A federal judge in Billings has refused to put a consolidated lawsuit challenging the National Park Service’s bison management practices on hold, allowing the case to move forward against a 2024 bison management plan covering the Greater Yellowstone Area.

The U.S. District Court denied the federal government’s request to pause the litigation, which was brought in early January by the Alliance for the Wild Rockies and the Council on Fish & Wildlife. The suit takes aim at how the National Park Service manages bison that stray outside Yellowstone National Park’s boundaries — through culling, roundups, captures, and hazing operations.

The Science Dispute

At the heart of the lawsuit is a disagreement over brucellosis, a bacterial disease that roughly 60 percent of Yellowstone bison test positive for. Plaintiffs contend that only 10 to 15 percent of those animals are actually capable of transmitting the disease to livestock, and they argue the federal management plan relies on outdated assumptions rather than current science.

The groups point to a 20-year national study on brucellosis transmission in support of their claims. Notably, all 15 confirmed or suspected brucellosis cases recorded in Montana livestock since 2010 have been linked to elk, not bison.

Mike Garrity, executive director of the Alliance for the Wild Rockies, said the current approach is misaligned with the evidence. “The bison management plan is based on outdated assumptions that thousands of bison need to be slaughtered to stop brucellosis infections in cattle,” he said. Garrity called the court’s decision “a great step in the right direction,” adding that management of the nation’s official mammal should be grounded in sound science.

Scale of the Issue

The federal government oversees approximately 20,000 bison on public lands across the region. Of those, around 8,000 roam unfenced — including roughly 5,000 within Yellowstone itself. The park has capacity for up to 10,000 bison, meaning the population is well below the upper threshold even as management pressure continues.

Related Litigation

The case is part of a consolidated proceeding that includes a separate 2024 lawsuit brought by the state of Montana. That suit focused on the federal government’s alleged failure to adequately consult with Montana before finalizing the bison management plan — a procedural objection distinct from the scientific arguments raised by the environmental groups.

With the court declining to pause proceedings, both challenges will now advance through the litigation process. The outcome could affect how the National Park Service conducts bison management operations across the Greater Yellowstone ecosystem for years to come.

Federal courtrooms have increasingly become the venue for high-stakes natural resource disputes in the Mountain West. Idaho’s attorney general’s office has similarly been engaged in federal litigation over state policy questions — most recently wrapping up its defense of the state’s Defense of Life Act in federal court.