Abstract

Criminal law operates on the foundational presumption of liberum arbitrium—that the human agent is a rational, autonomous actor capable of exercising free will in choosing between lawful conduct and criminal transgression. However, contemporary advancements in criminal psychology, forensic psychiatry, and cognitive neuroscience increasingly challenge this binary legal construct of culpability. This research paper conducts an interdisciplinary, doctrinal, and empirical evaluation of the intersection between Criminal Psychology and the Indian Criminal Justice System, specifically analyzing the transition from the colonial statutory regime (IPC, 1860; CrPC, 1973; IEA, 1872) to the newly enacted Bharatiya Nyaya Sanhita (BNS), Bharatiya Nagarik Suraksha Sanhita (BNSS), and Bharatiya Sakshya Adhiniyam (BSA) of 2023. First, the study examines the psychological etiology of criminal behaviour, contrasting psychopathy (Antisocial Personality Disorder), prefrontal cortex dysfunction, and socio-criminogenic conditioning against the strict legal threshold of mens rea. Second, it critically evaluates the legislative decision to reframe “unsoundness of mind” under Section 84 of the IPC into “mental illness” under Section 22 of the BNS, exploring its harmonization—and lingering dissonance—with the Mental Healthcare Act, 2017. Third, the paper investigates the constitutional and evidentiary admissibility of psychological investigative tools—namely Narco-analysis, Polygraph, and Brain Electrical Oscillation Signature (BEOS) profiling—under the shadow of Selvi v. State of Karnataka (2010) and the mandatory forensic paradigm of Section 176(3) of the BNSS. Finally, the study addresses the role of criminal psychology in capital sentencing post-Bachan Singh and Manoj v. State of Madhya Pradesh (2022), advocating for the institutional integration of forensic psychologists across Indian district courts and correctional facilities.

Keywords: Criminal Psychology, Section 22 Bharatiya Nyaya Sanhita, Legal vs. Medical Insanity, M’Naghten Rules, Forensic Deception Detection, Selvi v. State of Karnataka, Psychopathy and Mens Rea, Psychological Autopsy, Capital Sentencing Mitigation.

1. Introduction: The Epistemological Divide Between Law and Psychology

At the heart of criminal jurisprudence lies the Latin maxim “Actus non facit reum nisi mens sit rea”—an act does not make a person guilty unless the mind is also guilty. While substantive criminal law requires the prosecution to establish a blameworthy mental state (intention, knowledge, recklessness, or negligence), the discipline of Criminal Psychology investigates the deeper cognitive, affective, developmental, and neurobiological mechanisms that drive an individual toward deviant and antisocial conduct.

Historically, a sharp epistemological divide has separated the courtroom from the clinic:

• The Legal Paradigm is normative, binary, and retrospective. It seeks to answer a singular question at a frozen moment in time: Did the accused, at the exact moment of committing the offence, possess the cognitive capacity to know the nature of the act or that it was contrary to law? Based on this determination, the law assigns a binary outcome: guilty (deserving of retributive or deterrent punishment) or not guilty by reason of mental incapacity.
• The Psychological Paradigm is descriptive, dimensional, and longitudinal. It views human agency not as an all-or-nothing switch, but as a continuum shaped by genetic predispositions (such as MAOA gene polymorphism), neuroanatomical deficits (such as amygdala hypo-reactivity and prefrontal cortex impairment), childhood trauma, personality pathology, and situational stressors.

With the implementation of the Bharatiya Nyaya Sanhita (BNS), 2023, the Bharatiya Nagarik Suraksha Sanhita (BNSS), 2023, and the Bharatiya Sakshya Adhiniyam (BSA), 2023 on July 1, 2024, Indian criminal law has attempted to modernize its terminology and forensic architecture. Yet, the fundamental tension between psychological determinism and legal responsibility remains one of the most contested frontiers in Indian jurisprudence.

2. Theoretical Frameworks of Criminal Psychology: Understanding the Offender’s Mind

Before examining statutory provisions, a rigorous legal analysis requires categorizing the primary psychological models that explain criminogenic behaviour and their direct implications for mens rea.

