ons _v._ United States, 307 U.S. 588 (1939), another
milk case; and Mulford _v._ Smith, 307 U.S. 38 (1939), in which certain
restrictions on the sale of tobacco, under the Agricultural Adjustment
Act of 1938 (52 Stat. 31), were sustained in an opinion by Justice
Roberts, who spoke for the Court in the latter case.

[473] United States _v._ The William, 28 Fed. Cas. No. 16,700, 614,
620-623 _passim_ (1808). Other parts of this opinion are considered
below in connection with the prohibiting of interstate commerce. _See
also_ Gibbons _v._ Ogden, 9 Wheat. 1, 191 (1824); United States _v._
Marigold, 9 How. 560 (1850).

[474] 289 U.S. 48 (1933).

[475] Ibid. 57, 58.

[476] 5 Stat. 566 Sec. 28.

[477] 9 Stat. 237 (1848).

[478] 24 Stat. 409.

[479] 35 Stat. 614; 38 Stat. 275.

[480] 29 Stat. 605.

[481] 192 U.S. 470 (1904).

[482] 223 U.S. 166 (1912); _cf._ United States _v._ California, 332 U.S.
19 (1947).

[483] 239 U.S. 325 (1915).

[484] Ibid. 329.

[485] 236 U.S. 216 (1915).

[486] Ibid. 222. _See also_ Robert B. Cushman, National Police Power
Under the Commerce Clause, 3 Selected Essays on Constitutional Law,
62-79.

[487] Groves _v._ Slaughter, 15 Pet. 449, 488-489 (1841).

The Issue

A little reflection will suffice to show that, as a matter of fact, any
regulation at all of commerce implies some measure of power to prohibit
it, since it is the very nature of regulation to lay down terms on which
the activity regulated will be permitted and for noncompliance with
which it will not be permitted. It is also evident that when occasion
does arise for an outright prohibition of an activity, the power to
enact the required prohibition ordinarily must belong to the body which
is vested with authority to regulate it, which in this instance is
Congress.

What, then, are the outstanding differences between such conditional
prohibitions of commerce and that with which this resume deals? There
seem to be three such differences. First, there is often a difference of
_modus operandi_ between the statutes already considered and those about
to be considered. The former impinge upon persons or agencies engaged in
interstate commerce and their activities in connection therewith,
whereas the latter look primarily to things, or the subject matter, of
the trade or commerce prohibited. Secondly, there is a difference in
purpose between the two categories of Congressional statutes. The
purpose of the acts already t