Are lie-detector tests legally valid?

Context: On August
26, the Central Bureau of Investigation (CBI) conducted a second round of
polygraph tests on seven people, in connection with the rape and murder of a
resident doctor at the R.G. Kar Medical College and Hospital in Kolkata. The
central agency, which has been investigating the crime since August 13
following a Calcutta High Court orders, had obtained permission from a Kolkata
court to conduct the polygraph tests. The Court also remanded the main accused
to judicial custody for 14 days.

Deception
detection tests (DDTs)/Polygraph tests

·      
About: Polygraph or Lie Detector
Test is a procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin
conductivity while a person is asked and answers a series of questions. A Numerical
value is assigned to each response to conclude whether the person is
telling the truth, is deceiving, or is uncertain.

·      
Accuracy of
tests: Polygraph and narco tests are not scientifically proven to be 100% accurate and remain
controversial in the medical field. Despite this, investigative agencies
have recently used these tests as a "softer alternative" to torture to extract the truth from
suspects.

·      
Types: Polygraph Test- Measures
physiological changes like heart rate, blood pressure, respiration, and skin
conductivity while a person answers questions.

Narco-Analysis Test- The
subject is administered a drug (like sodium pentothal) that lowers inhibitions,
making it easier for them to speak freely.

Brain Mapping (P300) - Electrodes
are used to measure brainwave activity when the subject is shown images or
asked questions related to the crime.

Legal
status in India

·      
About: While lie
detection tests can be used as investigative tools, the results are not
admissible as sole evidence in court. The Supreme Court has ruled that such
tests violate Article 20(3) of the Indian Constitution, which protects against
self-incrimination.

·      
Violation of Article 20(3): Polygraph, narco-analysis, and brain mapping
tests conducted without the
accused's consent violate Article 20(3) of the Indian
Constitution, which protects the right
against self-incrimination.

·      
Necessity of Consent: As these
tests involve the accused providing potentially self-incriminating information, obtaining their consent is mandatory to avoid
breaching constitutional rights.

·      
Judicial and Human Rights Concerns: The use of
narco-analysis and similar tests raises significant
concerns about judicial integrity and human rights, particularly
regarding individual rights and freedoms.