Free Term Paper on Insanity Defense

The issue of mental health and insanity has been a controversial one in the court system since the early 13th century. At the time, defendants claiming mental health issues during the commission of a crime were able to pursue different types of judicial outcomes rather than being classified as simply guilty or not guilty. However, the progression of the insanity defense has changed, especially over the past 100 years, which has changed the understanding of its tenets for both the defendant and the general public.


I. Background

II. Legal Developments

III. Controversies of the Insanity Defense

IV. Conclusion


Insanity DefenseOne of the earliest recorded tests for insanity was the “wild beast” test. Created in the 13th century by an English judge in King Edward’s court, the defendant was deemed insane by demonstrating that his or her mental capacity was not greater than that of a wild beast (Lunde 1975). In the early 18th century, the defendant was deemed insane if he or she could no more control his or her actions than a wild beast (Washington v. United States 1967); in other words, the defendant claiming insanity was unable to maintain any sort of self-control and therefore was unable to refrain from committing the crime with which he or she was charged.

The first insanity case involving “not guilty by reason of insanity” as a separate verdict of acquittal was the Hadfield decision. In 1800, James Hadfield attempted to murder King George III with a firearm. He claimed that God had called upon him to undergo self-sacrifice in order to carry out the act. His defense counsel argued that he was delusional and murder of the king was not an intention of Hadfield in his right mind. The jury’s verdict of not guilty by reason of insanity was groundbreaking in initiating a new era of criminal defense (Caesar 1982; Gall 1982; Robin 1997).

Legal Developments

Although the Hadfield decision was an important pioneering step, it was not until almost 50 years later that the landmark McNaghten case drastically changed the insanity defense. In 1843, Daniel McNaghten planned to assassinate England’s Prime Minister Robert Peel but accidentally murdered his secretary instead. During the trial, McNaghten’s attorneys presented psychiatric testimony stating he was under the form of mental delusions that caused him to attempt the murder of Peel. The jury determined that McNaghten had no soundness of mind at the time of the offense and was found not guilty by reason of insanity. He was committed to Bedlam, where he remained until his death (Biggs 1955). The McNaghten decision was not taken well by the residents of England, especially Queen Victoria, who demanded a legislative review of the case. The House of Lords called a judges’ review of the law’s standards of the insanity defense. From this meeting, the McNaghten rule (Rex v. McNaghten 1843), or “right-wrong” test of insanity, was formed, which based a decision of insanity on the perception of the defendant’s knowledge of right and wrong. The test was instituted in not only England but also the United States.

The main criticism of the McNaghten rule was that it considered only impairments of personality and not mentally ill offenders’ inability to emotionally restrain themselves but still have the recognition that an act is wrong. This “irresistible impulse test,” whose origins date back to 1840, was recognized as a separate basis of a determination of insanity. In 1929, the court of appeals in the District of Columbia held in Smith v. United States that an accused must be able not only to prove the inability to determine right and wrong but also to demonstrate the failure to control impulse (Robin 1997).

In 1954, the Court of Appeals for the District of Columbia found that the McNaghten rule, used by all federal courts and many states as a test of insanity for approximately 100 years, was outdated. A modernized version of the rule was implemented with the Durham rule, as the McNaghten rule was found to disregard advances in medical science (Durham v. United States 1945). Monte Durham was convicted of housebreaking in a bench trial; his only defense was that he was of unsound mind. Judge David Bazelon created the Durham rule, which stated that a defendant was not responsible for a crime if the act was a result of a mental disease. The purpose of the new rule was to enable communication between psychiatric experts and the court to ensure proper evaluation of potential insanity (Robin 1997).

The Durham rule was used as the court standard of insanity for approximately two decades. However, an updated definition of insanity was adopted from the American Law Institute (ALI) as a result of United States v. Brawner (1972): “A person is not responsible if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity to appreciate the wrongfulness of his conduct or to confirm his conduct to the requirements of law” (pp. 66–67). The purpose of the ALI-Brawner test, or substantial capacity test, was to cease the reliance on psychiatric testimony and allow the jury to determine insanity. It is also noted in the substantial capacity test that mental disease does not include irregularities caused by recidivist behavior and antisocial behavior.

