Insanity Defense

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Related to Plea of temporary insanity: Mental disease or defect

Insanity Defense



Another form of the insanity defense is volitional insanity, or Irresistible Impulse. A defense of irresistible impulse asserts that the defendant, although able to distinguish right from wrong at the time of the act, suffered from a mental disease or defect that made him or her incapable of controlling her or his actions. This defense is common in crimes of vengeance. For example, suppose that a child has been brutally assaulted. If an otherwise conscientious and law-abiding mother shoots the perpetrator, the mother may argue that she was so enraged that she became mentally ill and incapable of exerting self-control. Very few states allow the volitional insanity defense.

The insanity defense should not be confused with Incompetency. Persons who are incompetent to stand trial are held in a mental institution until they are considered capable of participating in the proceedings.The insanity defense also should be kept separate from issues concerning mental retardation. The U.S. Supreme Court ruled in 2002 in Atkins v. Virginia, 536 U.S. 304, 122 S. Ct. 2242, 153 L. Ed. 2d 335 (2002) that the execution of mentally retarded criminals constituted "cruel and unusual punishment" and that it was prohibited by Eighth Amendment. But if a person is acquitted by reason of insanity, execution is not an option.

The insanity defense reflects the generally accepted notion that persons who cannot appreciate the consequences of their actions should not be punished for criminal acts. Most states regulate the defense with statutes, but a few states allow the courts to craft the rules for its proper use. Generally, the defense is available to a criminal defendant if the judge instructs the jury that it may consider whether the defendant was insane when the crime was committed. The judge may issue this instruction if the defendant has produced sufficient evidence at trial to justify the theory. Sufficient evidence invariably includes Expert Testimony by psychologists and psychiatrists.

When invoking insanity as a defense, a defendant is required to notify the prosecution. In some states, sanity is determined by the judge or jury in a separate proceeding following the determination of guilt or innocence at trial. In other states, the defense is either accepted or rejected in the verdict of the judge or jury. Even if evidence of insanity does not win a verdict of not guilty, the sentencing court may consider it as a mitigating factor.


"Complete madness" was first established as a defense to criminal charges by the common-law courts in late-thirteenth-century England. By the eighteenth century, the complete madness definition had evolved into the "wild beast" test. Under that test, the insanity defense was available to a person who was "totally deprived of his understanding and memory so as not to know what he [was] doing, no more than an infant, a brute, or a wild beast" (Feigl 1995, 161).

Colin Ferguson

Colin Ferguson was convicted in March 1995 for crimes associated with a massacre in Long Island, New York, on December 7, 1993. Ferguson killed six persons and injured nineteen after opening fire with an automatic pistol on a crowded commuter train.

Ferguson's trial was marked with controversy. He discharged his court-appointed attorneys, who believed him mentally incompetent to stand trial, and was allowed by the judge to act as his own attorney. He dropped the insanity defense prepared by his attorneys and argued that a mysterious gunman had committed the shootings.

His bizarre courtroom behavior appeared to contradict the judge's conclusion that Ferguson was competent to stand trial. Though many witnesses identified Ferguson as the gunman, he insisted a white man had taken the gun from his bag while he slept, shot the passengers, and then escaped, leaving Ferguson, who is black, to take the blame. During the trial he asserted that he had been charged with ninety-three counts only because the crime occurred in 1993.

Attorneys Ronald L. Kuby and william m. kunstler, whom Ferguson had discharged, had asked the judge before trial to find that Ferguson's paranoia and delusional state made him mentally incompetent to stand trial. Yet Ferguson refused to be examined by either prosecution or defense psychiatrists, believing he was not insane. The judge allowed Ferguson to stand trial, believing he could understand the nature of the charges against him and could assist in his own defense.

