https://en.wikipedia.org/wiki/Ignorantia_juris_non_excusat:
> Ignorantia juris non excusat (Legal principle)
> Ignorantia juris non excusat or ignorantia legis neminem excusat (Latin for "ignorance of the law excuses not" and "ignorance of law excuses no one" respectively) is a legal principle holding that a person who is unaware of a law may not escape liability for violating that law merely by being unaware of its content.
> European-law countries with a tradition of Roman law may also use an expression from Aristotle translated into Latin: nemo censetur ignorare legem (nobody is thought to be ignorant of the law) or ignorantia iuris nocet (not knowing the law is harmful).
And if Wikipedia is no authority for you maybe the bible is:
Leviticus 5:17: "If a person sins and does what is forbidden in any of the LORD's commands, even though he does not know it, he is guilty and will be held responsible."