The Insanity Defense and its Controversies
By: Isabella Liu
Edited by: Lauren Levinson and Oscar Guzzino
On March 30th, 1981, six shots fired in Washington, D.C., coldly echoed around the United States. The country watched in horror as President Ronald Reagan and three others were wounded as a result of an assassination attempt carried out by 25-year-old John Hinckley Jr. After the initial shock wore off, the public seemed to reach a consensus: the perpetrator certainly had to be found guilty, right? After all, attempting to assassinate the president of the United States is one of the worst offenses in the nation. However, on June 21st, 1982, Hinckley was found not guilty by reason of insanity, and the verdict elicited outrage from all over the country. Soon, the insanity defense was under fire. People found it unfathomable how an attempted assassin could be found not guilty, and claimed that mental illness was no excuse for an act this heinous. However, the verdict would not be changed, and Hinckley spent nearly thirty years in psychiatric care instead of prison following the trial.
The attempted assassination of Ronald Reagan is just one of many cases in which the use of the insanity defense received severe public backlash, contributing to its growing controversial nature. The defense has been repeatedly criticized, with people even calling for its abolishment. It is crucial to explore why this defense is so controversial to understand the nuances behind being found “not guilty by reason of insanity” (NGRI). In this article, we will explore three main points: malingering, unclear definitions of insanity, and the perpetuation of the stigmatization of mental illnesses.
Malingering
A major issue surrounding the insanity plea is the potential for defendants to fake or exaggerate mental illnesses in order to receive a less harsh punishment, also known as malingering. This concern is justified, as there have been past cases in which a defendant has been proven to malinger in court. For example, in 1996, a man named Anthony Montwheeler kidnapped his first ex-wife and their son. However, as the court found him “guilty except for insanity,” Montwheeler was ultimately not sentenced to prison. [1] Two decades later, in 2016, Montwheeler was released from the Oregon State Hospital. [2] In January 2017, he was arrested for the kidnapping and murder of his second ex-wife, as well as causing a fatal car crash. However, Montwheeler had earlier admitted to faking mental illness in 1996 to avoid a prison sentence for the kidnapping–the rationale behind his release from the hospital – and was left with a malingering confession that would restrict his ability to use the same defense for the 2017 case. [2] After a four-year-long legal battle, Montwheeler pleaded guilty to second-degree murder, first-degree manslaughter and third-degree assault, and was sentenced to life in prison. [3] Montwheeler’s case embodies a dominating concern regarding the insanity defense: if an individual were to malinger, they could potentially escape a prison sentence and be released back into society, where they pose a danger to a greater number of people.
Malingering is commonly assumed to be overused, often seen as an “easy” way out for criminals, and that most individuals who plead NGRI are faking their illnesses. However, data shows that around 84% of those who plead NGRI had schizophrenia or other severe mental illnesses. Furthermore, out of the 141 individuals observed who used this plea over the span of eight years, there were only three cases where the diagnostician was “unwilling or unable to specify the nature of the patient’s mental illness.” [4] Therefore, there is an empirical gap between the public perception of the amount of insanity defense cases involving malingering and the statistics verifying its infrequency, perpetuating the common misbelief that the insanity defense is a kind of “loophole” that criminals can use to avoid punishment.
Difficulty in Defining Insanity
Another controversial aspect of the insanity defense is its potential for varied interpretations of how legal insanity is defined. The primary tests for legal insanity include the M’Naghten rule, the Irresistible Impulse Test, the Durham Rule, and the Model Penal Code. The M’Naghten rule, a standard test for criminal insanity globally, is “bifurcated” into two sections, with the first determining that the defendant is insane if they were “incapable of knowing what they were doing” at the time of the offense. [5] The second question evaluates whether the defendant knew of the wrongfulness of their action. An example of the M’Naghten rule in practice is the case of Andrea Yates, where in 2001, she drowned her five children in her bathtub. According to Yates, she “believed that it was Satan who put the thought in her mind to drown the children,” making her perceive the murders as justified. [6] In her initial 2002 trial, Yates was found guilty. [7] In a 2006 retrial, however, Yates was ultimately found NGRI using the M’Naghten rule: Yates, while committing the murders, could not distinguish moral actions from crimes, and was therefore not in the right mind to make conscious decisions.
