delivered the opinion of the Court.
■ This is an appeal, under § 238 of the Judicial Code, from a final decree of the federal court for western Washington dismissing a bill brought to enjoin the enforcement of § 4 of chapter 111 of the Laws of Washington, 1921. That section prohibits common carriers for hire from using the highways by auto vehicles between fixed termini or over regular routes, without having first obtained from the Director of Public Works a certificate declaring that
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public convenience and necessity require such operation. The highest court of the State has construed the section as applying to common carriers engaged exclusively in interstate commerce.
Northern Pacific Ry. Co.
v.
Schoenfeldt,
Buck, a citizen of Washington, wished to operate an auto stage line over the Pacific Highway between Seattle, Washington and Portland, Oregon, as a common carrier for hire exclusively for through interstate passengers and express. He obtained from Oregon the license prescribed by its laws. Having complied with the laws of Washington relating to motor vehicles, their owners and drivers
(Carlsen
v.
Cooney,
That part of the Pacific Highway which lies within the State of Washington was built by it with federal aid pursuant to the Act of July 11, 1916, c. 241, 39 Stat. 355, as amended February 28, 1919, c. 69, 40 Stat. 1189, 1200, and the Federal Highway. Act, November 9, 1921, c. 119, 42 Stat. 212. Plaintiff claimed that the action taken by the Washington officials, and threatened, violates rights conferred by these federal acts and guaranteed both by the Fourteenth Amendment and the Commerce Clause.' In support of the decree dismissing the bill this argument is made: The right to travel interstate, by auto vehicle upon the public highways may be a privilege or immunity of citizens of the United States. Compare
Crandall
v.
Nevada,
The argument is not sound. It may be assumed that § 4 of the state statute is consistent with the Fourteenth Amendment; and also, that appropriate state regulations adopted primarily to promote safety upon the highways and conservation in their use are not obnoxious to the Commerce Clause, where the indirect 'burden imposed upon interstate commerce is not unreasonable. Compare
Michigan Public Utilities Commission
v.
Duke,
By motion to dismiss filed in this Court, the State makes.the further contention that Buck, is estopped from seeking relief against the provisions of § 4. The argument is this: Buck’s-claim is not that* the Department’s action is unconstitutional because arbitrary or unreasonable. It-is that § 4 is unconstitutional because use of the highways for interstate commerce is.denied unless the prescribed certificate shall have been secured. Buck applied for .a certificate. Thus he invoked the exercise of the. power which he now assails.. One who invokes the provisions of a law may not thereafter question, its constitutionality. . The argument is unsound. It is true that one cannot in the same proceeding both assail a statute arid-rely upon-it.
Hurley
v.
Commission of Fisheries,,
Reversed.
Notes
An additional ground for refusing, the certificate was that the applicant did not appear to have financial ability. This ground of rejection does not require separate consideration; among other reasons, because the plaintiff later asserted, in his bill, that he possessed the requisite financial ability, and the motion to dismiss admitted the allegation.
