concurring:
I concur in Judge Leventhal’s carefully reasoned and skillfully crafted opinion for the court. I add this note as a concurrence-for-emphasis.1
In Judge Leventhal’s opinion for the court the Commission has properly been allowed wide discretion in fashioning a new and more flexible rule on remand. The point I wish chiefly to emphasize is that the Commission on remand must give careful consideration to arguments raised by petitioning pipelines concerning market pressures, the ambiguity of the Commission’s orders on timing of payments and the contribution of advance payments to capital development by producers and to enhancement of gas supply. Thus I believe the court’s opinion must be read as not allowing the Commission discretion to institute a new rule that is little more forthcoming in its allowances for advance payments than the now-void thirty-day rule.
As we have noted, the advance payment program constituted a significant and recognized departure from traditional regulatory principles.2 This departure was deemed necessary to serve the important public purpose of “facilitatpng] capital formation by [natural gas] producers to finance development and production of new . supplies” in order to “alleviat[e] the impending natural gas shortage.” 3 The program aimed to stimulate the process of capital formation by allowing the transfer from pipelines to producers of interest-free sums reasonably targeted for purchase or expenditures for production of identified gas supplies.4 Natural gas producers were thus relieved of financing costs ordinarily associated with the accumulation of capital for exploration and development of new supplies.
With such significant advantages to be gained from advance payments, it is certainly correct, as Judge Leventhal has pointed out, that producers could be “expected” to bargain with the pipelines for *218advance payments to be made.5 Likewise, producers could be expected to press the pipelines for advances to be made on the most favorable terms possible — i. e., as long as possible in advance of their eventual “qualifying” expenditure.6 This pressure for what we have termed “extended front-end” advances7 was increased because the availability to producers of interest-free advance payments became one of the few negotiable terms of gas supply contracts in the otherwise closely regulated natural gas market.
As a result of tight gas supplies during the years of the program at issue here,8 bargaining attempts of the producing companies met with particular success as pipelines scrambled to secure supplies of gas for customers. Since it was in order to relieve this plight of tight supply that the program was initiated, however, this superior bargaining position of the producers and their consequent bargaining success should have come as no surprise to the Commission.
Furthermore, no evidence on the record suggests thát contracts providing for advance payments were negotiated covertly. Instead, all available information suggests that the high degree of administrative, judicial, and public scrutiny afforded the advance payment program made the terms of the vast majority of advance payment contracts well known to outside parties, and certainly to the responsible regulators.
It is thus particularly astonishing that, as noted in the court’s opinion, “[t]he advance payment orders [issued by the Commission during the program] did not specify the permissible interval between the advance and its appropriate expenditure.”9 Order No. 465 contained what has properly been described as a totally “unelaborated statement” that advance payments would be allowed only where “reasonable and appropriate,” with no specific reference to the critical issue of how long in advance of designated use such payments could be made.10 Subsequently, Order No. 449 made a completely unimpressive advance toward specificity by declaring that only those advances made within a “reasonable time” of eventual expenditure would be allowed.11 Until long after the expiration of the advance payment program, therefore, the Commission through its applicable Orders provided only the most cryptic and ambiguous guidelines concerning the issue central to the present litigation.12
It thus was practically inevitable that the “flood” of advance payments propelled by Order No. 465 did not abate during the time between the two advance payment orders, or thereafter.13 The Commission bears much responsibility for this situation, for the opacity of the Commission’s orders on the issue of permissible timing could only have contributed to the disruptive effect of advance payment bargaining on the other*219wise tightly metered minuet of producers, pipelines, consumers, and regulators.14
The court’s opinion has bent over backward to emphasize that the lack of clear regulatory guidance weakened the resistance of pipelines to the “untoward advances” of producers in eliciting extended front-end payments by pipelines.15 We have been somewhat less definite, however, in suggesting the extent of the relief that should be afforded the pipelines on remand. We have noted that the objective of the advance payment program was to facilitate the development of capital by producers in order to enhance gas supply,16 and that advance payments by definition involve the transfer of capital from pipelines to producers.17 We have also noted the argument of the pipelines that all advance payments must be sustained for reason of such a capital contribution, and the contrary argument of the Commission that no. allowance should be made for many payments that “for the extended period between receipt [by the producers] and expenditure . made no . contribution of developmental capital [for ‘qualifying expenditures’] while providing producers with a non-price incentive of the type the program explicitly sought to avoid ‘as much as possible.’ ”18
