About

• The Polygraph Test (commonly known as “lie detector test”) is a procedure that detects several physiological indicators, including pulse, blood pressure, respiration, and skin conductivity, which indicate if a person is being untruthful when asked a series of questions. 
• This test is based on the assumption that physiological responses that are triggered when a person is lying are different from what they would be otherwise.
• Polygraph tests are used to detect truthfulness of individuals by crime investigation departments, national security agencies, etc. 
• However, accuracy of polygraph tests and ethical issues associated with the tests are highly debated.

Supreme Court rulings about Polygraph Test

• In the case of Selvi vs State of Karnataka & Anr (2010), the Supreme Court ruled that lie detector tests must be voluntary and only conducted with the informed consent of the accused.
• The court also ruled that results of the tests cannot be considered to be “confessions”, but any information or material subsequently discovered with the help of such a voluntarily-taken test can be admitted as evidence.
• In the D.K. Basu vs. State of West Bengal case, 1997, the SC ruled that involuntary administration of the polygraph and narcos test will amount to cruel, inhuman, and degrading treatment in the context of Article 21 or the Right to Life and Liberty.