Which version of the insanity defense posits that a person could not control conduct?

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

Answer: (B)

The key idea is whether mental illness can impair a person’s ability to control their actions. The version that says someone could not control conduct focuses on volitional impairment caused by the disorder—a mental illness that prevents resisting the urge to act. This is the irresistible impulse standard: if the person couldn’t control their actions even though they understood right from wrong, they may be found not criminally responsible.

In contrast, M'Naghten centers on knowing right from wrong; the substantial capacity test (MPC) looks at a substantial impairment of either understanding or ability to conform conduct; and the Durham rule attributes liability to whether the act was the product of a mental disease. So the option describing inability to control conduct corresponds to the irresistible impulse standard.