RT

However, it is to be noted that none of this legislation operated in the
field of industrial relations. So when the Court was confronted in 1918,
in the case of Hammer _v._ Dagenhart,[512] with an act which forbade
manufacturers and others to offer child-made goods for transportation in
interstate commerce,[513] it held the act, by the narrow vote of five
Justices to four, to be not an act regulative of commerce among the
States, but one which invaded the reserved powers of the States. "The
maintenance of the authority of the States over matters purely local,"
said Justice Day for the Court, "is as essential to the preservation of
our institutions as is the conservation of the supremacy of the federal
power in all matters entrusted to the Nation by the Federal
Constitution."[514] As to earlier decisions sustaining Congress's
prohibitory powers, Justice Day said: "In each of these instances the
use of interstate transportation was necessary to the accomplishment of
harmful results. * * * This element is wanting in the present case.
* * * The goods shipped are in themselves harmless. * * * When offered
for shipment, and before transportation begins, the labor of their
production is over, and the mere fact that they were intended for
interstate commerce transportation does not make their production
subject to federal control under the commerce power. * * * 'When
commerce begins is determined, not by the character of the commodity,
nor by the intention of the owner to transfer it to another State for
sale, * * *, but by its actual delivery to a common carrier for
transportation, * * *' (Mr. Justice Jackson in _In re Greene_, 52 Fed.
Rep. 113). This principle has been recognized often in this court. Coe
_v._ Errol, 116 U.S. 517 * * *."[515]

The decision in Hammer _v._ Dagenhart was, in short, governed by the
same general conception of the interstate commerce process as that which
governed the decision in the Sugar Trust Case. Commerce was envisaged as
beginning only with an act of transportation from one State to another.
And from this it was deduced that the only commerce which Congress may
prohibit is an act of transportation from one State to the other which
is followed in the latter by an act within the normal powers of
government to prohibit. Commerce, however, is primarily _traffic_; and
the theory of the Child Labor Act was that it was designed to discourage
a widespread and pernicious interstate traffic in the