Which insanity standard holds that a defendant is not guilty if, at the time of the offense, they did not understand whether the act was right or wrong due to a mental defect?

Which insanity standard holds that a defendant is not guilty if, at the time of the offense, they did not understand whether the act was right or wrong due to a mental defect?

• A. M'Naghten test
• B. Irresistible impulse test
• C. Substantial capacity test
• D. Duress

Answer: (A)

The key idea is how insanity defenses judge a defendant’s mental state about right and wrong at the time of the crime. The M'Naghten rule says a person is not guilty if, because of a mental disease or defect, they did not understand the nature and quality of the act or did not know that what they were doing was wrong. That cognitive understanding of wrongness is exactly what the scenario describes, making this standard the best fit. By contrast, the irresistible impulse standard focuses on the inability to control actions despite knowing right from wrong, the substantial capacity test blends understanding with the ability to conform conduct, and duress centers on external threats rather than mental illness affecting knowledge of right and wrong.

The key idea is how insanity defenses judge a defendant’s mental state about right and wrong at the time of the crime. The M'Naghten rule says a person is not guilty if, because of a mental disease or defect, they did not understand the nature and quality of the act or did not know that what they were doing was wrong. That cognitive understanding of wrongness is exactly what the scenario describes, making this standard the best fit. By contrast, the irresistible impulse standard focuses on the inability to control actions despite knowing right from wrong, the substantial capacity test blends understanding with the ability to conform conduct, and duress centers on external threats rather than mental illness affecting knowledge of right and wrong.