I consider the foundation of the [Federal] Constitution as laid on this ground: That "all powers not delegated to the United States, by the Constitution, nor prohibited by it to the States, are reserved to the States or to the people." [10th Amendment] To take a single step beyond the boundaries thus specifically drawn around the powers of Congress is to take possession of a boundless field of power, no longer susceptible of any definition.
 

– Thomas Jefferson, Opinion on the Constitutionality of a National Bank, [1791]