The opinion of the court, however, adopts a middle position. While rejecting the pipeline’s argument for carte blanche authority to make advances,19 we have also rejected the Commission’s overly narrow view of the *220role of advance payments in enhancing capital formation and gas supply. Any front-end advance payment, according to this court’s definition, is one made prior to its use for “qualifying expenditures.”20 Also we have noted that only a subclass of front-end advance payments may properly be disallowed current rate base treatment. This class of payments on remand will necessarily be smaller than that excluded by the Commission according to the thirty-day rule. Thus we have not determined that every advance is insupportable for the simple reason of its payment prior to expenditure; instead, we urge strict scrutiny only of those payments that may have been “extravagant” because they were made too long in advance of qualifying expenditures.
We reach this conclusion, I believe, in part because payments made at any interval (whether thirty days or much longer) in advance of qualifying expenditures inevitably enhanced the formation of capital in the hands of producers, and, unless diverted eventually for other “nonqualifying” purposes, may have facilitated the development of new gas supplies by reenforcing the capital foundation of the producing firms and freeing other funds for immediate productive use. It will be the task of the Commission on remand to define with some specificity and with greater latitude than previously those advance payments that were, and those that were not, “reasonable and appropriate” in conforming to the stated objectives of the program in thus aiding capital development for the purpose of enhancing gas supplies.
I have some difficulty, however, with the court’s discussion of the undesirable consequences of competition among pipelines for supplies of gas. Though bidding among pipelines for gas by offering advance payments inevitably had the effect of raising prices, it cannot lightly be assumed that an increase in prices did not lead to a corresponding increase in supply. As a general matter, only in a situation of total inelasticity of supply can an increase in prices not be expected to lead to a corresponding increase in supply. No such situation of total inelasticity has been demonstrated here, and as Judge Leventhal notes, “[E]ven in the regulatory context market pressures retain some vitality.”21 Thus it is clearly within the purview of our decision for the Commission to give close consideration to the extent to which bidding for gas supplies had the effect of raising prices and thus enhancing natural gas supply, in keeping with the overall goals of the advance payment program. I believe that the burden of proof rests with the Commission to demonstrate that the new rule it derives on remand distinguishes effectively between those advance payments that reasonably could, and those that reasonably could not lead to an increase in supply commensurate with any increase in price.
The Commission on remand will also want to take careful note of the losses incurred by the pipelines as a result of the Commission’s rate base ruling. Though Judge Leventhal has noted for the court that the Commission’s action to date has been to defer, rather than indefinitely to disqualify certain advance payments for rate base, he has also noted that “substantial sums were involved” and that “deferral has resulted in considerable losses for the pipelines’ stockholders” because of interest lost during the period of deferral.22 Such losses are not to be taken lightly, and clearly a very close question is presented as to whether these losses are substantial enough to bar the admittedly retroactive clarification by the Commission of the ambiguous language of its earlier orders on the issue of timing.23
The Commission will also wish to consider the equities in specific cases of a denial of current rate base to pipeline companies that may have exercised reasonable judgment in *221making advance payments in the context of tight gas supplies and ambiguous regulatory guidance. The pipelines have made out a convincing case that their responsibility to obtain adequate supplies for consumers during a period of scarce supply compelled them to “bid competitively for gas reserves by offering extended front-end advances.”24 Though we have not endorsed application of any “competitive business judgment” rule in this case, we have noted that circumstances may be “anticipate^] . where a pipeline’s investors might determine in their sound business judgment that they should take the risks associated with obtaining needed gas supplies, at least where there is a colorable legal argument that . . . [the] expenditures are permissible.” 25
I believe that under the circumstances of this case there was at least a “colorable legal argument” that many of the advance payments made would subsequently be approved by the Commission, and that any exercise of sound judgment by pipeline companies in weighing factors of consumer demand, scarce supply, and ambiguous regulation must not be lightly rebuffed by the Commission on the basis of an imputed greater wisdom of hindsight.
