Selvi & Ors vs State Of Karnataka & Anr

The Supreme Court addressed the legality of involuntary scientific techniques such as narcoanalysis, polygraph tests, and BEAP tests in criminal investigations, emphasizing the conflict between effective investigation and individual rights. The Court held that the right against self-incrimination under Article 20(3) extends to testimonial evidence, and thus, the results of these tests cannot be used as evidence in court. The judgment underscored the necessity of consent for such tests and affirmed the protection of personal liberty under Article 21, ultimately ruling against the involuntary use of these techniques without consent.