2.1 The Paradox of Psychopathy in Criminal Law

One of the most profound dilemmas in forensic psychology is the status of the psychopathic offender (evaluated clinically using Robert Hare’s Psychopathy Checklist-Revised or PCL-R). Neuroimaging studies consistently demonstrate that individuals scoring high on psychopathy exhibit structural and functional deficits in the paralimbic system, rendering them incapable of experiencing genuine empathy, guilt, or fear of punishment.

However, under Indian criminal law (both Section 84 IPC and Section 22 BNS), emotional or moral insanity is not recognized as a defence. Because a psychopath possesses intact cognitive faculties—understanding the physical nature of murder and knowing that the law prohibits it—the Indian judiciary treats the psychopath as fully culpable, frequently citing cold-bloodedness and lack of remorse as aggravating factors warranting the death penalty under the “rarest of rare” doctrine (Bachan Singh v. State of Punjab, 1980).

2.2 Psychology of Collective Violence: Mob Lynching under Section 103(2) BNS

The newly introduced Section 103(2) of the BNS, which prescribes death or life imprisonment for murder committed by a group of five or more persons acting in concert on grounds of race, caste, community, sex, language, or personal belief, is a direct legislative response to the psychological phenomenon of Deindividuation (Festinger, Pepitone, & Newcomb, 1952; Zimbardo, 1969). In a crowd setting, individual self-awareness and personal moral accountability dissolve into an anonymous collective identity, drastically lowering the threshold for extreme brutality. By imposing joint and equal maximal liability on every member of the lynching mob, Section 103(2) BNS attempts to erect a powerful statutory counter-deterrent against psychological diffusion of responsibility.

3. From “Unsoundness of Mind” (Sec. 84 IPC) to “Mental Illness” (Sec. 22 BNS): A Doctrinal Shift

3.1 Textual Evolution of the Insanity Defence

For 164 years, Section 84 of the Indian Penal Code, 1860 embodied the classic 1843 English M’Naghten Rules, stating:

“Nothing is an offence 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 the Bharatiya Nyaya Sanhita, 2023, this provision is re-enacted as Section 22, with one deliberate lexical substitution:

“Nothing is an offence which is done by a person who, at the time of doing it, by reason of mental illness, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.”

3.2 Critical Evaluation of Substituting “Unsoundness of Mind” with “Mental Illness”

At first glance, replacing the archaic Victorian phrase “unsoundness of mind” with “mental illness” appears to be a progressive alignment with contemporary psychiatric nomenclature and Section 2(1)(s) of the Mental Healthcare Act, 2017 (MHCA)—which defines mental illness as “a substantial disorder of thinking, mood, perception, orientation or memory that grossly impairs judgment, behaviour, capacity to recognize reality or ability to meet the ordinary demands of life, mental conditions associated with the abuse of alcohol and drugs, but does not include mental retardation…”

However, a rigorous doctrinal analysis reveals three complex legal challenges arising from this substitution:

