when power exists under the Constitution to legislate upon a given
subject--say interstate commerce or taxation--it is not for the
judiciary to seek to correct abuses by Congress of that power, or to
question Congressional motives. As said in the decision sustaining the
constitutionality of the oleomargarine law:[1]

The judiciary is without authority to avoid an act of Congress
lawfully exerting the taxing power, even in a case where to
the judicial mind it seems that Congress had, in putting such
power in motion, abused its lawful authority by levying a tax
which was unwise or oppressive, or the result of the
enforcement of which might be to indirectly affect subjects
not within the powers delegated to Congress, nor can the
judiciary inquire into the motive or purpose of Congress in
adopting a statute levying an excise tax within its
constitutional power.

[Footnote 1: _McCray v. United States_, 195 U.S., 27.]

The Court, however, has had great difficulty with these cases and
developed sharp differences of opinion. For example, the case upholding
the anti-lottery statute as a valid exercise of the power to regulate
commerce[1] was twice ordered for reargument and finally decided by a
bare majority of 5 to 4. The Child Labor Law of 1916 was declared
unconstitutional[2] and the Narcotic Drug Act was sustained[3] by a
similar vote, 5 to 4. In the Narcotic Drug case the four dissenting
justices, speaking through Chief Justice White, characterized portions
of the statute as "beyond the constitutional power of Congress to enact
... a mere attempt by Congress to exert a power not delegated, that is,
the reserved police power of the states." In the Lottery case the