delivered the opinion of the Court.

This is an appeal from the decree of a three-judge district court granting a permanent injunction against the enforcement of temporary rates. § 266, Jud. Code.

The appellants are five named persons, individúally and as members of the Pennsylvania Public Utility Commission, and the Utility Consumers League of York, Pennsylvania, intervening defendant below, an unincorporated association of consumers of electric current in the territory served by the appellee. The latter is a public utility corporation organized under the laws of Pennsylvania, which generates, transmits, distributes and sells electric energy to approximately 30,000. customers in and about York, Pennsylvania.

An investigation to determine the reasonableness-of ap-pellee’s rates was instituted on January 27, 1936. During its progress the state legislature recodified the utility law of Pennsylvania. Act of May 28, 1937, P. L. 1053, Pur-don’s Pa. Stat. Ann., 1938 Supp., Title 66, § 1101 et seq. It enacted a temporary rate section, 310, which is the source of this controversy.

Acting under § 310, the commission, after notice and argument;- issued a temporary rate order on July 13,1937, requiring the utility to file rate schedules which would effect a reduction of approximately $435,000 in annual gross operating revenues. This order was replaced by another on July 27, 1937, which commanded ,an identical reduction. This time the commission itself prescribed a *108schedule of rates. The utility filed a bill in equity in a statutory court in the Middle District of Pennsylvania. On October 15, 1937, a permanent injunction issued.1 The Commission did not appeal. On November 30, 1937, another order was issued seeking to establish the same temporary rates and to secure the same reduction in gross revenues as the orders of July 13 and 27.

On December 14, 1937, the utility filed a bill in the United States District Court for the Eastern District of Pennsylvania to enjoin this order. A three-judge court was convened under § 266 of the Judicial Code. By stipulation of the parties the application for an interlocutory injunction brought to hearing on January 17, 1938, was treated as an application for a permanent injunction. On October 14, 1938, a permanent injunction issued.

The court concluded as a matter of law that the utility had ho plain, speedy and adequate remedy in the' state court's; that the order is void because the “commission acted in direct violation of the mandatory provisions of the Public Utility Act which requires rates for [the company] to be fixed under paragraph (b) of section 310”; that the order is unconstitutional because (1) it violates the procedural requirements of due process, (2) it fails to permit the utility to earn a fair return on the fair value of its property used and useful in the public service, (3) it confiscates the company’s property, and (4) it is not supported by substantial evidence.2

Jurisdiction.of the Statutory Court. — Except as modified by the Johnson Act,3 jurisdiction exists in a statutory court, called pursuant to § 266 of the Judicial Code, to hear and finally determine bills in equity seeking tem*109porary and permanent injunctions against the order of a state administrative commission on the ground of irreparable injury.4 By this amendatory act, where the' order attacked as violative of the Federal Constitution affects the rates of a public utility, does not interfere with interstate commerce and has been made after notice and hearing, the jurisdiction of the district court' to enjoin its enforcement is withdrawn, unless no “plain,, speedy and efficient remedy may be had, at law or in equity, in the courts of such State.” No challenge to the jurisdiction was made in, the statutory court or on appeal.' In response to questions from the bench, counsel for the commission conceded that there was no remedy in the state courts which would satisfy the Johnson Act.

The reason for this concession lies, so far as a remedy in equity is concerned, in the provision of the Pennsylvania statute forbidding an injunction against an order, “except in a proceeding questioning the jurisdiction of the commission.”5 The bill in certain allegations attacks the section of the Public Utility Law under which this order issued as violative of the Fourteenth Amendment in that it empowered the commission to fix non-compensatory and discriminatory temporary rates, in an arbitrary manner. In one sense this questions the ju*110risdiction of the commission. If § 310 is invalid, there is no other provision to authorize temporary rates. Jurisdiction is a word of uncertain meaning. As used im § 1111, supra, it apparently refers to proceedings by the commission under the terms of the statute. In this use it would permit an injunction, equitable grounds being shown,.where the public utility is not covered by the act. Otherwise, action in excess of the powers of the commission, such as a confiscatory rate, might be deemed beyond its” jurisdiction. At any rate, without an authoritative determination by the state courts, we cannot say, for this character of ^proceeding, that the remedy in the state courts is plain, speedy and ’ efficient.6 The remedy' at law by appeal is ineffective to protect the utility’s position pendente lite. The supersedeas does not postpone the application of the temporary rates.7 The statutory court had jurisdiction of the bill.

