PublicationsPsycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns

March 16, 20210

This paper aims to critically analyse Section 45 of the Indian Evidence Act, 1872, and the admissibility of expert evidence, insofar as the practice of psycho-analytic tests and the admissibility of self-incriminatory statements obtained from the same. With the help of judicial pronouncements, this paper illustrates the reliability concerns surrounding the application of such tests, and concerns regarding possible infringements upon the Constitutional right against self-incrimination. Further, I aim to uncover the position on psycho-analytic tests in a hypothetical scenario where reliability concerns may be mitigated, and accuracy may be guaranteed, and whether constitutional concerns may, or should, still arise in such a scenario.

Enshrined in Section 45 of the Indian Evidence Act, expert evidence is an exception to the rule against hearsay. While evidence of a witness’ opinion is usually prohibited by the application of the rule, Section 45 carves out an exception for certain scenarios. Namely, where the question arises on certain specific scenarios, namely, “a point of foreign law, or of science or art, or as to the identity of handwriting or finger impression.[1]”  The subjects enumerated in the section are those which require a specialized body of knowledge to interpret. The court is empowered to take cognizance of the opinion of any person, or “expert”, possessing such specialized body of knowledge. Though not a witness of the fact, an expert must furnish the judge with the necessary scientific opinion, which, if intelligible, convincing, and tested, becomes an important factor of consideration, along with other evidence[2].

The concept of expert evidence grants a powerful weapon to the court, to admit into evidence, an individual’s opinion. Naturally then, concerns may arise when such a power is wielded, as to the integrity of a trial. These may stem from concerns as to the admission of certain tests aimed to uncover a witness’ “psychological state”, and the expert interpretations of the same. Further, from possible constitutional infringements, including a witness’ right against self-incrimination. Expert evidence, being an exception to the Rule Against Hearsay, has the potential of stripping the accused of this Constitutional right, and as such, the application of Section 45 must be kept on a short leash. In this paper, I shall discuss the admissibility of incriminatory statements obtained specifically from psychoanalytic tests such as polygraph examinations. The practice and admissibility of these tests have raised a debate as to whether they infringe upon an individual’s “privacy of mind”. Further, whether an expert’s analysis of such a test, revealing that certain incriminatory statements made by the accused are true, should be barred under Article 20(3) of the Constitution of India.

A hotly debated topic in the judicial landscape, when it comes to the admissibility of expert evidence, is concerning the evidence obtained from drug-induced revelations, such as those achieved through narco-analyses. Similar, but more important to the subject of this paper, are those statements and confessions achieved via tests that may come under the category of involving a psychological analysis of the individual, namely, polygraph tests. For this paper, we will focus on two grounds upon which the practice of these tests and their admission as evidence may, or have been alleged to, compromise the fairness of a trial. These grounds are the reliability and constitutionality of such tests.

Tackling the problem of reliability first, concerns have been raised as to the accuracy of tests designed to uncover the truth in a statement of the witness. Judicial opinion has largely been skeptical of their reliability in decisions as to whether or not to admit polygraph tests. An authoritative source on the matter in the case of United States v Scheffer[3]. The judgment tackles the reliability of polygraph tests, and answers the question in the negative, stating that the same does not have the scientific finality required to be admitted as evidence. The case revolves around a member of the United States Air Force, on trial for the alleged ingestion of methamphetamine. He was subjected to both a urine test, as well as a polygraph examination, for both of which he had given his consent, on an earlier occasion. While a urine test confirmed, beyond doubt, the presence of illegal substances in his body, a polygraph test showed no deception when claiming that such substances were not ingested by him. The respondent sought to enter the polygraph test into evidence, claiming the defence of “innocent ingestion”. This was denied, relying on the Military Rule of Evidence 707, which stated that polygraph tests were not to be admitted into evidence. The military judge justified the relevant rule, and the subsequent denial of admission by stating that, “The polygraph is not a process that has sufficient scientific acceptability to be relevant.” It was also stated that there was a danger that undue weight might be given to the polygraph examiner’s testimony, and arguments surrounding the same would consume an unjustified amount of time. The Court took cognizance of the scientific community’s extremely polarizing views on polygraph techniques, with some studies claiming their accuracy and reliability, while others finding their accuracy to be not more than 50 per cent. Justice Kennedy, giving his opinion on the matter, upheld the per se exclusion of polygraph tests, stating that it would be wrong to invalidate the exclusion, and the binding effect that the court’s holding would have on subsequent judicial proceedings would be a detrimental outcome. Thus, the respondent’s plea for the admission of the polygraph test was denied, citing the lack of reliability of such a test.

