cannot be encroached upon by the States; but where, in relation to the subject-matter, different rules may be suitable for different localities, the States may exercise powers which, though they may be said to partake of the nature of the power granted to the general government, are strictly not such, but are simply local powers, which have full operation until or unless circumscribed by the action of Congress in effectuation of the general power. Cooley v. Port Wardens of Philadelphia. . . .
Whenever, however, a particular power of the general government is one which must necessarily be exercised by it, and Congress remains silent, this is not only not a concession that the powers reserved by the States may be exerted as if the specific power had not been elsewhere reposed, but, on the contrary, the only legitimate conclusion is that the general government intended that power should not be affirmatively exercised, and the action of the States cannot be permitted to effect that which would be incompatible with such intention. Hence, inasmuch as interstate commerce, consisting in the transportation, purchase, sale, and exchange of commodities, is national in its character, and must be governed by a uniform system, so long as Congress does not pass any law to regulate it, or allowing the States so to do, it thereby indicates its will that such commerce shall be free and untrammelled. . . .
That ardent spirits, distilled liquors, ale and beer, are subjects of exchange, barter and traffic, like any other commodity in which a right of traffic exists, and are so recognized by the usages of the commercial world, the laws of Congress and the decisions of courts, is not denied. Being thus articles of commerce, can a State, in the absence of legislation on the part of Congress, prohibit their importation from abroad or from a sister State? or when imported prohibit their sale by the importer? If the importation cannot be prohibited without the consent of Congress, when does property imported from abroad, or from a sister State, so become part of the common mass of property within a State as to be subject to its unimpeded control? . . .
The doctrine now firmly established is, as stated by Mr. Justice Field, in Bowman v. Chicago, &c. Railway Co., 125 U.S., 507, "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, the improvement of harbors, the establishment of beacons and buoys to guide vessels in and out of port, the construction of bridges over navigable rivers; erection of wharves, piers, and docks, 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 where 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 into 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. Thus the absence of regulations as to interstate commerce with reference to any particular subject is taken as a declaration that the importation of that article into the States shall be unrestricted. It is only after the importation is completed, and the property imported has mingled with and become a part of the general property of the State, that its regulations can act upon it, except so far as may be necessary to insure safety