By 1840, most jurisdictions had refined the wildbeast test to cognitive insanity and supplemented that with irresistible impulse insanity. However, in 1843, a well-publicized assassination attempt in England caused Parliament to eliminate the irresistible impulse defense. Daniel M'Naghten, operating under the delusion that Prime Minister Robert Peel wanted to kill him, tried to shoot Peel but shot and killed Peel's secretary instead. Medical testimony indicated that M'Naghten was psychotic, and the court acquitted him by reason of insanity (M'Naghten's Case, 8 Eng. Rep. 718 [1843]). In response to a public furor that followed the decision, the House of Lords ordered the Lords of Justice of the Queen's Bench to craft a new rule for insanity in the Criminal Law.

What emerged became known as the M'Naghten Rule. This rule migrated to the United States within a decade of its conception, and it stood for the better part of the next century. The intent of the M'Naghten rule was to abolish the irresistible-impulse defense and to limit the insanity defense to cognitive insanity. Under the M'Naghten rule, insanity was a defense if


Through the first half of the twentieth century, the insanity defense was expanded again. Courts began to accept the theories of psychoanalysts, many of whom encouraged recognition of the irresistible-impulse defense. Many states enacted a combination of the M'Naghten rule supplemented with an irresistible-impulse defense, thereby covering both cognitive and volitional insanity.

The insanity defense reached its most permissive standard in Durham v. United States, 214 F. 2d 862 (D.C. Cir. 1954). The Durham rule excused a defendant "if his unlawful act was the product of mental disease or mental defect." The Durham rule was lauded by the mental health community as progressive because it allowed psychologists and psychiatrists to contribute to the judicial understanding of insanity. But it was also criticized for placing too much trust in the opinions of mental health professionals. Within seven years of its creation, the rule had been explicitly rejected in 22 states. It is used only in New Hampshire.

Is There a Need for the Insanity Defense?

Though the insanity defense is rarely invoked in criminal trials, it remains a controversial issue. Legislators and the public generally question the need for the defense after a defendant in a highly publicized murder case is found not guilty by reason of insanity. For example, when John Hinckley successfully used the defense after shooting President ronald reagan to impress the actress Jodie Foster, there was a public outcry. Legal and medical commentators have divided opinions about the need for the insanity defense.

Those who wish to retain it note that forty-eight of the fifty states have some type of insanity defense. This, they claim, is evidence of the need for such a defense. The public is given a distorted view of who uses the defense and how it is employed. In fact about one percent of criminal defendants invoke the defense. More important, criminals rarely "beat the rap" by Pleading insanity. When an insanity defense is employed, it means the defendant admits committing the criminal behavior and is now seeking a not guilty verdict on the basis of his state of mind. If the jury does not agree, the defendant will be convicted, and generally will serve a longer sentence than will someone convicted of the same crime who has not pleaded insanity.

Juries find for only about 20 percent of the defendants who plead insanity. Even this figure does not reflect the reality that many insanity pleas are the result of plea bargains, which indicates that prosecutors agree that such pleas are sometimes appropriate.

Finally, the fact that most highly publicized cases involve murder disguises the true demographics: 60 to 70 percent of insanity pleas are for crimes other than murder. They range from assault to shoplifting.

All these myths have led to the belief that criminals can avoid punishment by claiming insanity. The truth is that the insanity defense is a risky one at best.


Based on this argument, proponents of the insanity defense do not support its application to a person who willingly consumes a powerful hallucinogen and then commits a criminal act. Nor would they allow its application to a person who is able to control a mental disorder through medication but fails to do so. But they do support the defense for a person who unwittingly consumes hallucinogens and then commits a crime.

Some opponents attack the insanity defense for confusing psychiatric and legal concepts, in the process undermining the moral integrity of the law. Both sides agree that the word insane is a legal, not medical, term. It is too simplistic to describe a severely mentally ill person merely as insane, and the vast majority of people with a mental illness would be judged sane if current legal tests for insanity were applied. The legal tests for insanity, moreover, require that a defendant's mental condition become so impaired that the fact finder may conclude the person has lost his or her free will. Because free will is not a concept that can be explained in medical terms, it may be impossible for a psychiatrist to determine if the mental impairment affected the defendant's capacity for voluntary choice. Without a way to measure insanity, it makes no sense to let prosecution and defense psychiatrists spar over the issue. A jury's decision based on psychiatrists' opinions may be grounded on unreliable evidence.

