Article 1, Section 8, Clause 18: Necessary and Proper Clause

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 Elastic Clause exists so that the Constitution does not have to spell out exactly how the powers of Congress are to be exercised. However, they are not a blanket grant of legislative power; the laws must be necessary and proper.

This clause was an immediate focus of controversy during the ratification debates. Critics, such as Patrick Henry, argued that the Elastic Clause would give Congress essentially unrestricted power. Hamilton, in Federalist 33, argued that the clause should be interpreted narrowly, to permit only execution of powers granted in the Constitution. Madson in Federalist 44 agreed with Hamilton, and argued that without this clause, the Constitution would be a dead letter.

The first great debates over the clause revolved around the establishment of a national bank. Southern politicians feared the North would use this bank to exploit the South. In the ensuing debates, Hamilton argued that necessary did not mean absolutely necessary but meant that the law was a reasonable means to further a constitutionally authorized federal power. Hamilton countered Madison with Madison’s own words from Federalist 44:

No axiom is more clearly established in law or in reason than wherever the end is required, the means are authorized; wherever a general power to do a thing is given, every particular power for doing it is included.

The Marshall Court ruled in 1819 that

We admit, as all must admit, that the powers of the Government are limited, and that its limits are not to be transcended. But we think the sound construction of the Constitution must allow to the national legislature that discretion with respect to the means by which the powers it confers are to be carried into execution which will enable that body to perform the high duties assigned to it in the manner most beneficial to the people. Let the end be legitimate, let it be within the scope of the Constitution, and all means which are appropriate, which are plainly adapted to that end, which are not prohibited, but consistent with the letter and spirit of the Constitution, are constitutional.

This seems to have inevitably lead to a rather expansive view of the Necessary and Proper Clause, particularly in combination with the Commerce Clause.

If necessary is now interpreted very broadly, what of proper?  In 2012, in striking down the individual mandate of the Affordable Care Act, the Court ruled that the mandate cannot

be sustained under the Necessary and Proper Clause as an integral part of the Affordable Care Act’s other reforms. Each of this Court’s prior cases upholding laws under that Clause involved exercises of authority derivative of, and in service to, a granted power…. The individual mandate, by contrast, vests Congress with the extraordinary ability to create the necessary predicate to the exercise of an enumerated power and draw within its regulatory scope those who would otherwise lie outside it. Even if the individual mandate is “necessary” to the Affordable Care Act’s other reforms, such an expansion of federal power is not a “proper” means for making those reforms effective

In other words, if the effect of a law is to bring new areas under the regulatory scope of the government that are not enumerated in the Constitution, it does not matter that it also serves an enumerated end; it may be necessary (in the broad sense) but is still not proper.