Mont. Code Ann. § 30-14-904
30-14-904 Burden of rebutting prima facie case of discrimination
30-14-904 . Burden of rebutting prima facie case of discrimination. (1) In a proceeding for a violation of 30-14-901 , if proof is made that there has been discrimination in price, the burden of rebutting the prima facie case by showing justification is upon the person charged with a violation of 30-14-901 .
(2) A seller may rebut the prima facie case by showing that a lower price to a purchaser was made in good faith to meet an equally low price of a competitor.