By Aishi Ghosh
ABSTRACT
The fast growth of neurotechnology creates new challenges for the legal system, especially how evidence is interpreted in constitutional frameworks. This article examines the admissibility of brain-based evidence obtained through functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) in criminal proceedings. It analyzes the constitutional tensions particularly the rights against self-incrimination under Article 20(3) and the right to privacy under Article 21, while comparing these with evolving standards in the United States and Europe. Through a comparative and critical analysis of scientific limitations, this article argues that the current probative value of neuro-evidence is outweighed by its prejudicial impact and scientific unreliability. It concludes by advocating for a statutory framework in India to explicitly regulate neuro-evidence before its adoption compromises the integrity of the judicial process.
INTRODUCTION
Rapid advancement in neuroscience has significantly influenced the legal domain. Technologies now claim to detect lies, uncover memories, and even interpret aspects of a person’s mental states. Whether the obsolete Brain Electrical Activation Profile (BEAP) tests in India or the commercial fMRI-based lie detection in the United States, Courts have faced the difficulty of ascertaining if “brain data” can be relied upon as evidence.1 While such technologies may appear highly scientific and objective, their intersection with fundamental rights raises critical questions. This article explores whether the forceful extraction of cognitive responses violates constitutional protections and whether the current scientific consensus supports the reliability of this evidence for forensic use.
BRAIN DATA AS EVIDENCE
Brain data refers to information recorded from the activity of the central nervous system, often using EEG, which records electrical signals, or fMRI, which tracks blood flow changes within the brain.2 Proponents argue these methods can reveal experiential knowledge i.e., whether a defendant’s brain recognizes certain information, such as recognizing a crime scene or assessing relevant cognitive processes that may be relevant to determining mens rea (mental intention). Brain data does not fall within traditional categories of physical evidence, unlike DNA or fingerprint, but rather reflects a physiological correlate of a mental state, placing it between tangible evidence and testimony.
CORE LEGAL ISSUES
The admission of brain data raises some core issues: firstly, the issue of testimonial compulsion i.e., the forceful extraction of brain responses undermines the protection against self-incrimination. Secondly, there is an implication of a breach of privacy. The state’s access to a person’s neural activity may intrude into the inner sanctum of the mind. Lastly, the question of reliability arises. The scientific methodology behind these technologies must meet strict legal standards before being considered credible evidence. The ongoing debate questions whether such techniques are sufficiently accurate and dependable for forensic use.
INDIAN LEGAL POSITION
The Selvi v. State of Karnataka (2010) judgment made it clear that forcing someone to undergo techniques like narco-analysis, polygraph, and BEAP tests violates the right against self-incrimination under Article 20(3).3 The Court reasoned these techniques constitute testimonial compulsion, since they extract personal knowledge directly from an individual’s mind. While in Selvi the Court specifically addressed BEAP, the reasoning extends to modern neurotechniques as well.
Further, the Justice K.S. Puttaswamy (Retd.) v. Union of India (2017) judgment strengthened the constitutional foundation against involuntary neuro-evidence. The right to privacy was recognized as a fundamental right under Article 21.4 The nine-judge bench emphasized an individual’s control over personal information and decisional autonomy.5 Since brain data reveals the most intimate form of personal information- thoughts, memories, and beliefs. Any state-compelled extraction of cognitive responses would face strict scrutiny under the Puttaswamy framework. It requires the state to show legitimate aim, proportionality, and statutory backing. Moreover, the privacy framework in the Puttaswamy judgment extends to cognitive liberty- the right to control one’s own thoughts. Although constitutional protections already restrict such practices, there is no specific statutory framework relating to neuro-evidence.
FOREIGN JURISDICTIONS (USA & EUROPE)
In the United States, the Fifth Amendment protects against testimonial self-incrimination, but Courts have not definitively classified brain data as testimonial.6 Scholarly analysis suggests that compelled neuro-searches may survive the Fifth Amendment challenge but face significant hurdles under the Fourth Amendment which guards against unreasonable searches and Federal Rule of Evidence 403 which excludes evidence whose prejudicial effect outweighs its probative value.7 Under the European Union’s General Data Protection Regulation, brain data is often treated as sensitive data (particularly as biometric or health data) requiring explicit consent.8 The European Court of Human Rights emphasizes proportionality. Forced extraction of cognitive data is viewed as a severe intrusion into personal autonomy and dignity.9 India provides stronger constitutional protections than the American Fourth Amendment, though not as extensive as those in the EU.
