A U.S. District Court judge in Billings has rejected the federal government’s effort to pause a consolidated lawsuit challenging the National Park Service’s bison management plan in the Greater Yellowstone Area.

The Alliance for the Wild Rockies and the Council on Fish & Wildlife filed suit early this year against the National Park Service over its 2024 bison management strategy. The groups contend that the federal culling of bison that leave Yellowstone National Park rests on scientific assumptions that no longer hold merit.

The Core Dispute

At the heart of the case is disagreement over brucellosis risk. While roughly 60 percent of bison in Yellowstone test positive for the disease, the plaintiffs argue that only 10 to 15 percent of the herd can actually transmit it to livestock. They say the government’s approach to eradication is outdated and too aggressive.

Montana’s livestock brucellosis record supports the plaintiffs’ skepticism. Since 2010, the state has recorded 15 cases in livestock animals. State Department of Livestock officials attribute all 15 cases—or suspected cases—to elk, not bison.

“The bison management plan is based on outdated assumptions that thousands of bison need to be slaughtered to stop brucellosis infections in cattle. This is no longer accepted science, and the government needs to change its management practices to keep up,” said Mike Garrity, executive director of the Alliance for the Wild Rockies.

Numbers and Scale

The federal government manages approximately 20,000 bison across public lands, with about 8,000 roaming unfenced. Yellowstone alone holds roughly 5,000 unfenced bison and could sustainably support up to 10,000, according to the suit.

The lawsuit consolidated with a separate Montana state lawsuit filed in 2024. That state action alleged the federal government failed to adequately consult with Montana before implementing the bison management plan.

The judge’s denial of the federal pause request keeps the case moving forward, avoiding a delay that federal lawyers sought. The decision signals the court will not interrupt proceedings on what amounts to a fundamental disagreement over wildlife management science and the proper balance between disease control and population sustainability in the Greater Yellowstone ecosystem.