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  • Deb Ganapathy & Sarthak Sahoo

Mind the Gap: Psychiatry, Neuroscience & Lacunae in the Insanity Defence

‘My friend!’ I exclaimed, ‘man is but man; and, whatever be the extent of his reasoning powers, they are of little avail when passion rages within, and he feels himself confined by the narrow limits of nature.’

— Johann Wolfgang von Goethe, The Sorrows of Young Werther


In October 2022, the Home Minister of India announced that the government would be introducing new drafts of the Indian Penal Code, 1860 (‘IPC’) and the Code of Criminal Procedure, 1973. This introduction comes considering the suggestions of the Committee for Reforms in Criminal Law established two years prior. With the possibility of such new legislation, criminal jurisprudence has a moment to review, update, and radically transform the understanding of crime in India.

One important area of focus, especially with the trending public discourse on mental health, is the insanity defence and its state in India. This has been a pertinent issue in Indian law. For instance, a study was conducted by the Department of Psychiatry, Pondicherry Institute of Medical Sciences across 13 High Courts in India wherein the defence was invoked. Out of 102 cases, 76 (74.50%) did not fall under the scope of the defence. This was buttressed by irrelevant acquittals for lack of evidence and breach of due procedure (7.84%).[1] Therefore, with a mere success rate of 17.65%, the insanity defence is not reflective of the normative standard to be expected. In comparison, the United States of America has displayed a success rate of 26% in an eight-state survey. This does not yet account for the varying standards of such a defence in the United States across different states. In light of the same, the present article attempts to expand and explicate a more robust means of evaluating insanity pleas.

Legal Background & Affective Defence

In order to make policy prescriptions for creating a robust and contemporary legal regime, it is important to understand the scope of the insanity defence as it exists today. Section 84 of the IPC provides for the defence of an, ‘[a]ct of a person of unsound mind’. Placed in Chapter IV of the IPC, it is a general exception that excuses the imputability that arises from offences. The provision, based on the historical McNaughton Rule, states that if a person, owing to ‘unsoundness of mind’ is incapable of knowing either ‘the nature of the act’ or ‘that he is doing what is either wrong or contrary to law’, then such liability under the offence must be vacated.

These two conditions, however, are seen to be outdated given the latest understanding of psychology and criminology. Whereas both of the conditions are cognitive in nature — they concern the knowledge of the act’s nature — the affective or emotive causes that do not give rise to mens rea have been ignored. These refer to the ability to control conduct notwithstanding the knowledge of the act. The United Kingdom, with its Homicide Act of 1957 has made an exception by introducing diminished responsibility in such cases and a charge of manslaughter instead of murder.

This is not without exception in the common law either. Courts have long previously taken cognizance of the emotive aetiology of acts which negate any guilty intention. The Battered Women Syndrome, which vacates criminal liability in cases of abused wives killing their husbands, is now accepted as part of the relevant jurisprudence.

Therefore, as a preliminary step, it is imperative for the Legislature to update its understanding of criminal conduct considering updated medical consensus on what constitutes guilt for crimes.

Addressing Issues Relating to Psychiatric Evaluations

In the same study as referred to above, out of 102 cases wherein insanity was pleaded, a psychiatrist’s opinion could not be obtained for 26 cases. It is relevant to mention that there is a strong correlation between the availability of psychiatric opinions and the acquittal of mentally ill accused. In addition to this there is a strong correlation between the availability of documentary evidence of one’s mental illness and the likelihood of acquittal. From the relatively small sample study that has been referred to throughout this article, there is a presumed real possibility of convictions being made because of a lack of psychiatric evidence. It can also be inferred that jurisdictions such as the United States see more accused be declared Not Guilty for Reason of Insanity (NGRI) in part due to a comparatively robust mental health infrastructure.

There are several lacunae to be addressed with regard to the adjudication of the insanity defence in India. Even in cases where a psychiatrist is available, there is no standardised procedure through which a plea of insanity can be verified. Psychiatry residents in India often lack the required experience to deal with forensic issues in a holistic manner, for which only two weeks of training are mandated.[2] Beginners may be easily intimidated during cross examination. In order to provide proper psychiatric evaluations, it is essential that expert witnesses in court have the independence and training to not be pressured by any party to give false and unreliable evidence.

