Insanity Defense Misconceptions

Written by Harleen Dimopoulos (Sweetheart Harley)


The purpose of this paper is to examine the misconceptions of the insanity defense used during trials and forensic psychology. This analysis will go into detail about what the insanity defense is, how often the insanity defense is given, how does media impact the misconceptions of these areas, and how can misconception of the public pertaining to the insanity defense be corrected.

Insanity Defense

What is the insanity defense?

When a crime is committed, the person who committed it can only be convicted if they are competent, the insanity defense is used when a crime is committed and the violator’s guilty mind is absent which could lead to them not being able to stand trial due to being incompetent, but one can claim insanity and still be competent to stand trial (Bartol & Bartol, 2019, p. 304).

The insanity defense law has been changed over the years but the current one in place is the Insanity Defense Reforms Act (IDRA) that sets the standard for federal courts in which the offender is pleading insanity (Bartol and Bartol, 2019, p. 304). For an individual to be tested with state and federal laws of insanity, they must first have a documented mental disorder, if they do then they go through a series of tests (Bartol and Bartol, 2019, p. 304). As per Bartol and Bartol (2019) the test consists of:

“Right/ Wrong Test: “Did the person know the difference between right and wrong?” Right/Wrong Test With Volitional Prong: “If the person knew the difference, was he unable to appreciate the criminality of his actions or control his conduct to conform the criminality of his actions or control his conduct to conform to the requirements of the law?” Product Rule: “Was the person’s behavior a product of mental illness?” Model Penal Code: “Did the person lack the substantial capacity to appreciate the wrongfulness of his actions or to conform his conduct to the requirements of the law?” IDRA (Federal): “Did the person lack the capacity to appreciate the wrongfulness of his actions?”” (p. 304-305).

How often is it given?

The insanity plea is a rare occurrence and most often is linked with high profile cases, but there is an average of one insanity plea for almost every 5,000 arrests (Peters and Lecci, 2011, para. 3). As per Hooper (2002), “In fact, the insanity defense is used in less than 1% of criminal proceedings and is successful in approximately one-quarter of those cases” (para. 2).

Not all states have the insanity defense as an option in criminal proceedings, and in these cases the defendant can plead that they have a psychological disorder, or mens rea, or guilty mind, in which the defendant can be found partially guilty of a crime due to a mental disorder (Bartol and Bartol, 2019, p. 316). “Some specific, mental health–related defenses that have been raised include PTSD, automatism (e.g., sleepwalking), substance abuse disorders, dissociative disorders, duress, and extreme emotional disturbance, to name but a few” (Bartol and Bartol, 2019, p. 316).

Misconceptions and Public Knowledge


The general public assumes that 37%-50% of criminal cases use the insanity defense in trial, which could lead to impacting a jury’s verdict if they are called to court for a case that does used the insanity defense (Peters and Lecci, 2011, para. 3).

“The widespread public belief that defendants frequently use the insanity defense to avoid punishment is largely attributable to high profile cases and the attention the media gives them. The public also believes that the availability of the insanity defense will result in the opportunity for those faking mental illness to avoid punishment” (Grachek, 2006, p. 1487).

Politicians and the media have highlighted the insanity defense as a form that criminals use to get off sentencing or prison time, while when someone is found guilty by reason of insanity their time served in a psychiatric facility is often longer than they would have served as a prison sentence (Costanzo and Costanzo, 2013, para.18). As per Bartol and Bartol, “They often do not realize, for example, that defendants found NGRI do not often “go free,” but are subject to civil commitment and hospitalization” (p. 313). Defendants found not guilty by reason of insanity do not walk free after the hearings in court, but instead federal and state governments require the person to be evaluated in a hospital and kept inpatient (Bartol and Bartol, 2019, p. 314).

Individuals pleading insanity are often seen as cold and emotionless during trial and this is because in order for an incompetent defendant to stand trial they must be medicated, which usually takes place from the time they are detained until the verdict is given, so the jury may perceive the defendant as emotionless for the crimes they committed, which is a misconception because the medication used to make them competent enough to stand trial reflects them in a different light (Bartol and Bartol, 2019, p. 313-314). “Most states require NGRI patients to prove they are no longer mentally ill and dangerous in order to be released, and this is not easy to do, particularly when the individual was originally charged with a violent crime” (Bartol and Bartol, 2019, p. 314).

What can be done?

To change misconceptions about the insanity defense it starts with psychological education not only for youth, but those in politics, health, law, business, and education to understand risk assessment and mental health background of those who are put on trial and use the insanity defense (Costanzo and Costanzo, 2013, para. 2-3). Cognitive neuroscience has had findings that criminal behavior, excessive compulsions, violence, as well as aggression can be linked to brain tumors, dementia in the frontal lobe, and hormonal or neurotransmitter imbalances of the brain (Costanzo and Costanzo, 2013, para. 21). The public should also be educated that many offenders deny mental illness or the insanity plea due to the insanity plea correlating to admission of a crime and if the offender claims the insanity plea and is found not guilty due to reason of insanity, they lose all chance of getting a bargain plea or less sentence time when the sentencing occurs (Grachek, 2006, p. 1488).


In conclusion, the insanity defense is used when an offender’s mind is absent, or they are incompetent. The offender must go through the Insanity Defense Reforms Act which is a series of question conducted by psychologists to determine if the offender is, or is not competent, and if not, can they stand trial. Opposed to popular belief, less than 1% of offender’s plead guilty by reason of insanity, only one-fourth who plead reason of insanity are granted it, and a very small fraction of criminal’s fake insanity. This is because pleading guilty by reason of insanity is an admission, that they committed the crime, but if found not guilty by reason of insanity the offender loses any chance of bargaining or lessening their sentence.

Public misconceptions about the insanity defense have been around for decades and fueled by the media and high-profile cases. Some public misconceptions are that the offender is trying to get out of the prison system, when those convicted by reason of insanity spend more time in rehabilitation centers than they would in a prison sentence. There is a lack of education surrounding the insanity defense, which in turn can cause jurors to be biased as well as the public seeing it in a different light than what it is. Cognitive neuroscientists and psychologists should be working with schools, educators, politicians, and the media to educate people on what pleading insanity really entails, instead of glamorizing the high-profile cases.


Bartol, C. R., & Bartol, A. M. (2019). Introduction to forensic psychology: Research and application (5th ed.). Sage Publications.

Costanzo, M. L., & Costanzo, M. A. (2013). Teaching Clinical (and Nonclinical) Psychology Through Applications to the Legal System: Violence Risk Assessment and the Insanity Defense. Teaching of Psychology, 40(3), 252–256.

Grachek, J. E. (2006). The Insanity Defense in the Twenty-First Century: How Recent United States Supreme Court Case Law Can Improve the System. Retrieved from

Hooper, J. F. (2002). Does the insanity defense have a legitimate role? Psychiatric Times. Retrieved from

Peters, M., & Lecci, L. (2011). Predicting verdicts, adherence to judge's instructions, and assumptions about the disposition of the defendant in a case involving the insanity defense. Taylor & Francis Online. Retrieved from