A phrase begins life as a literary expression; its felicity leads to its lazy repetition; and repetition soon establishes it as a legal formula, undi… - Felix Frankfurter

The ultimate touchstone of constitutionality is the Constitution itself and not what we have said about it.

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.

Congress is, after all, not a body of laymen unfamiliar with the commonplaces of our law. This legislation was the formulation of the two Judiciary Committees, all of whom are lawyers, and the Congress is predominately a lawyers' body.