"Ignorance Of The Law Excuses No Man"
Context: When John Selden, jurist, antiquary, Orientalist, and author, says that ignorance of the law excuses no man from obeying it, he is repeating a legal maxim–"Ignorantia legis neminem excusat"–almost as old as law itself. Christopher St. German in Dialogues in English . . . (1554) says: "Ignorance of the law though it be invincible doth not excuse"; G. Delamothe in The Treasure of the French Tongue (1596) says: "Ignorance doth not excuse the fault"; and Thomas Adams in Meditation upon the Creed (1629) says: "Ignorantia Iurus will excuse no man." At first glance this principle seems somewhat unfair to the one who unknowingly breaks the law, but examination shows that it is the only possible system. Were it not the principle, anyone could commit even the most heinous crime if he were careful to keep himself in ignorance of what the law is; and, furthermore, it would be impossible to convict anyone who stoutly maintained that he was ignorant of the law he had violated. The complete remark that Selden made brings out this fact:
Ignorance of the law excuses no man; not that all men know the law, but because 'tis an excuse every man will plead, and no man can tell how to confute him.