American lawyer who defended, usually without charge, persons accused in many prominent civil-liberties cases in the 1920s.

Educated at Columbia University (B.A., 1902; M.A. and LL.B., 1905), Hays was admitted to the New York bar. In 1914–15 he practiced international law in London. Among the proceedings in which he appeared as a defense attorney were the Scopes trial, Dayton, Tenn., 1925; the Sweet segregation–violence case, Detroit, 1925 (both the above with Clarence S. Darrow); the American Mercury censorship case, Boston, 1926; the Sacco–Vanzetti case, Boston, 1921–27; and the Scottsboro case, Alabama, from 1931. In 1933 he went to Germany to defend the alleged burners of the Reichstag. From 1912 he was general counsel of the American Civil Liberties Union; in 1924 he was New York state chairman of the Progressive Party.