February 9, 2023

Selvi v. State of Karnataka (2010)- Admissibility of Lie Detector Tests

Selvi v. State of Karnataka, (2010) is a landmark case on the issue of narco test, where the court considered this conflict of desirability of efficient investigation and the preservation of individual liberties, in detail.

Background of the case

The case was reached in Supreme Court through Criminal Appeals. The legal questions in this batch of criminal appeals was related to the involuntary administration of certain scientific techniques, namely narcoanalysis, polygraph examination and the Brain Electrical Activation Profile (BEAP) test for the purpose of improving investigation efforts in criminal cases.

The NARCOANALYSIS TECHNIQUE involves the intravenous administration of sodium pentothal, a drug which lowers inhibitions on part of the subject and induces the person to talk freely.

POLYGRAPH EXAMINATION AND THE BEAP TEST are methods which serve the respective purposes of lie-detection and gauging the subject’s familiarity with information related to the crime. These techniques are essentially confirmatory in nature, wherein inferences are drawn from the physiological responses of the subject.

The contentions raised by the parties

The objections were raised against these methods, in respect of instances where individuals who were the accused, suspects or witnesses in an investigation have been subjected to these tests without their consent.

But, on the other side, it was defended by citing the importance of extracting information which could help the investigating agencies to prevent criminal activities in the future as well as in circumstances where it is difficult to gather evidence through ordinary means. It was also urged that administering these techniques does not cause any bodily harm and that the extracted information will be used only for strengthening investigation efforts and will not be admitted as evidence during the trial stage.

The assertion was that improvements in fact-finding during the investigation stage will consequently help to increase the rate of prosecution as well as the rate of acquittal. Yet another line of reasoning is that these scientific techniques are a softer alternative to the regrettable and allegedly widespread use of `third degree methods’ by investigators.

Questions, framed by the court

I. Whether the involuntary administration of the impugned techniques violates the `right against self-incrimination’ enumerated in Article 20(3) of the Constitution?

I-A. Whether the investigative use of the impugned techniques creates a likelihood of incrimination for the subject?

I-B. Whether the results derived from the impugned techniques amount to `testimonial compulsion’ thereby attracting the bar of Article 20(3)?

II. Whether the involuntary administration of the impugned techniques is a reasonable restriction on `personal liberty’ as understood in the context of Article 21 of the Constitution.

The court’s analysis

The involuntary administration of the techniques prompts questions about the protective scope of the `right against self-incrimination’ which finds place in Article 20(3) of our Constitution.

The grievances

 The person being interrogated could possibly make self-incriminating statements on account of apprehensions that these techniques will extract the truth. Such behaviour on part of investigators is more likely to occur when the person being interrogated is unaware of his/her legal rights or is intimidated for any other reason.

It is a settled principle that a statement obtained through coercion, threat or inducement is involuntary and hence inadmissible as evidence during trial. However, it is not settled whether a statement made on account of the apprehension of being forcibly subjected to the impugned tests will be involuntary and hence inadmissible.

It is also conceivable that an individual who has undergone either of these tests would be more likely to make self-incriminating statements when he/she is later confronted with the results.

What constitutes `incrimination’ for the purpose of Article 20(3)?

Article 20(3) of the Constitution, gives the protection against self-incriminatory question. (We have also discussed Article 20(3) in detail, here)

Article 20(3) reads as follows:

“No person accused of any offence shall be compelled to be a witness against himself.”

It could be argued that the compulsory administration of the impugned tests can prove to be useful in instances where the cooperating witness has difficulty in remembering the relevant facts or is wilfully concealing crucial details. Such situations could very well arise when a person who is a coaccused is offered immunity from prosecution in return for cooperating with the investigators. Even though the right against self-incrimination is not directly applicable in such situations, the relevant legal inquiry is whether the compulsory administration of the impugned tests meets the requisite standard of `substantive due process’ for placing restraints on personal liberty.

Rule against adverse inferences from silence

Indian law incorporates the `rule against adverse inferences from silence’ which is operative at the trial stage. This position is embodied in a conjunctive reading of Article 20(3) of the Constitution and Sections 161(2), 313(3) and Proviso (b) of Section 315(1) of the CrPC. The gist of this position is that even though an accused is a competent witness in his/her own trial, he/she cannot be compelled to answer questions that could expose him/her to incrimination and the trial judge cannot draw adverse inferences from the refusal to do so.

Some commentators have argued that the `rule against adverse inferences from silence’ should be broadly construed in order to give protection against non-penal consequences. It is reasoned that the fact of a person’s refusal to answer questions should not be held against him/her in a wide variety of settings, including those outside the context of criminal trials.

A hypothetical illustration of such a setting is a deportation hearing where an illegal immigrant could be deported following a refusal to answer questions or furnish materials required by the concerned authorities. This question is relevant for the present case because a person who refuses to undergo the impugned tests during the investigative stage could face non-penal consequences which lie outside the protective scope of Article 20(3).

For example, a person who refuses to undergo these tests could face the risk of custodial violence, increased police surveillance or harassment thereafter. Even a person who is compelled to undergo these tests could face such adverse consequences on account of the contents of the test results if they heighten the investigators’ suspicions. Each of these consequences, though condemnable, fall short of the requisite standard of `exposure to criminal charges and penalties’ that has been enumerated in Section 161(2) of the CrPC. Even though Article 20(3) will not be applicable in such circumstances, reliance can be placed on Article 21 if such non-penal consequences amount to a violation of `personal liberty’ as contemplated under the Constitution.

