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Case Law Relating To The Constitutionality Of Techniques

Case Law

The legal questions in this batch of criminal appeals relate 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.

Smt. Selvi and Others vs. State of Karnataka and another



J M Panchal, K G Balakrishnan (CJI), R V Raveendran


The present case is a compilation of various criminal appeals taken up the honourable SC challenging the prominent techniques used by the police personnel to interrogate people who are either accused or suspects or even the witnesses as well on the ground that these techniques are employed on them without their consent. The objection was raised by the petitioners as to basically three scientific techniques to which people are subjected for interrogation purposes, namely:

  • The polygraph examination.
  • The narco-analysis.
  • The BEAP [brain electrical activation programme].

The administration of these techniques was considered by the petitioners to be violative of the fundamental right of “right against self incrimination” guaranteed under Article 20 [3] of the Indian Constitution.

Major Provision

  • Article 20(3), Indian Constitution- “provides protection to a person accused of an offence that he shall not be compelled to be a witness against his own self.”
  • Art. 21- “Protection to right to life and personal liberty.”
  • Sec. 161 (2), CrPC, 1973 – during the examination conducted by the police the witness will be required answer truthfully all the questions relevant to the case, excluding the questions that might expose them to a charge of an offence, a forfeiture or fine. 

Contentions Before the Court


The petitioners contended that in the name of these techniques the investigating authorities use “third degree methods” to extract information which is violative of their fundamental right guaranteed under Article 20(3) as well as their human rights.


  1.   The respondents contended that these methods were important to gather information necessary to constitute evidence which is otherwise difficult to gather through normal means.
  2. Citing examples of certain provisions of both the CrPC, 1973 and the Indian Evidence Act, 1872 the respondents contended that these provisions impose a responsibility on the citizens to cooperate with the authorities.
  3. The respondents contended that applying these techniques does not involve causing bodily injuries or harm of any sort and the information extracted is used to strengthen the probe and shall not be used as evidence at the stage of trial.
  4. It was again contended by the respondents that these methods basically accelerate the process of investigation and helps in increasing the number of prosecutions as well as acquittals.
  5. The last contention was that such information gathered by applying these scientific methods, cannot be treated as a testimony given under compulsion.


  • Whether administering the above mentioned disputed techniques infringe the fundamental right of guaranteed by Art. 20 (3) – “Right against self-incrimination.”
  • Whether the use of such methods is likely to incriminate the person subjected to it.
  • Whether after applying such techniques the information gathered amounts to “testimonial compulsion”.
  • Whether compulsory disposition of these techniques amounts to a “reasonable restriction” on the personal liberty of an individual (to be understood in reference to Art. 21 of the Indian Constitution).

Final Verdict

In its final verdict the court declared the impugned techniques administered involuntarily amounts to violation of “right against self-incrimination” as well as of vital human rights of an individual. The court held that:

  • The safeguard guaranteed under Art. 20 (3) extends from the stage of trial to the stage of investigation.
  • Art. 20 (3) r/w Sec. 161 (2) of CrPC, 1973 shields to all those persons who are subjected to examination during investigation like suspects, witnesses and accused.
  • The information gathered through it cannot be admitted as evidence, if obtained under compulsion.
  • The choice of the subject to remain silent or to speak is protected by Art. 20 (3) whether the subsequent testimony leads to incrimination or acquittal.
  • This forcible application of such techniques leads to interference with one’s psychological privacy.
  • The court made it clear that even if a subject gives his/her voluntary acquiesce to endure these techniques, then also such statements released by him would not form admissible evidence because they were made by him in an unconscious or semi-conscious state of the mind.
  • The court finally directed that the authorities should follow the guidelines issued by the NHRC (National Human Rights Commission) while administering such techniques on a person.


The Apex court reached at this decision after noting a lot of points about these impugned methods. The court stated that as far as polygraph tests are concerned, the results retrieved from them are not reliable because most of the time they are made under distorted condition of mind, nervousness, fear, confusion, anxiety, the surrounding environment of the area where this test is about to be conducted etc.. Secondly in the narco-analysis test the subject under the influence of drugs is not giving information willingly and he might release statements that are irrelevant and unreliable. The Supreme Court clearly asserted that subjecting an individual to “narco-analysis”, “brain mapping test” and “polygraph test”, is sheer violation of personal privacy and called it as, “cruel, inhuman and degrading treatment”.  

The court made it clear that even if the subject consents to application of these tests still the statements made him/her are involuntary.

Read Also: Delhi High Court: “Court Cannot Replace Government Policy”

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