delivered the opinion of the Court.
This case turns upon the power of the Interstate Commerce Commission to award reparations with respect to shipments .which moved -under rates approved or prescribed by it.
The respondent carriers maintained a rate of $1.045 per hundred' pounds for shipment of sugar from California points to Phoenix, Arizona. On complaint of petitioner and others, the Commission, after hearing, on June 22, 1921, found that the rate attacked had been, then was, and for the future would be, unreasonable to the extent that it exceeded 96.5 cents,
1
and ordered the establishment
The date of the first shipment made by petitioner on which reparation was awarded was February 21, 1923, and of the last February 5,1925, so that all were made between the effective dates of the first and second orders above mentioned.
The respondents objected that they should not be required to pay reparations on shipments which moved under rates approved or prescribed by the Commission as reasonable. To this that body replied, “ We reserve- the right, upon a more comprehensive record, to modify our
. The carriers having failed to pay the amount -awarded, the petitioner sued therefor in the District Court, and recovered judgment. The Circuit Court of Appeals reversed, and entered judgment for respondents. 4 This Court granted certiorari. Whether, as the petitioner argues, the Commission correctly construed its authority, is to be determined by examination of the legislation defining its powers.
The exaction of unreasonable rates by a public carrier was forbidden by the common law.
Interstate Commerce Comm.
v.
Baltimore & Ohio R. Co.,
But we are here specially concerned with the Interstate Commerce Act of 1887
5
and with some of the changes or
The Act altered the common law by lodging in the Commission the power theretofore exercised by courts, of determining the reasonableness of a published rate.
9
If the finding on this question was against the carrier, reparation
Under the Act of 1&87 .the Commission was without power either to prescribe a given rat'e thereafter to be. charged
(Interstate Commerce
Comm. v.
Cincinnati, N. O. & T. P
.
Ry. Co.,
The Hepburn Act
13
and the' Transportation Act
14
evince an enlarged and different policy on the part of
But it is suggested that the -mere setting'.of 'limits by Commission order leaves the carrier free to name any rate within those limits, and, as at common law, it must at its peril publish a reasonable rate within the bound
The report and order of 1921 involved in the present case declared in terms that 96.5 cents was, and for the future would be, a reasonable rate. There can be no question that when the carriers, pursuant to that finding, published a rate of 96 cents, the legal rate thus established, to which they and the shipper were bound to conform, became by virtue of the Commission’s order also a lawful— that is, a reasonable — rate.
Specific rates prescribed for the future take the place of the legal tariff rates -theretofore in force by the voluntary action of the .carriers, and themselves become the legal rates. As to such rates there is therefore no. difference between the legal or published tariff rate and the lawful rate. The carrier cannot change a rate so prescribed and take its chances of an adjudication that the substituted rate will be found reasonable. It is bound to conform to the order of the Commission. If that body sets too lów a rate, the carrier has no redress save a new hearing-and the fixing of a more adequate rate for the fixture. It cannot have reparation from the shippers for a rate collected, under the order upon the ground that it was unreasonably
In
Oklahoma Operating Co.
v. Love,
If by act of Congress maximum rates were declared lawful for certain classes of service, neither carrier nor shipper could thereafter draw into question in the courts the conduct of the other if it conformed to the legislative mandate, save by an attack on'the constitutionality of the statute. By the amendatory legislation Congress has delegated to the Commission as its administrative arm its undoubted power to declare, within constitutional limits, what are lawful rates for the service to be performed by the carriers. The action of the Commission in fixing such rates for the future is subject to the same tests as to its validity as would be an act of Congress intended to accomplish the same purpose.
As has been pointed out, the systém now administered by the Commission is dual in nature. As respects a rate made by the carrier,' its adjudication finds the facts and may involve a liability to pay reparation. The Commission may, and often does, in the same proceeding, and m a single report and order, exercise its additional authority by fixing rates or rate limits for the future. But the fact that this function is combined with that of passing upon the rates theretofore and then in effect does not alter the character of the action. 18
The Commission in its-report confuses legal concepts , in stating that the doctrine of res judicata does not affect its action in a case like this one. It is unnecessary to 'determine whether an adjudication with respect to reasonableness of rates theretofore charged is. binding in another proceeding, for that question is not here presented. • The rule of estoppel by judgment obviously applies only to bodies exercising judicial functions; it is manifestly inapplicable to legislative action. The Commission’s error arose from a failure to recognize that when it prescribed a maximum reasonable rate for the future, it was performing a legislative function, and that when it was sitting to award reparation, it was sitting for a purpose judicial in its nature. In the second capacity, while not bound by the rule of res judicata, it was bound ,to recognize the validity of the rule of conduct prescribed by it and not to repeal its own enactment with retroactive effect. It could repeal the order as it affected' future action, and substitute a new rule of conduct as often as occasion might require, but this was obviously the limit of its power, as of that of the legislature itself.
The argument is pressed that this conclusion will work serious inconvenience in the administration of the Act; will require the Commission constantly’ to reexamine the fairness of rates prescribed, and will, put an unbearable
• Where the Commission has, upon complaint and after hearing, declared what is the maximum reasonable rate to be charged by a carrier, it may not at a later time, and upon the same or additional evidence as to the fact situation existing when its previous order was promulgated, by declaring, its own finding as to reasonableness erroneous, subject a carrier which conformed thereto to the payment of reparation measured -by what the Commission now holds it should have decided in the earlier proceeding to be a reasonable rate.
The judgment is
Affirmed.
Notes
62I. C. C. 412.
95 I. C. C. 244.
140 I. C. C. 171.
49 F. (2d) 563.
Act of February 4, 1887, 24 Stat. 379.
Id.,
§ 6.
Kansas City Southern Ry. Co. v. Carl,
Id., §§ 8, 9, 10.
Id., § 1.
Id.,
§ 13.
Texas & P. R. Co.
v.
Abilene Cotton Oil Co.,
Interstate Commerce Comm.
v.
Cincinnati, N. O. & T. P. Ry. Co.,
See Baer Bros. Co. v. Denver & R. G. R. Co., supra, p. 487.
Compare
Prentis
v.
Atlantic C. L. Co.,
§4, 34 Stat. 589.
§§ 418-421, 41 Stat. 484-488.
As a statute fixing or limiting rates to be charged by one whose business is affected by a public interest may be declared void for violation of the due process and equal protection clauses
(Dow
v.
Beidelman,
Chicago, M. & St. P. Ry. Co.
v.
Minnesota,
Oklahoma Operating Co.
v. Love,
Interstate Commerce Comm.
v.
Cincinnati, N. O. & T. P. Ry. Co.,
