The Mashpee Wampanoag Tribe is now suing the U.S. Department of the Interior.

Tribal attorneys filed a lawsuit in federal court September 27 challenging a Sept. 7 determination from the department that reversed an Obama-era decision to secure 321 acres of tribal land into trust. The latest ruling declared that the tribe was not under federal jurisdiction in 1934 — the year the Indian Reorganization Act was passed.

The new complaint, which was filed in U.S. District Court for the District of Columbia against the department and Interior Secretary Ryan Zinke, alleges that the agency “failed to apply established law” by “contorting relevant facts and ignoring others to engineer a negative decision” with respect to the tribe’s land.

The suit alleges that the recent department decision “indefensibly reverses course” from the administrative decisions it has made for other tribes in regard to federal jurisdiction and “badly ignores” the case law interpreting what that phrase means, documents show.

“The (tribe) therefore files this complaint to challenge the department’s 2018 decision and correct (its) arbitrary, capricious and unlawful actions,” the suit states. The suit goes on to reassert evidence that the tribe submitted during its bid for federal recognition and throughout the course of the lawsuit to prove it was under federal jurisdiction.

“We are urgently petitioning the United States Congress and the federal courts to end this nightmare — to prevent what appears to be an intentional return to the dark days of the termination era, when tribal lands were taken out of trust and the federal relationship with tribal governments disavowed,” Chairman Cedric Cromwell said.

The Interior Department took 321 acres in Mashpee and Taunton into trust for the tribe in 2015, declaring it a sovereign reservation. Under such designation the federal government holds the title to the property but the tribe may decide how to develop or use the land for its own benefit.