All of the considerations discussed above I understand to be subsumed within the court’s, instruction that the Commission on remand devise a new and more flexible rule concerning advance payments. As noted in the court’s opinion: “The advance payment orders . . . were instinct with the attitude of flexibility and experimentation” and “allowed a certain discretion to the pipelines and encouraged them to develop practical financing packages . . . .”26 Though the pipelines have erred in arguing for an overbroad and overgenerous rule of universal allowances,27 they certainly have not erred in resisting the Commission’s correspondingly narrow and excessively rigid thirty-day rule. As has been made amply clear in the court’s opinion, there is nothing pernicious about advance payments per se; 28 instead, I believe, only those advance payments that overstrain the bounds of reasonableness may be denied current rate base treatment by the Commission. Having failed once, a serious burden rests with the Commission to buttress its new rule with reasoned support.
. See Citizens to Save Spencer County v. United States Environmental Protection Agency, et al., 195 U.S.App.D.C. 30, 600 F.2d 844 (D.C.Cir. 1979) (Leventhal, J., concurring).
. See, e. g., 196 U.S.App.D.C. 193, 606 F.2d at 1100 (advance payment program was a recognized “departure from the usual rule of public utility regulation that current rates should reflect the cost of supplying service to current rate payers ... . ”); id. at 202, 606 F.2d at 1109-1110 (describing advance payment program as a clear “departure” from, and “modification” of the “used and useful” principle); id. at 208 of 196 U.S.App.D.C., at 1115 of 606 F.2d (“any permission to transfer advances pri- or to gas delivery . . entailed some variance from the . . . [regulatory] situation [prior to the commencement of the advance payments program], its terms of benefit to producer and of cost to pipeline and customer.”).
. See id. at 192, 606 F.2d at 1099. See also id. at 195 of 196 U.S.App.D.C., at 1102 of 606 F.2d (“theory” of the program was that “increased availability of capital would encourage investment, which in turn would yield additional gas supply”).
. See id. at 208, 606 F.2d at 1115 (“A producer receiving an extended front-end advance, to use without restriction for a significant period prior to expenditure, is in effect given a sum of money.”).
. See id. at 192, 606 F.2d at 1099.
. The court’s opinion has employed the term “qualifying expenditure” to identify “those producer expenses permissible under the [advance payments] program.” See id. at 192, 606 F.2d at 1099.
. The court has devised the novel and useful term “extended front-end advance” to describe those advance payments barred from current rate base treatment by Commission orders here under review. See id. at 195, 606 F.2d at 1102.
. These years were 1973, governed by FERC Order No. 465, and 1974-75, governed by FERC Order No. 499. See id. at 194, 606 F.2d at 1101.
. See id. at 196, 606 F.2d at 1103.
. See id. at 198, 606 F.2d at 1105.
. See id.
. The Commission order barring current rate base treatment to certain “extended front-end advances” made by Tennessee Gas Pipeline Company, for example, was issued on 9 July 1976, see FPC Docket No. RP73-113, Opinion No. 769, more than six months subsequent to the expiration of the advance payment program on 31 December 1975.
. See 198, 606 F.2d at 1105 (“Despite the Commission’s signal in Order No. 499 that it intended to focus on the critical timing requirement, the flood [of advance payments] did not abate.”).
.As noted in the court’s opinion, producers may have been “emboldened by . [the] indefiniteness [of the advance payment orders on timing]” and therefore the “producers pressed their bargaining advantage, inducing pipelines to make advances long before the funds were used for qualifying expenditures.” Id. at 196, 606 F.2d at 1103. See also id. (pipelines’ “weakened resistance” to competitive pressures was materially aided by “[t]he belief (or hope) that the Commission would permit rate-base treatment of extended front-end advances”).
