delivered the opinion of the Court.
This case is a sequel to Standard Oil Co. v. Federal Trade Comm’n, 340 U. S. 231 (1951), wherein the Court held that § 2 (b) of the Clayton Act, 38 Stat. 730, as amended by the Robinson-Patman Act, 49 Stat. 1526, 15 U. S. C. § 13 (b), afforded a seller a complete defense to a charge of price discrimination if its lower price was “made in good faith to meet a lawful and equally low price of a competitor.” 340 U. S., at 246. We remanded the case with instructions that the Federal Trade Commission make findings on Standard’s contention that its discriminatory prices were so made. The subsequent findings are not altogether clear. The Commission, acting on the same record, seemingly does not contest the fact that Standard’s deductions were made to meet the equally low prices of its competitors. However, Standard was held not to have acted in good faith, and the § 2 (b) defense precluded, because of the Commission’s determination *398that Standard's reduced prices were made pursuant to a price system rather than being “the result of departures from a nondiscriminatory price scale.” 49 F. T. C. 923, 954. The Court of Appeals found no basis in the record for such a finding and vacated the order of the Commission, holding that Standard’s “ 'good faith’ defense was firmly established.” 233 F. 2d 649, 655. In view of our former opinion and the importance of bringing an end to this protracted litigation, we granted certiorari. 352 U. S. 950 (1956). Having concluded that the case turns on a factual issue, decided by the Court of Appeals upon a fair assessment of the record, we affirm the decision below.
The long history of this 17-year-old case may be found both in the original opinion of the Court of Appeals, 173 F. 2d 210, and in the original opinion of this Court, supra. The case arose as a companion to similar complaints filed by the Commission against Gulf Oil Company, the Texas Company, and Shell Oil Company. In its petition for certiorari, the Commission stresses the existence of an industry-wide “dual price system,” asserting that the decision below would “insulate from attack a price pattern deeply entrenched in the industry — not only in the Detroit area, but also elsewhere in the country.” The pendency of the Gulf, Texas, and Shell complaints is mentioned twice, and the Commission states in a footnote that “[proceedings thereon have been deferred until the disposition of this case.” However, on April 3, 1957, the Commission decided that “it will not now be practicable to try the issues raised” in the companion complaints “irrespective of the final outcome of . . . the matter of Standard Oil Company,” and dismissed all three of the companion cases. The claim that the asserted dual pricing system was of industry-wide scope is not vital to the Commission’s position here, was not alleged in its complaint, and is not *399included among its findings; 1 therefore, we limit our consideration of the pricing system contention to Standard alone.
The Commission urges us to examine its 8-volume record of over 5,500 pages and determine if its finding that Standard reduced prices to four “jobbers” 2 pursuant to a pricing system was erroneous, as held by the Court of Appeals.3 The Commission contends that a § 2 (b) defense is precluded if the reductions were so made. If wrong in this, it maintains that the “good faith” element of a § 2 (b) defense is not made out by showing that competitors employ such a pricing system,4 and in any *400event is negatived by Standard’s failure to make a bona fide effort to review its pricing system upon passage of the Robinson-Patman Act.5
On the present posture of the case we believe that further review of the evidence is unwarranted. As stated in Federal Trade Comm’n v. American Tobacco Co., 274 U. S. 543, 544 (1927), although “[t]he statement of the petition for certiorari that the judgment and opinion below might seriously hinder future administration of the law was grave and sufficiently probable to justify issuance of the writ,” it now appears that “[p] roper decision of the controversy depends upon a question of fact,” and therefore “we adhere to the usual rule of non-interference where conclusions of Circuit Courts of Appeals depend on appreciation of circumstances which admit of different interpretations.” Moreover, in Universal Camera Corp. *401v. Labor Board, 340 U. S. 474, 491 (1951), we decided that substantiality of evidence on the record as a whole to support agency findings “is a question which Congress has placed in the keeping of the Courts of Appeals. This Court will intervene only in what ought to be the rare instance when the standard appears to have been misapprehended or grossly misapplied.” We do no more on the issue of insubstantiality than decide that the Court of Appeals has made a “fair assessment” of the record.6 That conclusion is strengthened by the fact that the finding made by the Court of Appeals accords with that of the trial examiner, two dissenting members of the Commission, and another panel of the Court of Appeals when the case was first before that court in 1949, all of them being agreed that the prices were reduced in good faith to meet offers of competitors.
