ORS 618.101: Evidentiary presumptions regarding weights and measures law.

For the purposes of ORS 618.010 to 618.246, proof of the existence of a weight or measure or a weighing or measuring instrument or device in or about any building, enclosure, stand or vehicle in which or from which it is shown that buying or selling is commonly carried on is presumptive proof of the regular use of such weight or measure or weighing or measuring instrument or device for commercial purposes and of such use by the person in charge of such building, enclosure, stand or vehicle.