162) Under the M'Naghten
rule, (163) the trier of fact must determine whether the defendant could understand the difference between right and wrong and, if not, whether this was due to a mental disease or defect.
For example, the law of insanity is replete with a series of tests: the M'Naghten
cognitive test, (14) the irresistible impulse addition to the M'Naghten
test, the Durham Product Test, (15) the pure medical test used in Norway, (16) and the Model Penal Code's combination of cognitive and volitional tests with the additional overlay of a "substantial capacity" standard.
A slim majority of United States jurisdictions use the M'Naghten
test to determine whether a criminal defendant qualifies for an insanity acquittal.
insanity test even more restrictive than the M'Naghten
But legislatures also routinely restrict the kinds of mental illness which qualify as legal insanity, as Congress famously did in the wake of the attempted assassination of President Reagan by substituting a statutory version of the restrictive M'Naghten
Rule for the then-prevalent federal standard which permitted a finding of insanity based on defects in impulse control.
Under Florida's M'Naghten
Rule, "an accused is not criminally responsible if, at the time of the alleged crime, [he] was, by reason of mental infirmity, disease, or defect unable to understand the nature and quality of his actor its consequences or was incapable of distinguishing right from wrong.
Rule, Model Penal Code, Irresistible Impulse Rule, Durham Rule, and Deific Decree Exception) (2)
129) The historic M'Naghten
test of insanity exculpated a defendant suffering from a "defect of reason, from a disease of the mind," if he did not know the nature and quality of his actions or, even if he did, did not know that they were wrong.
Indeed, he (and Hawthorne) actually anticipated by a few years the use of such an argument in courts of law, as modern American jurisprudence regarding an insanity plea derives from the famous English M'Naghten
case of 1843 and the resulting declaration of the Law Lords in 1848The first American legal case argued--and won--on the grounds of temporary insanity was the famous Sickles trial of 1859.
Most formulations of the dominant M'Naghten
test stand for the proposition that one is excused from criminal responsibility if, provided other elements of the defense are satisfied, one lacks the capacity to know (or, in some jurisdictions, to "appreciate") the wrongfulness (or, in many jurisdictions, the "criminality") of one's conduct.
The pivotal case in defining legal insanity was the M'Naghten
case of 1843.
New York followed the M'Naghten
test, (42) under which acquittal required that Thaw not know the difference between right and wrong, or the nature and quality of his act.