the common defense and general welfare of the United States.

[Footnote 1: Const., Art. I, Sec. 8, Clause 1.]

The only tax which Congress was expressly forbidden to lay was a tax on
exports.[1] It was, however, provided that indirect taxes (duties,
imposts, and excises) should be uniform throughout the United States,[2]
and that direct taxes should be apportioned among the states according
to population.[3] The last mentioned provision was a concession to the
fears of the wealthier states lest their citizens be taxed unduly for
the benefit of the poorer states, and represented one of the great
compromises by which the ratification of the Constitution as a whole was
secured.

[Footnote 1: Const., Art. I, Sec. 9, Clause 5.]

[Footnote 2: Id., Art. I, Sec. 8, Clause 1.]

[Footnote 3: Id., Art. I, Sec. 2, Clause 3. Sec. 9, Clause 4.]

The Constitution nowhere specified just what taxes were to be deemed
"direct" (Madison in his notes of the Constitutional Convention records:
"Mr. King asked what was the precise meaning of direct taxation? No one
answd.")[1] or what kind of uniformity was intended by the provision
that indirect taxes should be uniform, and more than a century was to
elapse before either of these fundamental questions was finally
settled. The answer to the latter question (that the term "uniform"
refers purely to a geographical uniformity and is synonymous with the
expression "to operate generally throughout the United States") was
given by the Supreme Court in the year 1900 in the celebrated case of