1. The Narrowing vs. Broadening Dilemma (Intellectual Disability): Under the IPC, “unsoundness of mind” was a wide, non-clinical legal umbrella that effortlessly encompassed both psychiatric disorders (e.g., paranoid schizophrenia, bipolar mania) and severe neurodevelopmental conditions (such as Intellectual Disability / “mental retardation” or severe Autism Spectrum Disorder). If courts interpret “mental illness” under Section 22 BNS strictly by importing the definition from Section 2(1)(s) of the Mental Healthcare Act, 2017—which explicitly excludes mental retardation—an unintended statutory lacuna could emerge regarding offenders with severe intellectual disabilities, unless courts read Section 22 BNS expansively alongside the Rights of Persons with Disabilities Act, 2016.
2. Retention of the Cognitive-Only Test (Rejection of Volitional Insanity): Despite updating the diagnostic label to “mental illness,” Section 22 BNS retains the rigid 19th-century M’Naghten cognitive filter (“incapable of knowing…”). Modern psychiatry recognizes that severe mental illnesses (such as Obsessive-Compulsive Spectrum Disorders, severe impulse-control disorders, or command hallucinations in affective psychoses) frequently destroy an individual’s volitional capacity (the ability to control one’s conduct) even when their cognitive awareness remains technically intact. Unlike the American Law Institute (ALI) Model Penal Code Test or the Irresistible Impulse Test, Section 22 BNS still affords no protection to an accused who knew the act was wrong but was pathologically incapable of restraining the impulse due to mental illness.
3. Legal Insanity vs. Medical Insanity (Surendra Mishra & Dahyabhai Precedents): Under settled Supreme Court jurisprudence—most notably Dahyabhai Chhaganbhai Thakkar v. State of Gujarat (AIR 1964 SC 1563), Surendra Mishra v. State of Jharkhand (2011 11 SCC 495), and Prakash Nayi v. State of Goa (2023)—the mere clinical diagnosis of a medical mental illness (medical insanity) does not automatically establish exemption from criminal liability (legal insanity). Under Section 108 of the Bharatiya Sakshya Adhiniyam, 2023 (formerly Section 105 IEA), the burden of proving the existence of circumstances bringing the case within the general exception of Section 22 BNS remains squarely on the accused (on a preponderance of probabilities), while the court must presume the absence of such circumstances until proved otherwise.

3.3 Procedural Safeguards for Accused with Mental Illness under BNSS, 2023

Correspondingly, Chapter XXVII of the Bharatiya Nagarik Suraksha Sanhita, 2023 (Sections 367 to 382)—replacing Chapter XXV of the CrPC—modernizes the procedural handling of accused persons who are incapable of making their defence due to mental illness or intellectual disability, mandating referral to a psychiatrist or clinical psychologist, and emphasizing care and treatment in public mental health establishments in harmony with the Mental Healthcare Act, 2017.

4. Forensic Psychology in Investigation: Deception Detection, Profiling, and Constitutional Limits

Modern criminal psychology extends far beyond the insanity defence; it plays an operational role during crime investigation through Offender Profiling, Psychological Autopsies, and Forensic Deception Detection Tests (FDDTs).

4.1 The Constitutional Boundary: Selvi v. State of Karnataka (2010)

During the early 2000s, Indian investigating agencies increasingly relied on three neuro-psychological techniques to extract investigative leads from suspects:

1. Polygraph Examination (Lie Detector): Measures autonomic physiological arousal (respiration, galvanic skin response, blood pressure, heart rate) triggered by the psychological stress of deception.
2. Narco-Analysis (Truth Serum): Involves the intravenous administration of Sodium Pentothal (thiopental sodium), a barbiturate that depresses the central nervous system, lowers inhibitions, and induces a hypnotic, semi-conscious state in which the subject is presumed less capable of fabricating complex lies.
3. Brain Electrical Oscillation Signature (BEOS) Profiling / P300 Brain Mapping: An electroencephalographic (EEG) technique developed in India by Dr. Champadi Raman Mukundan that measures event-related potentials (specifically the P300 wave and electrical oscillations) to detect “Experiential Knowledge”—distinguishing whether a suspect personally participated in an act (“remembrance”) versus merely hearing about it (“knowing”), without requiring any verbal response from the subject.

In the landmark judgment of Selvi & Ors. v. State of Karnataka (2010 7 SCC 263), a three-judge bench of the Supreme Court of India struck down the involuntary administration of all three techniques, laying down foundational rules of constitutional neuro-law:

