kable lesson of recent cases is that
the preservation of our Federal System depends today mainly upon
Congress.

The Commerce Clause as a Restraint on State Powers

DOCTRINAL BACKGROUND

The grant of power to Congress over commerce, unlike that of power to
levy customs duties, the power to raise armies, and some others, is
unaccompanied by correlative restrictions on State power. This
circumstance does not, however, of itself signify that the States were
expected still to participate in the power thus granted Congress,
subject only to the operation of the supremacy clause. As Hamilton
points out in The Federalist, while some of the powers which are vested
in the National Government admit of their "concurrent" exercise by the
States, others are of their very nature "exclusive," and hence render
the notion of a like power in the States "contradictory and
repugnant."[522] As an example of the latter kind of power Hamilton
mentioned the power of Congress to pass a uniform naturalization law.
Was the same principle expected to apply to the power over foreign and
interstate commerce?

Unquestionably one of the great advantages anticipated from the grant to
Congress of power over commerce was that State interferences with trade,
which had become a source of sharp discontent under the Articles of
Confederation, would be thereby brought to an end. As Webster stated in
his argument for appellant in Gibbons _v._ Ogden: "The prevailing motive
was to regulate commerce; to rescue it from the embarrassing and
destructive consequences, resulting from the legislation of so many
different States, and to place it under the protection of a uniform
law." In other words, the constitutional grant was itself a regulation
of commerce in the interest of uniformity. Justice Johnson's testimony
in his concurring opinion in the same case is to like effect: "There was
not a State in the Union, in which there did not, at that time, exist a
variety of commercial regulations; * * * By common consent, those laws
dropped lifeless from their statute books, for want of sustaining power
that had been relinquished to Congress";[523] and Madison's assertion,
late in life, that power had been granted Congress over interstate
commerce mainly as "a negative and preventive provision against
injustice among the States,"[524] carries a like implication.

That, however, the commerce clause, unimplemented by Congressional
legislation, took from the States a