An insanity defense is based on the theory that most people can choose to follow the law; but a few select persons cannot be held accountable because mental disease or disability deprives them of the ability to make a rational / voluntary choice. Such individuals need special treatment as opposed to prison; punishment is not likely to deter future antisocial conduct of these mentally diseased individuals.

As far back as ancient Rome, legal codes distinguished between those who were "lunatics" and not accountable and those who were sane and responsible.

The Shift in Perception

Before the 1970's, the public outcry over a jury finding a person "not guilty by reason of insanity" ("NGRI") was not nearly as great as it is today. In that time period, insanity acquitees regularly spent many years (even a lifetime) locked in institutions for the criminally insane. An insanity acquittal was a showing of compassion and a recognition of the cruelty to inflict punishment on someone who did not know his actions were wrong. More importantly, the public could rest assured that a person committed to a mental institution would not be walking the streets anytime in the near future (if ever).

In the past twenty years, however, this country has seen a more rapid release of NGRI's from hospitals. This pattern of early release is due to two factors: (1) court rulings that insanity acquitees are entitled to the same constitutional due process and equal protection rights of civil patients; this makes it more difficult to keep an individual in a hospital after recovering from mental illness; and (2) advances in psychiatric treatment. Thus, for the very first time, large numbers of NGRI's could return to the streets. Accordingly, the public is less receptive to a NGRI verdict because the length of confinement may be exceptionally short and a person released is able to exert all rights of a regular citizen; as the person technically has not committed a crime.

In order to fully understand the controversy surrounding the defense of insanity, it is necessary to trace its roots through history -- beginning in 1843 -- when the first uniform insanity rule was developed.

Early Uses -- The M'Naghten Rule

The insanity defense traces its roots back to the 1843 assassination attempt on British Prime Minister Robert Peel. In this case, a psychotic individual named Daniel M'Naghten intentionally and with premeditation killed an assistant to a prime minister of England because he believed he was being persecuted. The defendant plead insanity at the trial. The prosecution attempted to prove sanity by illustrating M'Naghten's behavior in planning and executing the attack. Several physicians testified as to the defendant's even though they never examined the defendant; their conclusions were based on hearing the testimony and observing the defendant's behavior. After the judge gave weight to the physician's opinion, the prosecution agreed to stop the case and the defendant was declared insane.

As could be expected, Queen Victoria and the House of Lords strongly disapproved of the verdict; so they called on fifteen judges of the common law courts, including Lord Chief Justice Tindal, to answer a series of questions about of the law of insanity as applied in M'Naghten. Their responses established the specific test to be applied by a jury in an insanity case and became known as the M'Naghten Rule. Text of M'Naghten Rule

The M'Naghten standard was the predominant test used in the United States from the mid-1800's until approximately 1962. It signaled the beginning of a long process of attempting to integrate the growing body of the psychiatric field with legal principles to define appropriate standards of insanity to use in defense. The test reached its high point in 1851 when it was adopted in the federal court system and a majority of the state courts. In 1982, when Hinckley was tried, only 16 states still used the M'Naghten test; a majority, like the District of Columbia, had adopted some version of the Model Penal Code.

Under the M'Naghten test of insanity, also called the "right-wrong test," a person was not criminally responsible if at the time of the crime, he did not know the nature of the act or that it was wrong. The jury was required to answer two questions: (1) did the defendant know what he was doing when he committed the crime?; or (2) did the defendant understand that his actions were wrong? This test allowed a prosecutor to prove sanity easily by simply showing a defendant understood the moral consequences of an action; mental illness did not matter.

Up until a few decades into the 19th Century, medical testimony was rare at an insanity trial. Often the only evidence of the defendant's mental state was a statement by the defense counsel. If a physician were available, the doctor simply gave a generic list of behaviors generally present in a mentally ill individual; the physician did not examine the defendant. At the time, the medical profession knew little about mental disease and believed insanity to be incurable. The prevailing treatment of the day involved leeches to remove "tainted" blood from the insane.

Changes in Psychiatric Field Bring Changes to Insanity

The psychiatric field began to change in the early part of the 19th Century. New theories of the cause of insanity were developed and optimism on a cure was prevalent. Medical professionals began studying mental illness and it became apparent that the M'Naghten Rule was not working. The test needed to be revised -- but the question was how to revise it.

Irresistible Impulse -- An Alternative to M'Naghten

Many jurisdictions believed that M'Naghten's insanity test was correct, but did not go far enough. The law should not only acquit a person not knowing an act was wrong, but should also acquit one who was unable to prevent themselves from committing the act despite knowledge of wrongfulness. The theory was that mental disease could force one to act against their will--a person could be driven by an Irresistible Impulse.

Criticisms of the test were obvious -- all men have impulses, but society demands that you resist them or face the consequences. Almost anyone can claim a lack of control. Plus, there was no practical way to identify which impulses could have been resisted and which could not. In spite of the notable flaws with the Irresistible Impulse test, by the beginning of the 20th Century almost one-half of the states adopted Irresistible Impulse to supplement the M'Naghten rule.

The Durham Test

The 1950's saw a surge in interest in the field of psychology. The mental problems experienced after World War II brought government attention to the problems of psychiatric disorders. The invention of new psychiatric drugs gave the public hope for a cure of mental problems.

Frustrated with the M'Naghten/Irresistible Impulse standard, the federal circuit court in the District of Columbia discarded the test and adopted the Durham Test in the 1954 case of Durham v. United States, 214 F.2d 862 (1954). The test provided that a person was not criminally responsible if the unlawful act was a product of mental disease or defect. A jury was required to answer two questions: (1) did the defendant have a mental disease or defect?; and (2) if so, was the disease or defect the reason for the unlawful act? Both of the answers had to be "yes" to return a verdict of not guilty by reason of insanity. The test was a recognition of that mental illness was a disease that could be treated and possibly cured.

The test never received wide acceptance in the United States; thirty states and five federal circuits examined the test and ultimately rejected it. In 1972, the D.C. Circuit abandoned the test, declared the Durham experiment a failure, and adopted the American Law Institute Test.

American Law Institute Test

In 1953, a group of distinguished legal and medical professionals known as the American Law Institute ("ALI") began studying the issue of criminal responsibility. The ALI drafted the Model Penal Code test in 1962 and attempted to solve problems of earlier insanity tests. It was designed to implement some psychiatric advances and to avoid the causation problems present in the Durham test. The ALI Test was viewed as broader more expansive test of insanity as compared to the outdated M'Naghten test. Compared to M'Naghten, it lowered the insanity standard from an absolute knowledge of right from wrong to a substantial incapacity to appreciate the difference between right and wrong; thereby recognizing degrees of incapacity. ALI also broadened the insanity test to include a volitional or "irresistible impulse" component. The test focused on the "defendant's understanding of his conduct" and also on the "defendant's ability to control his actions."

Basically, it was a combination of the M'Naghten and Irresistible Impulse tests, only rewritten with different language. By the early 1970's, every federal circuit court except the First and D.C. Circuit had abandoned M'Naghten (whether alone or with the Irresistible Impulse test) and adopted ALI. The ALI Test was seen as a breakthrough and by 1962, it was the law in a majority of states and, until October 1984, the law in a majority of federal courts. Since Hinckley's trial took place in a federal court adopting ALI, it was the test at issue in the his trial. Under the ALI test in federal court, the burden was on the government to prove beyond a reasonable doubt that the defendant was not insane, once enough evidence was presented to raise the issue.

Insanity Test After the Hinckley Verdict

After Hinckley's verdict was announced, the public was outraged (link to public opinion polls) and a number of changes were made to the ability to use insanity as a defense.