Massachusetts McHoul (ALI Rule) & Dual-Prong Jurisprudence Engine
Trial Archetype PresetsMA Focus
Evidentiary Record (Toggles)4 Active
Statutory Standard FrameworkMass. Supreme Judicial Court
Commonwealth v. McHoul
ALI Model Penal Code § 4.01 dual prong: Cognitive OR Volitional incapacity.
M'Naghten Rule (1843)
Pure cognitive test: Did not know the nature or wrongfulness of act.
Irresistible Impulse
Power of control was completely destroyed by mental disease.
Federal IDRA (18 U.S.C. § 17)
Severe mental defect: Unable to appreciate nature & wrongfulness. Volitional barred.
Prong 1: Cognitive Capacity
Appreciation of Criminality / Wrongfulness
Applicable
Lacks substantial capacity to appreciate the wrongfulness of conduct due to mental disease or defect.
Incapacity Level: HighProng Satisfied
Prong 2: Volitional Capacity
Conforming Conduct to Requirements of Law
Applicable
Lacks substantial capacity to conform conduct to the requirements of the law.
Incapacity Level: SevereProng Satisfied
Burden of Proof & Procedural PresumptionMass. Prosecution Shift
In Massachusetts, sanity is initially presumed. Once defense presents evidence creating reasonable doubt, the burden shifts entirely to the Commonwealth to prove criminal responsibility beyond a reasonable doubt.
Presumption of SanityPreponderance (Defense)Proof Beyond Reasonable Doubt (Prosecution)
0%: Default Presumption51%: Standard Affirmative Defense95%+: Commonwealth Standard Once Raised
Trial Finding ProjectionNot Guilty / Insane
Lack of Criminal Responsibility
Under the Massachusetts McHoul standard, satisfaction of either the cognitive OR volitional prong establishes lack of criminal responsibility unless the Commonwealth proves both capacities beyond a reasonable doubt.
Model Jury Instruction Protocol
"The defendant is presumed to have been sane. But if the evidence warrants a reasonable doubt, the Commonwealth must prove beyond a reasonable doubt that at the time of the offense the defendant had substantial capacity both to appreciate the wrongfulness of their conduct and to conform their conduct to the requirements of the law."