​Introduction:

 

         The intersection of severe mental illness and criminal accountability poses a profound challenge to the American legal system. While mental illness should not automatically excuse criminal activity, courts must become more attentive when deciding how a defendant's psychiatric history and medical adherence affect their legal culpability. In criminal law, a serious mental illness cannot be introduced as a viable insanity defense if it reflects only a general diagnosis or an emotional struggle. To meet the legal threshold, the illness must significantly hinder the defendant's mental capacity during the commission of the crime, rendering them unable to understand the wrongfulness of their actions. Conversely, prosecutors often attempt to introduce a defendant's failure to take prescribed psychiatric medication as evidence of voluntary recklessness. However, medical noncompliance should only be weaponized by the prosecution if it can be proven entirely voluntary. Because the severity of certain mental illnesses directly impairs a patient's capacity to choose treatment, courts must evaluate the underlying psychiatric reasons for noncompliance before allowing it to dictate criminal responsibility.

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Analysis: 

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         The baseline legal standards for criminal insanity focus strictly on the defendant’s mental state at the exact time of the offense. Under Tennessee law, for example, insanity operates as an affirmative defense when, as a result of a severe mental disease or defect, the suspect is entirely unable to appreciate the wrongfulness of their acts. Similarly, the Model Penal Code states that a person is not responsible for criminal conduct if, at the time of such conduct, a mental disease or defect leaves them lacking substantial capacity either to appreciate the criminality of their behavior or to conform their conduct to the requirements of the law. Both frameworks protect defendants by isolating their psychological state during the criminal act. Crucially, neither statute factors prior medication noncompliance into the definition of insanity, primarily because evaluating whether a patient's noncompliance was truly "voluntary" is highly unpredictable. While standard rules of character evidence generally restrict prosecutors from introducing a defendant's prior bad acts to prove bad character, they do allow evidence of prior actions to demonstrate specific intent, knowledge, preparation, or a malicious state of mind. Prosecutors frequently leverage this exception, arguing that a defendant's prior decision to stop medication proves a reckless, conscious choice to risk a psychological break. However, applying this logic to an insanity defense is legally flawed unless the state can prove the defendant possessed a rational, conscious baseline when they stopped their treatment.

 

         The complexity of navigating medication noncompliance within a statutory insanity framework is vividly demonstrated in the landmark pre-trial case State v. Wierson, decided by the Supreme Court of Georgia. Michelle Wierson was charged with first-degree vehicular homicide and reckless driving after causing a fatal car crash while speeding during an acute psychiatric crisis. Medical records revealed that despite her severe bipolar disorder diagnosis and a rigorous treatment plan requiring multiple prescribed psychiatric medications, Wierson had discontinued her regimen weeks prior to the accident. Before the case could go to trial, two independent psychiatrists concluded that at the exact time of the crash, Wierson was under an intense delusion, leaving her entirely unable to distinguish right from wrong. Relying on these findings, Wierson filed a notice of intent to pursue an insanity defense. In response, the prosecution moved to introduce evidence of her medication noncompliance, arguing that she had "voluntarily induced" her own psychotic state and should therefore be barred from claiming insanity. However, the Georgia Supreme Court ruled decisively in favor of Wierson, explicitly overruling prior judicial restrictions. The court held that because Georgia’s insanity statutes focus exclusively on the defendant's mental capacity at the exact moment the crime is committed, evidence of prior medication noncompliance is fundamentally irrelevant and inadmissible to defeat a statutory insanity defense.

 

         Extensive medical research strongly supports the Georgia Supreme Court’s skepticism toward treating medication noncompliance as a simple, voluntary choice. Bipolar disorder itself is a primary driver of treatment non-adherence, with studies showing that 50% to 60% of individuals with the disorder frequently skip doses or discontinue their medications entirely. A primary catalyst for this is a clinical condition known as anosognosia—a neurological impairment that strips a patient of the capacity to recognize or perceive their own illness. When a suspect is biologically incapable of comprehending that they are sick, they cannot understand the medical necessity of their prescription regimen. This profound lack of awareness, compounded by the cognitive dysfunction, regimen complexity, and frequent substance use co-occurring with severe bipolar disorder, makes noncompliance a symptom of the disease rather than a voluntary refusal of care. Thus, Wierson's failure to adhere to her doctor's treatment plan was an extension of her underlying illness. Because she was in an escalating manic state, her judgment was entirely compromised; she should not have been driving, but her illness actively prevented her from recognizing that danger.

 

         To understand the necessity of this distinction, the legal system must contrast cases like Wierson with instances where medication noncompliance is genuinely voluntary and deliberate. For example, consider a defendant with a history of manageable mental illness who consciously decides to stop taking their medication simply because they dislike mild side effects, such as dry mouth or slight fatigue, or because they falsely assume alternative holistic treatments will suffice. If this individual possesses a clear, rational baseline at the time of their decision, understands the predictable risk of a severe psychological relapse, and subsequently commits a crime during a subsequent breakdown, their noncompliance can be reasonably characterized as a knowing, reckless choice. In such a scenario, the prosecution has a legitimate basis to introduce the prior noncompliance under evidentiary rules to establish a reckless state of mind. This stark contrast demonstrates why courts cannot adopt a one-size-fits-all approach: voluntary noncompliance by a rational actor reflects criminal recklessness, whereas involuntary noncompliance driven by a neurological inability to perceive reality reflects the illness itself.

 

 

Conclusion

 

         Ultimately, the distinction between a knowing rejection of treatment and a symptom-driven medical lapse must dictate how evidence is handled in a court of law. A suspect suffering from severe delusions, paranoia, or acute anosognosia lacks the cognitive baseline required to make a legally meaningful choice about their medical regimen. Therefore, the legal system should only treat medical noncompliance as proof of recklessness if the prosecution can definitively prove that the defendant knowingly rejected the medication despite possessing a full, rational understanding of the risks at the time they stopped. If the noncompliance was instead a direct byproduct of a severe mental illness, it has no place in a trial to undermine a defendant's statutory right to an insanity defense. The insanity defense must never become an easily abused loophole, but it must remain an accessible pathway to justice for those whose illnesses genuinely shatter their perception of right and wrong. By forcing courts to rigorously evaluate the root medical causes of medication noncompliance, the legal system can successfully balance public safety with genuine accountability.​​

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Bibliography

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Tennessee Code Annotated: Title 33, Chapter 7, Section 33-7-301

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Model Penal Code: § 4.01 (Insanity Defense standard)

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State v. Wierson: S24G1299 (Ga. 2025) (Supreme Court of Georgia pre-trial evidentiary ruling)

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Loots, Elke, et al. (2021): "Interventions to Improve Medication Adherence in Patients with Schizophrenia or Bipolar Disorders." International Journal of Environmental Research and Public Health, vol. 18, no. 19.

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Mert, Derya Güliz, et al. (2015): "Perspectives on Reasons for Medication Nonadherence in Psychiatric Patients." Patient Preference and Adherence, vol. 9.

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