to flow from its own power, whether dormant or exercised,
except as otherwise expressly provided in the Act itself or in future
legislation. The other was by declaring expressly and affirmatively that
continued State regulation and taxation of this business is in the
public interest and that the business and all who engage in it 'shall be
subject to' the laws of the several States in these respects. * * * The
power of Congress over commerce exercised entirely without reference to
coordinated action of the States is not restricted, except as the
Constitution expressly provides, by any limitation which forbids it to
discriminate against interstate commerce and in favor of local trade.
Its plenary scope enables Congress not only to promote but also to
prohibit interstate commerce, as it has done frequently and for a great
variety of reasons. * * * This broad authority Congress may exercise
alone, subject to those limitations, or in conjunction with coordinated
action by the States, in which case limitations imposed for the
preservation of their powers become inoperative and only those designed
to forbid action altogether by any power or combination of powers in our
governmental system remain effective."[767] The generality of this
language enforces again the sweeping nature of Congress's power to
prohibit interstate commerce.[768]

The Police Power and Foreign Commerce

ORIGIN OF POLICE POWER

In Gibbons _v._ Ogden[769] cognizance was taken of the existence in the
States of an "immense mass" of legislative power to be used for the
protection of their welfare and the promotion of local interests.[770]
In Marshall's opinion in Brown _v._ Maryland[771] this power is
christened "the Police Power," a name which has since come to supply one
of the great titles of Constitutional Law. Counsel for Maryland had
argued that if the State was not permitted to _tax_ imports in the
original package before they left the hands of the importer, it would
also be unable to prevent their introduction into its midst although
they might comprise articles dangerous to the public health and safety.
"The power to direct the removal of gunpowder," the Chief Justice
answered, "is a branch of the police power, which unquestionably
remains, and ought to remain, with the States;" and the power to direct
"the removal or destruction of infectious or unsound articles" fell
within the same category.[772]

STATE CURBS ON ENTRY OF FOREIGNERS

In s