Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications

Introduction

The insanity plea, also known as the mental disorder defense, is a legal defense in which the defendant declares to have been unable to understand the essence and effects of their deeds at the time of the offense due to a mental disorder. In other words, the defendant claims that they were legally insane at the time the crime was committed and, therefore, should not be held fully responsible for their actions. To plead insanity successfully, the defendant usually has to substantiate that they were suffering from mental health problems and that this condition did not allow them to realize their actions.

The success rate of the plea can be affected by various factors, such as changes in laws and legal standards, public opinion, and media reports. Moreover, the exact requirements for an insanity defense may vary by jurisdiction. There are several essential points of the insanity plea phenomenon, such as the reason for stating so, the frequency of such cases, and whether or not it is a legitimate defense.

Insanity Plea

The stability of the appearance of this argument in criminal cases remains unclear. From the defendant’s point of view, they need to avoid any punishment, especially if it concerns imprisonment. Nevertheless, most of them confess their deeds for unknown reasons, leaving the insanity plea a relatively rare manifestation.

Taking into account the case of Jeffrey Dahmer, the infamous American serial killer and sex offender, the trial lasted a considerable amount of time solely for the jury’s hesitation about the murderer’s mental state (Whitbourne, 2017). In addition, Dahmer’s attorney denied him being involved in any of the filed crimes, as, according to him, such brutal crimes could have been committed only by a person legally fitting the definition of insane. Dahmer has no known sort of mental illness and has never been reported or blamed for having one, which might have been an additional argument for letting him free.

In turn, the frequency of the insanity plea varies depending on the jurisdiction and the specific case. In the United States, it is estimated that less than 1% of criminal defendants use the insanity defense. However, the success rate of the insanity plea is even lower, with less than 25% of those who plead insanity being successful in their defense (Tate, 2022). As can be seen from the above-mentioned Jeffrey Dahmer example, this case can be regarded as further evidence of such a constant rate. The jury rejected his excuse of being mentally ill, as they considered him to be responsible for his deeds (Whitbourne, 2017).

Nevertheless, there might have been negative consequences for the defendant even if he convinced the jury about his mental state. As Goodman (2022) conveniently points out, “Most defendants should not agree to these pleas because of the ineffective mental health hospitals and a lack of protections for defendants” (p. 27). As noted, such a reason for not being guilty is tricky to balance and turn to one’s advantage.

The legality of the insanity plea is a controversial topic that has been under discussion for a long time. It is reasonably difficult to estimate a person’s mental health, as they can simply lie and play the fool to avoid the upcoming penalty. Returning to the Jeffrey Dahmer example, he did not even try to contradict the jury’s verdict but confessed in detail and admitted his actions. Probably, the insanity plea should be allowed as a legitimate defense, but only when the case involves repeated horrific crimes.

Although it is challenging to identify its validity, it might motivate the defendant to ponder his actions. In this case, considerable observation in the form of a guard or remote supervision is highly recommended. It is critical to note that the insanity defense cannot be considered an excuse for not getting imprisoned and is often not used successfully. It is now the responsibility of the defendant to prove that they were undoubtedly insane at the time of their actions, which can be a complicated task.

Conclusion

To summarize, there are various sides to the problem of the insanity plea as a justification for a person’s criminal actions. They include the reason behind proclaiming so, the frequency rates of the cases, and the legalization of the insanity plea. In short, as was seen from the example of Jeffrey Dahmer, the frequency rate of such a case is a relatively rare occurrence due to its infrequency and believability.

The issue has advantages and disadvantages for different sides of the conflict, and does not seem to decrease in the discussion. It is worth noting that the insanity plea is typically only used in cases where the defendant has a documented history of mental illness. Again, from a defendant’s perspective, confirmation of the presence of the insanity plea has its consequences, either positive or negative. In short, it is a significantly controversial and dangerous defense strategy and is successful only in a small percentage of cases.

References

Goodman, S. (2022). Insanity-plea bargains: A constitutionally and practically good idea? University of Pennsylvania Journal of Constitutional Law, Forthcoming, 25, 1-27. Web.

Tate, B. (2022). Examining the effect of religiosity, moral disengagement, personal attribution, comprehension, and proximity on juror decision-making regarding insanity pleas. Psychiatry, Psychology and Law, 29(6), 809-831. Web.

Whitbourne, S. K. (2017). Abnormal psychology: Clinical perspectives on psychological disorders. McGraw-Hill Education.

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LawBirdie. (2025, September 8). Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications. https://lawbirdie.com/insanity-plea-in-criminal-justice-legitimacy-frequency-and-legal-implications/

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"Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications." LawBirdie, 8 Sept. 2025, lawbirdie.com/insanity-plea-in-criminal-justice-legitimacy-frequency-and-legal-implications/.

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LawBirdie. (2025) 'Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications'. 8 September.

References

LawBirdie. 2025. "Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications." September 8, 2025. https://lawbirdie.com/insanity-plea-in-criminal-justice-legitimacy-frequency-and-legal-implications/.

1. LawBirdie. "Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications." September 8, 2025. https://lawbirdie.com/insanity-plea-in-criminal-justice-legitimacy-frequency-and-legal-implications/.


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LawBirdie. "Insanity Plea in Criminal Justice: Legitimacy, Frequency, and Legal Implications." September 8, 2025. https://lawbirdie.com/insanity-plea-in-criminal-justice-legitimacy-frequency-and-legal-implications/.