683 Opinion of the Court. probably unwillingly abandoned competitive practices and entered into the combination. But none of the distinctions mentioned, or any other differences relied on by these particular respondents, justifies a holding that there was no substantial evidence to support the Commission's findings that they cooperated with all the others to achieve the ultimate objective of all—the elimination of price competition in the sale of cement. These respondents' special contentions only illustrate that the Commission was called upon to resolve factual issues as to each of them in the light of whatever relevant differences in their practices were shown by the evidence. For aside from the testimony indicating the differences in their individual sales practices, there was abundant evidence as to common practices of these respondents and the others on the basis of which the Commission was justified in finding cooperative conduct among all to achieve delivered price uniformity. The evidence commonly applicable to these and the other respondents showed that all were members of the Institute and that the officers of some of these particular respondents were or had been officers of the Institute. We have already sustained findings that the Institute was organized to maintain the multiple basing point system as one of the "customs and usages" of the industry and that it participated in numerous activities intended to eliminate price competition through the collective efforts of the respondents. Evidence before the Commission also showed that the delivered prices of these respondents, like those of all the other respondents, were, with rare exceptions, identical with the delivered prices of all their competitors. Furthermore, there was evi tition. As a result of that meeting the offending company agreed that it would "play the game 100%"; that it would not countenance "chiseling"; that it would not knowingly invade territory of its competitors, or "tear down the price structure." Opinion of the Court. 333 U. S. dence that all of these respondents, including those who sold cement on a zone basis in sections of southern California, employed the multiple basing point delivered price system on a portion of their sales. Our conclusion is that there was evidence to support the Commission's findings that all of the respondents, including the California companies, Northwestern Portland and Superior Portland, Huron and Marquette, cooperated in carrying out the objectives of the basing point delivered price system. Unfair Methods of Competition.-We sustain the Commission's holding that concerted maintenance of the basing point delivered price system is an unfair method of competition prohibited by the Federal Trade Commission Act. In so doing we give great weight to the Commission's conclusion, as this Court has done in other cases. Federal Trade Comm'n v. R. F. Keppel & Bro., 291 U. S. 304, 314; Federal Trade Comm'n v. Pacific States Paper Trade Assn., 273 U. S. 52, 63. In the Keppel case the Court called attention to the express intention of Congress to create an agency whose membership would at all times be experienced, so that its conclusions would be the result of an expertness coming from experience. We are persuaded that the Commission's long and close examination of the questions it here decided has provided it with precisely the experience that fits it for performance of its statutory duty. The kind of specialized knowledge Congress wanted its agency to have was an expertness that would fit it to stop at the threshold every unfair trade practice that kind of practice which, if left alone, "destroys competition and establishes monopoly." Federal Trade Comm'n v. Raladam Co., 283 U. S. 643, 647, 650. And see Federal Trade Comm'n v. Raladam Co., 316 U. S. 149, 152. We cannot say that the Commission is wrong in concluding that the delivered-price system as here used pro 683 Opinion of the Court. vides an effective instrument which, if left free for use of the respondents, would result in complete destruction of competition and the establishment of monopoly in the cement industry. That the basing point price system may lend itself to industry-wide anti-competitive practices is illustrated in the following among other cases: United States v. United States Gypsum Co., 333 U. S. 364, Sugar Institute v. United States, 297 U. S. 553. We uphold the Commission's conclusion that the basing point delivered price system employed by respondents is an unfair trade practice which the Trade Commission may suppress.19 The Price Discrimination Charge in Count Two.—The Commission found that respondents' combination to use the multiple basing point delivered price system had effected systematic price discrimination in violation of § 2 of the Clayton Act as amended by the Robinson-Patman Act. 49 Stat. 1526, 15 U. S. C. § 13. Section 2 (a) of that Act declares it to "be unlawful for any person engaged in commerce . . . either directly or indirectly, to discriminate in price between different purchasers of commodities of like grade and quality . . . where the effect of such discrimination 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 such discrimination, or with customers of either of them Section 2 (b) provides that proof of discrimination in price (selling the same kind of goods cheaper to one purchaser than to another) makes out a prima facie case of violation, but permits the seller to 19 While we hold that the Commission's findings of combination were supported by evidence, that does not mean that existence of a "combination" is an indispensable ingredient of an "unfair method of competition" under the Trade Commission Act. See Federal Trade Comm'n v. Beech-Nut Packing Co., 257 U. S. 441, 455. 333 U.S. Opinion of the Court. rebut "the prima-facie case thus made by showing that his lower price . . . was made in good faith to meet an equally low price of a competitor . . The Commission held that the varying mill nets received by respondents on sales between customers in different. localities constituted a "discrimination in price between different purchasers" within the prohibition of § 2 (a), and that the effect of this discrimination was the substantial lessening of competition between respondents. The Circuit Court of Appeals reversed the Commission on this count. It agreed that respondents' prices were unlawful insofar as they involved the collection of phantom freight, but it held that prices involving only freight absorption came within the "good faith" proviso of § 2 (b). The respondents contend that the differences in their net returns from sales in different localities which result from use of the multiple basing point delivered price system are not price discriminations within the meaning of 2 (a). If held that these net return differences are price discriminations prohibited by § 2 (a), they contend that the discriminations were justified under § 2 (b) because "made in good faith to meet an equally low price of a competitor." Practically all the arguments presented by respondents in support of their contentions were considered by this Court and rejected in 1945 in Corn Products Co. v. Federal Trade Comm'n, 324 U. S. 726, and in the related case of Federal Trade Comm'n v. Staley Co., 324 U. S. 746. As stated in the Corn Products opinion at 730, certiorari was granted in those two cases because the "questions involved" were "of importance in the administration of the Clayton Act in view of the widespread use of basing point price systems." For this reason the questions there raised were given thorough consideration. Consequently, we see no reason for again reviewing the questions that were there decided. 683 Opinion of the Court. In the Corn Products case the Court, in holding illegal a single basing point system, specifically reserved decision upon the legality under the Clayton Act of a multiple basing point price system, but only in view of the "good faith" proviso of § 2 (b), and referred at that point to the companion Staley opinion. 324 U. S. at 735. The latter case held that a seller could not justify the adoption of a competitor's basing point price system under § 2 (b) as a good faith attempt to meet the latter's equally low price. Thus the combined effect of the two cases was to forbid the adoption for sales purposes of any basing point pricing system. It is true that the Commission's complaint in the Corn Products and Staley cases simply charged the individual respondents with discrimination in price through use of a basing point price system, and did not, as here, allege a conspiracy or combination to use that system. But the holdings in those two cases that § 2 forbids a basing point price system are equally controlling here, where the use of such a system is found to have been the result of a combination. Respondents deny, however, that the Corn Products and Staley cases passed on the questions they here urge. Corn Products Co. was engaged in the manufacture and sale of glucose. It had two plants, one in Chicago, one in Kansas City. Both plants sold "only at delivered prices, computed by adding to a base price at Chicago the published freight tariff from Chicago to the several points of delivery, even though deliveries are in fact made from their factory at Kansas City as well as from their Chicago factory." 324 U. S. at 729. This price system we held resulted in Corn Products Co. receiving from different purchasers different net amounts corresponding to differences in the amounts of phantom freight collected or of actual freight charges absorbed. We further held that “price discriminations are necessarily involved where |