Court case(2010) 7 SCC 263

A batch of criminal appeals, the first filed in 2004, challenged orders of trial courts and High Courts allowing investigating agencies to subject accused persons, suspects and witnesses to narco-analysis (injection of sodium pentothal), polygraph (lie detector) and brain electrical activation profile tests without their consent. The agencies argued that the tests were scientific aids to investigation and that their results were not statements in court. The appellants said the tests extracted information from the mind by force and intruded into personal liberty.

Balakrishnan CJ held that the involuntary administration of all three techniques is unconstitutional. The responses given during narco-analysis and the physiological readings in polygraph and BEAP tests are testimonial in character, since they convey the subject's personal knowledge, and the compulsion is both physical and psychological; so Article 20(3) is violated for an accused, and section 161(2) CrPC protects witnesses. Independently, the tests infringe Article 21 because they violate mental privacy and the substantive due process standard of a fair and reasonable procedure, amounting to cruel, inhuman or degrading treatment. Even a voluntary test result is not admissible as a confession or statement, though material subsequently discovered with its help can be admitted under section 27 of the Evidence Act. The National Human Rights Commission's 2000 guidelines on polygraph tests must be followed.