Mistake of law as a defense: Which is true?

• A. Not a defense in general; there is an exception for attempting to commit a crime where you believed it was a crime
• B. It is a defense for all offenses
• C. It is a defense for strict liability offenses
• D. It is never a defense when the act is a crime

Answer: (A)

Mistake of law is not a defense in general because people are expected to know the law, and punishment attaches to the act itself rather than to the defendant’s belief about its illegality. The only narrow exception is for attempts to commit a crime: if the defendant genuinely believed that the conduct was illegal, that belief can defeat the mens rea required for an attempted offense. In other words, for an attempt, the accused must prove a certain intent to commit the crime as defined by law, and a true belief that the conduct is illegal can negate that specific intent. So the statement that mistake of law isn’t a general defense, but there is a limited exception for attempting to commit a crime when the defendant believed the act was illegal, is the correct one.