A license cannot be revoked because a man is redheaded or because he was divorced, except for a calling, if such there be, for which redheadedness or an unbroken marriage may have some rational bearing. If a State licensing agency lays bare its arbitrary action, or if the State law explicitly allows it to act arbitrarily, that is precisely the kind of State action which the Due Process Clause forbids.

Barsky v. Board of Regents, 347 U.S. 442, 470 (1954). - Judicial opinions