In the recent case of Amlesh Kumar v. State of Bihar (2025), the Supreme Court (SC) set aside a Patna High Court order, ruling that any forced or involuntary narco test is unconstitutional. The Court reiterated that such orders violate the landmark guidelines established in Selvi v. State of Karnataka (2010).
Scientific Mechanism of Narco Analysis :
Unlike Polygraph tests which measure physiological responses (BP, pulse), Narco Analysis relies on chemical intervention.
- The Substance: Sodium Pentothal (also known as Sodium Thiopental).
- The Class: It is a fast-acting barbiturate (acts as a CNS depressant).
- The Mechanism: It induces a hypnotic/sedated state, neutralizing the subject’s imagination and lowering inhibitions to lie. It is often termed a “Truth Serum.”
| Feature | Narco Analysis | Polygraph Test |
| Method | Chemical Injection (Invasive) | Physical Sensors (Non-invasive) |
| Basis | Lowered inhibition/sedation | Physiological triggers (Pulse, BP) |
| Legal Status | Needs Consent | Needs Consent |
Constitutional Mandate & Legal Safeguards :
The SC has flagged forced tests as a violation of the ‘Golden Triangle’ of Fundamental Rights (Articles 14, 19, and 21).
- Article 20(3) – Self Incrimination: “No person accused of any offence shall be compelled to be a witness against himself.” A forced test effectively compels the accused to speak.
- Article 21 – Personal Liberty & Privacy: Forced intrusion into a person’s mental process violates the Right to Privacy and bodily integrity.
Guidelines & Evidentiary Value?
The Selvi v. State of Karnataka (2010) judgment is the bedrock for these procedures.
1. The Guidelines:
- Consent: Must be informed and voluntary.
- Magistrate: Consent must be recorded before a Judicial Magistrate.
- Legal Aid: The accused must have access to a lawyer during the process.
2. Evidentiary Value:
- Not a Confession: Statements made during the trance are not admissible as primary evidence (confessions) because the subject has no conscious control/choice.
- Discovery of Facts: Under the Evidence Act (and corresponding BNSS sections), only new material facts discovered based on the statement (e.g., finding a hidden weapon) are admissible.
Landmark Judgments on Narco Analysis :
Maneka Gandhi v. Union of India (1978): Established the ‘Golden Triangle’ (Art 14, 19, 21).
Selvi v. State of Karnataka (2010): Mandatory consent; forced tests violate Art 20(3).
Amlesh Kumar v. State of Bihar (2025): Reaffirmed that forced tests are invalid even for investigation.
Q. Consider the following pairs regarding scientific tests used in criminal investigations:
| Test | Key Characteristic/Substance | |
| 1. | Narco Analysis | Uses Sodium Pentothal to induce a hypnotic state. |
| 2. | Polygraph Test | Measures physiological variables like blood pressure and pulse. |
| 3. | Brain Mapping | Direct injection of barbiturates to map neural responses. |
