Which of the following is a listed defense related to mental state?

• A. Capacity
• B. Insanity
• C. Mistake
• D. Duress

Answer: (B)

Defenses that hinge on the defendant’s mental state look at whether, at the time of the offense, the person could understand what they were doing or control their actions. Insanity is the classic mental-state defense: if a defendant has a mental disease or defect that prevents them from knowing right from wrong or from conforming their conduct to the law, they may be found not criminally responsible. Courts typically apply one of two standards. Under the traditional test, if the person could not appreciate that what they were doing was wrong, they meet the insanity defense. Under newer formulations, the focus is on whether the person lacked substantial capacity to appreciate the criminality of the conduct or to conform their conduct to the law due to a mental condition. The other options don’t rest on the mental-state theory in the same way: capacity relates more to overall ability to form the required intent or to participate in proceedings; mistake concerns erroneous beliefs about facts or law that can negate mens rea in some situations; duress involves being forced to commit a crime by external threat, not a mental-state defect at the time of the act.