outside the national jurisdiction, or were so arbitrary and without
basis for classification as to amount to confiscation, relief might be
obtained under the due process clause of the Fifth Amendment.

[Footnote 1: See, e.g., _Union Tank Line Co. v. Wright_, 249 U.S., 275.]

[Footnote 2: _Brushaber v. Union Pacific R.R._, 240 U.S., 24.]

By far the most important and interesting of the implied limitations of
the federal taxing power remains to be noticed. That is the limitation
which prohibits the National Government from burdening by taxation the
property or revenues or obligations of a state, or the emoluments of a
state official, or anything connected with the exercise by a state of
one of its governmental functions. In other words, while the National
Government may tax income from bonds issued by England or France or
their cities, it is powerless to tax the income from bonds of Rhode
Island or the smallest of its towns.

This implied limitation, nowhere categorically expressed but enunciated
in a series of decisions of the Supreme Court, has not always met with
acquiescence from the executive and legislative branches of the
Government. In fact, Congress is now engaged in an effort to do away
with it, at least in so far as concerns the right to tax the income from
state and municipal bonds. To-day, however, it still stands as one of
the most striking and unique characteristics of our governmental system.
It will be discussed more at length in the next chapter.