Another major argument against the insanity defense challenges its supposed moral basis. Critics contend that modern criminal law is concerned more with the consequences of crime and less with moral imperatives. If a person commits a criminal act, that person should be convicted. Mental illness can be taken into consideration at the time of sentencing. This line of reasoning supports laws that several states have adopted, which abolish the insanity defense and replace it with a new verdict of guilty but insane. This verdict carries a criminal penalty. It allows the judge to determine the length of imprisonment, which occurs in a hospital prison, and shifts the burden to the defendant to prove he is no longer dangerous or mentally ill in order to be released.

Finally, critics argue that the insanity plea is a rich person's defense. Only wealthy defendants can retain high-priced psychiatric experts. Persons represented by public defenders are usually afforded a psychiatric examination for the defense, but they may not get the same quality of exam, nor are they typically able to hire more than one examiner. Because a two-tiered criminal justice system is morally repugnant, critics contend that the insanity defense must be abolished.

In 1964, the American Law Institute (ALI) began to reassess the insanity defense in the course of promoting a new Model Penal Code. What emerged from the Model Penal Code Commission was a compromise between the narrow M'Naghten test and the generous Durham rule. The ALI test provided that a person was not responsible for criminal conduct if, at the time of the act, the person lacked "substantial capacity" to appreciate the conduct or to conform the conduct to the Rule of Law. The ALI test provided for both cognitive and volitional insanity. It also required only a lack of substantial capacity, less than complete impairment. The ALI version of the insanity defense was adopted by more than half the states and all but one federal circuit.

Several years later, another dramatic event led to another round of restrictions on the insanity defense. In 1981, John W. Hinckley, Jr., attempted to assassinate President ronald reagan. Hinckley was prosecuted and acquitted of all charges by reason of insanity, and a resulting public outcry prompted Congress to enact legislation on the issue. In 1984, Congress passed the Insanity Defense Reform Act (Insanity Act) (18 U.S.C.A. § 17 [1988]) to abolish the irresistible-impulse test from federal courts. Initially, Reagan had called for a total abolition of mental illness as a defense to criminal charges, but his administration backed down from this position after intense Lobbying by various professional organizations and trade associations.

The Insanity Act also placed the burden on the defendant to prove insanity. Before the Insanity Act, federal prosecutors bore the burden of proving the defendant's sanity Beyond a Reasonable Doubt.

Most states joined Congress in reevaluating the insanity defense after Hinckley's acquittal. The legislatures of these states modified and limited the insanity defense in many and varied ways. Some states shifted the Burden of Proof, and some limited the applicability of the defense in the same manner as Congress did. A few states abolished the defense entirely. Chief Justice william h. rehnquist, of the U.S. Supreme Court, opined in a dissent that it is "highly doubtful that due process requires a State to make available an insanity defense to a criminal defendant" (Ake v. Oklahoma, 470 U.S. 68, 105 S. Ct. 1087, 84 L. Ed. 2d 53 [1985]).


When a party successfully defends criminal charges on a ground of insanity, the consequences vary from jurisdiction to jurisdiction. Usually, the defendant is committed to a mental institution. On the average, a defendant found not guilty by reason of insanity and committed to a mental institution is confined for twice as long as is a defendant who is found guilty and sent to prison. Very few acquitted insanity defendants are given supervised release, and even fewer are released directly following their verdict.

The detention of an insanity acquittee is limited by law. The acquittee must be allowed periodic review in the mental institution, to determine whether continued treatment is necessary. In addition, a hospital facility may not hold an insanity acquittee indefinitely merely because the acquittee has an antisocial personality (Foucha v. Louisiana, 504 U.S. 71, 112 S. Ct. 1780, 118 L. Ed. 2d 437 [1992]).

