BILLINGS, Mont - A legal dispute over whether migrating bison can roam freely across 70,000 acres outside Yellowstone National Park is before a Montana judge after attorneys offered closing arguments in the case Monday.

State officials opened the Gardiner Basin just north of the park to migrating bison last year after they had been barred for decades. It was an attempt to curb periodic slaughters that have killed thousands of the animals to prevent the spread of the disease brucellosis to cattle.

But county officials and ranchers who live outside the park want state District Judge Wayne Phillips to restore restrictions on the animals' movements.

They say the bison threaten the safety of residents in the basin and could spread brucellosis to livestock.

A trial in the case that began earlier this year concluded Monday.

State veterinarian Marty Zaluski testified that the disease transmission risk is unchanged or slightly lower since bison were let back into the Gardiner Basin. That gave state and federal officials more room to manage the wild animals, while newly-constructed fences will keep them away from the two cattle ranches that still operate in the area, Zaluski said.

The two sides have until Nov. 26 to submit their final arguments and conclusions, after which Phillips has said he will rule.

Hundreds of bison flooded into the basin two winters ago before the state formally lifted restrictions in the area.

During prior testimony in the lawsuits, an undersheriff from Park County said dozens of complaints came in from residents worried about their safety. And county officials have said public property was damaged by bison that pushed up against or knocked down fences and other structures.

Plaintiffs in the case also said there should have been more environmental studies done on the potential for brucellosis exposures and other problems before the free-roaming policy was adopted in April 2011. That formal adoption came after hundreds of bison already had been allowed into the basin.

Scientists and state officials have said that another wild animal, elk, are the biggest threat for the spread of brucellosis because they are more numerous and their movements are unrestricted.

Three conservation groups - Bear Creek Council, Greater Yellowstone Coalition and Natural Resources Defense Council - have intervened in the case on the side of the state. Their attorney, Tim Preso, said Monday that the ranchers and others opposed to bison in the basin do not speak for all of its residents.

"They don't represent the larger group of people in the Gardiner Basin that moved there to be closer to wildlife," he said. "If we can't conserve bison on the boundary of Yellowstone National Park, where we saved them from extinction, where can we do it?"

Most bison stayed inside Yellowstone last winter due to relatively mild conditions. Thousands have flooded out in other years.

The most recent count of the park's bison herd tallied 4,320 animals - enough to trigger a major migration this winter if conditions are right.