While the M’Naghten rule emphasizes cognition, the Irresistible Impulse Test determines if an individual is NGRI if they demonstrate that “they suffered from a mental disease or defect that made it impossible for them to resist an impulse to commit a crime.” [8] However, the Irresistible Impulse Test poses several obstacles in defining the defendant’s insanity. For one, because this method studies the volitional component of insanity, there is less “robust scientific literature” support, making it more difficult to validate a defendant’s claim compared to the M’Naghten rule. [5] However, due to the broadness of Irresistible Impulse Test’s scope, critics argue that “because a defendant did not refrain from a particular criminal behavior, mental health evaluators could use this as evidence that the defendant could not resist his or her impulse, thereby concluding that all criminal behavior not resisted equals insanity.” [9]
The Durham Rule, established by Durham v. United States (1954), finds a defendant insane if their “unlawful act was a ‘product of a mental disease or defect.’” [9] Similar to the Irresistible Impulse Test, the Durham Rule is a broader standard for testing legal insanity, leading to criticism of its incoherency. The difficulty of defining insanity is most clearly demonstrated through the vagueness of the definition of “mental disease or defect,” as it can lead to inconsistent application of the Durham Rule across cases that employ a variety of psychiatrists. Ultimately, the Durham Rule was overturned in United States v. Brawner (1972), as the court who created the rule in Durham v. United States failed to “explicate what abnormality of mind was an essential ingredient” to the concept of “mental disease or defect,” leading to conflicting evaluations of defendants’ mental states. [10] Therefore, the Durham Rule was overturned.
In 1962, the American Law Institute established the Model Penal Code (MPC): a legal framework offering standardized rules for criminal courts. [11] One of the many new rules developed under the MPC included a new statute for insanity which states that “a person is not responsible for criminal conduct” if they “[lack] substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law” at the time of the crime due to a mental disease or defect. [9] The MPC’s insanity rule combines both the cognitive aspect of the M’Naghten rule and the volitional aspect of the Irresistible Impulse Test, solidifying its effectiveness in accounting for a range of scenarios. As a result, over two-thirds of states have used the MPC to reform their criminal codes and define mens rea (the mental state of the defendant) in court.
Since Irresistible Impulse Test and the Durham Rule declined in use due to the complicated nature of their evaluations of insanity, their failures, as well as the variety of tests for insanity having the potential to conflict with one another, illustrate how difficult it is to properly define legal insanity in a way that will produce the best outcome in most cases. The lack of consistent definitions across different evaluations has the potential to impair the legal system’s legitimacy.
Stigmatization of Mental Illness
As seen with the attempted assassination of Ronald Reagan, a majority of the public’s opinion on the insanity plea is negative. Widespread criticism of the defense perpetuates the stigma around mental illnesses, as disorders such as schizophrenia are often attributed to cases dealing with legal insanity. Empirical evidence proves the implicit bias against the mentally ill. In a 2003 study, two groups of laypeople were surveyed about their attitudes regarding the mentally ill and their capacity to commit crimes. The participants were given a newspaper article about a man on death row looking to appeal his sentence, basing his argument on the fact that the crime was committed when he was 16. The study found that the group who had received “a scenario in which the defendant had been described at trial as exhibiting psychopathic traits (e.g. remorselessness, pathological lying) were significantly more likely to support a death sentence and less likely to believe he should receive any treatment in prison.” [12] In other words, characteristics commonly associated with mental illnesses affect the perceived threat level of an individual, and those who express these traits are often seen as more dangerous.
The jaundiced view of the mentally ill is further perpetuated through publicity of the insanity plea. When the media reports on cases involving the insanity defense, they primarily focus on violent and heinous crimes – crimes that account for only a small portion of cases using the insanity defense. As a result, messages and narratives portray defendants as “dangerous” and “deserving of punishment.” [13] The public, having received the image of a criminal committing abhorrent crimes under the influence of their mental illness, generalizes the mentally ill as perilous individuals. Therefore, the selective portrayal of the insanity defense in the media stigmatizes mental illnesses by presenting them as a driving influence for criminals.
