The Supreme Court verdict restricting the use of narco-analysis and similar techniques on suspects is a welcome and overdue one.

The recent verdict of the Supreme Court that narco-analysis, polygraph and brain mapping tests can no more be conducted on an accused or a suspect without his or her consent has been hailed by members of the legal fraternity and human rights activists as a notable contribution to the cause of personal liberty and privacy.

At the same time, comments have been made by some people of authority that the ruling is a setback to scientific investigation. Some have demanded that Parliament be persuaded to permit polygraph and brain mapping tests.

These comments are devoid of legal and constitutional backing and stem from an erroneous understanding of one the foundational principles of the Indian criminal jurisprudence system that no person can be forced to incriminate himself or herself. Article 20(3) of the Constitution which embodies the guarantee against self- incrimination says: “No person accused of an offence shall be compelled to be a witness against himself.”

In my considered opinion, the court's decision has set at rest a controversy on an important question of constitutional importance. It also virtually spells the demise of certain questionable practices that have been frequently resorted to by the police without any rhyme or reason, and that should have ended long ago. Forty-five years ago, while preparing my thesis on the subject of self-incrimination, in partial fulfillment of the requirement for the degree of Master of Laws, I had studied the subject in depth and detail and reached the conclusion that such procedures are unconstitutional and violate the privilege against self-incrimination.

A distinction has to be drawn between physical evidence obtained from the body of the accused and testimony obtained orally. While the former is admissible in evidence, the latter is hit by the constitutional privilege against self-incrimination. The reason is that physical testimony such as fingerprints, a sample of blood, a strand of hair and so on, are not testimony about the body but the body itself, which is wholly unchangeable except in rare cases where evidence is tampered with. They are neither oral nor documentary evidence, but belong to a third category of material evidence that is outside the realm of testimony.

There is this rational distinction between oral testimony and physical testimony. While an accused could be forced to make a clean breast of the ‘offence' he or she is alleged to have committed by threat, torture, inducement, drugging and so on which is false in its entirety, no amount of threat or inducement can alter the nature of the physical evidence. In appropriate cases even force can be used to extract physical evidence, for compulsion alone is not the component idea of the privilege against self incrimination, but testimonial compulsion. Therefore, statements obtained from an accused by means of the “truth serum,” being testimonial in character, come within the protective umbrella of the constitutional privilege against self-incrimination.

Narco-analysis has the added danger of the accused pouring out both fact and fancy under the influence of the drug. The statements obtained are also influenced by the suggestions of the interrogator; a person can be made to make a wide variety of unreliable and half-true statements.

As regards polygraph and brain mapping, though they are not testimonial in nature, their probative value is insignificant. In West Africa, persons suspected of a crime were often made to pass a bird's egg to one another. If anyone broke the egg, then he or she was considered guilty, based on the idea that their nervousness was to blame. In ancient China, the suspect held a handful of rice in his or her mouth during a prosecutor's speech. Because salivation was believed to cease at times of emotional anxiety, the person was considered guilty if by the end of that speech the rice remained dry. The use of polygraph and brain mapping is no different.

An important aspect that has to be addressed in this connection is that permitting these tests to be performed at the drop of a hat will make the officers of the investigating agency lazy and complacent. This amply justifies the classic observation of the jurist Wigmore in his treatise on the Law of Evidence: “It is better to rub red pepper on a poor devil's eyes, instead of hunting after evidence under the hot sun.”

Besides, the officials may develop a tendency to approach the case on hand euphorically and with a false sense of confidence that they can unravel the hidden aspects by resorting to techniques that lack scientific validity besides being unconstitutional. That in turn makes them slaves to technology, depriving them of independent judgment and investigative acumen. This will vindicate Rousseau's concept of slavery evident from his following words: “Every man born in slavery is born for slavery. Salves lose everything in their chains, even their desire of escaping from them. They love their servitude as the comrades of Ulysses loved their brutish condition”

(The author is a former Acting Chief Justice of the Madras High Court.)

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