📚 Case Law: Selvi v. State of Karnataka [2010 SC]

🔎 Issue:

The legal questions in this batch of criminal appeals relate to the involuntary administration of certain scientific techniques, namely narco-analysis, polygraph examination and the Brain Electrical Activation Profile (BEAP) test for the purpose of improving investigation efforts in criminal cases. This issue involves tensions between the desirability of efficient investigation and the preservation of individual liberties.

🧠 Polygraph examination

The theory behind polygraph tests is that when a subject is lying in response to a question, he/she will produce physiological responses that are different from those that arise in the normal course. Instruments such as cardiographs, pneumographs, cardio-cuffs and sensitive electrodes are used to measure respiration, blood pressure, pulse, and galvanic skin resistance. The truthfulness of the subject is then assessed on this basis.

💉 Narco-analysis technique

This test involves intravenous administration of sodium pentothal, which induces a hypnotic trance. The subject, under this state, is more likely to divulge information. Though useful for investigators, such involuntary administration raises concerns under Article 20(3).

⚖️ What constitutes ‘incrimination’?

Incrimination includes extracting material or information that can be compared with evidence already possessed by investigators. For example, handwriting samples and specimen signatures. The Supreme Court held that compulsory administration of these tests violates the right against self-incrimination.

📌 Decision:

• No victim can be compelled to undergo these tests.
• Forcible administration intrudes upon mental privacy and can cause stigma.
• Test results obtained through compulsion cannot be admitted as evidence.
• Article 20(3) protects an individual’s choice between speaking and remaining silent.