Statutory Basis for the Order. — Sec. 3108 contains several subsections. The commission fixed the temporary rates under subsection (a). The district court concluded as a matter of law that this action was invalid because they could only be fixed under subsection (b). The two subsections are set out below.9 In its opinion, without *111discussing § 310 (b), the court declared § 310 (a) unconstitutional because it permitted the commission to fix a temporary rate based upon the single factor of original cost less depreciation.10 The commission, however, did not confine itself to that one element in setting the fair value of the appellee’s property, for the purpose of temporary rates, at $5,250,000. It gave weight to reproduction cost, original cost, going concern value and the necessity for working capital, and it allowed on this rate base a return of more than six per cent. This, of course, *112■satisfies the requirement of § 310 (a) that the temporary rates shall produce not less.than 5% on the “original cost,, less accrued depreciation.”

Appellee’s first contention is that the decree may be sustained for the sole reason that the commission should have proceeded under subsection (b) because the appellee does not. have continuing property records. As the conclusion of the lower court on this point is not supported by a state decision, we analyze for ourselves the provisions of the sections. It is clear from the language of § 310 (a) that it is applicable not only to public utilities whose reports to the commission show the original cost of their physical property but also to those whose original cost is not so shown. The last clause of the section authorizes the commission to estimate such cost. There is no provision in 310 (a) which, limits its application to those utilities which maintain the continuing property records of § 502.11 Section 310 (b), sée note 9, furnishes a partial alternative for § 310 (a). Where there aré no continuing property records, as provided by § 502, the commission must in fixing- the temporary rate arrange for at least a five per cent return on original cost under (a) or the return of an operating income under (b) equal to that for the year 1935 or a subsequent year, as determined by the commission.

*113Appellee urges next that the section permits the commission to disregard present cost, depreciate original cost, omit indirect and overhead items of construction, and exclude allowances for working capital or going concern value. Although these items were considered by the commission, the appellee contends that the order is invalid because § 310 (a) might have been complied with by providing a return of 5% on the original cost depreciated. The argument seems to be that a statute which permits an unconstitutional determination is invalid, even though it is actually applied in a constitutional manner.12

The commission drew the order in accord with the prior ruling of the Middle District Court on a former order in this rate proceeding.13 The former order had also i'hced temporary rates but had not set out the findings of value deemed essential by the court. Although the reversal of the commission's order had actually turned on the failure to show the factual basis for the rates, as the district court had stated that compliance with Smyth v.. Ames14 was necéssary in temporary rate making, the commission based the order now under review on evidence requisite under that rule. By taking, this position, it interprets the statute as requiring consideration of elements other than original cost in fixing temporary rates. It is not suggested that the commission omitted consideration of any necessary element in the present order. If we assume with the appellee that the constitutionality of a *114delegation of rate making authority is to be tested by what a rate making body may rightfully do under the delegation rather than what it' does, appellee’s case is advanced not one whit. We have here an interpretation of the Pennsylvania statute by the board charged'with its enforcement that it must weigh all the essential elements of valuation required by our past decisions.

There is nothing in the language of § 310. (a) which •requires a different construction. The commission is authorized to fix temporary rates. There is no requirement as to how the rates are to be determined, except that they shall be sufficient to return a given minimum — not less than 5%. on the original cost, less depreciation. The language authorizing the fixing of temporary rates is cast, except as to the limitation just referred to, in much the same pattern as the language of § 309 authorizing the determination of permanent rates. The latter section reads: “. . . the commission shall determine the just and reasonable rates ...” A different construction would raise the novel and important question of the constitutionality of a temporary rate, based solely on depreciated original cost, with provision for recoupment of the loss from insufficient temporary rates.15 In the absence of an *115authoritative state decision, we áre reluctant to accept a construction which brings forward that issue, particularly when the case may reasonably be determined upon the interpretation of the officials of the state charged with the administration of the act.16 This course observes the very salutary rule that “this Court will not decide an issue of constitutionality if the case may justly and reasonably be decided under a construction of the statute under which the act is clearly constitutional.”17

