State v. Johnson

Majority - Doris, J.

Yes. The M’Naghten test for criminal responsibility is an outmoded standard that must be replaced. The court adopts a new standard, based on the Model Penal Code, which holds that a person is not criminally responsible if a mental disease or defect results in a substantial impairment of their capacity either to appreciate the wrongfulness of their conduct or to conform their conduct to the law. The M’Naghten rule, which focuses exclusively on cognitive capacity (the ability to 'know' right from wrong), is based on antiquated psychological theories that inaccurately view the human mind as compartmentalized. Modern science recognizes that mental illness affects the whole personality, including volitional and emotional capacities, which M'Naghten ignores. The old rule's 'all-or-nothing' requirement of total cognitive incapacity is unrealistic and prevents the jury from receiving a complete picture of the defendant's mental state from expert witnesses. The new standard rectifies these deficiencies by recognizing volitional impairment, adopting the more realistic 'substantial capacity' threshold, and using language that allows for a meaningful dialogue between experts, lawyers, and the jury. Ultimately, this new test properly frames the issue of responsibility as a legal and moral question for the jury to decide based on community standards, rather than as a purely medical diagnosis.