Footnote Four

Carolene Products is best known for its "Footnote Four", which is considered to be "the most famous footnote in constitutional law." ^[2] The Court applied minimal scrutiny (rational basis review) to the economic regulation in this case, but proposed a new level of review for certain other types of cases.
Justice Stone suggested there were reasons to apply a more exacting standard of judicial review in other types of cases. Legislation aimed at discrete and insular minorities, who lack the normal protections of the political process, should be an exception to the presumption of constitutionality, and a heightened standard of judicial review should be applied. This idea has greatly influenced equal protection jurisprudence, and judicial review.

[edit] Text of Footnote Four

“

There may be narrower scope for operation of the presumption of constitutionality when legislation appears on its face to be within a specific prohibition of the Constitution, such as those of the first ten amendments, which are deemed equally specific when held to be embraced within the Fourteenth… It is unnecessary to consider now whether legislation which restricts those political processes which can ordinarily be expected to bring about repeal of undesirable legislation, is to be subjected to more exacting judicial scrutiny under the general prohibitions of the Fourteenth Amendment than are most other types of legislation. Nor need we inquire whether similar considerations enter into the review of statutes directed at particular religious … or national … or racial minorities …: whether prejudice against discrete and insular minorities may be a special condition, which tends seriously to curtail the operation of those political processes ordinarily to be relied upon to protect minorities, and which may call for a correspondingly more searching judicial inquiry.

”

Footnote Four introduced the idea of levels of judicial scrutiny. In keeping with the New Deal Revolution, Footnote Four established the rational basis test for economic legislation, an extremely low standard of judicial review. The "rational basis test" mandates that legislation (whether enacted by Congress or state legislatures) which deals with economic regulation must be rationally related to a legitimate state interest.
Therefore, Footnote Four outlines a higher level of judicial scrutiny for legislation that met certain conditions:

1. On its face violates a provision of the Constitution (facial challenge).
2. Attempts to distort or rig the political process.
3. Discriminates against minorities, particularly those who lack sufficient numbers or power to seek redress through the political process.

This higher level of scrutiny, now called "strict scrutiny", was first applied in Justice Black's opinion in Korematsu v. U.S. (1944).
Some argue that this "most famous footnote" was in fact written not by Justice Stone, but by his law clerk, Louis Lusky.^[3] In fact, the cited work above (while quite useful on the origin and growth of the footnote) does not claim that the law clerk was the author, and implies the opposite through letters between the justices. In his later work, Our Nine Tribunes: The Supreme Court in Modern America, however, Lusky includes facsimiles of the original drafts of the footnote, the first of which is in his own hand. Stone edited the second, typed draft and, at the behest of the Chief Justice, added certain passages. While Justice Stone was doubtless intimately involved in the writing of the footnote, it seems clear that original authorship belongs to Lusky.