The legal system implicitly perpetuates the idea that mental illnesses are responsible for making an individual dangerous by relying on judges and attorneys who, like the public, hold misconceptions about mental illnesses due to inadequate knowledge. A study surveying attorneys on their understanding of cases involving mental illnesses concluded that 74% of the lawyers “have never received training in recognizing mental illness and 83% have never received education concerning mental health law.” [14] Furthermore, around half of the respondents seemed to prefer a client without a mental illness. As a result, “the stigma of mental illness may affect the degree of advocacy that defendants with mental illness receive from their attorneys.” [14]
The stigmatization of mental illnesses has also impacted the workings of the criminal justice system, as people with mental illnesses are grossly overrepresented in correctional facilities. The National Alliance on Mental Illness (NAMI) found that “nearly two in five people who are incarcerated have a history of mental illness,” and a majority of those incarcerated had been charged with non-violent offenses. [15] Since lawyers and judges hold implicit biases against people with mental illnesses, these individuals find themselves more likely to be imprisoned. However, statistics indicate that many incarcerated individuals with mental illnesses were charged for non-violent crimes, which contradicts the common misconception that the mentally ill are dangerous, violent, and cannot be left on the street. As both the legal and criminal justice systems disfavor those with mental illnesses, the law is not only affected by the stigmatization of mental health but also complicit in perpetuating it.
Conclusion
While the insanity plea is only used in around 1% of felony cases in the United States, its controversies severely impact defendants with mental illnesses and the justice system as a whole through its changing methods of evaluating legal insanity in court. Although it may be easy to criticize those such as Hinckley for being seemingly pardoned despite their crimes due to a concept as vague as “insanity,” it’s crucial to note that around 75% of cases using the insanity defense are unsuccessful, and that the public misconceptions of the defense can potentially cause real harm to those with mental illnesses. As the insanity defense continues to take shape in future cases, we must keep in mind the potential gaps in its structure for malingering and contradictory language, as well as how its use and perception can perpetuate negative stereotypes.
Notes:
1. Langerman, Joseph. 2018. “The Montwheeler Effect: Examining the Personality Disorder Exclusion in Oregon’s Insanity Defense.” Lewis & Clark Law Review. https://heinonline.org/HOL/P?h=hein.journals%2Flewclr22&i=1057.
2. Fraser, Jayme. 2018. “He Said He Faked Mental Illness to Avoid Prison. Now, Accused in 2 Killings, He’s Sent back to a State Hospital.” ProPublica. https://www.propublica.org/article/anthony-montwheeler-sent-back-to-hospital.
3. Pat Caldwell, Malheur. 2021. “‘Evil’ Murderer Gets Life Sentence after Emotional Family Statements about Their Losses.” Oregonlive. https://www.oregonlive.com/crime/2021/03/evil-murderer-gets-life-sentence-after-emotional-family-statements-about-their-losses.html.
4. Perlin, Michael L. 2017. "The Insanity Defense: Nine Myths That Will Not Go Away.” Articles & Chapters. 1128. https://digitalcommons.nyls.edu/fac_articles_chapters/1128
5. Cornell Law School. 2018. “Insanity Defense.” LII / Legal Information Institute. Cornell Law School. 2018. https://www.law.cornell.edu/wex/insanity_defense.
6. Resnick, Phillip. 2007. “The Andrea Yates Case: Insanity on Trial.” Clev. St. L. Rev 147 (2). https://engagedscholarship.csuohio.edu/cgi/viewcontent.cgi?article=1174&context=clevstlrev.
7. Yates v. State of Texas. 2005. 171 SW 3d 215. Texas Court of Appeals
8. Cornell Law School. n.d. “Irresistible Impulse Test.” LII / Legal Information Institute. https://www.law.cornell.edu/wex/irresistible_impulse_test.
9. Asokan, T.V. 2016. “The Insanity Defense: Related Issues.” Indian Journal of Psychiatry 58 (6): 191. https://doi.org/10.4103/0019-5545.196832.
10. “United States of America v. Archie W. Brawner, Appellant, 471 F.2d 969 (D.C. Cir. 1972).” n.d. Justia Law. https://law.justia.com/cases/federal/appellate-courts/F2/471/969/259681/.
11. Devendorf, John. 2023. “What Is the Model Penal Code?” LawInfo.com. LawInfo. December 12, 2023. https://www.lawinfo.com/resources/criminal-defense/what-is-the-model-penal-code.html.
12. Edens, John F., Laura S. Guy, and Krissie Fernandez. “Psychopathic Traits Predict Attitudes toward a Juvenile Capital Murderer.” Behavioral Sciences & the Law 21, no. 6 (2003): 807–28. https://doi-org.turing.library.northwestern.edu/10.1002/bsl.567.