Both parties acknowledge that discrimination pursuant to a price system would preclude a finding of “good faith.” Federal Trade Comm’n v. A. E. Staley Mfg. Co., 324 U. S. 746 (1945); Federal Trade Comm’n v. Cement Institute, 333 U. S. 683 (1948); Federal Trade Comm’n v. National Lead Co., 352 U. S. 419 (1957). The sole question then is one of fact: were Standard’s reduced prices to four “jobber” buyers — Citrin-Kolb, Stikeman, Wayne, and Ned’s — made pursuant to a pricing system rather than to meet individual competitive situations?
*402We have examined the findings of the Commission, which relies most heavily on the fact that no competitors’ offers were shown to have been made to Citrin-Kolb, Stikeman, or Wayne prior to the time Standard initially granted them the reduced tank-car price.7 All three of these “jobbers,” however, were granted the tank-car price before the passage of the Robinson-Patman Act in 1936, and the trial examiner excluded proof of pre-1936 offers on the ground of irrelevancy. The Commission approved this ruling, and on remand failed to reopen the record to take any further proof. In our former opinion in this case, we said, “There is no doubt that under the Clayton Act, before its amendment by the Robinson-Patman Act, [such] evidence would have been material and, if accepted, would have established a complete defense to the charge of unlawful discrimination.” 340 U. S., at 239-240. The proof should have been admitted; its absence can hardly be relied on by the Commission now as a ground for reversal. In any event, the findings that were made are sufficient for our disposition of the case.
It appears to us that the crucial inquiry is not why reduced prices were first granted to Citrin-Kolb, Stikeman, and Wayne, but rather why the reduced price was continued subsequent to passage of the Act in 1936. The findings show that both major and local suppliers made numerous attempts in the 1936-1941 period to lure these “jobbers” away from Standard with cut-rate prices, often*403times much lower than the one-and-one-half-cent reduction Standard was giving them.8 It is uncontradicted, as pointed out in one of the Commission dissents, that Standard lost three of its seven “jobbers” by not meeting competitors’ pirating offers in 1933-1934. All of this occurred in the context of a major gasoline price war in the Detroit area, .created by an extreme overabundance of supply — a setting most unlikely to lend itself to general pricing policies. The Commission itself stated:
“It may well be that [Standard] was convinced that if it ceased granting tank-car prices to Citrin-Kolb, Wayne, and Stikeman and continued to refuse the tank-car price to Ned’s Auto Supply Company it would lose these accounts. It had substantial reasons for believing this to be the case, for all of these concerns, except Ned’s Auto Supply Company, had already been recognized as entitled to the tank-car price under the commonly accepted standards of the industry, and Ned’s had achieved a volume of distribution which brought it within the range where it was likely to be so recognized by a major oil company at any time.” 49 F. T. C., at 952-953.
The findings as to Ned’s, the only one of the “jobbers” initially to receive the tank-car price post Robinson-Patman, are highly significant. After a prolonged period of haggling, during which Ned’s pressured Standard with information as to numerous more attractive price offers made by other suppliers, Standard responded to an ultimatum from Ned’s in 1936 with a half-cent-per-gallon reduction from the tank-wagon price. The *404Commission concedes that this first reduction occurred at a time when Ned’s did not meet the criteria normally-insisted upon by Standard before giving any reduction. Two years later, after a still further period of haggling9 and another Ned’s ultimatum, Standard gave a second reduction of still another cent.
In determining that Standard’s prices to these four "jobbers” were reduced as a response to individual competitive situations rather than pursuant to a pricing system, the Court of Appeals considered the factors just mentioned, all of which weigh heavily against the Commission’s position. The Commission’s own findings thus afford ample witness that a “fair assessment” of the record has been made. Standard’s use here of two prices, the lower of which could be obtained under the spur of threats to switch to pirating competitors, is a competitive deterrent far short of the discriminatory pricing of Staley, Cement, and National Lead, supra, and one which we believe within the sanction of § 2 (b) of the Robinson-Patman Act.
