able to the doctrine that a State law unnecessarily interfering with foreign or interstate commerce is unconstitutional, as a regulation of such commerce, regardless of the intention with which it was passed. That case involved the validity of a State law imposing a tax upon common carriers for every ton of freight carried by them within the limits of the State. It was held that the law was virtually a tax upon freight itself, and was, therefore, unconstitutional as to interstate freights. The decision of the Court goes entirely upon the operative effect of the law, and not at all upon the intention with which it was passed. Strong, J., who delivered the opinion, said: “How can it make any difference that the legislative purpose was to raise money for the support of the State government, and not to regulate transportation? It is not the purpose of the law, but its effect, which we are now considering.”
One of the reasons urged by the Court against the constitutionality of the law was, that if the constitutionality of State laws operating to impose a tax upon interstate freights was conceded, the States would virtually have it in their power to exclude such freights, since they could practically accomplish that result by making the tax so high as to prohibit the bringing of them within the State. This argument, which has also been employed in some subsequent cases, was deemed conclusive of the unconstitutionality of the law. It would seem, nevertheless, to be clearly fallacious. It proves too much. It would prohibit all State laws affecting foreign or interstate commerce. Thus it could be said that to admit the right of a State to impose quarantine restrictions upon foreign commerce would virtually empower the States to exclude foreign commerce by making the restrictions so severe as virtually to prohibit such commerce. In the case of the State Tax on Railway Gross Receipts, 15 Wall. 284, a case decided at the same time as the preceding case, a State law taxing common carriers according to their gross receipts was held constitutional, and yet, applying the reasoning of the preceding case, it would seem to be unconstitutional. The operative effect of the two laws would, probably, be nearly the same. The gross receipts of most roads are made up chiefly of earnings from the carrying of freight and passengers, and a tax on gross receipts would simply create an additional burden to be borne by the passenger and freight traffic. Of this additional burden, interstate freight and passenger traffic would have to bear its proportionate part. Then, why not argue that the right to impose such
