Section 8. The Congress shall have power to lay and collect taxes, duties, imposts and excises, to pay the debts and provide for the common defense and general welfare of the United States; but all duties, imposts and excises shall be uniform throughout the United States;
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To establish post offices and post roads;
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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.
Maryland's argument hinged on the assertion that the bank was not strictly necessary for the powers given above, and therefore was unconstitutionally chartered. Chief Justice Marshall argues persuasively against this, first noting:
It was impossible for the framers of the constitution to specify, prospectively, all these means, both because it would have involved an immense variety of details, and because it would have been impossible for them to foresee the infinite variety of circumstances, in such an unexampled state of political society as ours, for ever changing and for ever improving. How unwise would it have been, to legislate immutably for exigencies which had not then occurred, and which must have been foreseen but dimly and imperfectly! The security against abuse is to be found in the constitution and nature of the government, in its popular character and structure. The statute book of the United States is filled with powers derived from implication. The power to lay and collect taxes will not execute itself. Congress must designate in detail all the means of collection. So also, the power of establishing post-offices and post-roads, involves that of punishing the offence of robbing the mail. But there is no more necessary connection between the punishment of mail-robbers, and the power to establish post-roads, than there is between the institution of a bank, and the collection of the revenue and payment of the public debts and expenses.
He also draws the distinction between "necessary" and "absolutely necessary" as used in the Constitution:
Compare these terms as they are used in that part of the constitution now in question, with the qualified manner in which they are used in the 10th section of the same article. In the latter, it is provided that 'no state shall, without the consent of congress, lay any imposts or duties on imports or exports, except what may be absolutely necessary for executing its inspection laws.' In the clause in question, congress is invested with the power 'to make all laws which shall be necessary and proper for carrying into execution the foregoing powers,' &c. There is here then, no qualification of the necessity; it need not be absolute; it may be taken in its ordinary grammatical sense. The word necessary, standing by itself, has no inflexible meaning; it is used in a sense more or less strict, according to the subject. This, like many other words, has a primitive sense, and another figurative and more relaxed;
And sums up his guiding principle:
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.
Now, how is this relevant today? Well, people seem up in arms about federal funding for the arts and, to a certain extent, the sciences which don't help the military. Lets take another look at Article I, Section 8:
The Congress shall have power.... To promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries;
Now, on the surface this is talking about the patent office, copyright, etc. However, what is the spirit of this line? Of course, this is interpretation, but it seems fairly apparent that the important part is "promote the progress of science and useful arts". In the 18th century, modern research was unknown, and the government was too focused on its own survival to worry about the National Council for the Arts, but I argue that it is fairly clear that these are things that are "necessary and proper" to "promote the progress of science and useful arts".
Obviously, many strict constitutionalists disagree completely with everything I have said. My goal is not to convince them (although that would be nice) but to point out that this is not a new issue; and that before they start bringing fragments like "our founding fathers" they should look at how our founding fathers judged and interpreted the constitution.