Affirmed.
The Commission admits that not all of the major suppliers were using the asserted dual price system, stating in its brief that Standard’s two largest competitors in the Detroit area, Socony-Vacuum and Sun Oil Company, sold only at the higher tank-wagon price. The Commission findings reveal that those suppliers who did offer a tank-car price to the Standard customers in question were not offering a uniform price: both Shell and the Texas Company, for example, made offers of two cents per gallon off the tank-wagon price, as contrasted with Standard’s one-and-one-half-cent reduction.
The particular tag “jobbers” is of no significance here in the light of our affirmance of the Court of Appeals’ conclusion that the reductions in price complained of were not made pursuant to a pricing system. Standard’s use of the word, while not an accurate description of the economic function performed by the four purchasers, is as consistent with a desire to placate customers to whom Standard was not forced by lower offers to give a reduced price as it would be with any asserted reduction of prices pursuant to a pricing system.
“. . . [W]e are unable to discern any basis for the conclusion that petitioner’s prices ‘were not the result of departures from a nondiscriminatory price scale.’ The record affirmatively demonstrates to the contrary. Petitioner sold invariably at its uniform tank-wagon price, except when at different times it reduced its price to meet competitive offers in order to retain a customer.” Standard Oil Co. v. Federal Trade Comm’n, 233 F. 2d 649, 654. (Emphasis added.)
This contention falls of its own weight, for the conclusion that the reductions here were not made pursuant to a pricing system *400negates the fact assumption underlying the Commission’s argument that there is no good faith when one price system is being matched against another. There is no showing or serious contention by the Commission that the offers of Standard’s competitors were unlawful. Indeed, the Court of Appeals stated, “[I]n the instant situation there is no finding, no contention and not even a suspicion but that the competing prices which petitioner met were lawful.” 233 F. 2d, at 654. The Commission admits that it “did not actually adjudicate the legality of the competing prices which Standard allegedly met . . . .” In the manner of a casual aside, the Commission belatedly suggests now that the competitors’ prices were unlawful since they were similar to Standard’s reductions and the latter were unlawful because made pursuant to a pricing system. If this be thought sufficient to raise the question, the foundation of the Commission’s logic is destroyed by our affirmance of the finding that Standard’s reductions were not made pursuant to any price system.
Our disposition eliminates the necessity of considering this last point. Nor need we consider the Commission’s claim that the Court of Appeals held the question involved here to be one of law. An examination of the court’s statement, 233 F. 2d, at 651, indicates it had reference to the broader issue of Standard’s “good faith” under §2 (b).
Labor Board v. Pittsburgh S. S. Co., 340 U. S. 498, 502-503 (1951); see also Labor Board v. American National Ins. Co., 343 U. S. 395, 409-410 (1952). Those cases cannot be distinguished from the present one on the basis of the statutes involved. Compare National Labor Relations Act, § 10(e), 61 Stat. 147, 29 U. S. C. § 160(e), with Federal Trade Commission Act, § 5 (c) and (d), 52 Stat. 112-113, 15 U. S. C. §45 (c), (d). In Universal Camera, supra, the Court indicated that the review standard established in that case would apply to all instances of court review of agency decisions. 340 U. S., at 488-490.
The Commission brief also claims that reduction pursuant to a pricing system was admitted in the 1940 answer filed by Standard. That portion of the answer referred to, however, was concerned with establishing an alternative and altogether different defense, namely, cost justification on the basis of functional customer classification. Such defense could be argued even if the reductions were held made pursuant to a pricing method, and therefore is consistent with the claim of good faith meeting of competition.
The Commission places great importance on the fact that only one of these offers was a standing offer. This is not a situation involving only one or two competitive raids, however; continuation of reductions once granted is warranted by § 2 (b) when competitors’ reduced price offers are recurring again and again in a cutthroat market.
The findings indicate that similar haggling over an extended period of time occurred before each of the other “jobbers” obtained a reduced price. The great time consumed in the haggling process tends to negate any idea that the participants were only deciding whether a given purchaser met Standard's four well-defined “jobber” criteria— annual volume of one to two million gallons, own delivery facilities, bulk'storage capable of taking tank-car delivery, and responsible credit rating.