The Montana Stockgrowers Association and two other plaintiffs filed a state court lawsuit seeking to order the capture, hazing, or slaughter of bison (also known as buffalo) by a Montana state agency in the Horse Butte area just outside the west boundary of Yellowstone National Park.

In response to recent land management changes that have entirely eliminated cattle from Horse Butte, Montana has allowed more freedom of movement for bison that migrate into the Horse Butte area during the winter season.

Nevertheless, claiming a fear that bison will transmit a disease (brucellosis) to cattle, the stockgrowers and their allies asked a Montana court to order the state to continue to capture and kill bison under a plan that was developed when cattle still grazed on the butte.

Earthjustice intervened in this case on behalf of local landowners and conservation groups to stop the stockgrowers from reinstating a bison slaughter, and in 2010 the Montana court rejected the attempt to require the Montana Department of Livestock to haze, harass and slaughter all bison that cross the Yellowstone National Park boundary into the Horse Butte area.