MASHPEE — The Trump administration on Friday delivered an unprecedented and potentially crushing blow to the Mashpee Wampanoag Tribe.

After more than two years of legal uncertainty, the U.S Department of the Interior — the agency charged with protecting tribal trust assets — issued a finding that it could not keep 321 acres of land taken into trust for the tribe under the Obama administration, casting an ominous shadow on the Cape tribe's future and its proposed $1 billion casino in Taunton.

The Interior Department was sued in 2016 by neighbors of the planned casino-resort after the agency took the tribe’s land into trust in 2015. A federal judge ruled that the Secretary of the Interior did not have the authority to take the land into trust because the tribe was not under federal jurisdiction at the time of the passage of the Indian Reorganization Act in 1934 and therefore did not qualify under a definition of Indian used by Interior officials.

Since the 2016 U.S. District Court ruling, the agency has been considering whether Massachusetts had exercised authority over the Mashpee tribe in a manner that could be viewed as a surrogate for the federal jurisdiction requirement under the 1934 law.

That law remains the primary governing tool over Indian affairs, promoting self-determination and self-government.

The lawsuit, as in similar cases, rested on the interpretation of four words: “now under federal jurisdiction,” a phrase that has vexed tribes seeking trust status for newly acquired land with the federal government over the years, most notably the Narragansett Tribe’s efforts in Rhode Island, which culminated in the Supreme Court decision known as Carcieri v. Salazar.

View a timeline of the tribe's quest for land over the years

But the Carcieri decision never established the criteria by which a tribe could demonstrate it was under federal jurisdiction, prompting the Interior’s solicitor to issue an interpretation of the ambiguous phrase in 2014.

In a letter sent Friday to Mashpee Wampanoag Tribal Chairman Cedric Cromwell, Assistant Secretary of Indian Affairs Tara Sweeney wrote that after reviewing the evidence and submissions, the state’s history of exercising authority over the tribe provides no indication of federal authority sufficient to prove it was “under federal jurisdiction.”

While the evidence “demonstrates a federal awareness of the Massachusetts Indians and the Commonwealth's regulation of their affairs, it does not establish or reflect any federal actions taken on behalf of, or for the benefit of, the Mashpee Tribe or its members as such,” Sweeney wrote. “Because the Tribe was not ‘under federal jurisdiction’ in 1934, the Tribe does not qualify under the IRA's first definition of ‘Indian.’ Nor does it qualify under the second definition, as that definition has been interpreted by the United States District Court for the District of Massachusetts.”

Mashpee signed Remand Decision byCape Cod Times on Scribd

Having struck out in federal court and with the executive branch, the tribe’s road to maintaining its land and the resulting economic benefits are narrowing. Hopes for the future of the tribe’s land now rest with legislation pending before Congress that would reaffirm the reservation outright, ending the ongoing litigation and preventing future legal challenges to it in court.

That legislation was introduced by U.S. Rep. William Keating, D-Mass., and a twin bill has been introduced in the Senate. Keating said Friday’s ruling was what congressional leaders feared, blaming Trump administration officials for “turning their backs” on the historic tribe, which traces its roots back some 12,000 years in the region.

“This tribe held the first Thanksgiving,” he said. “This is clearly on the doorstep of the Trump administration.”

Keating said Trump’s Justice Department “should be appealing” the ruling.

“We’ll be moving forward with our legislation,” Keating said.

In a statement, Cromwell said the ruling was a “tremendous blow” to the tribe and a “grave injustice initiated by an out-of-state casino developer,” referring to Chicago-based Neil Bluhm, who is backing a competing casino proposal in Brockton and who had initially thrown financial support behind the lawsuit brought by neighbors of the tribe’s planned Taunton casino

“I am asking people of good will and all those concerned with justice for the indigenous people of this land — the first Americans — to stand with us in calling on Congress to protect our reservation and ensure we are don’t become the first Tribe since the dark days of the Termination Era to lose its land,” Cromwell said.

Federal Indian law experts have said the Interior Department must seek congressional approval to take the land out of trust. The federal government issued a proclamation of the tribe’s reservation after it was taken into trust and it is unclear what the removal of trust status would mean for the reservation, according to the experts.

“All of this is unsettled because there’s not much precedent here,” said Gregory Ablavsky, professor of law at Stanford University Law School.

The removal of trust status must come through federal legislation, he said.

Robert Anderson, director of the Native American Law Center at the University of Washington School of Law, previously said a ruling against the tribe “would be totally inconsistent with federal Indian policy since the 1950s.”

Within Indian Country, the ruling is telling regarding the current administration’s land policies toward Indians, according to Derrick Beetso, general counsel for the National Congress of American Indians.

Michelle Littlefield, a plaintiff in the 2016 lawsuit, wrote in a text message that Keating's legislation would reaffirm “a no decision,” suggesting the Interior Department's original decision had been voided by Friday’s ruling.

“It’s over,” she wrote.

— Follow Tanner Stening on Twitter: @tsteningCCT.