tained the tax on the second
ground mentioned in Helvering _v._ Gerhardt--that the burden of the tax
was borne by private persons--and did not consider whether the function
was one which the Federal Government might have taxed if the
municipality had borne the burden of the exaction.[250]

THE RULE OF UNIFORMITY

Whether a tax is to be apportioned among the States according to the
census taken pursuant to article I, section 2, or imposed uniformly
throughout the United States depends upon its classification as direct
or indirect.[251] The rule of uniformity for indirect taxes is easy to
obey. It exacts only that the subject matter of a levy be taxed at the
same rate wherever found in the United States; or, as it is sometimes
phrased, the uniformity required is "geographical," not
"intrinsic."[252] The clause accordingly places no obstacle in the way
of legislative classification for the purpose of taxation, nor in the
way of what is called progressive taxation.[253] A taxing statute does
not fail of the prescribed uniformity because its operation and
incidence may be affected by differences in State laws.[254] A federal
estate tax law which permitted a deduction for a like tax paid to a
State was not rendered invalid by the fact that one State levied no such
tax.[255] The term "United States" in this clause refers only to the
States of the Union, the District of Columbia, and incorporated
territories. Congress is not bound by the rule of uniformity in framing
tax measures for unincorporated territories.[256] Indeed, in Binns _v._
United States,[257] the Court sustained license taxes imposed by
Congress but applicable only in Alaska, where the proceeds, although
paid into the general fund of the Treasury, did not in fact equal the
total cost of maintaining the territorial government.

PURPOSES OF TAXATION

Regulation by Taxation

The discretion of Congress in selecting the objectives of taxation has
also been held at times to be subject to limitations implied from the
nature of the Federal System. Apart from matters which Congress is
authorized to regulate, the national taxing power, it has been said,
"reaches only existing subjects."[258] Congress may tax any activity
actually carried on, regardless of whether it is permitted or prohibited
by the laws of the United States[259] or by those of a State.[260] But
so-called federal "licenses," so far as they relate to trade within
State limits, merely express "th