The Necessary and Proper Clause

Article I, Section 8 ends its list of congressional powers by authorizing Congress to make all laws which shall be necessary and proper for carrying into execution the foregoing powers and all other powers vested in the federal government. Opponents of ratification called it the sweeping clause and warned it would allow unlimited federal power, while defenders said it simply made explicit the authority to choose means to carry out listed powers. The first great dispute over it came in 1791, when Alexander Hamilton argued that it allowed Congress to charter a national bank and Thomas Jefferson argued that it did not.

In McCulloch v. Maryland, decided March 6, 1819, Chief Justice John Marshall sided with Hamilton's view, holding that necessary means convenient or useful rather than absolutely indispensable, and that if the end is legitimate and within the scope of the Constitution, all appropriate means not prohibited are constitutional. The clause has supported laws creating federal crimes, agencies, and programs, and in United States v. Comstock in 2010 the Court upheld civil commitment of dangerous federal prisoners as a necessary and proper extension of federal criminal powers.

The clause has limits. In NFIB v. Sebelius in 2012, Chief Justice John Roberts wrote that the individual health insurance mandate could not be justified under the clause because compelling people to buy insurance was not a proper means of regulating commerce, though the Court upheld the mandate as a tax. Supporters of a broad reading say a modern national government needs flexibility to carry out its responsibilities, while critics say an expansive reading erases the idea that federal powers are limited and enumerated.