• Violation of Article 20(3) (Right Against Self-Incrimination): Rejecting the narrow view that brain-mapping or polygraph readings are merely “physical/bodily measurements” akin to fingerprints or DNA, Chief Justice K.G. Balakrishnan held that extracting information stored in a person’s neural pathways or subconscious mind constitutes testimonial compulsion.
• Violation of Article 21 (Mental Privacy and Cognitive Liberty): Nearly seven years before K.S. Puttaswamy v. Union of India (2017), Selvi recognized a person’s right over their own mental processes, holding that forcible intrusion into an individual’s mind violates substantive due process and amounts to cruel, inhuman, and degrading treatment.
• Evidentiary Status under BSA, 2023: Even when administered voluntarily with informed consent recorded before a Judicial Magistrate (following the 2000 National Human Rights Commission guidelines), the direct test results cannot be admitted as substantive evidence of guilt. However, any physical fact or material object subsequently discovered as a consequence of information obtained during a voluntary test is admissible under Section 23(2) Proviso of the Bharatiya Sakshya Adhiniyam, 2023 (equivalent to the iconic Section 27 of the Indian Evidence Act).

4.2 Non-Invasive Psychological Investigative Methods under BNSS & BSA

Unlike invasive narco-analysis, two non-invasive branches of investigative psychology have gained strong judicial recognition in India:

• Criminal Investigative Profiling (Behavioural Evidence Analysis): Originating from the FBI’s Behavioral Science Unit (distinguishing Organized vs. Disorganized offenders) and David Canter’s Investigative Psychology model (Interpersonal Coherence and Geographical Profiling), criminal profiling assists police in serial homicides, cyber-stalking, and sexual offences by deducing offender characteristics from crime-scene behaviour (modus operandi vs. psychological signature).
• Psychological Autopsy in Equivocal Deaths: In cases where the manner of death hovers ambiguously between Suicide, Homicide (Sec. 103 BNS), and Abetment of Suicide / Dowry Death (Sec. 108 & Sec. 80 BNS), a Psychological Autopsy reconstructs the deceased’s cognitive, emotional, and behavioural state prior to death through structured interviews with family, analysis of digital footprints, and psychiatric history. In high-profile investigations (such as the Burari Mass Deaths of 2018 involving shared psychotic disorder/folie à famille, and Subhash Kumar v. State), Indian courts and the CBI (via CFSL’s Forensic Psychology Division) have utilized psychological autopsies as corroborative expert opinion under Section 39 of the Bharatiya Sakshya Adhiniyam, 2023 (formerly Section 45 IEA).

5. The Fallibility of Human Memory: Eyewitness Psychology and Witness Protection

A substantial portion of criminal convictions in India rests on ocular (eyewitness) testimony. Yet, cognitive psychology—pioneered by Elizabeth Loftus—has empirically demonstrated that human memory does not function like a video recorder; rather, it is a reconstructive process split into three fragile stages: Encoding, Storage, and Retrieval.

1. Estimator Variables (At the Crime Scene): High stress activates the sympathetic nervous system (the Yerkes-Dodson Law), causing the “Weapon Focus Effect”—where a victim fixates visually on a gun or knife, drastically impairing their ability to encode the perpetrator’s facial features. Furthermore, the Cross-Race Effect and poor lighting distort initial perception.
2. System Variables & the Misinformation Effect (During Investigation): Post-event exposure to leading police questions, co-witness discussions, or media photographs alters the witness’s original memory trace without their conscious awareness (confabulation).
3. Procedural Corrective in Section 54 of the BNSS (Test Identification Parade – TIP): Recognizing the psychological vulnerability of eyewitnesses, Section 54 of the BNSS (updating Section 54A CrPC) introduces critical safeguards for the Test Identification Parade (regulated substantively as corroborative evidence under Section 7 of the BSA, formerly Section 9 IEA):
   • Where the person identifying the suspect is mentally or physically disabled, the identification process shall take place under the supervision of a Judicial Magistrate, who must ensure the person identifies the suspect using methods they are comfortable with.
   • Crucially, the entire identification process must be recorded by audio-video electronic means, allowing the trial court to scrutinize whether police officers used subtle psychological cues or suggestive positioning during the lineup.

6. Psychological Evaluation in Capital Sentencing: The Manoj v. State of M.P. Paradigm

Perhaps the most transformative development in Indian criminal psychology over the past five years has occurred not at the stage of determining guilt, but at the stage of sentencing in capital punishment cases.

