"We are of the considered opinion that no individual can be forced and subjected to such techniques involuntarily, and by
doing so it amounts to unwarranted intrusion of personal liberty," a bench headed by Chief Justice K G Balakrishnan said.
The Apex Court ruled that forcing an accused, a suspect or a witness to undrgo such tests is against the Article 20 (3) of the Constitution, which prohibits self-incrimination.
It added that conducting such test on an unwilling individual is violates the scheme of legal process and the result derived from such mode of investigation even if it is done with the person's consent is an unadmissable piece of evidence.
However, the Court said that the anything obtained by the investigators from such techniques thorugh voluntary participation of the person concerned can be used by the agencies for further investigation.