• The majority of excuses are personal in nature. They claim that the defendant acted on the basis of some disability or some abnormal condition-such as intoxication, insanity, or immaturity-and that the defendant should not be held responsible for his or her actions.
• Where a defendant suffers from a known disability, that disability alone is not sufficient to excuse him or her of criminal responsibility. Only when the disability has the effect of in some way producing or contributing to the criminal activity in question will the actor be excused.
• Excuses recognized by law include (1) duress, (2) intoxication, (3) mistake, (4) age,
(5) entrapment, (6) insanity, (7) diminished capacity, and, to a limited degree, (8) various “syndromes.”
• The defense of duress, sometimes also called compulsion, is based on the notion that people do not willfully engage in acts that they are compelled or coerced to perform. In most jurisdictions, effective use of the duress defense must be based on a showing that the defendant feared for his or her life, was in danger of great bodily harm, or was acting so as to prevent the death or bodily harm of another. Likewise, for the duress defense to be effective, the threat under which the defendant acted must have been immediate, clear, and inescapable and must not have arisen from some illegal or immoral activity of the defendant.
• Voluntary intoxication is generally not a defense because individuals are responsible for their impaired state, and the law generally holds that those who voluntarily put themselves in a condition so as to have little or no control over their actions must be held to have intended whatever consequences ensue.
• Involuntary intoxication may serve as a defense if it creates in the defendant either an incapacity to appreciate the criminality of his or her conduct or an incapacity to conform his or her behavior to the requirements of the law.
• Mistake of fact will preclude criminal liability in instances in which the actions undertaken would have been lawful had the situation been as the acting person reasonably believed them to be. However, mistake of law, or ignorance of the law, rarely provides an effective defense.
• Infancy, or immaturity, defenses claim that certain individuals should not be held criminally responsible for their activities by virtue of their youth. Most jurisdictions do not impose full criminal culpability on children under the chronological age of 18, while a number of states set the age of responsibility at 16, and some at 17.
• The entrapment defense is built on the assertion that had it not been for government instigation, no crime would have occurred. Two approaches to assessing entrapment can be found in the law: the subjective and the objective. The subjective approach excludes from criminal liability otherwise innocent individuals who were lured into the commission of the crime through the government’s instigation. The objective approach to entrapment, also referred to as the outrageous government conduct defense, is based on the claim that methods employed by the government to bring about a conviction in the case are offensive to moral sensibilities.
• In recent years, a number of new and innovative defense strategies based on the use of “syndromes” have been proposed-with varying degrees of success. Among the syndromes through which claims for the expansion of traditional defenses have been made are battered woman’s syndrome, premenstrual syndrome, sexual abuse syndrome, urban survival syndrome, and black rage syndrome.
• Although courts have been reluctant to recognize the claim that syndromes negate mens
rea, the use of syndromes in expanding the applicability of traditional defenses has met with greater success. Nonetheless, the future of syndrome-based defenses remains very much in doubt.
• Insanity is a social and legal term rather than a medical one. Psychiatrists speak instead of mental disorders and do not use the term insanity, making it difficult to fit expert psychiatric testimony into legal categories. Nonetheless, the legal concept of insanity still has its basis in some disease of the mind.
• Competency to stand trial focuses on the defendant’s condition at the time of trial rather than at the time of the crime. Competency to stand trial exists when a defendant has sufficient present ability to consult with his or her lawyer with a reasonable degree of rational understanding and has a rational as well as factual understanding of the proceedings against him or her.
• The insanity defense recognizes that some people, by virtue of mental disease or mental defect, cannot morally and justly be held accountable for their actions. Insanity can affect criminal liability in two ways: (1) It may result in a finding that the mens rea required for a specific crime was lacking at the time the crime was committed or (2) it may lead to a showing that although the requisite mens rea was present at the time of the crime, the defendant should be excused from legal responsibility because of mental disease or defect.
• The defense of insanity is an affirmative defense and must be raised by the defendant. If successful, an insanity defense results in a verdict of not guilty by reason of insanity (NGRI).
• The M’Naughten rule, an early test, held that a person was insane if he or she “was laboring under such a defect of reason, from disease of 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 he was doing what was wrong.”
• The claim of irresistible impulse is a defense in some jurisdictions. The irresistible impulse test asks whether, at the time the crime was committed, a mental disease or disorder prevented the defendant from controlling his or her behavior.
• The Durham rule, also known as the product rule, holds that an accused is not criminally responsible if his or her unlawful act was the product of mental disease or mental defect.
• The American Law Institute’s substantial capacity test, which is incorporated into the
Model Penal Code, says that a person is not responsible for criminal conduct if at the time of such conduct, and as a result of mental disease or defect, he or she lacked substantial capacity either to appreciate the criminality of the conduct or to conform the conduct to the requirements of the law.
• A guilty but mentally ill (GBMI) verdict establishes that a defendant, although mentally ill, was sufficiently in possession of his or her faculties to be morally blameworthy for the criminal act.
• The defense of diminished capacity, also called diminished responsibility, is available in some jurisdictions. It is based on claims that a defendant’s mental condition at the time of the crime, although not sufficient to support the affirmative defense of insanity, might still lower criminal culpability. A finding of diminished capacity may result in a verdict of guilty to lesser charges.
• The insanity defense is not widely used and is raised in only about 1 percent of all criminal cases. Defendants found “not guilty by reason of insanity” are rarely set free but are instead committed to a mental hospital until confinement is no longer deemed necessary.
• Because of the difficulties associated with assessing insanity from a legal perspective, a number of jurisdictions have eliminated the insanity defense. While some states no longer allow defendants to raise the insanity defense as an excuse to a criminal charge, defendants in all jurisdictions may still claim that the presence of mental disease at the time of the crime left them unable to form the mens rea needed for criminal activity.