Though the court’s opinion in other language has not accepted petitioners’ argument that the Commission must be “estopped” from denying current rate base to advance payments because the Commission was on notice of the payments and the pipelines relied justifiably on agency silence, see id. at 209-210, 606 F.2d at 1116— 1117, the court’s view on this issue is perhaps best summed up in its exceedingly cautious statement that “agency silence . . . [with regard to the scope of a departure from a well-rooted regulatory principle] must be construed to mean that traditional [regulatory] principles retain their vitality.” Id. at 203, 606 F.2d at 1110. This modest statement, however, must be placed side by side with the court’s repeated observation that the advance payment program constituted an express departure from recognized regulatory principles. See id. at 193,202-203, 208, 606 F.2d at 1100, 1109-1110, 1115. Thus it is certainly consistent with the court’s position to argue that the “vitality” of the Commission’s regulatory principles has been diminished at least to the extent that the Commission itself has backed away from those principles. It would be insupportable for the Commission to bind an industry to regulatory principles from which the Commission has itself departed; thus I believe it is only with some difficulty that we conclude that “agency silence” on the issue of timing of advance payments did not convey a tacit and irreversible assurance that advance payments would be upheld if made in full view of the Commission and in arguable compliance with the Commission’s ambiguous regulations.
. We have suggested, for example, that the Commission on remand has “latitude to take . . . into account ... the view that the ability of the pipelines to resist untoward advances was materially weakened by the agency’s handling of the issue,” id. at 213 n. 97, 606 F.2d at 1120 n. 97, and “whether the pipelines were caught between a rock and a hard place and took actions which they reasonably believe were in the best interests of their customers,” id. at 213 n. 97, 606 F.2d at 1120 n. 97. The Commission also has oeen urged to take into consideration more generally the “significant factor” of “the impact on the industry of the entire course of Commission action in the development and administration of the advance payment program.” Id. at 213, 606 F.2d at 1120.
. See, e. g. id. at 192-195, 606 F.2d at 1099, 1102.
. See id. at 195, 606 F.2d at 1102 (an advance payment, as an interest-free loan, “substitutes for capital raised in financial markets”); id. at '208, 606 F.2d at 1115 (“A producer receiving an extended front-end advance . . is in effect given a sum of money.”).
. See id. at 205, 606 F.2d at 1112.
. See id. at 205, 606 F.2d at 1112.
. See id. at 195, 606 F.2d at 1102.
. See id. at 206, 606 F.2d at 1113.
. See id. at 201, 606 F.2d at 1108.
.See cases cited in id. at 209 n. 77, 606 F.2d at 1116 n. 77 (hardship on the affected parties a factor to consider in evaluating limitations on retroactivity of agency action).
.See id. at 199, 606 F.2d at 1106: id. at n. 44 (quoting dissenting view of Commissioner Holloman that, inter alia, “[a] pipeline . faced with . [the] competitive climate [in the natural gas market] would be remiss in its attempts to attach new supplies of gas on behalf of itself and its customers if it did not use . . . [the] tool [of offering extended front-end advances] to enter into gas supply contracts”).
.Id. at 196 n. 30, 606 F.2d at 1103 n. 30. We have also noted that at least one administrative law judge ruling on this case found that a pipeline company’s “unchallenged good faith and business judgment qualified] advances as reasonable and appropriate.” Id. at 199 -200 n. 45, 606 F.2d at 1106-1107 n. 45.
. Id. at 212, 606 F.2d at 1119.
. As noted in the court’s opinion, pipelines have argued that “the sole test for determining whether the advance payments made . were to be included in rate base [should have been] whether they were made in order to obtain commitments for additional gas supplies.” Id. at 201, 606 F.2d at 1108.
. See, e. g., id. at 195, 606 F.2d at 1102.