In Cooley v. Port Wardens,51 decided in 1851, the Supreme Court, three justices dissenting, accepted the principle that had been suggested by Webster and approved by Justice Woodbury, and upheld a pilotage law of Pennsylvania on the ground that, though it was a regulation of commerce, it was with reference to a matter properly lending itself to local state control, and one for the regulation of which Congress had not legislated. Justice Curtis, delivering the opinion of the court, said: "When the nature of a power like this [the commerce power] is spoken of, when it is said that the nature of the power requires that it should be exercised exclusively by Congress, it must be intended to refer to the subjects of that power, and to say that they are of such a nature as to require exclusive legislation by Congress. Now the power to regulate commerce, embraces a vast field, containing not only many but exceedingly various subjects, quite unlike in their nature, some imperatively demanding a single uniform rule, operating equally on the commerce of the United States in every port; and some, like the subject now in question, as imperatively demanding that diversity, which alone can meet the local necessities of navigation. Either absolutely to affirm, or deny, that the nature of this power requires exclusive legislation by Congress, is to lose sight of the nature of the subjects of this power, and to assert concerning all of them, what is really applicable to but a part . . . It is the opinion of a majority of the court that the mere grant to Congress of the power to regulate commerce, did not deprive the States of power to regulate pilots." 52

50 7 How. 283; 12 L. ed. 702. 5112 How. 299; 13 L. ed. 996.

The doctrine of Cooley v. Port Wardens is, at the present time, the accepted doctrine of the Supreme Court. In Bowman v. R. R. Co.53 the doctrine is declared to be firmly established.54

52 Justice McLean, in a dissenting opinion, restated his doctrine of the exclusiveness of the federal power, including such matters of local regulation as that of pilotage. Justice Daniel, though concurring in the judgment rendered, declared that he did so because this was a matter which the States had never surrendered to the Federal Government, and which was not implied in the commercial power which had been granted to that government.

53 123 U. S. 465; 8 Sup. Ct. Rep. 689; 31 L. ed. 700.

54" The doctrine now firmly established is that where the subject upon which Congress can act under its commercial power is local in its nature or sphere of operation, such as harbor pilotage, or improvement of harbors, the establishment of beacons and buoys to guide vessels in and out of port, the construction of bridges over navigable rivers, the erection of wharves, piers and clocks, and the like, which can be properly regulated only by special provisions adapted to their localities, the State can act until Congress interferes and supersedes its authority; but when the subject is national in its character, and admits and requires uniformity of regulation, affecting alike all the States, such as transportation between the States, including the importation of goods from one State to another, Congress can alone act upon it and provide the needed regulations. The absence of any law of Congress on the subject is equivalent to its declaration that commerce in that matter shall be free."

The rule thus stated as to the. distinction between subjects requiring general and those necessitating, or at least rendering highly desirable, local regulation, is a simple and rational one. It is, however, one which, in application, has not infrequently given rise to considerable difficulty, there being no definite criteria for distinguishing between these two classes of subjects. This has made it necessary that each case should be determined by itself, the Supreme Court in each instance deciding whether the state law in question is, or is not, regulative of a matter properly requiring national control.55