On New Year's Day this year, the country was rocked by the news of a horrific accident in Delhi -- 20-year-old Anjali Singh, who was on a scooter, was hit by a car, and her body dragged for several kilometres. Soon after, news reports indicated that investigating officers may consider a lie detector test for the five main accused persons in the crime. This is not the first time a lie detector test has been brought up in the course of an investigation in a high profile case: the accused in the Shraddha Walkar case, Aaftab Poonawala underwent polygraph tests; these tests have begun on three suspects in the murder of a Tamil Nadu Minister's brother and a court has now allowed narcoanalysis and polygraph tests to be conducted on an accused person in the case of Ankita Bhandari, a 19-year-old murdered in Uttarakhand, as per news reports. These are just a few of the recent cases where such "scientific" tests are being used on those accused of crimes.

In 2010, a Supreme Court ruling said that the use of narcoanalysis, brain mapping and polygraph tests on the accused, suspected and witnesses to a crime, without their consent, was unconstitutional and violated their right against self-incrimination. It also said that such test results could not be admitted in evidence; however any information/material subsequently discovered with the help of tests undertaken voluntarily, could be admitted.

Despite the ruling however, these tests continue to be used, to date. But how scientific are they? Several countries across the world have disbarred or significantly cut down on their use - is there any evidence to suppose that they truly work? Do such invasive procedure violate the rights of those who undergo them? And have they led to any investigative breakthroughs in India?

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