Severe mental illnesses, when left untreated, have been consistently linked to episodes of violent behavior, as evidenced by a growing body of psychiatric and forensic literature (1). In criminal jurisprudence, the insanity defense serves as a legal safeguard for individuals with mental illness who lack the capacity to form mens rea, the guilty intent required for criminal responsibility. In such cases, the law recognizes that the individual may not be held criminally liable (2). Over the years, the courts have acquitted individuals with severe mental illness on the grounds of unsoundness of mind.

The concept of the insanity defense and its post-acquittal protocol vary across nations. In India, the decision of not guilty by reason of unsoundness of mind is based on McNaughten’s Rule under Section 84 Indian Penal Code according to which “Nothing is an offense which is done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.”

In India, the success rate of insanity pleas remains relatively low, with studies indicating an acquittal rate of approximately 17.6% (3). In the United States, verdicts of not guilty by reason of insanity account for 26% (4). What happens to such acquitted individuals with mental illness is an important area to be explored. This procedural framework has evolved, most recently with the enactment of the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS) code under Section 374(1)(a) of the BNSS, which replaces the Criminal Procedure (formerly Section 335 (1)(a) of Criminal Procedure Code (CrPC)), individuals acquitted on grounds of insanity are to be placed in a mental health establishment, reflecting the dual imperative of public protection and ensuring prompt psychiatric care (5).

This study explores the life events of mentally ill offenders—from the onset of criminal behavior to court proceedings and post-acquittal outcomes. It examines the psychiatric diagnoses involved, the nature of the offenses committed, the behavior related to the offenses, the legal proceedings the individuals underwent, the legal provisions mentioned in favor of acquittal, the duration of stay in a mental health establishment, and the aftermath of acquittal.

By analyzing these dimensions, the study aims to contribute to a nuanced understanding of how mental illness is related to criminal liability and to inform future reforms in forensic psychiatry, psychiatric care, and legal policy in India.

A detailed perusal of the inpatient records and judgment copies of five acquitted patients, who were detained for safe custody at the Institute of Mental Health, Kilpauk, was conducted. The sociodemographic profiles, nature of the crimes, victims’ relationships with the accused, legal proceedings, factors favoring an unsoundness defense, and the laws cited for their acquittal and placement into a mental health establishment were studied.

Out of the five patients, all of them were males and belonged to a rural background. Their sociodemographic details are tabulated in Table 1. The nature of the offense was serious crimes like murder, attempt to murder, and setting fire to property. The victims were mostly close relatives or caretakers of the patient.

The duration of illness at the time of the alleged crime ranged from 6 months to 23 years. The time gap between filing an First Information Report (FIR) and the acquittal of the cases was between 1 and 11 years. The findings are tabulated in Table 2. The crime scene details suggested no specific motive for the act, and there were no deliberate efforts to escape from the scene. Findings are tabulated in Table 3. None of them was on adequate psychiatric treatment just before the incident. Section 84 IPC was quoted in the judgments to acquit the patients on grounds of unsoundness. Details of legal proceedings are mentioned in Table 4.

All the individuals in this case series hailed from rural backgrounds. Except for one individual, all others were school dropouts and were not regular in their job. This was consistent with prior studies on forensic psychiatric populations in India (6). Most were unmarried or experiencing marital discord, which resulted in poor social support. Illiteracy and unemployment status might have contributed to the financial constraints, irregular access to mental healthcare and even delayed recognition of psychiatric symptoms. (7). Similar demographic patterns were observed in studies done previously, underscoring the intersection of social disadvantage and psychiatric morbidity in criminal contexts (6).

As this study is a case series from a single institution, it may not accurately reflect the overall number of patients acquitted and their alleged offenses statewide.

This study highlights the need for larger-scale research on prisoners who are acquitted on the grounds of unsoundness. Future research should focus on developing structured discharge protocols, expanding community-based rehabilitation options, and improving legal awareness among caregivers. Further studies involving the families of these patients are also important to explore the hesitation in re-establishing relationships and the practical challenges they face in caregiving and reintegration.

This case series highlights the complexities in the lives of individuals acquitted on grounds of unsoundness of mind and placed in a mental health establishment. Despite legal exoneration, prolonged inpatient stay remains in such individuals, often due to chronicity of illness and limited family support. The findings emphasize the need for services that provide timely assessments, regular legal reviews, and culturally sensitive reintegration strategies.

Strengthening collaboration between mental health professionals, legal authorities, and social services is essential to uphold the rights and dignity of this vulnerable population and to promote humane, rights-based approaches in forensic mental health care.