United States v. Carolene Products Company, 304 U.S. 144 (1938), the Supreme Court upheld the federal government's power to prohibit filled milk from being shipped in interstate commerce. In his majority opinion for the Court, Associate Justice Harlan F. Stone wrote that economic regulations were "presumptively constitutional" under a deferential standard of review known as the "rational basis test". The case is most notable for Footnote Four, in which Stone wrote that the Court would exercise a stricter standard of review when a law appears on its face to violate a provision of the United States Constitution, restricts the political process in a way that could impede the repeal of an undesirable law, or discriminates against "discrete and insular" minorities. Footnote Four would influence later Supreme Court decisions, and the higher standard of review is now known as "strict scrutiny". National Labor Relations Board v. Mackay Radio and Telegraph Company In National Labor Relations Board v. Mackay Radio and Telegraph Company, 304 U.S. 333 (1938), the Supreme Court held that workers who strike remain employees for the purposes of the National Labor Relations Act (NLRA). The Court granted the relief sought by the National Labor Relations Board, which sought to have the workers reinstated by the employer. However, the decision is much better known today for its obiter dicta in which the Court said that an employer may hire strikebreakers and is not bound to discharge any of them if or when the strike ends. The Mackay doctrine, as the striker replacement portion of the ruling is known, is one of the most significant Supreme Court rulings in American labor law, and has defined collective bargaining in the United States since its publication. "Mackay Radio was more than a decision that provided an instrumental method for a firm to replace economic strikers and to resist their return to employment after a strike. It was also a decision that established important practices that constituted the conduct of union-management bargaining during the post-New Deal Era." The ruling is also highly controversial, even more than 80 years later. It is strongly and uniformly condemned by labor unions, and resolutely defended by employers. Among academics in the political sciences and other related disciplines, "the doctrine continues to provoke the notice and the nearly universal condemnation of scholars." Johnson v. Zerbst In Johnson v. Zerbst, 304 U.S. 458 (1938), the Supreme Court held that defendants