IRRESISTIBLE IMPULSE

A test applied in a criminal prosecution to determine whether a person accused of a crime was compelled by a mental disease to commit it and therefore cannot be held criminally responsible for her or his actions; in awrongful deathcase, a compulsion to commit suicide created by the defendant.

In most jurisdictions, a person may defend criminal charges on a ground of insanity. The insanity defense comes in two main forms. First, a defendant may argue that because of mental disease or defect, he or she lacked the capacity to distinguish right from wrong. This is cognitive insanity.

Second, a defendant may argue that because of mental disease or defect, she or he was unable to act in conformance with the law. This is volitional insanity, and it is known as the irresistible impulse defense. Under this defense, a defendant may be found not guilty by reason of insanity even though she or he was capable of distinguishing right from wrong at the time of the offense.

The success of an irresistible impulse defense depends on the facts of the case. For example, assume that a child has been molested. If the child's mother shoots and kills the suspected molester, the mother could argue that she was so enraged by the violation of her child that she was unable to control her actions. The mother need not have been diagnosed as mentally ill. Rather, she would need to show that she was mentally ill at the time of the shooting, and that the illness impaired her self-control.

Irresistible impulse emerged as a defense in the nineteenth century, when psychoanalysts formulated the concept of moral insanity to describe the temporary inability of otherwise sane persons to resist criminal behavior. Courts began to recognize the condition as one that rendered conduct involuntary and therefore not suitable for punishment. For the better part of a century, many states allowed both cognitive insanity and irresistible impulse insanity as defenses.

Congress and most states abolished the irresistible impulse defense after John Hinckley was acquitted on grounds of insanity for the attempted assassination of President ronald reagan in 1981. Only a handful of states currently allow irresistible impulse as a defense to criminal charges. These states permit it as a supplement to the cognitive insanity defense, which is the only insanity defense recognized in most jurisdictions. On the federal level, Congress abolished the irresistible impulse defense in the Insanity Defense Reform Act of 1984 (18 U.S.C.A. §§ 1 note, 17).

In some states, the irresistible impulse defense has never been adopted. In others, it has been adopted and subsequently withdrawn. Where it has been rejected, the reasons are generally the same: to prevent sane persons from escaping liability simply because they were unable to control their actions. In the words of one court, "There are many appetites and passions which by long indulgence acquire a mastery over men … but the law is far from excusing criminal acts committed under the impulse of such passions" (State v. Brandon, 53 N.C. 463 [1862]).

Under the model penal code definition of irresistible impulse, a person may be found not guilty by reason of insanity if, at the time of the offense, he or she lacked "substantial capacity either to appreciate the criminality of [the] conduct or to conform [the] conduct to the requirements of law" (§ 4.01(1) [1962]). The "lacked substantial capacity" language creates a low threshold for the defendant: in some states, the defendant must allege complete impairment in order to invoke the defense.

Irresistible impulse is also a factor in civil actions. When a person commits suicide, survivors may sue for damages with a wrongful death claim or similar action if they can show that the suicide was caused by the actions of another person. In such a case, the plaintiffs must prove that the defendant caused a mental condition that caused the decedent to experience an irresistible impulse to commit suicide.