ny and all power over foreign and
interstate commerce was by no means universally conceded; and Ogden's
attorneys directly challenged the idea. Moreover, as was pointed out on
both sides in Gibbons _v._ Ogden, legislation by Congress regulative of
any particular phase of commerce would still leave many other phases
unregulated and consequently raise the question whether the States were
entitled to fill the remaining gaps, if not by virtue of a "concurrent"
power over interstate and foreign commerce, then by virtue of "that
immense mass of legislation," as Marshall termed it, "which embraces
everything within the territory of a State, not surrendered to the
general government,"[525]--in a word, the "police power."

The commerce clause does not, therefore, without more ado, settle the
question of what power is left to the States to adopt legislation
regulating foreign or interstate commerce in greater or less measure. To
be sure, in cases of flat conflict between an act or acts of Congress
regulative of such commerce and a State legislative act or acts, from
whatever State power ensuing, the act of Congress is today recognized,
and was recognized by Marshall, as enjoying an unquestionable
supremacy.[526] But suppose, _first_, that Congress has passed no act;
or _secondly_, that its legislation does not clearly cover the ground
which certain State legislation before the Court attempts to cover--what
rules then apply? Since Gibbons _v._ Ogden both of these situations
have confronted the Court, especially as regards interstate commerce,
hundreds of times, and in meeting them the Court has, first and last,
coined or given currency to numerous formulas, some of which still
guide, even when they do not govern, its judgment.

DOCTRINAL BACKGROUND; WEBSTER'S CONTRIBUTION

The earliest, and the most successful, attempt to set forth a principle
capable of guiding the Court in adjusting the powers of the States to
unexercised power of Congress under the commerce clause was that which
was made by Daniel Webster in his argument in Gibbons _v._ Ogden, in the
following words: "He contended, * * *, that the people intended, in
establishing the Constitution, to transfer from the several States to a
general government, those high and important powers over commerce,
which, in their exercise, were to maintain a uniform and general system.
From the very nature of the case, these powers must be exclusive; that
is, the higher branches of co