As opined by Suresh Bada Math et al. in ‘Insanity Defense: Past, Present, and Future’, psychiatric evaluations must be comprehensive, and involve a review of, inter alia, documentation regarding the accused’s mental illness, history of substance abuse, ‘family history, personal history and premorbid personality’. The review article also provides several standardised procedures in the form of questionnaires that have been developed to better assess the validity of the insanity plea, and provides a strong basis for standardising psychiatric evaluations.

There is, however, still a glaring issue that needs to be addressed. The lack of documentation regarding mental illness has, as previously stated, a strong correlation with convictions in cases where the defence is pleaded. The democratisation of mental health services in a country that is plagued with issues of public health access issues will require comprehensive policy overhauls that are beyond the scope of this article.

Neurolaw And Its Potential

There are still options available to buttress psychiatric evaluations and assess the veracity of insanity pleas. Recent literature in the field supports the belief that neuroscientific techniques can reliably assess an accused’s capacity to understand the nature of their actions or determine any intention to commit a criminal act.

In this context, it is important to refer to two United States cases, specifically Roper v. Simmons (2005) and Commonwealth of Pennsylvania v. Pirela (2007). The former is a landmark judgement by the Supreme Court of the United States which established the unconstitutionality of awarding the death penalty to persons under the age of 18. This decision was in part influenced by neuroimage evidence that established a connection between mental immaturity and age. The latter decision, by the Supreme Court of Pennsylvania, was to deem capital punishment to be unjustifiable for an individual whose frontal lobe was damaged in a manner that established a diminished responsibility. These adduce practical precedent to the use of such techniques.

Daniel Lawer Egbenya and Samuel Adjorlolo’s work titled, ‘Advancement of neuroscience and the assessment of mental state at the time of offence’ argues that there are certain parts of the brain, which, when damaged, impair one’s ability to make moral judgements or have intention. Specifically, portions of the prefrontal cortex are involved in assessments of wrongness of actions. Further, evidence suggests that intention is governed by the presupplementary motor area (pre-SMA), and lesions in that area can hamper self-control and decision-making. Referring back to the IPC, intention and knowledge of wrongness are essentials to establishing a defence under Section 84. Neuroscientific evidence would help solidify an insanity defence, especially under the view of the expanded scope thereof, as argued before.

However, given the logistical costs involved in the iterative use of such technology for the panoply of criminal cases that might warrant such use, it is paramount that neurolaw is limited to a secondary aid in justice delivery, giving primacy to psychiatric methods. This is confounded by the seriously impaired judicial, as well as medical, infrastructure in India, which adds to the cost of access and use of such technology, thereby rendering its consistent and practical use infeasible.

The merits of such a neurolegal regimen notwithstanding, policy recommendations in this vein further face a major infirmity. This is the crucial and cornerstone evolution of the Right to Privacy in India. The application of the neuroscientific techniques discussed above may be faced with concerns of privacy under Article 21 and the right against self-incrimination under Article 20. Informed consent and privacy safeguards must be kept in mind in the operationalisation of these techniques.


The current state of mental health infrastructure in India, as well as antiquated legal provisions, impair the fair and just application of such a defence when reasonable and valid. To respond to the inadequacy of the insanity defence regime in India, this article put forward a three-pronged approach that would (i) address the legal inadequacies by introducing defences that incorporate emotive reasons that vitiate mens rea, (ii) address the inadequacies of psychiatric evaluations by introducing greater standardisation, and (iii) introduce a more widespread use of neuroscientific techniques to buttress existing evidences. This approach can be contested, and its implementation would surely pose legal and practical challenges. However, it is in the interest of justice that people are not persecuted for their mental illnesses, and that legal mechanisms ensure the same.


[1] Kindly refer to the sub-head in the study entitled ‘High Court verdict’ on page 151 which reads, ‘There were four cases (3.92%), in which the accused was acquitted due to lack of evidence and another four cases (3.92%), in which the trial was vitiated as the lower courts did not follow the due procedure’.

[2] Kindly refer to page 45 of the Guidelines of Post Graduate Psychiatry Training in India as hyperlinked above.

This article has been authored by Deb Ganapathy, Junior Editor at RSRR and Sarthak Sahoo, Assistant Editor. This blog is a part of the RSRR Editor’s Column Series.


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