It is nicknamed the elastic clause because it can stretch. This handful of words is the source of vast federal power the Constitution never lists, and the fight over it began with a bank.
The Necessary and Proper Clause, at the end of Article I, Section 8, lets Congress make all laws necessary and proper for carrying out its other powers. It is the constitutional permission slip for the means to achieve listed ends.
The argument over it is as old as the republic. When Congress proposed a national bank in 1791, Jefferson and Madison said no: necessary must mean truly essential, and a bank was not. Hamilton said necessary just meant useful or convenient, and the bank was fine. Two readings, two visions of federal power.
The Supreme Court settled it in 1819. In McCulloch v. Maryland, Chief Justice John Marshall sided with Hamilton's broad reading. The Constitution, he wrote, was intended to endure for ages to come, and to be adapted to the various crises of human affairs, so its powers could not be cramped to only the indispensable.
That elasticity is why it is called the elastic clause. It is the basis of implied powers, the authority Congress exercises that is not explicitly written but is reasonably tied to powers that are.
