That a legislature may delegate to a commission as its agent the application to specific cases of a rule legislatively declared, is established.24 There would thus seem to be no constitutional difficulty in Congress laying down certain principles of railway rate regulation, and intrusting to a commission or other administrative body the task of determining the rates which conform to these requirements. If, therefore, it be desired that interstate railway rates shall be fixed by federal authority, it is clear that it is not necessary that Congress should itself determine each specific rate. Congress must, however, lay down the rule or rules by which the body to which this function is delegated shall be guided.25

By the act of June 29, 1906, it is declared by Congress that "charges for interstate transportation of passengers as property shall be just and reasonable;" and to the Interstate Commerce Commission is given the authority, after having decided that a rate in force is not a proper one, "to determine and prescribe what will be the just and reasonable rate or rates, charge or charges to be thereafter observed in such case as the maximum to be charged." Thus the only rule for determining the rates which Congress has declared for the guidance of the Commission in the fixing of specific rates is that they shall be just and reasonable. The determination of when these very general requirements are met by a rate is left in each case, to the judgment of the Commission. It is certainly open to question whether Congress has not in fact really delegated to the Commission the legislative which they have over corporations chartered by them or permitted to do business within their borders, furnishes no argument to sustain the federal rate-making power except as to corporations chartered by the United States, is without force, for the States in fact are recognized to derive their rate-making power not solely from this source but from the common-law principle that all public services are subject to governmental regulation, as regards the reasonableness of their charges, etc.

24 See Chapter IXV.

25 Cf. Reeder, Rate Regulation as Affected by the Distribution of Governmental Power in the Constitution. See also post, Chapter LXIII (The Separation Of Powers. 739. The Separation Of Powers).

The constitutional principles involved in the power of the courts to review decisions of the Interstate Commerce Commission is considered in the chapter entitled "The Conclusiveness of Administrative Decisions," and also in connection with Due Process of Law.