In mcculloch v. maryland, justice marshall ruled that congress could charter a national bank and that maryland could not tax it. marshall pointed to the to support this decision.

Marshall pointed to the "necessary and proper" clause of Article I, Section 8, of the United States Constitution.

After enumerating a number of the powers of Congress, including borrowing money, coining money, regulating commerce, etc, Section 8 of Article I closes with by saying Congress shall have power "to make 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 or Officer thereof." 

The statement of the Marshall court in regard to the chartering of a national bank held significance beyond that issue as well.  The ruling said:  "Let the ends be legitimate, let it be within the scope of the Constitution, and all means which are appropriate, which are plainly adopted to that end, which are not prohibited, but consist with the letter and spirit of the Constitution, are constitutional."

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