CONSENT, CUSTODY AND DERIVATIVE EVIDENCE: A CRITICAL ANALYSIS OF THE POST SELVI REGIME ON NARCO-ANALYSIS AND POLYGRAPH TESTING IN INDIA.

Narco-analysis and polygraph examinations are used in Indian criminal investigations as forensic tools to elicit information from suspects, raising significant questions of scientific reliability, evidentiary value, and constitutional protection. In Selvi v. State of Karnataka, the supreme court of India held that involuntary narco-analysis, polygraph, and brain-mapping tests violate Articles 20(3) and 21 of the Constitution, however the court permitted the use of such test when there is voluntary consent from the person subject to safeguards. This study analyzes the post-Selvi regime by exploring three interconnected questions: the legality of consent acquired in detention settings, the scientific reliability and limitations of the techniques, and the admissibility of facts discovered through information obtained during testing. Adopting a doctrinal approach the paper studies Selvi v. State of Karnataka, the National Human Rights Commission's guidelines, and the transition from Section 27 of the Indian Evidence Act, 1872 to Section 23(2) of the Bharatiya Sakshya Adhiniyam, 2023.It argues that information obtained through compromised or unreliable testing can nonetheless influence the outcome of a trial by way of the discovery exception. Ultimately, the paper advocates for firmer consent safeguards, uniform forensic protocols, independent judicial supervision and well-defined boundaries on the derivative use of test-generated information.