In the past, Supreme Court has recognised the rights of prisoners (undertrials as well as convicts) as well as individuals in other custodial environments to receive `fair, just and equitable’ treatment.

For instance, in Sunil Batra v. Delhi Administration, (1978) 4 SCC 494, it was decided that practices such as `solitary confinement’ and the use of bar- fetters in jails were violative of Article 21. Hence, in circumstances where persons who refuse to answer questions during the investigative stage are exposed to adverse consequences of a non-penal nature, the inquiry should account for the expansive scope of Article 21 rather than the right contemplated by Article 20(3).

Do the results derived from the impugned techniques amount to `testimonial compulsion’ thereby attracting the bar of Article 20(3)?

It is quite evident that the narcoanalysis technique involves a testimonial act. A subject is encouraged to speak in a drug-induced state, and there is no reason why such an act should be treated any differently from verbal answers during an ordinary interrogation. Therefore, the court held that there is no obstruction to the proposition that the compulsory administration of the narcoanalysis technique amounts to `testimonial compulsion’ and thereby triggers the protection of Article 20(3).

Next question is whether the results obtained through polygraph examination and the BEAP test are of a testimonial nature. In both these tests, inferences are drawn from the physiological responses of the subject and no direct reliance is placed on verbal responses. In some forms of polygraph examination, the subject may be required to offer verbal answers such as `Yes’ or `No’, but the results are based on the measurement of changes in several physiological characteristics rather than these verbal responses.

In the BEAP test, the subject is not required to give any verbal responses at all and inferences are drawn from the measurement of electrical activity in the brain.

The court’s Decision

The court held that,

  • The compulsory administration of the impugned techniques violates the `right against self- incrimination’. This is because the underlying rationale of the said right is to ensure the reliability as well as voluntariness of statements that are admitted as evidence. Supreme Court has recognised that the protective scope of Article 20(3) extends to the investigative stage in criminal cases and when read with Section 161(2) of the Code of Criminal Procedure, 1973 it protects accused persons, suspects as well as witnesses who are examined during an investigation.

The test results cannot be admitted in evidence if they have been obtained through the use of compulsion.

  • Article 20(3) protects an individual’s choice between speaking and remaining silent, irrespective of whether the subsequent testimony proves to be inculpatory or exculpatory.
  • Forcing an individual to undergo any of the impugned techniques violates the standard of `substantive due process’ which is required for restraining personal liberty. Such a violation will occur irrespective of whether these techniques are forcibly administered during the course of an investigation or for any other purpose since the test results could also expose a person to adverse consequences of a non-penal nature.
  • The compulsory administration of any of these techniques is an unjustified intrusion into the mental privacy of an individual. It would also amount to `cruel, inhuman or degrading treatment’ with regard to the language of evolving international human rights norms.
  • Furthermore, placing reliance on the results gathered from these techniques comes into conflict with the `right to fair trial’. Invocations of a compelling public interest cannot justify the dilution of constitutional rights such as the `right against self-incrimination’.
  • No individual should be forcibly subjected to any of the techniques in question, whether in the context of investigation in criminal cases or otherwise. Doing so would amount to an unwarranted intrusion into personal liberty.
  • However, the court left room for the voluntary administration of the impugned techniques in the context of criminal justice, provided that certain safeguards are in place.
  • Even when the subject has given consent to undergo any of these tests, the test results by themselves cannot be admitted as evidence because the subject does not exercise conscious control over the responses during the administration of the test.
  • However, any information or material that is subsequently discovered with the help of voluntary administered test results can be admitted, in accordance with Section 27 of the Evidence Act, 1872.
  • THE NATIONAL HUMAN RIGHTS COMMISSION HAD PUBLISHED `GUIDELINES FOR THE ADMINISTRATION OF POLYGRAPH TEST (LIE DETECTOR TEST) ON AN ACCUSED’ IN 2000. These guidelines should be strictly adhered to and similar safeguards should be adopted for conducting the `Narcoanalysis technique’ and the `Brain Electrical Activation Profile’ test.

The text of these guidelines has been reproduced below:

(i) No Lie Detector Tests should be administered except on the basis of consent of the accused. An option should be given to the accused whether he wishes to avail such test.

(ii) If the accused volunteers for a Lie Detector Test, he should be given access to a lawyer and the physical, emotional and legal implication of such a test should be explained to him by the police and his lawyer.

(iii) The consent should be recorded before a Judicial Magistrate.

(iv) During the hearing before the Magistrate, the person alleged to have agreed should be duly represented by a lawyer.

(v) At the hearing, the person in question should also be told in clear terms that the statement that is made shall not be a `confessional’ statement to the Magistrate but will have the status of a statement made to the police.

(vi) The Magistrate shall consider all factors relating to the detention including the length of detention and the nature of the interrogation.

(vii) The actual recording of the Lie Detector Test shall be done by an independent agency (such as a hospital) and conducted in the presence of a lawyer.

(viii) A full medical and factual narration of the manner of the information received must be taken on record.


Selvi v. State of Karnataka, (2010)