THE JUROR STANDS IN THE COURTROOM. Everyone is silent and is seemingly holding their breaths. After a few seconds that lasted more like minutes, the juror declares in a loud voice, “We find the defendant not guilty by reason of insanity”. Scenes such as this are highly popularized and dramatized in TV shows like Criminal Minds, CSI, or Law And Order. And like any avid fan of crime dramas, we think we know what it means. But do we?
Establishment of Guilt
If someone accidentally hits another person with their car, is the driver guilty of a crime? If a person kills in the act of self defense, will that person be held liable for taking a life? What if the perpetrator is mentally insane? What happens when a guilty mind is absent?
There are three elements of a crime, and these elements come together to establish guilt or criminal liability. Every crime involves an act (actus reus), state of mind (mens rea), and causation. Not Guilty by Reason of Insanity (NGRI) revolves around the second element, mens rea. Mens rea is the qualification that a person had the required state of mind during the commission of the crime. Examples of this would be premeditation, recklessness, or negligence. If this qualification is absent, a guilty verdict cannot be found. Under this framework, an NGRI plea proposes that a defendant is not guilty because of insanity.
Insanity is not just a psychiatric term. It is actually a legal term. In a legal perspective, insanity goes around the premise that the defendant was not of sound mind when a criminal act was committed. However, an NGRI does not apply to every mentally ill defendant. This is because suffering from a mental disorder does not necessarily prove insanity.
Insanity assessment helps to determine if a person should be granted an NGRI verdict. Contrary to what we see in TV crime shows, insanity pleas have a high failure rate. Only 1% of criminal pleas in the U.S. are NGRI. And within this diminutive percentage, only 25% successfully establish insanity.
Certain criteria need to be met to validate insanity. And this is no easy feat. The courts rely on the judgement and expertise of a forensic psychologist or psychiatrist in establishing a defendant’s mental state at the time of the crime. These experts use certain guidelines when performing insanity assessment on an individual. They determine legal insanity by applying one or more of the following guidelines:
Established by the English House of Lords in the 19th century, the M’Naghten Rule determines that a person cannot differentiate between right and wrong when committing the crime. Moreover, the person did not possess the mental capacity to understand the nature and quality of the crime. This rule is also known as the right-or-wrong test.
The rule was established in 1843 in England following the trial of Daniel M’Naghten, who killed the prime minister’s secretary, thinking he was the prime minister Robert Peel himself. M’Naghten harbored a delusion that the government was conspiring against him. He was acquitted of murder and was institutionalized for the rest of his life.
The Durham Rule is another insanity assessment tool used to evaluate the validity of an insanity claim. With this rule, a defendant cannot be held criminally responsible for a crime if the act was a result of a mental illness. This rule requires the jury to establish whether or not the defendant suffers from mental illness, and if there exists a causal relationship between the disease and the crime.
This rule was adopted by the United States Court of Appeals in 1954. It was established following the case of Monte Durham, a 23 year old convicted of housebreaking in 1953. Durham had been in and out of mental institutions prior to his conviction. The Court of Appeals overturned his conviction, giving rise to this new rule for insanity assessment.
Irresistible Impulse Test
One problem that arose with the M’Naghten Rule was the establishment of insanity among individuals who understood right from wrong, and yet could not control impulses due to mental illness. The Irresistible Impulse Test addresses this problem. Under its parameters, a defendant may be found not guilty due to the inability to control impulses leading to the commission of a crime. This test is suitable for mental conditions like manias and paraphilias.
The Model Penal Code
This rule states that an individual is not responsible for a crime where, due to mental disease, he or she did not have the “substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.”
The courts adopted this rule in 1972 in an attempt to improve existing frameworks for insanity. It is broader, more comprehensive and encompassing of the complexities involved with insanity assessment. But like the previous rules, it is not without flaws.
When dealing with an insanity assessment, a forensic psychologist must possess the necessary skills and training for such a critical task. If you want to gain more insight about forensic psychology, check out our post, “Differences Between Therapeutic Psychology and Forensic Psychology”.