ignorance of fact

In law, ignorance is categorized into two types: ignorance of the law (ignorantia juris) and ignorance of fact (ignorantia facti).1

Generally, ignorance of the law is not a valid defense for criminal charges, as it's presumed individuals know the law. This principle, often stated as "ignorance of the law excuses no one" (ignorantia juris neminem excusat), is considered essential for effective legal administration. However, some legal systems may allow for defenses based on mistake of law in specific situations, particularly for conduct not obviously immoral or dangerous, if the individual made a good-faith effort to understand the law.123

Ignorance of fact, on the other hand, can be a defense if the mistaken belief about facts negates the required criminal intent. For example, if someone takes an item believing it is theirs, they lack the intent to steal and thus may not be guilty of larceny. In civil matters, ignorance of fact can also affect liability or provide grounds for recovery.13