Confiscation. — There remains for examination the ap-pellee’s argument-that the decree of the district court enjoining the enforcement of the order should be sustained because it is confiscatory. The commission, as of November 30, 1937, fouiid the rate base, revenue, expenses and rate, as set out below.18 Appellee urges here that the commission’s figures are erroneous in the follow-, ing particulars: (1) The rate base should be $5,866,081; (2) the rate should be 7y2 per cent; (3) two items of expense, disallowed by the commission should be added to the operating expenses, (a) some increase in annual salaries and (b) rate case^expenses on books to November *11615,1937; (4) allowance should be made for a prospective loss of annual profit by reason of the loss of a large customer, through abandonment of railway service by York Railways Company.

(1) The commission estimated the original cost as of December 31, 1936, at $4,576,169.73. The company estimated the original cost as of November 30, 1936, exclusive of financing charges, at $4,619,364.00 and its book cost as of December 31, 1936, at $4,578,793.00. If, to the highest of these items, we add $164,000 for working capital and $142,851.07, representing net additions to September 30, 1937, the amounts claimed by the company, the original cost rate base is found to be not more than $4,926,215.07.

The commission excluded the cost of financing because there was no evidence of any .actual expenditures for such purpose or of any studies of such cost. We 'find no error in this.19 Theré was here no foundation for an estimate.20 Appellee’s suggestion that evidence supporting its claim is found in the capitalization chart of York Railways Company, the owner of appellee’s common stock, is not accepted. This shows the. discount, $298,-825.00, paid by the parent company on $2,706,000 face amount of bonds of various issues between 1909 and 1925. It appears that $1,027,904 of the proceeds was expended for construction work of the York Edison Company, apparently appellee’s predecessor. Nothing is shown as to the cost of this money to the appellee. It may have given notes for or been charged with this exact amount, without a finance charge. The financing cost to appellee may have been covered by the interest rate.

*117. The commission made no specific allowance for going concern value. It did, however, state that it had weighed the going concern value with other factors to determine fair value. It gave practical effect to this consideration when it fixed fair value several hundred thousand dollars in excess of its average of original and reproduction cost, both depreciated. In the computations by the company of original and reproduction costs, allowances were made for the overhead expense of creating the aggregate of land, buildings, and equipment, making up the utility. No tangible evidence of any unusual situation justifying any definite further allowance appears in the testimony of appellee’s witness Seelye. The plant of the utility without the utilization of its production by the community would be of little value. Expenditures to secure customers through advertisement and solicitation, as well as to install connections do not appear separate from the ordinary operating and construction costs. The appellee points to the character of the territory served, the company’s ability to earn, the efficiency of the management, the.adequate available power supply and the excellent capital structure as indicative of a going concern value above tangible property plus overhead. To appraise these elements apart from and in addition to reasonable cost figures would require evidence of a failure on the part of the commission to give reasonable weight to these factors. This evidence is lacking here.21

For depreciated reproduction cost as of November 30, 1936, the commission accepted the estimate of the company for direct costs, $3,981,347. It added 19%, $756,456, *118for indirect costs and reached a total of $4,737,803. This finding reduced the indirect costs from the 24.3 per cent claimed by the company. Evidence was introduced before the commission supporting each percentage estimate. The amount of these indirect costs likely to be incurred is too uncertain for us to conclude that the percentage adopted is erroneous.22 We cannot see that the failure of the commission’s witness Bierman to inspect the property made less valuable his estimate on the proper percentage to be applied for indirect costs. These indirect costs are of the character of interest, supervision, cost of financing, taxes and legal expense.

The utility states that the commission, in- fixing the reproduction cost, erred by refusing to consider the effect of a claimed increase, of prices. The commission, on November 30, 1937, fixed reproduction cost upon a computation based by the utility upon prices as of November 30, 1936. This showed a gross cost of $5,572,134, depreciated and reduced by the commission, as explained in the preceding paragraph, to $4,737,803. The utility presented a further computation, showing as of May 31, 1937, that increased prices, due to a rising level, would increase the gross cost to $6,019,832. The argument is that the later-estimate should have been considered.23 Proportionally reduced to accord with the action of the commission, this latter figure would become $5,118,465. If to this higher reproduction cost we add working capital, there appears a reproduction cost depreciated figure of $5,282,465.

