Wednesday.

“We haven’t shied away from making our beliefs known, and I don’t think we’re going to get shy now,” said Robert Tadlock, a lawyer with Patagonia, in a phone interview on Thursday.

“This is certainly a step we’ve never taken before in this context. But the president’s decision is unprecedented. And so it calls for a different kind of response.”

A fixed-screen, black-and-white statement on the company’s web site is more pugnacious. “The president stole your land,” it reads, calling the reduction “an illegal move” and inviting visitors to join a network of activists and post about the issue on social media.

Patagonia and its partners warned they were ready to go to court last summer, after the Trump administration indicated that it was serious about carving up Bears Ears.

Apart from a lingering resentment of Obama, Utahans opposed to the Bears Ears monument have expressed seemingly clashing concerns – they are worried about potential environmental impact from increased tourism to the area; yet they also insist upon the right to preserve access to the land for energy and drilling interests.

Proponents of the monument point out that federal dollars are needed to preserve the area’s cultural sites and to manage tourism, which could provide a much-needed economic boost for the region.

National monuments are protected sites of historical, cultural or scientific interest managed by a patchwork of federal agencies.

Legal analysts disagree on whether the president has the authority to shrink Bears Ears and similar conservation sites without action by Congress.

“The president doesn’t have the authority under the Antiquities Act to do what he did,” said Tadlock, Patagonia’s lawyer, referring to the 1906 law giving the president the power to create a monument. “The executive only has power to manage federal land to the extent Congress grants that power.”

In a letter sent to the interior secretary, Ryan Zinke, in July, 121 legal scholars supported that theory.

But the opposing view has been advanced by Todd Gaziano of the Pacific Legal Foundation and professor John Yoo, best known for his work in the George W Bush administration to strike torture from the list of war crimes.

“Trump has the right to reverse the national monuments created by previous presidents without an act of Congress, but by the same token, the Constitution creates a check by allowing future presidents to reverse Trump too,” the pair wrote in a July editorial.

The government has 60 days to respond to Patagonia’s complaint. “I wouldn’t expect the decision certainly on the substance until sometime next year, but it’s very hard to predict how quickly it will go,” Tadlock said.

Tadlock dismissed the notion that Patagonia was out for a political win from taking on Trump.

“We feel that this is not about who the administration is. This is not about the politics of it,” he said.

“This is about the issue of public lands. We’ve been consistent on this issue for 40 years. It’s something we’ve fought for since we’ve started and it’s a big reason honestly why the company is still going, to be a voice on these issues.”