The insanity defense rests on the assumption that criminal responsibility requires free choice

Evidence

The criminal law justifies holding persons responsible for their actions on the assumption that they are able to choose between acceptable and unacceptable behavior. This assumption supplies the rationale for the insanity defense: Criminal law should not punish those who cannot choose between acceptable and unacceptable behavior. But how does one define the inability to choose that exempts a person from the operation of the criminal law? Under the M’Naghten test, a defendant is responsible for criminal actions unless “the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, he did not know he was doing what was wrong.” — G. Alan Tarr, Judicial Process and Judicial…, 1882

Categorization

• DEFINE: Defines the M’Naghten test and the free-choice rationale underpinning the insanity defense.
• XREF: connects to: Criminal law assesses dangerousness, not actual mental states or free will. — Richard A. Posner, What Has Pragmatism to Offer Law?, 85; Motives are freely constituted rather than psychologically forced.

Broader Connections

• Criminal law assesses dangerousness, not actual mental states or free will. #complicates (0.85) — Richard A. Posner, What Has Pragmatism to Offer Law?, 85
• Motives are freely constituted rather than psychologically forced. #corroborates (0.80)