Earl Warren

“ Morton Salt Co., 334 U.S. 37, 45, 68 S.Ct. 822, 827, 92 L.Ed. 1196, the Court said, 'Congress meant by using the words 'discrimination in price' in § 2 that in a case involving competitive injury between a seller's customers the Commission need only prove that a seller had charged one purchaser a higher price for like goods than he had charged one or more of the purchaser's competitors.' [15] The commentators have generally shared this view. ”

“ These assumptions, we now conclude, were firmly rooted in the structure of the statute, for it is only by equating price discrimination with price differentiation that § 2 (a) can be administered as Congress intended. ”

“ As we read that provision, it proscribes price differences, subject to certain defined defenses, [17] where the effect of the differences 'may be substantially to lessen competition or tend to create a monopoly in any line of commerce, or to injure, destroy, or prevent competition with any person who either grants or knowingly receives the benefit' of the price differential, 'or with customers of either of them.' See Federal Trade Comm. ”

“ However, the legislative history of these amendments leaves no doubt that Congress was intent upon strengthening the Clayton Act provisions, not weakening them, and that it was no part of Congress' purpose to curtail the pre-existing applicability of § 2 (a) to price discriminations affecting primary-line competition. [8]
The federal courts, both before and after the amendment of § 2 (a) , have taken this view of the scope of the statute in cases involving impairment of primary-line competition. See Porto Rican American Tobacco Co. ”

“ The existence of competition among buyers who are charged different prices by a seller is obviously important in terms of adverse effect upon secondary-line competition, but it would be merely a fortuitous circumstance so far as injury to primary-line competition is concerned. ”

“ In view of our disposition of the case, it is unnecessary for us either to accept or reject that construction.↑ The statement in full is as follows:↑ See, e.g., Porto Rican American Tobacco Co. of Porto Rico v. American Tobacco Co., supra; Atlas Building Products Co. ”