In the seminal judgment of Bachan Singh v. State of Punjab (1980 2 SCC 684), the Constitution Bench mandated that before imposing the death sentence, courts must weigh both the crime and the criminal, giving liberal and expansive weight to mitigating circumstances—including whether the offence was committed under the influence of extreme mental or emotional disturbance, and the probability that the accused can be reformed and rehabilitated. For four decades, however, trial courts frequently conducted sentencing hearings on the same day as conviction, evaluating reformation without any empirical psychological assessment.

This judicial vacuum was decisively corrected by the three-judge bench decision in Manoj & Ors. v. State of Madhya Pradesh (2022 SCC OnLine SC 677) (followed by the Constitution Bench referral in Re: Framing Guidelines Regarding Potential Mitigating Circumstances to be Considered While Imposing Death Sentences, 2022). In Manoj, the Supreme Court Issued binding operational directives that place Criminal and Clinical Psychology at the center of capital sentencing:

• The State and the trial court must proactively collect Mitigation Information encompassing the accused’s early family background, socio-economic deprivation, history of childhood abuse or trauma, educational deficits, and lifelong psychological conditioning.
• The Court mandated that the state must produce a psychiatric and psychological evaluation report of the accused conducted by a qualified mental health professional from a premier institution (looking beyond Section 22 BNS insanity to identify sub-clinical trauma, personality disorders, cognitive impairments, and post-incarceration behavioral adaptability).
• By recognizing that an offender’s criminal act is often the culmination of cumulative bio-psycho-social disadvantages rather than pure metaphysical evil, Manoj integrates the Biopsychosocial Model of Criminology directly into Article 21 sentencing jurisprudence.

7. Structural Recommendations and Conclusion

While the enactment of the Bharatiya Nyaya Sanhita, Bharatiya Nagarik Suraksha Sanhita, and Bharatiya Sakshya Adhiniyam (2023) modernizes India’s statutory text—replacing “unsoundness of mind” with “mental illness” (Section 22 BNS), mandating crime-scene forensics for serious offences (Section 176(3) BNSS), and expanding expert opinion definitions (Section 39 BSA)—the institutional integration of criminal psychology in India remains nascent. To bridge the chasm between psychological science and courtroom practice, four structural reforms are imperative:

1. Statutory Clarification of “Mental Illness” under Section 22 BNS: The legislature or the Supreme Court should issue an authoritative clarification confirming that “mental illness” under Section 22 BNS encompasses severe Intellectual Disabilities and Neurodevelopmental Disorders (notwithstanding their exclusion under Section 2(1)(s) of the Mental Healthcare Act, 2017 for clinical governance purposes), ensuring that cognitively impaired defendants are not stripped of a general exception previously available under “unsoundness of mind.”
2. Adoption of the Volitional Prong in the Insanity Defence: In alignment with the 42nd Law Commission of India’s contemplation and comparative Commonwealth reforms, Section 22 BNS should be judicially or legislatively expanded to include an irresistible volitional impairment prong (“or was incapable of controlling his conduct in accordance with the law”), bringing Indian law in step with modern neuropsychiatry.
3. Institutionalizing Forensic Psychologists at District Courts & Prisons: Currently, India has fewer than a dozen specialized Forensic Psychology divisions within Central and State Forensic Science Laboratories (such as NFSU Gandhinagar/Delhi and CFSL). Every District and Sessions Court complex and Central Prison should be statutorily staffed with licensed Forensic and Clinical Psychologists to conduct timely competency evaluations under Section 367 BNSS, assist in child-witness interviews under POCSO, administer structured risk-assessment tools (such as HCR-20) during parole/bail hearings, and prepare Manoj-compliant mitigation reports.
4. Replacing Coercive Interrogation with the PEACE Investigative Interviewing Model: Rather than relying on fragmented 15-day police custody across 40 or 60 days under Section 187(2) BNSS or seeking pseudoscientific shortcuts through narco-analysis, Indian police academies should mandate training in the cognitive-psychology-based PEACE Model (Preparation and Planning, Engage and Explain, Account, Closure, and Evaluation) and the Cognitive Interview technique (Fisher & Geiselman), which scientifically enhance accurate memory retrieval and detect deception without violating constitutional rights under Articles 20(3) and 21.

