Insanity, in a legal context, term designating a mental incapacity that fundamentally
modifies a person's status under criminal or civil law. Criminal Law In criminal
law, a person's mental condition is directly relevant to three major issues: (1)
competence to stand trial; (2) degree of responsibility for the commission of
a criminal offense; and (3) imposition of an appropriate sentence after conviction.
The issue of competence (or fitness) to stand trial is concerned with a person's
mental condition at the time of the trial. The U.S. Supreme Court has ruled that
a defendant must have "sufficient present ability" to consult with and understand
a lawyer and must also have "a rational as well as factual understanding of the
proceedings against him." An incompetent defendant may not be tried in a criminal
court. The insanity defense is available to an accused person as a means of absolution
from criminal responsibility for his or her conduct. The defense is concerned
with the state of the accused's mind at the time the crime was committed. Because
the insanity defense represents a legal test of criminal responsibility and is
not intended to be a medical definition of mental incapacity, much controversy
has arisen over the legal criteria courts should apply in determining whether
a person should be acquitted on the basis of insanity. The most celebrated test,
which is still applied (with some modifications) in some states and Canada, is
known as the McNaghten Rules (formulated in Great Britain in 1843); its major
provision is whether the accused understood that what he or she was doing was
wrong. The McNaghten test is often supplemented by the so-called irresistible
impulse test, which absolves an accused from responsibility if, because of mental
illness, the person was not capable of controlling his or her conduct. An increasing
number of jurisdictions in the U.S. have replaced these tests with one formulated
by the American Law Institute's 1962 Model Penal Code: "A person is not responsible
for criminal conduct if at the time of such conduct as a result of mental disease
or defect he lacks substantial capacity either to appreciate the criminality (wrongfulness)
of his conduct or to conform his conduct to the requirements of law." Defendants
acquitted on the basis of insanity are sometimes committed to mental institutions
for long periods, although since the 1960s offenders judged insane have been held
for an average of only about two years if deemed no longer dangerous. In recent
years some U.S. and Canadian courts have applied a doctrine of diminished responsibility
that supplements the insanity defense. Under this doctrine, even if the incapacity
of an accused person does not meet the criteria for the insanity defense, mental
illness will result in the reduction of the severity of the charge; for example,
the accused may be convicted of manslaughter instead of the more serious charge
of murder. Where the court is granted a certain amount of discretion in the imposition
of a sentence, a convicted person who was mentally ill at the time of the offense
may be given a lesser sentence. More often than not, cases involving insanity
pleas do not actually go to trial, but adverse public reaction often arises when
such a defense is involved in well-publicized cases. In fact, no standard criterion
for insanity exists among the states of the U.S., and states such as Montana,
Idaho, and Utah have abolished the plea. In 1984 President Ronald Reagan signed
legislation that restricted the insanity defense in federal cases. Groups such
as the American Medical Association have in principle supported the concept that
the insanity defense in criminal trials should be replaced by statutes that provide
for acquittal and appropriate commitment under the "mens rea" rule, which holds
that a defendant, through mental disease or defect, lacks the state of mind required
as an element of the offense charged. Civil Law Mental incapacity is also critical
in a number of civil law situations. A person suffering from severe mental illness
may be committed to a mental hospital for treatment against his or her will. In
cases of severe mental illness, a person may be declared "incompetent" to manage
his or her own affairs, and care of all property may be transferred to some form
of guardianship. A person's "insanity" may prevent involvement in specific types
of legal activities; for example, a court may hold that the person lacks the capacity
to make a will, to enter into a contract or into marriage, to be divorced, to
be sued, or to be a witness in a trial. The tests of incapacity vary both by jurisdiction
and by the nature of the specific legal activity at issue. Also, by reason of
insanity, a person may be prevented from exercising a variety of rights or privileges.
