Misconceptions of the Insanity Plea
Students in Dr. Emily Stark’s Social Psychology course complete a research project where they identify a misconception related to psychology, conduct both background research and an empirical project measuring belief in that misconception, and summarize their findings in a short blog post paper or by creating an infographic. The goal is to build student research skills as well as showcase the importance of thinking critically about information encountered in the media or in popular culture. This post is one of the papers submitted for this project. For more information on this project, just use the contact page to contact Dr. Stark.
By Rylen Fleischman
Individuals frequently make the mistake of believing that many criminals successfully use the insanity defense plea to avoid legal consequences and potentially walk free. Despite the use of the word “insanity” in everyday language, it is deemed as legal terminology and not a psychiatric term. This defense is used only when the defendant is not mentally competent enough at the time of the alleged crime to be held responsible for the act. We can see this happen in 1982, when a man named John Hinckley was put on trial for his attempt to kill former U.S. President Ronald Reagan. This assassination attempt injured 3 additional people; A service agent, a police officer, and the President’s secretary press who walked away from this traumatic event with permanent brain damage (Lilienfeld et al., 2010). In short, Hinckley was a young man who had fallen for an actress in a movie he had seen on screen. Through a snowball of delusion and failed attempts to get the actress’s attention, he believed that killing the president would make her appreciative of his love for her. The jury found Hinckley not guilty due to reasons of insanity, which created a huge uproar from the public. A news poll was posted during this time to ABC News showing that 76% of Americans objected to that verdict (Lilienfeld et al., 2010). This verdict was difficult to understand for citizens because there was concrete evidence showing that he was the individual to take part in the act, however what they failed to take into consideration was Hinckley’s mental state at the time. Other high-profile cases have used this defense as well, such as Jeffrey Dahmer and Andrea Yates, both who faced charges for their violent and brutal murders (Lilienfeld et al., 2010).
Two studies performed within the same year looked at the use and perception of the insanity defense in criminal cases. Bonnie et al. (1996) determined in a study how defense attorneys’ assessments of their clients’ competency influenced their decision to utilize the insanity plea. Using data from Michigan’s Center for Forensic Psychiatry, the team examined 139 cases between the years 1990-1992 in which insanity was clinically supported. Their findings show that the insanity defense has rarely been used, and if so only when the attorney deems it fit. The purpose of Cirincione’s (1996) study was to address the public misconception about the insanity defense. By analyzing data in seven states and over 7,000 felony cases, Cirincione found that the public's view on the frequency to which the insanity defense is used is false (Cirincione, 1996). According to PBS, nearly all studies found that the insanity defense is raised in less than 1 percent of felony cases, and is successful in only a fraction of those. The majority of those cases that are successful are the result of a plea agreement in which the prosecution and the defense agree to a not guilty by reason of insanity plea (Murdock & Navasky, 2002). Cirincione also pointed out biases that primarily focus on violent crimes and do not include misdemeanor cases in research. This study proved that the insanity defense is not frequently used and not an easy way out, but a true legal approach used in genuine mental health cases when deemed appropriate.
At Minnesota State University, Mankato, a study was conducted through a social psychology course in the spring of 2025 to evaluate several different misconceptions using a class designed survey. My contribution to the study focused on the misconception of the insanity plea. I developed survey questions that related to this topic and analyzed the finalized data. Participation in the survey was voluntary, and respondents could skip any questions they preferred not to answer. While the full survey consisted of 67 questions, my section included only three multiple choice questions located near the beginning. Results of this study showed that 49% of participants believed insanity is a real excuse for committing a crime, while 52% did not (Question 9).
When asked whether the insanity defense should be used in court when applicable, support increased as 58% of participants agreed it should be used, and the other 43% disagreed (Question 10). I made an interesting observation when comparing these results, as nearly 10 respondents who voted no to this defense being real in question nine changed their vote to yes when asked whether it should be used in court in question ten. Lastly, participants were asked how often they believed the insanity defense is successfully used in court. Nearly half of the respondents (48%) believed it was successful less than 20% of the time, 21% believed it was successful 20–35% of the time, 22% said 35–50%, and 9% believed it succeeded more than 50% of the time (Question 11).
Despite its occasional appearance in the media or high profile cases, research has historically proven that it is rarely used. In truth, the insanity plea is raised in less than 1% of cases, and is successful in an even smaller percentage (Murdock & Navasky, 2002). The results of this study show how common this misconception is to the general public, as respondents were nearly split fifty-fifty on each response. By bringing attention to the topic of the insanity plea and its importance to those applicable, we can further our knowledge and create accepting environments for mental health issues in the legal system.
References
Bonnie, R. J., Poythress, N. G., Hoge, S. K., & Monahan, J. (1996). Decision-making in criminal defense: An empirical study of insanity pleas and the impact of doubted client competence. Journal of Criminal Law and Criminology, 87(1). https://scholarlycommons.law.northwestern.edu/cgi/viewcontent.cgi?article=6903&context=jclc
Cirincione, C. (1996). Revisiting the insanity defense: Contested or consensus? Bull Am Acad Psychiatry Law, 24(2). https://jaapl.org/content/jaapl/24/2/165.full.pdf
Lilienfeld, S. O., Lynn, S. J., Ruscio, J., & Beyerstein, B. L. (2010). 50 great myths of popular psychology. Wiley-Blackwell. https://scottlilienfeld.com/wp-content/uploads/2021/01/50-Great-Myths-of-Popular-Psyc hology-Shattering-Widespread-Misconceptions-about-Human-Behavior-by-Scott-O.-Lili enfeld-Steven-Jay-Lynn-John-Ruscio-Barry-L.-Beyerstein-z-lib.org_.pdf
Murdock, D., & Navasky, M. (2002). A crime of insanity - insanity on trial. FRONTLINE. PBS. https://www.pbs.org/wgbh/pages/frontline/shows/crime/trial/faqs.html