The power to tax is the power to destroy. - John Marshall

If the States may tax one instrument, employed by the Government in the execution of its powers, they may tax any and every other instrument. They may tax the mail; they may tax the mint; they may tax patent rights; they may tax the papers of the custom house; they may tax judicial process; they may tax all the means employed by the Government to an excess which would defeat all the ends of Government. This was not intended by the American people. They did not design to make their Government dependent on the States. [...] If the controlling power of the States be established, if their supremacy as to taxation be acknowledged, what is to restrain their exercising control in any shape they may please to give it? Their sovereignty is not confined to taxation; that is not the only mode in which it might be displayed. The question is, in truth, a question of supremacy, and if the right of the States to tax the means employed by the General Government be conceded, the declaration that the Constitution and the laws made in pursuance thereof shall be the supreme law of the land is empty and unmeaning declamation.

This great principle is that the Constitution and the laws made in pursuance thereof are supreme; that they control the Constitution and laws of the respective States, and cannot be controlled by them. From this, which may be almost termed an axiom, other propositions are deduced as corollaries, on the truth or error of which, and on their application to this case, the cause has been supposed to depend. These are, 1st. That a power to create implies a power to preserve; 2d. That a power to destroy, if wielded by a different hand, is hostile to, and incompatible with these powers to create and to preserve; 3d. That, where this repugnancy exists, that authority which is supreme must control, not yield to that over which it is supreme.

An unlimited power to tax involves, necessarily, a power to destroy; because there is a limit beyond which no institution and no property can bear taxation. A question of constitutional power can hardly be made to depend on a question of more or less. If the states may tax, they have no limit but their discretion; and the bank, therefore, must depend on the discretion of the state governments for its existence. This consequence is inevitable. The object in laying this tax, may have been revenue to the state. In the next case, the object may be to expel the bank from the state; but how is this object to be ascertained, or who is to judge of the motives of legislative acts?