It is furthermore to be observed that the commission’s figures do not differ far as to fair value,, from the estimate of an important witness for the utility, Mr. Seelye, who testified on March-12, 1937, that the fair value was not less than $5,500,000 and said later in answer to the com*119missioner’s question that the fair value, in his opinion, was $5,500,000. This estimate was reiterated on December 20, 1937, in the- affidavits of Mr. Seelye and Mr. Wayne, the President of the company, in support of the motion for temporary injunction.

For the purpose of passing upon the issue of confiscation in the temporary rates, we shall accept $5,500,000 as the fair value of the property as of November 30, 1937.

(2) The rate of return was fixed by the commission at six per cent. Witnesses for the utility brought out facts-deemed applicable in the determination of a proper rate of return on the fair value of the property. Their evidence took cognizance of the yield of bonds, preferred and common stocks of selected comparable utilities, the stagnant market for new issues, prevailing cost of money, the implications of the possible substitution of some gov-ernmentally operated or financed utilities for those privately owned and the dangers of a fixed schedule of rates in the face of possible inflation. From these factors they deduced that a proper rate of return would be from 7.8 per cent to 8 per cent. An accounting expert of the commission countered with tables showing yields of bonds of utilities; the yield to maturity of Pennsylvania public utility securities, approved by the commission between July 1, 1933, and May 7, 1937, long term and actually sold for cash to non-affiliated interests'; yield of Pennsylvania electric utilities; financial and operating statistics of Pennsylvania electric utilities; money rates, and other material information. He concluded 5.5 per cent was a reasonable rate of return.

It must be recognized that each utility presents an individual problem.24 The answer does not lie alone in *120average yields of seemingly comparable secürities or even in deductions drawn from, recent sales of issues authorized by this same commission. Yields of preferred and common stocks are to be considered, as well as those of the funded debt. When bonds and preferred stocks of well seasoned companies can be floated at low rates, the allowance of an over all rate return of a modest percentage will bring handsome yields to the common stock. Certainly the yields ,of the equity issues must be larger than that for the underlying securities. In this instance, the utility operates in a stable community, accustomed to the use of electricity and close to the capital markets, with funds readily available for secure investment. Long operation and adequate records make forecasts of net operating revenues fairly certain. Under such circumstances a six per cent return after all allowable charges cannot be confiscatory.

(3) and (4). The utility urges that two items of expense and a prospective loss should be added to the operating expenses, allowed by the commission, of $1,382,-829. The most important of these items is the rate case expenses. The company by its Exhibit'21 shows these incurred to November 15, 1937, to be $178,374.50. The commission from Exhibit 23 found them to be $127,935 for the twelve months ending September 30, 1937. The difference probably comes from the expenses before and after the period considered by the commission. We assume the higher figures to be correct. As the commission concluded that the prior rates of the company were obviously excessive, it allowed nothing for expense in defending -them. Consequently there is no discüssion of the reasonableness of the amount of the company’s charge and we accept them as reasonable. Even where the rates in effect are excessive, on a proceeding by a commission to determine reasonableness, we are of the vie^ that the utility should be allowed its fair and proper *121expenses for presenting its side to the commission. We do not refer to expense of litigation in the courts. “A. different case would be here if the company’s complaint-had been unfounded or if the cost of the proceeding had been swollen by untenable objections.” 25

In the allowance of these expenses, the period over which they are to be amortized will depend upon the character of services received or disbursements made. There could rarely be an anticipation of annually recurring charges for rate regulation. Under the circumstances here presented where full statistics on investment, inventory and labor requirements have been made which, asi cumulated, will form largely the basis of all future negotiations, we are of the opinion that amortization over a ten year period is reasonable.26 As such an adjustment produces an. estimated return very close to the reasonable rate, even with the addition to the operating expenses of the other items of increased salaries, $20,593, and prospective loss of annual profit, $15,089, we do hot enter into a discussion of them. Experience will add its weight to the other evidence on further hearing. The note below shows the calculation.27

At best, these estimates are prophecies of expected returns. The incalculable factors of business activity, un*122anticipated demand or forbearance, substitution and other variables lead us to approximations. We are satisfied the reduction required is not shown- to be confiscatory.

