ORS § 646.050
Upon proof being made, in any suit or other proceeding in which any violation of ORS 646.010 to 646.180 is at issue, that there has been discrimination in price, or in services or facilities furnished, or in payment for services or facilities rendered or to be rendered, the burden of rebutting the prima facie case thus made by showing justification is upon the person charged with the violation; but this section does not prevent a seller rebutting the prima facie case so made by showing that the lower price of the seller, or the payment for or furnishing of services or facilities to any purchaser or purchasers was made in good faith to meet an equally low price of a competitor or the services or facilities furnished by a competitor.
ORS 646.050