Understanding the Insanity Defense

Legal Tests to Determine “Insanity”

“Insanity” is a legal term that presupposes a medical illness or defect but is not synonymous with “mental illness,” “mental disorder,” and “mental disease or defect.” “Mental illness” is a more encompassing term than “insanity,” and thus, a person can be mentally ill – medically speaking – without legally being insane. Five tests of insanity have been applied at one time or another.

To establish a defense on the grounds of insanity, it must be clearly proved that, at the time of committing the act, 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, that he did not know that what he was doing was wrong.

The M’Naghten rule focuses exclusively on cognitive disability.

Under this rule, a person is insane if, at the time of the criminal act, he was laboring under such a defect of reason, arising from a disease of the mind, that he (1) did not know the nature and quality of the act that he was doing; or (2) if he did know it, he did not know that what he was doing was wrong.

This test requires total cognitive disability and does not allow for degrees of incapacity and nor does it recognize volitional incapacity in which a person is aware that conduct is wrong yet cannot control his behavior.

Some jurisdictions have broadened the scope of M’Naghtento include mental illnesses that affect volitional capacity. Generally speaking, a person is insane if, at the time of the offense:

1. he acted from an “irresistible and uncontrollable impulse”;
2. he was unable to choose between the right and wrong behavior;
3. his will was destroyed such that his actions were beyond his control.

The Model Penal Code provides that a person is not responsible for his criminal conduct if, at the time of the conduct, as the result of a mental disease or defect, he lacked substantial capacityto:

1. appreciate the “criminality” (or “wrongfulness”) of his conduct; or
2. to conform his conduct to the requirements of the law.

This test does not require total mental incapacity.

This rule, now defunct, provided that a defendant’s criminal behavior may be excused if he was suffering from a mental disease or defect at the time of the offense and the criminal conduct was the product of the mental disease or defect.

The Federal Test – In 1984, Congress enacted a statutory definition of insanity applicable to federal criminal trials. [18 U.S.C. § 17(a) (2000)] The federal law provides that a defendant may be excused based on insanity if he proves by clear and convincing evidence that, at the time of the offense, as the result of a severe mental disease or defect, he was unable to appreciate: (1) the nature and quality of his conduct; or (2) the wrongfulness of his conduct.

This test requires complete cognitive incapacity.

The Effect of an Insanity Acquittal – Mental Illness Commitment Procedures

Automatic Commitment – In many states, a person found “not guilty by reason of insanity” [NGRI] is automatically committed to a mental facility on the basis of the verdict. Under automatic-commitment laws, the NGRI-acquittee is not entitled to a hearing to determine whether he continues to suffer from a mental illness, or to determine whether his institutionalization is necessary for his protection or for that of society.

Discretionary Commitment – In some jurisdictions, commitment of an insanityacquittee is not automatic. Typically, however, the trial judge has authority to require a person found NGRI to be detained temporarily in a mental facility for observation and examination, in order to determine whether he should be committed indefinitely.

Criteria for Release – An insanity-acquittee may be detained as long as she is both mentally ill and dangerous to herself or others. [Foucha v. Louisiana, 504 U.S. 71 (1992)].

Length of Confinement – An insanity-acquittee is committed for as long as necessary until she meets the criteria for release. She may remain in a mental hospital for a longer period of time than she would have served in a prison had she been convicted of the crime that triggered her commitment. [Jones v. United States, 463 U.S. 354, 370 (1983)]

Sexual Predator Laws – More than fifteen states have enacted highly controversial “sexual predator” statutes which provide for commitment and treatment of sexual violators, defined generally as persons convicted of or charged witha sexually violent offense and who suffer from a mental abnormality or personality disorder which makes further sexual predatory acts likely. To invoke the law, a prosecutor typically files a petition in a state court seeking the individual’s involuntary commitment. If there is probable cause to believe that the person is a sexual predator, the individual is transferred to a mental facility for evaluation, after which a full hearing is held. If the court determines beyond a reasonable doubt that the individual is a sexually violent predator, he is committed until he deemed safe to be released into the community.

Four states – Idaho, Kansas, Montana, and Utah – have abolished the insanity defense, but permit a defendant to introduce evidence of his mental disease or defect in order to rebut the prosecution’s claim that he possessed the requisite mental state.

A number of states have adopted an alternative verdict, “guilty but mentally ill” [GBMI]. In all but two of these states, the insanity defense has been retained. In these states, the jury returns a NGRI verdict if the defendant was insane at the time of the crime; it returns a GBMI verdict if he is guilty of the offense, was sane at the time of the crime, but is “mentally ill,” as the latter.