Necessary and Proper Clause

The Necessary and Proper Clause authorizes Congress "to make all Laws which shall be necessary and proper for carrying into Execution" its other powers and all powers vested in the federal government. It is sometimes called the elastic clause because it stretches the reach of the enumerated powers.

The leading interpretation comes from McCulloch v. Maryland (1819), in which Chief Justice John Marshall upheld Congress's power to charter a national bank. Marshall read "necessary" to mean useful or conducive, not absolutely indispensable, so long as the end was legitimate and the means were consistent with the Constitution. Hamilton and Jefferson had argued opposite sides of the same question in the 1790s.

The clause matters because it determines how much room Congress has to act beyond its listed powers. Broad readings support much of modern federal law. Critics who stress federalism argue that a law is not "proper" if it intrudes on state sovereignty, and the Supreme Court has occasionally used that reasoning, as in parts of its 2012 ruling on the Affordable Care Act's individual mandate, which also turned on the Commerce Clause.