The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
Not until after the Civil War was the idea that the reserved powers of the states comprise an independent qualification of otherwise constitutional acts of the Federal Government actually applied to nullify, in part, an act of Congress. This result was first reached in a tax case, Collector v. Day. 1 Holding that a national income tax, in itself valid, could not be constitutionally levied upon the official salaries of state officers, Justice Nelson made the sweeping statement that
the States within the limits of their powers not granted, or, in the language of the Tenth Amendment, ‘reserved,’ are as independent of the general government as that government within its sphere is independent of the States. 2 In 1939, Collector v. Day was expressly overruled. 3 Nevertheless, the problem of reconciling state and national interest still confronts the Court occasionally, and was elaborately considered in New York v. United States, 4 where, by a vote of six-to-two, the Court upheld the right of the United States to tax the sale of mineral waters taken from property owned by a state. Speaking for four members of the Court, Chief Justice Stone justified the tax on the ground that
[t]he national taxing power would be unduly curtailed if the State, by extending its activities, could withdraw from it subjects of taxation traditionally within it. 5 Justices Frankfurter and Rutledge found in the Tenth Amendment
no restriction upon Congress to include the States in levying a tax exacted equally from private persons upon the same subject matter. 6 Justices Douglas and Black dissented, saying:
If the power of the Federal Government to tax the States is conceded, the reserved power of the States guaranteed by the Tenth Amendment does not give them the independence which they have always been assumed to have. 7