The procedural framework in Massachusetts illustrates the consequences that come with the insanity defense. Under chapter 123, section 16, of the Massachusetts General Laws Annotated, the court may order a person found not guilty by reason of insanity (an insanity acquittee) to be hospitalized for 40 days for observation and examination. During this period, the district attorney or the superintendent of the mental hospital may petition the court to have the insanity acquittee committed to the hospital. If the judge orders the commitment, the acquittee is placed in the hospital for six months.

After the first six months have expired, the commitment is reviewed again, and then once a year thereafter. If the superintendent of the mental health facility moves to discharge the acquittee, the district attorney must respond with any objections within 30 days of notice from the superintendent. The mental health facility is authorized to restrict the movement of criminal defendants and insanity acquittees, so a commitment is tantamount to incarceration.

Defendants' Rights

When Pleading insanity, a defendant might not want to present the best possible image at trial. In Riggins v. Nevada, 504 U.S. 127, 112 S. Ct. 1810, 118 L. Ed. 2d 479 (1992), defendant David Riggins was charged with robbing and murdering Las Vegas resident Paul Wade. After being taken into custody, Riggins complained that he was hearing voices in his head and that he was having trouble sleeping. A psychiatrist at the jail prescribed 100 milligrams per day of Mellaril, an antipsychotic drug. By the time of trial, the psychiatrist was prescribing 800 milligrams per day of Mellaril.

Just before trial, Riggins's attorney moved the court to suspend administration of the Mellaril. Riggins was pleading not guilty by reason of insanity, and his attorney wanted the jury to see Riggins in his natural state. According to one psychiatrist, Dr. Jack Jurasky, Riggins "would most likely regress to a manifest psychosis and become extremely difficult to manage" if he were taken off Mellaril.

The court denied the motion, and Riggins was convicted and sentenced to death. The Nevada Supreme Court affirmed Riggins's convictions and death sentence. On appeal to the U.S. Supreme Court, the convictions were reversed. According to the high court, Nevada had violated Riggins's due process rights under the Sixth and Fourteenth Amendments. In the absence of evidence that the treatment was medically appropriate and essential for Riggins's own safety or the safety of others, and without an exploration of less intrusive alternatives, the trial court had erred by denying Riggins's liberty interest in freedom from antipsychotic drugs.

According to the Court, the administration of the Mellaril jeopardized a number of Riggins's trial rights. Not only was it possible that the Mellaril had affected Riggins's outward appearance, and thus his defense, but the high daily dosage of Mellaril also might have affected Riggins's testimony, his ability to communicate with his attorney, and his ability to follow the proceedings. Although the defense had been allowed to present expert testimony on the nature of Riggins's mental condition, the Court concluded that the compromise of Riggins's trial rights was reversible error.

Uses and Abuses

Victims of abuse often allege temporary insanity in defending their own violent behavior. For example, in 1994, Virginia resident Lorena Bobbitt, charged with severing her husband's penis with a knife, was acquitted of assault charges on the ground of temporary insanity. At trial, Bobbitt testified that her husband had abused her physically and emotionally.

Critics complain that the insanity defense is abused by defense attorneys, who use it to free the perpetrators of deliberate criminal acts. However, 95 percent of all persons found not guilty by reason of insanity are detained in hospitals, and in practice, the insanity defense is rarely invoked and rarely successful. The insanity defense is used by defendants in only one percent of all felony cases, and it results in acquittal in only one-quarter of those cases.

Psychopaths and Sociopaths

When most people hear about the insanity defense, they automatically assume that it can be used applied to people commonly referred to as psychopaths and sociopaths. While traditionally there has been a small degree of difference between these two classifications, the American Psychiatric Associations most recent Diagnostic and Statistical Manual—Fourth Edition ("DSMIV") groups sociopathy and psychopathy under the heading "antisocial personality disorder." The DSM-IV lays out a limited and concise set of diagnostic criteria on which to base the diagnosis of antisocial personality disorder.