Shortly after implementation of the ALI-Brawner test, John Hinckley attempted to assassinate President Ronald Reagan on March 30, 1981. At trial, his psychiatrist testified that Hinckley suffered from schizophrenia and was unable to comprehend the magnitude of his act, even though he knew it was illegal. Based on the instruction of the law, the jury found Hinckley not guilty by reason of insanity and a national fury arose (“Insane on All Counts” 1982). The congressional response was the Insanity Defense Reform Act of 1984.

Prior to the passage of the Insanity Defense Reform Act, the majority of federal jurisdictions did not differentiate between the verdict of “not guilty by reason of insanity” and “not guilty”; in other words, a person judged not guilty by reason of insanity was treated the same by law as a person acquitted of a crime (Liu 1993). These jurisdictions did not require courts to inform the jury of the legal consequences of a not guilty by reason of insanity verdict because they felt as if the jury had no role in sentencing. The general rationale was that instruction of the repercussions of such a verdict would divert the jury from their roles as fact finders and compromise verdicts (Pope v. United States 1962). Defendants who were given the verdict not guilty by reason of insanity actually benefited in their defense because their burden of proof was different than that other cases. Generally, in federal and state courts, the burden of proof only had to meet a reasonable doubt regarding sanity.

After the Hinckley decision and the argued discrepancies of the insanity defense, Congress passed the Insanity Defense Reform Act of 1984, which made several changes to the federal law. First, the act allowed defendants to offer evidence that, at the time they committed a crime, demonstrated they were unable to appreciate the wrongfulness of their crime. Second, the responsibility of the burden of proof was switched from the prosecutor to the defense, which had to prove insanity with clear and convincing evidence. Next, the verdict not guilty by reason of insanity became a separate verdict along with guilty and not guilty. Finally and most important, the act addressed a serious loophole in federal law that allowed a defendant to escape commitment after being judged not guilty by reason of insanity (Ellias 1995).

Controversies of the Insanity Defense

The utilization of the insanity defense is not as cut and dried as is stated in the Insanity Defense Reform Act and has caused much controversy with the public. For instance, one might assume that the commitment of a person to a mental institution based on a verdict of not guilty by reason of insanity equates to commitment for life. However, this is not necessarily the case. In Foucha v. Louisiana (1992), the U.S. Supreme Court ruled that a person could not be held indefinitely through commitment with the verdict of not guilty by reason of insanity; therefore, once deemed not a threat to society and “cured,” a person could be released back into society. This may be seen as unfair compared with the probable life sentence received by many other persons convicted of the same type of crime.

A second controversy is the fact that not all states afford the right to the insanity defense. States such as Montana, Idaho, and Utah have banned the use of the insanity defense. In 2006, the U.S. Supreme Court upheld in Clark v. Arizona (2006) that states have the right to deviate from or even totally abolish the use of the defense tactic.


After implementation of the Insanity Defense Reform Act, empirical studies found that the majority of jurors were aware that the verdict not guilty by reason of insanity equated to the involuntary commitment to a mental hospital for the defendant (Ellias 1995). Although early use of the claim of insanity caused media buzz of the assumed overuse of the defense, public perception has settled into the realization of the small frequency of its actual use as well as the necessity of the defense. Although the potential for abuse of the insanity defense is there, as well as the constant controversy over its use, many would argue that there is benefit there for the often mistreated mentally ill offender. Rather than treating such a person like a “wild beast,” there are other options that will offer them the best treatment possible.


Catherine D. Marcum


Legal Citations:

  • Clark v. Arizona, Docket No. 05–5966 (2006).
  • Durham v. United States, 214 F.2d 862 (1954).
  • Foucha v. Louisiana, 504 U.S. 71 (1992).
  • Pope v. United States, 298 F.2d 507 (5th Cir. 1962).
  • Rex v. McNaghten, Clark and Finnelly, 200, 8 Eng. Rep 718, House of Lords (1843).
  • Washington v. United States, 390 F.2d 444 (1967).


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