McCulloch v. Maryland (1819)

“In the case now to be determined, the defendant, a sovereign State, denies the obligation of a law enacted by the legislature of the Union, and the plaintiff, on his part, contests the validity of an act which has been passed by the legislature of that State. The Constitution of our country, in its most interesting and vital parts, is to be considered, the conflicting powers of the Government of the Union and of its members, as marked in that Constitution, are to be discussed, and an opinion given which may essentially influence the great operations of the Government. 

No tribunal can approach such a question without a deep sense of its importance, and of the awful responsibility involved in its decision…But the Constitution of the United States has not left the right of Congress to employ the necessary means for the execution of the powers conferred on the Government to general reasoning. To its enumeration of powers is added that of making all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this Constitution in the Government of the United States or in any department thereof…The power of Congress to create and, of course, to continue the bank…is no longer to be considered as questionable…The Court has bestowed on this subject its most deliberate consideration. The result is a conviction that the States have no power, by taxation or otherwise, to retard, impede, burden, or in any manner control the operations of the constitutional laws enacted by Congress to carry into execution the powers vested in the General Government. 

This is, we think, the unavoidable consequence of that supremacy which the Constitution has declared …We are unanimously of opinion that the law passed by the Legislature of Maryland, imposing a tax on the Bank of the United States is unconstitutional and void… …This opinion does not deprive the States of any resources which they originally possessed. It does not extend to a tax paid by the real property of the bank, in common with the other real property within the State, nor to a tax imposed on the interest which the citizens of Maryland may hold in this institution, in common with other property of the same description throughout the State. But this is a tax on the operations of the bank, and is, consequently, a tax on the operation of an instrument employed by the Government of the Union to carry its powers into execution. Such a tax must be unconstitutional.”