When Benjamin Cardozo's appointment was being pressed on President Herbert C. Hoover, McReynolds joined with fellow justices Pierce Butler and Willis Van Devanter in urging the White House not to "afflict the Court with another Jew". When news of Cardozo's appointment was announced, McReynolds is claimed to have said "Huh, it seems that the only way you can get on the Supreme Court these days is to be either the son of a criminal or a Jew, or both."
According to John Frush Knox (1907–1997), McReynolds's law clerk for one term (1936–1937, following the seven-year clerkship of Maurice Mahoney), and one author of a memoir of his service, McReynolds never spoke to Cardozo at all. McReynolds did not attend the memorial ceremonies held at the Supreme Court in honor of Cardozo. He did not attend Felix Frankfurter's swearing-in, exclaiming "My God, another Jew on the Court!"