POLYGRAPH TEST (Syllabus: GS Paper 2 – Polity & Governance)

Context: Recently, the CBI conducted a polygraph test on the main suspect in the Kolkata doctor rape-murder case, to evaluate his credibility during the ongoing investigation.

Polygraph Test

• Definition: A polygraph, or lie detector test, is a procedure that measures and records several physiological indicators, including blood pressure, pulse, respiration, and skin conductivity, while a person answers a series of questions.
• Basis of the Test: The test operates on the assumption that physiological responses during lying differ from those when a person is telling the truth.
• Evaluation of Responses: These are assigned numerical values to determine whether the person is being truthful, deceptive, or uncertain.
• Historical Context: The concept of a polygraph-like test was first used in the 19th century by Italian criminologist Cesare Lombroso, who measured changes in blood pressure during interrogations.

Legal Admissibility of a Polygraph Test

• Violation of Article 20(3): Conducting polygraph, narco-analysis, and brain mapping tests without consent violates Article 20(3) of the Indian Constitution, protecting against self-incrimination.
• Judicial and Human Rights Concerns: The use of these tests raises concerns about judicial integrity and human rights, particularly regarding individual rights and freedoms.
• Criticism from Courts: Courts have criticized these tests for potentially constituting mental torture and violating the right to life and privacy under Article 21.

Landmark Judgments Related to Polygraph Tests

• Selvi v. State of Karnataka & Anr Case, 2010: The Supreme Court ruled that involuntary narco or lie detector tests infringe on an individual’s “mental privacy” and violate Article 20(3) against self-incrimination.
• D.K. Basu v. State of West Bengal Case, 1997: The Court deemed involuntary polygraph and narcos tests as cruel, inhuman, and degrading treatment, infringing on Article 21 or the Right to Life and Liberty.
• State of Bombay v. Kathi Kalu Oghad, 1961: The Court ruled that Article 20(3) does not cover physical evidence like fingerprints or blood samples, which can be used if voluntarily given.
• Other Observations: The Supreme Court noted that narco tests are not reliable as evidence and emphasized following the NHRC guidelines for polygraph administration. Information discovered through voluntary tests can be admitted under Section 27 of the Evidence Act, 1872, if it leads to a fact.