Conclusion

Criminal law cannot deliver substantive Nyaya (justice) if it continues to view the human mind through the static lens of 1843 Victorian morality. As neuroscience and criminal psychology illuminate the intricate architecture of human cognition, trauma, and impulse control, the Indian legal system must evolve from a purely retributive tribunal into a scientifically informed forum. Harmonizing the constitutional guarantees of cognitive liberty and fair trial with rigorous forensic psychology under the 2023 Sanhitas will not weaken criminal accountability; rather, it will ensure that state punishment is calibrated accurately to genuine moral culpability, while channeling pathologically impaired offenders toward evidence-based rehabilitation.

References & Authorities

1. Statutes & Legislative Instruments:
   • The Bharatiya Nyaya Sanhita, 2023 (Act 45 of 2023), §§ 22, 80, 103(2), 108, 111.
   • The Bharatiya Nagarik Suraksha Sanhita, 2023 (Act 46 of 2023), §§ 54, 176(3), 187(2), 367–382.
   • The Bharatiya Sakshya Adhiniyam, 2023 (Act 47 of 2023), §§ 7, 23(2), 39, 108.
   • The Mental Healthcare Act, 2017 (Act 10 of 2017), §§ 2(1)(s), 103, 105.
   • The Juvenile Justice (Care and Protection of Children) Act, 2015 (Act 2 of 2016), § 15.
2. Landmark Judicial Precedents:
   • Accused ‘X’ v. State of Maharashtra, (2019) 7 SCC 1 (Post-conviction mental illness as a mitigating factor in death penalty).
   • Bachan Singh v. State of Punjab, (1980) 2 SCC 684 (Aggravating and Mitigating psychological factors in capital sentencing).
   • Dahyabhai Chhaganbhai Thakkar v. State of Gujarat, AIR 1964 SC 1563 (Burden of proof and crucial point of time for insanity under Sec. 84 IPC).
   • M’Naghten’s Case, (1843) 8 ER 718 : 10 Cl & Fin 200 (HL) (Foundational cognitive test of legal insanity).
   • Manoj & Ors. v. State of Madhya Pradesh, (2023) 2 SCC 353 : 2022 SCC OnLine SC 677 (Mandatory psychological evaluation and mitigation reports in capital trials).
   • Prakash Nayi @ Sen v. State of Goa, (2023) 5 SCC 673 (Interplay between Section 84 IPC and the Mental Healthcare Act, 2017).
   • Selvi & Ors. v. State of Karnataka, (2010) 7 SCC 263 (Unconstitutionality of involuntary Narco-analysis, Polygraph, and BEOS profiling under Articles 20(3) and 21).
   • Shatrughan Chauhan v. Union of India, (2014) 3 SCC 1 (Insanity/schizophrenia as a supervening bar to execution of death sentence).
   • Surendra Mishra v. State of Jharkhand, (2011) 11 SCC 495 (Distinction between Medical Insanity and Legal Insanity).
3. Foundational Books & Empirical Literature in Criminal Psychology:
   • Bandura, A. (1999). Moral disengagement in the perpetration of inhumanities. Personality and Social Psychology Review, 3(3), 193–209.
   • Bartol, C. R., & Bartol, A. M. (2021). Criminal Behavior: A Psychological Approach (12th ed.). Pearson.
   • Canter, D. V., & Youngs, D. (2009). Investigative Psychology: Offender Profiling and the Analysis of Criminal Action. John Wiley & Sons.
   • Hare, R. D. (2003). The Hare Psychopathy Checklist-Revised (PCL-R) (2nd ed.). Multi-Health Systems.
   • Loftus, E. F. (1996). Eyewitness Testimony. Harvard University Press.
   • Raine, A. (2013). The Anatomy of Violence: The Biological Roots of Crime. Pantheon Books.