By MATTHEW BROWN

Associated Press

BILLINGS, Mont (AP) -- A decision to allow migrating bison to roam freely across 70,000 acres outside Yellowstone National Park goes before a Montana judge Monday, as local officials and ranchers press for restrictions on the animals' movements.

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. However, few cattle remain in the disputed area, and federal agriculture officials have eased sanctions when brucellosis infections occur.

But Park County officials say the bison threaten the safety of residents in the basin, and local ranchers and the Montana Farm Bureau Federation say brucellosis remains a danger.

In two separate lawsuits, the county and ranchers have asked District Judge Wayne Phillips to block bison from the basin. A trial in the case that began earlier this year is expected to conclude Monday when state veterinarian Marty Zaluski is scheduled to testify.

Zaluski said he will address the risk of brucellosis from bison and whether that's changed with the decision on the Gardiner Basin. Also lined up to testify is and Brian McCloskey, former regional director for the U.S. Agriculture Department's Animal and Plant Health Inspection Service.

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. Plaintiffs in the case also said there should have been more studies done on the potential for brucellosis exposures and other problems before the free-roaming policy was adopted in April 2011.

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.

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.

An immediate ruling is not expected. The two sides have until Nov. 26 to submit their final arguments and conclusions, after which Phillips has said he will rule.

Copyright 2012 The Associated Press.