a burden upon interstate traffic implied the power to prohibit such traffic.
The weakness in this argument is that it fails to recognize that the purpose of a law is to be considered and taken into account. Because a State may tax objects of interstate commerce for purposes of revenue, it by no means follows that it may tax them for the express purpose of excluding their admission into the State. The answer to the argument is contained in the following extract from the opinion of Swayne, J., in Gilman v. Philadelphia. Speaking of the power of the States to obstruct navigable streams by dams and bridges, he says: “Whenever it shall be exercised openly or covertly for a purpose in conflict with the Constitution or laws of the United States, it will be within the powers, and it will be the duty, of this Court to interpose with a vigor adequate to the correction of the evil;” or, in general terms, the power of the States to pass certain kinds of laws does not imply the power to pass them for an unconstitutional purpose. The notion that State laws “unreasonably” burdening foreign or interstate commerce are to be deemed unconstitutional as regulations of such commerce seems to have come as a modification of the extreme view of the law taken by the Court in the State Freight Tax Cases, and in the endeavor of the judges to avoid the logical consequences of that view. The position that any State law operating to impose a burden on foreign or interstate commerce was unconstitutional as a regulation of such commerce being untenable, in receding from that position the Courts passed to the position that only laws imposing unreasonable burdens upon foreign or interstate commerce were regulations of such commerce. This position, if not more defensible logically, is more satisfactory from a practical point of view.
We have now made a survey of all the more important cases and classes of cases decided in the Federal Supreme Court which bear upon the question of the respective powers of the State and Federal governments to enact laws operating upon foreign or interstate commerce. We have seen that the cases of Gibbons v. Ogden and Willson v. Black Bird Creek Marsh Co. state the principle that a sovereign power is to be regarded as a right to aim at a certain end, and not as the right to use certain means; that the United States in the exercise of the power to regulate foreign and interstate commerce, and a state in the exercise of some dis-