New Delhi, India (CNN) -- India's supreme court Wednesday ruled as unconstitutional the use of lie-detection technologies on suspects without their consent, attorneys said.
Indian investigators have put suspects through polygraph, truth-serum and brain-mapping examinations that prosecutors argued served as key methods to obtain leads in several complicated, high-profile cases.
But the supreme court declared that forced use of these methods infringes on an individual's right to silence when quizzed by officers, lawyer Manoj Goel said.
"Article 20 (3) of the (Indian) constitution guarantees citizens the right to remain silent during investigation," Goel said.
In his arguments, he insisted that subjecting suspects to lie-detection tests against their consent should be backed by a law.
"At present, there's no such legislation to give credence to such methods," said Goel, counsel for a petitioner who had challenged forcible extraction of information by investigators. Even if carried out with consent of the suspects, the court ruled that the tests cannot be treated as evidence, Goel said.
Human rights advocates have welcomed the ruling.
"This is a very welcome decision. It is about time we break away from old English law practices," said Sudhir Chopra, a law fellow at the Cambridge Central Asia Forum of the Cambridge University.
He maintained that the lie-detection techniques do not throw out conclusive results and that their forcible use breaches human rights.
The legal basis for much of India's state and federal police services is a law dating back to 1861, which was drafted in the wake of an 1857 uprising against British rule.
India gained its independence from Britain in 1947.
In its report last year, the Human Rights Watch said the Indian police had largely failed to evolve from the repressive forces of Britain's colonial regime.
Indian authorities, however, insist that the country is committed to the principles of fair trial.
On Monday, Indian Home Minister P. Chidambaram cited the court case of the Mumbai terror attack as an example.
Pakistani national Mohammed Ajmal Kasab was convicted for his involvement in the 2008 siege of India's financial capital. Two Indian suspects were acquitted by the trial court.
"He (Kasab) was given full opportunity to plead his case. ...the trial of Kasab underlines the fact that India is a country governed by the rule of law," Chidambaram said after the verdict two days ago.