The debate around the Deception detection tests in India sparked when on the night of Friday, October 2, the Uttar Pradesh government issued a press note stating the requirement of narco-test of the family of the victim in Hathras rape incident. This article will focus in detail about the deception detection tests like polygraph, narco-analysis test, and their constitutional validity along with its criticisms.


As society progresses, it gets more unpredictable; crime introduces itself in various structures and newer modes of execution. These require the use of modern techniques in legal cycles, for example, DNA fingerprinting, lie-detector tests, cerebrum planning, and narco-tests. These procedures are similarly pertinent in situations of ordinary crimes, as an open objection, or to compensate for deficiencies in the criminal justice system. Narco-test led on Abdul Karim Telgi in the stamp paper scam, and a couple of suspects in the Aarushi murder case are of contemporary relevance in the narco-test analysis. The methods include disclosure of ‘relevant facts’ about the accused. They are different from regular investigative practices, as they contain a specific level of participation from the accused. Such participation need not be intentional, and the methods are often coercive.

Courts of law in India have seen various difficulties in the constitutionality of these tests. While the decisions of the courts have been unequivocal, there are a few issues that were not tended to by them, either because the parties did not raise them before the Courts or on the grounds that they were not too menial to address. The constitutionality of these medical investigative tests depends on the facts and circumstances of a case as the law that stands on the status of medical investigative tests for evidentiary purposes is unclear in Indian statutes.

The ‘narco-test’ is a modern technique, used to extract the truth from the subject. It is an analysis done by a combination of medications for inciting an individual to a state of rest or sleep. Narco-test is produced by injecting a chemical compound on an individual/suspect where the subject is changed to a condition of hypnotism. However, the individual is sub-intentionally alert, with the expectation of bringing out the facts from the subliminal brain. The condition of semi-obliviousness happens because of an infusion of sodium pentothal/sodium amytal administered on the individual, while questions are often aimed to be asked in that state. In the somnific stage, the subject becomes less inhibited and is more likely to divulge information, which would usually not be revealed in the conscious state. Subjects may also divulge all of their fantasies, personal wishes, impulses, instinctual drive, illusions, delusions, conflicts, misinterpretations, among other things. The extraction of information from a subject through this cycle is known as ‘narco test’.


Medical investigative tests like narco-test may not have legal legitimacy as admissions made by a semi-cognizant subject are not acceptable in a court of law. Notwithstanding, the court may award restricted acceptability in the wake of considering the conditions under which the test was acquired. The primary proviso concerning the criminal investigation and trial in the Indian Constitution is Article 20(3). It manages the right against self-incrimination. The right against self-incrimination is a basic tenet of common law criminal jurisprudence. Article 20(3) which typifies this right reads as, “No individual blamed for any offense will be constrained to be an observer against himself”. Exposing an accused to the narco-test, as has been done by investigating agencies in India, is an obtrusive infringement of Article 20(3). The use of the Narco-Analysis test includes the principal question relating to human rights law as well. The legitimate situation of applying this strategy as an investigative guide raises certifiable issues like an infringement of a person’s rights to privacy.

The right against forced self-incrimination, commonly known as Right to Silence is revered in the Code of Criminal Procedure (CrPC) and the Constitution of India. Citizens’ right against self- implication is prudently provided in CrPC. Section.161 (2) of the Code of Criminal Procedure expresses that each individual “is bound to answer truthfully all questions, put to him by [a police] officer, other than questions the answers to which would have a tendency to expose that person to a criminal accusation, punishment or relinquishment”. Contentions have been made that the narco-test establishes mental torment and accordingly, disregards the right to privacy as it comes within the ambit of Article 21.

The right to remain silent has been conceded to the accused in the case of Nandini Sathpathy v. P.L.Dani, stating that nobody who has the right to keep quiet throughout the investigation can coercively remove proclamations from the accused. By performing these tests, persuasive interruption into one’s psyche is being reestablished, accordingly invalidating the legitimacy and authenticity of the Right to Silence. In this case, the defendant guaranteed that she had a right of silence by Article 20(3) of the Constitution and Section 161 (2) of Cr. P.C. The Apex Court maintained her requests. Along the same lines, in the USA, concerning the case of Townsend v. Sain, it was held that the applicant’s admission was naturally unacceptable as the police acquired it during a period when the petitioner was under the influence of a medication having the property of truth serum.

