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;....
Browsing about, I came across an interesting passage about this in Noah Knowles Davis's Elements of Deductive Logic, speaking of ambiguity and punctuation:
After the word "excises" a semicolon is frequently printed, whereas in the original draft, and in the authorized edition of March 3, 1877, it is followed by a comma. Alexander Hamilton held that the items of the rest of the section are additional powers; Madison, that they are limitations. The semicolon enlarges federal authority; the comma favors state-rights. (p. 188)
That is, if we take the punctuation after "excises" to be a semi-stop, the above passage says:
Congress shall have the power
to lay and collect taxes, duties, imposts and excises;
and
to pay the debts and provide for the common defense and general welfare of the United States (as long as all duties, imposts and excises shall be uniform throughout the United States)
And then it goes to enumerate powers beyond these two. But if we take the punctuation after "excises" to be a pause, the above passage says:
Congress shall have the power
to lay and collect taxes, duties, imposts and excises, in order to pay the debts and provide for the common defense and general welfare of the United States (but all of these duties, imposts and excises shall be uniform throughout the United States).
This confines the Congressional power with regard to taxation to three purposes: paying debts, providing for common defense, and providing for general welfare; i.e., Congress can't tax unless it is explicitly for one of these purposes, and this is one power.
As Davis says, the comma is standard; but, of course, it's a different question whether it should be read literally or instead as a sort of colloquial semicolon. As things stand, we publish it as a comma but in practice we treat it as a semicolon, at least to the extent that we do not require Congress to make explicit the purpose of each tax, but allow it to raise taxes and then decide how it will be apportioned (and, again, do not require that Congress make clear in each and every case how this apportionment is related to the three purposes). This is a state of affairs somewhat uncomfortable for those of us who are partisans of the Comma Theory of Taxation.
