Selvi v. State of Karnataka

This is the governing authority of the forensic-evidence module. For years it was debated whether the involuntary administration of scientific techniques — narco-analysis, polygraph examination, and the like — for the purpose of improving investigation violated Article 20(3). Selvi decides it, and it decides it by drawing a line that runs through the whole of forensic evidence: between techniques that extract testimony and techniques that take material.

Every later question about DNA, voice samples, handwriting exemplars or brain-profiling is answered by working out which side of that line the technique falls on.

The involuntary administration of scientific techniques such as narco-analysis tests and polygraph examinations, used to improve investigative efforts in criminal cases, was challenged as violating the right against self-incrimination.

The Chief Justice, speaking for the Court, drew the following conclusions.

• The right against self-incrimination and personal liberty are non-derogable rights; their enforcement is not suspended even during an emergency.
• The right of the police to investigate an offence and to examine any person cannot override the constitutional protection in Article 20(3).
• The protection is available not only at the stage of trial but also at the stage of investigation.
• The right protects persons formally accused, suspects, and even witnesses who apprehend making statements that could expose them to criminal charges or further investigation.
• The law confers on any person examined during an investigation an effective choice between speaking and remaining silent: it is for the person examined to decide whether the answer to a particular question would be inculpatory or exculpatory.
• Article 20(3) cannot be invoked by witnesses in proceedings that cannot be characterised as criminal proceedings.
• Compulsory narco-analysis amounts to testimonial compulsion and attracts the protection of Article 20(3).
• DNA profiling is not a testimonial act, so the protection cannot be granted against it.
• Compulsorily obtaining signatures and handwriting samples is testimonial in nature, but such acts are not incriminating by themselves when used for the purpose of identification.

Step one — the protected act is being a witness, not being investigated. Article 20(3) forbids compelling a person to be a witness against himself. It does not forbid the collection of evidence from his body.

Step two — testimonial means conveying personal knowledge. A technique that makes a person speak out of his own mind — narco-analysis is the plainest case — extracts the contents of his knowledge and is therefore testimonial. A technique that yields a physical characteristic existing independently of what he knows, such as a DNA profile, is not.

Step three — the identification exception. Handwriting and signature samples are testimonial in character, yet they are not incriminating in themselves when the purpose is comparison and identification. They prove who made a document, not what the person knows.

Step four — choice, not classification, at the interrogation table. Because the person being examined is the only one who can know whether an answer would incriminate him, the statute and the Constitution together give him the choice between speaking and staying silent, rather than giving the investigator a power to decide in advance.

Selvi answers any question of the form: may the police compel technique X? Apply the test in three moves — is the person within the protection, is the technique testimonial, and is it being used for identification only?

Place it alongside the current statutes, which is what an answer under the new codes must do. The Bharatiya Nagarik Suraksha Sanhita 2023 provides for medical examination and DNA profiling in ss. 51 to 53, for a forensic expert to visit the scene in s. 176(3) — a provision that comes into force in a State from a date that State Government notifies within five years, so it is not uniformly in force — for Government scientific experts in s. 329, and for specimen signatures and voice samples in s. 349. The Criminal Procedure (Identification) Act 2022 defines measurements, provides in s. 3 for their taking with a proviso for biological samples, and in s. 4 for retention by the National Crime Records Bureau for seventy-five years. Expert opinion itself is relevant under BSA s. 39(1) (IEA s. 45), with the facts bearing on such opinion relevant under BSA s. 40 (IEA s. 46) and the grounds of opinion under BSA s. 45 (IEA s. 51).

It does not forbid narco-analysis conducted with consent, and it does not decide what weight the results of any technique carry once lawfully obtained.