The inquiry occurs despite an individual being guaranteed the security against self-implication. While Article 20(3) may be argued as stating that the protection is accessible merely against articulations made in a court of law, the legal position is, in truth, different. The Supreme Court has remarked in State of Bombay v. Kathi Kalu Oghad that the assurance under this Article would be claimable not only for statements made in court but also, additionally, for past stages if the charge against the accused prompts their indictment, regardless of whether the trials have commenced or not. In any case, where the investigative agencies charge someone as an accused, these medical tests may create falsified outcomes that may also exonerate an offender of blame. On this ground, the legitimacy of the test has been held to be premature. Therefore, just an inculpatory articulation will draw in the protection under Article 20(3).


The Bombay High Court, in a significant verdict in Ramchandra Ram Reddy v The State of Maharashtra, maintained the legitimacy on the usage of P300 or brain mapping and narco-test. The Court additionally said that proof secured under the impact of the narco-investigation test is likewise acceptable as evidence. As crimes become increasingly advanced and criminals turn professionals, the use of narco-analysis can be beneficial, as the conscious mind does not speak out the truth, the unconscious may reveal vital information about a case. The judgment also held that these tests include negligible harm to the body of the subjects. The recent case of Selvi v. State of Karnataka ruled that 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. Notwithstanding, any data or material that is accordingly found with the assistance of willful managed test results can be considered admissible under Section 27 of the Indian Evidence Act, 1872.

The Supreme Court discovered that narco-test abused people’s right to privacy and added up to barbarous, brutal, or debasing treatment which is a violation of a citizen’s fundamental right under article 21. The Court found that driving a subject to go through narco-test, brain-mapping, or polygraph tests itself adds up to the imperative impulse, paying little heed to the absence of physical damage done due to the test or the idea of appropriate responses given during the tests.

Recently, the CBI has sought to conduct these tests on the driver and helper of the truck that hit the Unnao rape victim in Uttar Pradesh in July 2017. It also sought to conduct the tests on one accused in the Punjab National Bank alleged fraud case, but the court rejected the plea after the accused denied consent. In May 2017, the founder of INX Media, Indrani Mukerjea, who is confronting trials for the alleged murder of her daughter Sheena Bora in 2012, lie detector test was declined by the CBI, expressing that they had adequate proof against her. Accused in the famous Aarushi Talwar murder case were also subjected to the polygraph test, albeit inconclusively.


There are many criticisms of the validity, credibility and constitutionality as far as this test is concerned. Even though the medications are typically known by the common name of ‘truth serum’, yet ironically, the degree of truth acquired by the serum is a refute issue. This problem arises because some persons can retain their ability to deceive even in the hypnotic state, while others can become extremely suggestible to questioning. Also, investigators may frame questions in a manner that may prompt incriminatory responses. The drugs used don’t ensure that all subjects will equally blurt out only truthful statements. The statements made in a somnific state are not discretionary and are additionally not in a conscious state. Consequently, these have not been considered conclusive evidence in a court of law.

Often, it has been found that a person has furnished false information even after the administration of drugs. It is not much help in case of malingers or evasive, untruthful people. It is arduously challenging to suggest the correct dose of medications for a particular person. The dosage may vary depending on the will power, mental demeanour, and physical capacity of the subject.


The after-effects of these medical investigative tests, coupled with the questions asked during cross-examination, are not straightforward, providing an enormous fillip on numerous occasions. It goes further to express that narco-analysis has additionally replaced preventive criminology. The curl around the Aarushi Talwar murder case, at last, got more clear after leading the narco-examination test on other suspects. Exacting legitimate reasons neglect to legitimize the narco-examination test, which evokes facts not in general nature but in a way where the subject is intoxicated with some medications only to extract evidence of a specific crime that has occurred.

It dispenses with the right of the accused to remain silent. The test can have repercussions on the wellbeing of the accused, and sometimes some side effects are observed in the subject. While it may not unequivocally disregard an individual’s right to privacy whenever directed effectively, exacting procedural protections should be added to forestall maltreatment of the right to privacy. The only way one can see the justification of the narco-test is because when there is a practical necessity to get some reasonable evidence in a case to break the deadlock in favour of the investigative agency.

The investigative agencies and all the elements of the criminal justice system should use legal methods to bring offenders to justice not by incriminating the accused against himself, respecting the rights of an accused against being constrained to implicate himself. The exacting State may, in the best-case scenario, give investigative reasons to carry out the tests, but it lacks the legal legitimacy to do so, at least presently.

This article was first published on LiveLaw
Cover Image Credits: Suprem N.


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