Mont. Code Ann. § 44-1-1004

Patrol officers may stop any truck or motor vehicle in which livestock or livestock products are being transported and ascertain whether the driver of such truck or vehicle is rightfully in possession of such livestock or livestock products. If the patrol officers have good reason to believe that livestock or livestock products have been stolen, they may take possession of the same until the livestock or livestock products can be delivered into the custody of the sheriff or until such time as the facts as to the actual ownership can be ascertained.