Reversed.

concurring.

The decree below was clearly wrong. But in reversing it, the Court’s opinion appears to give new vitality needlessly to the mischievous formula for fixing utility rates in Smyth v. Ames, 169 U. S. 466. The force of reason, confirmed by events, has gradually been rendering that formula moribund by revealing it to be useless as a guide for adjudication. Experience has made it overwhelmingly clear that Smyth v. Ames and the uses to which it has been put represented an attempt to erect temporary facts into legal absolutes. The determination of utility rates — what may fairly be exacted from the public and what is adequate to enlist enterprise — does not present questions of an essentially legal nature in the sense that legal education and lawyers’ learning afford peculiar competence for their adjustment. These are matters for the application of whatever knowledge economics and finance may bring to the practicalities of business enterprise. The only relevant function of law in dealing with this intersection -of government and enterprise is to secure observance of those procedural safeguards in the exercise of legislative powers which are the historic foundations of due process.

Mr. Justice Bradley nearly fifty years ago made it clear that the real issue is whether courts or commissions and legislatures are the ultimate arbiters of utility rates, (dissenting, in Chicago, M. & St. P. Ry. Co. v. Minnesota, 134 U. S. 418, 461). Whatever may be thought of the wisdom of a broader judicial role in the controversies between public utilities and the public, there can be no *123doubt that the tendency, for a time at least, to draw fixed rules of law out of Smyth v. Ames has met the rebuff of facts. At least one important state has for decades gone on its way unmindful of Smyth v. Ames, and other states have by various proposals sought to escape the fog into which speculations based on Smyth v. Ames have enveloped the practical' task of administering systems of utility regulation.

Smyth v. Ames should certainly not be invoked when it is not necessary to do so. The statute under which the present case arose represents an effort to escape Smyth v. Ames at least as to temporary rates. It is the result of a conscientious and informed endeavor to meet difficulties engendered by legal doctrines which have been widely rejected by the great weight of economics opinion,1 by authoritative legislative investigations,2 by utility commissions throughout the country,3 and by impressive judicial dissents.4 As a result of this long process of experience and reflection, the two states in which utilities play the biggest financial part — New York and Pennsylvania — . have evolved the so-called recoupment scheme for temporary rate-fixing (thereby avoiding some of the most *124wasteful aspects of rate litigation) as a fair means of accommodating public and private interests. It is a carefully guarded device for securing “a judgment from experience as against a judgment from speculation,” Tanner v. Little, 240 U. S. 369, 386, in dealing with a problem of such elusive economic complexity as the determination of what return will be sufficient to attract capital in the special setting of a particular industry and at the same time be fair to the public dependent on such enterprise.

That this Court should not “decide an issue of constitutionality if the -case may justly and reasonably be decided under a construction of the statute under which the act is clearly constitutional” is, as an abstract proposition, basic to our judicial obligation. But this is not a formal doctrine of self-restraint. Its rationale is avoidance of conflict with the legislature. The opinion from which the preceding quotation is taken and the decisions to which it refers are all cases in which constitutionality was in obvious jeopardy. It is one thing to avoid unconstitutionally even at the cost of a tortured statutory construction. It is quite another to recognize the validity of a statute directed expressly to the situation in hand and so employed by the state authorities, when constitutionality of that statute is as incontestably clear as the decision of the New York Court of Appeals has demonstrated it to- be in sustaining the sister statute of the Pennsylvania Act, In the Matter of Bronx Gas & Electric Co. v. Maltbie, 271 N. Y. 364; 3 N. E. 2d 512. The Court’s opinion in the present case does not avoid issues of constitutionality. It accepts the much more dubious constitutional doctrines of Smyth v. Ames and its successors to solve the very easy constitutional issues raised by the Pennsylvania Act.