Mont. Code Ann. § 7-4-2113

In addition to any other penalty provided in this code, a county commissioner who neglects or refuses to perform any duty imposed on the commissioner without just cause, who willfully violates any law provided for the commissioner's government as an officer, who fraudulently or corruptly performs any duty imposed on the commissioner, or who willfully, fraudulently, or corruptly attempts to perform an act unauthorized by law as commissioner forfeits to the county $500 for every act, to be recovered on the commissioner's official bond, and is further liable on the official bond to any person injured by the act for all damages sustained.