Under the European Union’s GDPR, brain data is treated as sensitive personal data requiring explicit consent.8 Courts emphasize proportionality and human dignity.9
CRITICAL ANALYSIS
Admitting brain data as evidence gives rise to scientific uncertainty. Functional neuroimaging suffers from signal-to-noise limitations.10 An EEG or fMRI cannot reliably prove whether a specific memory belongs to a murderer or a first responder who saw the aftermath. Additionally, there is a high risk of false positives, with approximately 15-30% error rates reported in certain EEG studies.11 Moreover, colorful brain scans unduly prejudice jurors, who may overestimate the certainty and accuracy of science. As Walter Sinnott-Armstrong notes, the actual value of neuroimages in determining criminal responsibility remains quite minimal at present.12 Until neurotechnology achieves greater individual-level accuracy, the risk of convicting an innocent person based on a misinterpreted brain image is too high for a system that is based on the presumption of innocence.
The right against self-incrimination (Article 20(3)) protects not just verbal words but the mental processes that produce them. Supporters of admissibility argue that brain data is more like physical evidence, like a fingerprint, rather than testimony. If a defendant raises a mental-status defense e.g., insanity, the state should be allowed to verify it through brain scans. Refusing such evidence allows guilty individuals to hide behind mental privacy. However, forcing an accused to activate specific neurons to prove knowledge is a direct violation of the right to remain silent. This article, therefore, takes a firm stand that brain data obtained without consent should be considered inadmissible in criminal trials.
EVALUATION & RESEARCH INSIGHTS
Research by Brown & Murphy shows that while neuroimages appear highly convincing, they are not reliable diagnoses of a person’s past mental state.13 Studies highlight how irrelevant visuals mislead judges and juries into trusting weak or flawed conclusions. Consequently, Courts in common law jurisdictions have largely rejected lie-detection fMRI as evidence.14 The Indian judiciary’s principles laid down in Selvi v. State of Karnataka, reinforced by Puttaswamy’s judgment, stands out as a strong safeguard for protecting cognitive liberty from coercive state power.
India’s jurisprudence, particularly through Selvi and Puttaswamy, provides a strong safeguard against coercive neuro-evidence.
CONCLUSION
Neurotechnology is advancing faster than the legal system. While India’s Selvi and Puttaswamy judgments provide strong protection, future technologies, capable of reading content with higher accuracy, will demand a new legal response. The article recommends the enactment of a specific “Neuro-Evidence (Admissibility) Statute” in India, which should clearly ban the use of brain data obtained without consent and allow voluntary use only under strict scientific scrutiny, similar to the Daubert standard. The law must ensure that the pursuit of technological efficiency never comes at the cost of human dignity. The mind must remain a sanctuary, not a source of state-compelled testimony.
India should enact a dedicated “Neuro-Evidence (Admissibility) Statute” that prohibits involuntary extraction of brain data while permitting voluntary use under strict scientific standards. The justice system must ensure that technological progress does not compromise human dignity.
Footnotes
1. Teneille R. Brown & Emily R. Murphy, Through a Scanner Darkly…, Stanford Law Review (2009). ↩
2. Id. at 1128–35. ↩
3. Selvi v. State of Karnataka, (2010) 7 SCC 263. ↩
4. Justice K.S. Puttaswamy v. Union of India, (2017) 10 SCC 1. ↩
5. Id. ↩
6. Kansas v. Cheever, 571 U.S. 87 (2013). ↩
7. Josh A. Roth, Neurosearches, Cornell Law Review (2024). ↩
8. GDPR, Regulation (EU) 2016/679. ↩
9. S. & Marper v. UK (2008). ↩
10. Nature Neuroscience (2008). ↩
11. Id. ↩
12. Sinnott-Armstrong, Brain Images as Legal Evidence. ↩
13. Brown & Murphy, supra note 1. ↩
14. United States v. Semrau (2012). ↩
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