Polygraph and Narcoanalysis tests

About Deception Detection Tests (DDTs)

• Deception Detection Tests (DDTs) include polygraph, narcoanalysis, and brain mapping.
• These tests are used to obtain concealed information related to crime and have important clinical, scientific, ethical, and legal implications.

About Polygraph Test

• A polygraph test attempts to detect deception by measuring physiological responses while a person answers questions.
• Mechanism: Instruments such as cardio-cuffs and sensitive electrodes measure physiological responses during questioning, and numerical values are assigned to determine truth, deception, or uncertainty.
• Parameters Tracked: The test records blood pressure, pulse, respiration, sweat gland activity, and blood flow.
• Evaluation: The scientific community considers the test unreliable because it has not shown 100% accuracy, and experts say people can use countermeasures to mislead the results.

About Narcoanalysis Test

• Narcoanalysis attempts to obtain information by placing a person in a sedated or hypnotic state.
• Mechanism: Drugs such as sodium pentothal, scopolamine, and sodium amytal are administered intravenously to induce a hypnotic state in which the subject is expected to reveal information.
• Evaluation: The method has not been scientifically proven to be completely reliable and remains controversial in the medical field.

Legal Position in India

• D.K. Basu v. State of West Bengal (1997): The Supreme Court ruled that involuntary administration of polygraph and narcoanalysis tests amounts to cruel, inhuman, and degrading treatment under Article 21.
• Selvi v. State of Karnataka & Anr. (2010):
  • Consent Requirement: The Supreme Court in Selvi v. State of Karnataka (2010) held that these tests can be conducted only with voluntary consent.
  • Fundamental Rights: Involuntary tests violate the right against self-incrimination under Article 20(3) and amount to intrusion into mental privacy.
  • Admissibility: Test results are not confessions, but any information or material subsequently discovered through a voluntarily administered test may be admitted under Section 27 of the Indian Evidence Act, 1872 (now Bharatiya Sakshya Adhiniyam).
  • Refusal: Refusal to undergo these tests cannot be treated as evidence of guilt.
• NHRC Guidelines (2000):  The Supreme Court in Selvi  case directed that the National Human Rights Commission’s Guidelines for the Administration of Polygraph Test on an Accused (2000) must be strictly followed while conducting such tests.
  • NHRC Guidelines:
    • Voluntary Consent: The accused must willingly agree and may refuse the test.
    • Informed Consent: Police and the lawyer must explain the purpose, procedure, and legal consequences before consent.
    • Recorded Consent: Consent must be recorded before a Judicial Magistrate.
    • Documentation: Police must produce proof before the court that the accused voluntarily consented to the test.
    • Clarification: Statements made during the test are treated as police statements and not as confessions.

About Brain Mapping

• Brain mapping  is a deception detection test that measures electrical activity in the brain to identify concealed information related to a crime.
  • Mechanism: Electrodes are placed on the scalp and connected to a recording system to measure the brain’s electrical field potentials while the subject listens to words or stimuli.
    • The recorded brain responses are analyzed to determine whether the subject recognizes information related to the crime.
  • Parameters Tracked: The test records event-related potentials generated when the brain encounters a familiar stimulus.
    • The commonly used method in India is the Brain Electrical Activation Profile (BEAP), also known as the P300 Waves Test.
  • Purpose: The test is used to detect concealed information related to a crime without requiring the subject to give oral answers.
  • Evaluation: Brain mapping only assists the investigation by indicating whether the subject has knowledge related to the crime.
    • It cannot identify the exact lie or the information stored in the person’s brain, and its results do not have legal sanctity.