Shortly after the Convention, Richard Henry Lee wrote in his Letters of the Federal Farmer that the necessary and proper clause granted broad authority to Congress. He stated that it was “impossible” to determine what “may be deemed necessary and proper.” Lee turned out to be correct, because the necessary and proper clause has resulted in great congressional power.

Alexander Hamilton interpreted this clause broadly in 1791 when he argued for a first national bank. He argued that the necessary and proper clause gave Congress “implied powers.” Implied powers refer to those that are not explicitly listed in the text of the Constitution. Chief Justice John Marshall also interpreted the necessary and proper clause broadly years later when he determined that Congress had the power to establish a second national bank. In his famous opinion of McCullough v. Maryland (1819), he wrote: “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 consist with the letter and spirit of the constitution, are constitutional.”

Marshall reasoned in this decision that Congress had the power to create a second national bank because it was a reasonably connected to Congress’ power to “lay and collect taxes” and “to regulate commerce.” Marshall determined that the term “necessary and proper” did not mean “absolutely necessary.” If Congress had intended the clause to mean “absolutely necessary,” it would have included that word in the clause, Marshall reasoned.

But the argument on which most reliance is placed is drawn from that peculiar language of this clause. Congress is not empowered by it to make all laws which may have relation to the powers conferred on the Government, but such only as may be “necessary and proper” for carrying them into execution. The word “necessary” is considered as controlling the whole sentence, and as limiting the right to pass laws for the execution of the granted powers to such as are indispensable, and without which the power would be nugatory. That it excludes the choice of means, and leaves to Congress in each case that only which is most direct and simple.

Is it true that this is the sense in which the word “necessary” is always used? Does it always import an absolute physical necessity so strong that one thing to which another may be termed necessary cannot exist without that other? We think it does not. If reference be had to its use in the common affairs of the world or in approved authors, we find that it frequently imports no more than that one thing is convenient, or useful, or essential to another. To employ the means necessary to an end is generally understood as employing any means calculated to produce the end, and not as being confined to those single means without which the end would be entirely unattainable. Such is the character of human language that no word conveys to the mind in all situations one single definite idea, and nothing is more common than to use words in a figurative sense. Almost all compositions contain words which, taken in their rigorous sense, would convey a meaning different from that which is obviously intended. It is essential to just construction that many words which import something excessive should be understood in a more mitigated sense—in that sense which common usage justifies. The word “necessary” is of this description. It has not a fixed character peculiar to itself. It admits of all degrees of comparison, and is often connected with other words which increase or diminish the impression the mind receives of the urgency it imports. A thing may be necessary, very necessary, absolutely or indispensably necessary. To no mind would the same idea be conveyed by these several phrases. The comment on the word is well illustrated by the passage cited at the bar from the 10th section of the 1st article of the Constitution. It is, we think, impossible to compare the sentence which prohibits a State from laying “imposts, or duties on imports or exports, except what may be absolutely necessary for executing its inspection laws,” with that which authorizes Congress “to make all laws which shall be necessary and proper for carrying into execution” the powers of the General Government without feeling a conviction that the convention understood itself to change materially the meaning of the word “necessary,” by prefixing the word “absolutely.” This word, then, like others, is used in various senses, and, in its construction, the subject, the context, the intention of the person using them are all to be taken into view.

Let this be done in the case under consideration. The subject is the execution of those great powers on which the welfare of a Nation essentially depends. It must have been the intention of those who gave these powers to insure, so far as human prudence could insure, their beneficial execution. This could not be done by confiding the choice of means to such narrow limits as not to leave it in the power of Congress to adopt any which might be appropriate, and which were conducive to the end. This provision is made in a Constitution intended to endure for ages to come, and consequently to be adapted to the various crises of human affairs. To have prescribed the means by which Government should, in all future time, execute its powers would have been to change entirely the character of the instrument and give it the properties of a legal code. It would have been an unwise attempt to provide by immutable rules for exigencies which, if foreseen at all, must have been seen dimly, and which can be best provided for as they occur. To have declared that the best means shall not be used, but those alone without which the power given would be nugatory [of little significance], would have been to deprive the legislature of the capacity to avail itself of experience, to exercise its reason, and to accommodate its legislation to circumstances.