 Even if common knowledge is sometimes hard to achieve in practice, it serves as necessary presumption in regulating society. Roman lawgivers found out long ago that if citizens within their jurisdiction could plead innocence because of being unaware of the law, no offender could ever get convicted. So they invented principles like Ignorantia legis neminem excusat, “ignorance of the law excuses no one”. Societies that abide by the rule of law have to be organized in such a way that citizens in principle are in a position to know the law. The laws have to be properly published and distributed, for example, by being printed in a government gazette to which every citizen has access.