The Trace Evidence Doctor Speaks - The Insanity Defense

What is your opinion? Do you agree that the insanity defense in criminal law should be used?

It has been described as the most controversial of all criminal defense strategies. Despite several successful cases throughout the United States and Canada that have caused great public outrage, it is the least utilized and the least successful of defenses. The literature indicates that overall, the insanity defense has been raised in about one percent of cases, and only about 26 percent of those have led to a Not Guilty because of Insanity (NGRI) outcome.

The insanity defense says that a criminal defendant is not criminally liable for the offense. Instead, the question is whether the defendant should be held liable for the offense since they may not have had the mental state appropriate not to commit the deed. The theory behind the insanity defense is that a person who is insane cannot commit a criminal act.

Historically, courts did not consider the insanity defense; rather, it was a way for the defendant to receive a pardon or mitigate a sentence. The “Wild Beast” Test dates back to 1256, which determined a defendant to be insane if they were “totally deprived of understanding or memory, and does not know what he is doing, no more than an infant, a brute, or a wild beast.” (Strom, S. 12/9/2023).

The M’Naghten Test followed this test in 1843, in which a member of the American Psychological Association, Issac Ray, wrote “A Treatise on the Medical Jurisprudence of Insanity” in 1838. Soon after that, a defense attorney relied on this document to try a criminal case against Daniel M’Naghten, who had a mental disease that caused paranoid delusions. Because he believed the Catholic Church and the British government dispatched spies to kill him, he planned to kill the Prime Minister but missed and killed his secretary. The insanity defense was used, stating that the defendant could not distinguish right from wrong when the crime occurred. The jury acquitted M’Naghten based on this, much to the chagrin of Queen Victoria, who requested the House of Lords to determine the insanity defense. The rule states that for defendants to prevail on an insanity defense, they must show 1. They had a “defect of reason” from a “disease of the mind” at the time of the criminal act; 2. Due to the disease, they did not understand the nature or quality of their criminal act; or 3. If they understood the act’s nature, they could not appreciate whether it was right or wrong. The United States adopted this rule, setting a new jurisprudence standard.

In 1871, the New Hampshire Supreme Court rejected the M’Naghten Test, ruling that a defendant is not liable for a criminal act if it resulted from a mental illness. New Hampshire treats insanity rather than law and leaves the jury to decide whether the defendant did or did not act of their own volition due to a mental defect or whether the act was simply a deviation of their personality.

In 1887, the Alabama Supreme Court rejected the M’Naghten Rule in favor of The Irresistible Impulse Test, which requires the defendant to show the following:

1. They have a mental illness.

2. The mental illness caused an inability to control their actions or conform their actions to the law. Several states adopted this rule, and some use it in addition to the M’Naghten Rule.

The Durham Rule was established in 1954 and states that a defendant is not criminally liable for an act resulting from a mental illness they had at the time of the crime. This comes from the Washington, D.C., federal court case in which Durham had a history of mental illness and a lengthy criminal record. Courts had institutionalized him three times and released him three times, after which he committed another crime. The Durham Rule states, “An accused is not criminally responsible if the unlawful act was a product of mental disease or mental defect. The Durham Rule emphasized expert testimony regarding whether a defendant’s criminal acts resulted from a cognitive impairment. The Rule did not gain acceptance from other federal courts, and in 1972, the United States Court of Appeals for the District of Columbia abandoned it.

The Model Penal Code of 1962, created by the American Law Institute, stated that defendants are not criminally liable if their conduct resulted from a mental disease or defect, and 1. The defendant could not appreciate that the act was criminal, or 2. The defendant could not conform their acts to the requirements of the law. Many states adopted this code, but it faced deep opposition following the trial of John Hinckley, Jr, in 1982, following the attempted assassination of Ronald Reagan.

Attempted assassination of Ronald Reagan

Hinckley’s acquittal caused public outrage and was followed soon after Congress passed the Insanity Defense Reform Act of 1984. This act shifted the burden of proof from the prosecution to the defendant. Following Hinckley, some states abolished the insanity defense, including Idaho, Montana, and Utah.

These states use the M'Naghten Rule. The burden of proof is on the defendant.

• Alabama 

• California 

• Iowa 

• Louisiana 

• Minnesota

• Missouri

• Nebraska

• Nevada

• North Carolina 

• Ohio

• Pennsylvania

• South Carolina

• South Dakota

• Washington

Florida, New Jersey, and Oklahoma use the M'Naghten Rule, but the state bears the burden of proof.

Colorado and New Mexico use a modified M'Naghten Rule with the Irresistible Impulse Test. The burden of proof is on the state. Texas uses the M'Naghten Rule with the Irresistible Impulse Test. The burden of proof is on the state. Georgia uses a modified version of the M'Naghten Rule. The burden of proof is on the defendant. A guilty but mentally ill verdict is allowed. Mississippi uses the M'Naghten Rule. The burden of proof is on the state. An acquitted because of an insanity verdict is permitted.

The following states use a modified version of the Model Penal Code Rule. The defendant has the burden of proof.

• Arkansas

• Connecticut 

• Delaware

• District of Columbia 

• Illinois 

• Kentucky 

• Maine

• Maryland

• New York 

• Oregon

• Rhode Island

• Vermont

• Wisconsin

• Wyoming

Massachusetts, Michigan, North Dakota, Tennessee, and West Virginia utilize the Model Penal Code Rule. The state bears the burden of proof. Indiana uses a modified version of the Model Penal Rule. The burden of proof is on the defendant.

Alaska uses a modified M'Naghten Rule. The burden of proof is on the defendant. A guilty but mentally ill verdict is allowed. Arizona uses a modified M'Naghten Rule. The burden of proof is on the defendant. A guilty but insane verdict is permitted. Idaho, Kansas, and Montana have abolished the insanity defense. However, in Idaho and Montana, a guilty but insane verdict is allowed. Utah has abolished the insanity defense, but guilty by mental illness verdicts are allowed. New Hampshire uses the Durham standard. The burden of proof is on the defendant.

The insanity defense has many pros and cons. It’s important to remember that the defense doesn’t mean there are no consequences. Often, individuals are determined to need mental health rehabilitation and could be confined to a psychiatric facility for longer than a jail sentence. Psychiatrists and mental health professionals do not decide if the defendant is insane. The final decision lies with the judge and the jury.

What do you think? Should the insanity defense remain a part of our legal system?

Share your thoughts in the comments below—let’s open up the conversation on justice, accountability, and mental health.