Jailing people because of a mental health issue is illegal in Montana, but the Fort Peck Assiniboine and Sioux Tribes has its own laws. One tribal policy allows law enforcement to put citizens who thr …Jailing people because of a mental health issue is illegal in Montana, but the Fort Peck Assiniboine and Sioux Tribes has its own laws. One tribal policy allows law enforcement to put citizens who thr …