13. Kachulis, Louis. “Insane in the Mens Rea: Why Insanity Defense Reform Is Long Overdue.” Southern California Interdisciplinary Law Journal 26, no. 2 (2017): 357–78. EBSCOhost.
14. Frierson, Richard L, Mary S Boyd, and Angela Harper. 2015. “Mental Illness and Mental Health Defenses: Perceptions of the Criminal Bar.” The Journal of the American Academy of Psychiatry and the Law 43 (4): 483–91. https://pubmed.ncbi.nlm.nih.gov/26668226/.
15. “Criminalization of People with Mental Illness.” 2025. NAMI. October 23, 2025. https://www.nami.org/advocacy-at-nami/policy-positions/stopping-harmful-practices/criminalization-of-people-with-mental-illness/.
Bibliography:
Asokan, T.V. 2016. “The Insanity Defense: Related Issues.” Indian Journal of Psychiatry 58 (6): 191. https://doi.org/10.4103/0019-5545.196832.
Cornell Law School. 2018. “Insanity Defense.” LII / Legal Information Institute. Cornell Law School. 2018. https://www.law.cornell.edu/wex/insanity_defense.
Cornell Law School. n.d. “Irresistible Impulse Test.” LII / Legal Information Institute. https://www.law.cornell.edu/wex/irresistible_impulse_test.
“Criminalization of People with Mental Illness.” 2025. NAMI. October 23, 2025. https://www.nami.org/advocacy-at-nami/policy-positions/stopping-harmful-practices/criminalization-of-people-with-mental-illness/.
Devendorf, John. 2023. “What Is the Model Penal Code?” LawInfo.com. LawInfo. December 12, 2023. https://www.lawinfo.com/resources/criminal-defense/what-is-the-model-penal-code.html.
Edens, John F., Laura S. Guy, and Krissie Fernandez. “Psychopathic Traits Predict Attitudes toward a Juvenile Capital Murderer.” Behavioral Sciences & the Law 21, no. 6 (2003): 807–28. https://doi-org.turing.library.northwestern.edu/10.1002/bsl.567.
Fraser, Jayme. 2018. “He Said He Faked Mental Illness to Avoid Prison. Now, Accused in 2 Killings, He’s Sent back to a State Hospital.” ProPublica. https://www.propublica.org/article/anthony-montwheeler-sent-back-to-hospital.
Frierson, Richard L, Mary S Boyd, and Angela Harper. 2015. “Mental Illness and Mental Health Defenses: Perceptions of the Criminal Bar.” The Journal of the American Academy of Psychiatry and the Law 43 (4): 483–91. https://pubmed.ncbi.nlm.nih.gov/26668226/.
Kachulis, Louis. “Insane in the Mens Rea: Why Insanity Defense Reform Is Long Overdue.” Southern California Interdisciplinary Law Journal 26, no. 2 (2017): 357–78. EBSCOhost.
Langerman, Joseph. 2018. “The Montwheeler Effect: Examining the Personality Disorder Exclusion in Oregon’s Insanity Defense.” Lewis & Clark Law Review. https://heinonline.org/HOL/P?h=hein.journals%2Flewclr22&i=1057.
Pat Caldwell, Malheur. 2021. “‘Evil’ Murderer Gets Life Sentence after Emotional Family Statements about Their Losses.” Oregonlive. https://www.oregonlive.com/crime/2021/03/evil-murderer-gets-life-sentence-after-emotional-family-statements-about-their-losses.html.
Perlin, Michael L. 2017. "The Insanity Defense: Nine Myths That Will Not Go Away.” Articles & Chapters. 1128. https://digitalcommons.nyls.edu/fac_articles_chapters/1128
Resnick, Phillip. 2007. “The Andrea Yates Case: Insanity on Trial.” Clev. St. L. Rev 147 (2). https://engagedscholarship.csuohio.edu/cgi/viewcontent.cgi?article=1174&context=clevstlrev.
“United States of America v. Archie W. Brawner, Appellant, 471 F.2d 969 (D.C. Cir. 1972).” n.d. Justia Law. https://law.justia.com/cases/federal/appellate-courts/F2/471/969/259681/.
Yates v. State of Texas. 2005. 171 SW 3d 215. Texas Court of Appeals