According to the DSM-IV, antisocial personality disorder is characterized by pervasive pattern of disregard for, and violation of, the rights of others occurring since age 18, as indicated by three (or more) of the following: (1) failure to conform to social norms with respect to lawful behaviors as indicated by repeatedly performing acts that are grounds for arrest; (2) deceitfulness, as indicated by repeated lying, use of aliases, or conning others for personal profit or pleasure; (3) impulsivity or failure to plan ahead; (4) irritability and aggressiveness, as indicated by repeated physical fights or assaults; (5) reckless disregard for safety of self or others; (6) consistent irresponsibility, as indicated by repeated failure to sustain consistent work behavior or to honor financial obligations; (7) lack of remorse, as indicated by being indifferent to, or rationalizing, having hurt, mistreated, or stolen from another.

However it is defined, many in the legal community doubt whether the insanity defense covers this kind of behavior at all. The ALI's Model Penal Code test of insanity states that "the terms mental disease or defect do not include an abnormality that is manifested only by repeated criminal or otherwise antisocial conduct." In other words, the criteria laid down by the DSMIV for antisocial personality disorder would not allow for a claim of insanity under the Model Penal Code, the most widely used insanity test, or in other insanity tests used by states. Thus, sociopaths and psychopaths, while perceived as insane by most people, could likely not use the insanity defense as a defense in a court of law.

For this reason, most celebrated serial killers such as John Wayne Gacy and Ted Bundy, as well as persons whose mental stability seems to be of a questionable nature, such as Ted Kaczynski, have seen their insanity pleas fail or have never used the defense. In fact, in recent years, only Hinckley and Bobbitt are among celebrated cases who have used the defense successfully. For criminals with antisocial personality disorder, the insanity plea simply does not apply.

Further readings

American Psychiatric Association. 1994. Diagnostic and Statistical Manual of Mental Disorders—Fourth Edition. Washington D.C.: American Psychiatric Press.Bing, Jonathan L. 1996. "Protecting the Mentally Retarded from Capital Punishment: State Efforts Since Penry and Recommendations for the Future." New York University Review of Law and Social Change 22.

Campbell, Emily. 1990. "The Psychopath and the Definition of 'Mental Disease or Defect' Under the Model Penal Code Test of Insanity: A Question of Psychology or a Question of Law?" Nebraska Law Review 69.

Ellickson, Robert C. 1996. "Controlling Chronic Misconduct in City Spaces: Of Panhandlers, Skid Rows, and Public-Space Zoning." Yale Law Journal 105.

Giorgi-Guarnieri, Deborah, et. al. 2002. "Practice Guideline; Forensic Psychiatric Evaluation of Defendants Raising the Insanity Defense." Journal of the American Academy of Psychiatry and the Law 30 (June).

Kuby, Ronald L., and William M. Kunstler. 1995. "So Crazy He Thinks He Is Sane: The Colin Ferguson Trial and the Competency Standard." Cornell Journal of Law and Public Policy 5.

LaFond, John Q., and Mary L. Durham. 1992. Back to the Asylum: The Future of Mental Health Law and Policy in the United States. New York: Oxford Univ. Press.

Melville, John D., and David Naimark. 2002. "Punishing the Insane: The Verdict of Guilty but Mentally Ill." Journal of the American Academy of Psychiatry and the Law 30 (December): 553–5.

Morse, Stephen J. 1985. "Excusing the Crazy." Southern California Law Review 58.

Rogers, Richard, and and Daniel Shuman. 2000. Conducting Insanity Evaluations. 2d ed. New York: Guilford Press.

Semrau, Stanley, and Judy Gale. 2002. Murderous Minds on Trial: Terrible Tales from a Forensic Psychiatrist's Case Book. Toronto, Tonawanda, N.Y.: Dundurn Press.


M'naghten Rule.


insanity defense

n. the claim of a defendant in a criminal prosecution that he/she was insane when the crime was committed, usually only temporarily. (See: insanity, temporary insanity)
