Stupidity is no excuse of not thinking. Stanisław Jerzy Lec
Man has no right to kill his brother. It is no excuse that he does so in uniform: he only adds the infamy of servitude to the crime of murder. Percy Bysshe Shelley
Computers are our only opponents that don't always have no excuse when losing against me. Bobby Fischer
Ignorance of the law is no excuse for breaking it. Greek Proverb
That which is customary requires no excuse. Italian Proverb
Being ignorant of law is no excuse. Polish Proverb