Indian courts have held a similar position on the matter. Section 45 of the Indian Evidence Act states that the opinions of the individuals being specially skilled in the realm of science (among others), may be considered relevant facts. A similar suspicion as to the reliability of lie-detectors has militated against the consideration of such tests as a “science” under the meaning of Section 45[4], and the admission of a polygraph examiners report as expert evidence. In Selvi v State of Karnataka[5], the Court relied heavily on the Scheffer judgement, in concurring that there is a possibility for margin of error as well as a risk of escape techniques being used by the examinee. The Court further stated that the “measured changes in psychological responses”, which are relied upon to ascertain whether an examinee is telling the truth, may be brought about, not only by lying but also by nervousness, anxiety, fear, or confusion.

The mental state of the subject is of vital importance and may drastically alter the results of such a test. The Court also noted that “when the subject does not remember the facts in question, there will be no self-awareness of truth or deception and hence the recording of the physiological responses will not be helpful.” In Ranjitsingh v State of Maharashtra[6], when answering the question of admissibility of a P-300 test, the Court opined that the admissibility of a result of a scientific test will depend upon its authenticity and that such tests do not have the probative value to be relied upon as evidence. Thus, the position of courts is evident in the question of reliability. As long as there remains ambiguity as to the accuracy of such a test, and no effective way of mitigating the effects of numerous variables that may have an altering effect on the results of tests such as a polygraph examination, admitting into evidence the opinion of a polygraph examiner as to the veracity of a subject’s claims should not be allowed under Section 45. Doing so would lead to the unjustified weight being placed on the findings uncovered through arguably unreliable methods, therefore endangering the fairness of a trial.

The question may be posed, however, as to what the position would be if the practice of psycho-analysis eventually develops to a point where such tests may be undertaken with a guarantee as to its accuracy. I shall offer my opinion on this question in conjunction with the question of the constitutionality of polygraph examinations and similar tests. This is because, presuming these tests assume a high level of accuracy, the question invariably arises whether a compelled self-incriminatory statement can be admissible, by virtue of it being possibly impeded by Article 20(3) of the Indian Constitution. Unless reliability concerns are mitigated, the issue of self-incrimination would not arise. Thus, I shall proceed under this presumption of accuracy when tackling constitutionality.

The Indian Evidence Act contains a number of provisions empowering courts to compel witnesses to provide samples of handwriting, signatures, etc. Section 73[7] grants the courts the power to direct any person in court to write any words or figures for the purpose of comparison with any words or figures alleged to be written by such person. Such writing may also be subjected to the expert opinion of an individual considered as such under Section 47[8], which may be subsequently admitted as evidence. The question arises whether it would be feasible for the opinion of a polygraph examiner relating to the confession of an examinee to be similarly admitted into evidence.

The Court in Selvi v State of Karnataka gave its opinion on this matter by stating that the right against self-incrimination is an essential safeguard and its underlying rationale aims to ensure the reliability of the statements made by the accused. The Court also stated that the ‘rule against involuntary confessions’ aims to ensure that the testimony considered during trial is relevant. Thus, we see that the Court in the Selvi judgment upheld the right against self-incrimination, and ‘rule against involuntary confessions’ on the grounds of them being necessary to ensure reliability of statements, to protect against compelled, involuntary statements that may be false, and the methods that may be utilized by authorities to compel such statements. However, would such rules apply, or in fact be relevant, in the case of a self-incriminatory statement, collected by a polygraph test that guarantees its accuracy, and is verified by an expert examiner?

I would argue that in such a scenario, expert examination of a polygraph report must then take up the same relevance and admissibility as any other form of expert evidence, or scientific conclusion. To illustrate this point, I rely upon the cases of Badwaik v Badwaik[9] and State of Bombay v Kathi Kalu Oghad[10]. In the Badwaik case, the Court discusses the admissibility of a DNA test, when conclusive proof of legitimacy was already established under Section 112 of the Indian Evidence Act[11]. The appellant disputed the legitimacy of a child born to him and the respondent during the continuance of a valid marriage. The DNA test stated that the appellant was not the biological father of the child. However, the respondent argued that no proof was brought against the claim of the continuance of the valid marriage, and as such, Section 112 settles that this would be conclusive proof of legitimacy, notwithstanding the results of the DNA test. Section 4 further establishes that when a fact is declared as “conclusive proof” of another, no evidence shall be allowed for the purpose of disproving it. The Court in its judgment, however, reasoned that Section 112 was enacted at a time when the legislature had not contemplated the scientific advancements and subsequent accuracy of DNA tests. The Court opined that presumption of conclusive proof may afford legitimate means of arriving at an affirmative legal conclusion.

“While the truth or fact is known, in our opinion, there is no need or room for any presumption… Interest of justice is best served by ascertaining the truth and the Court should be furnished with the best available science and may not be left to bank upon presumptions, unless science has no answer to the facts in issue.[12]

The Court took cognizance of the fact that this view might go against public policy and cause the child to be bastardized but stated that it is not for the Court to forestall these consequences, as that would amount to denying the truth, and that  “truth must triumph” is the hallmark of justice.

In deciding Kathi Kalu Oghad, the Court discussed whether compelling someone to provide handwriting samples would be barred by Article 20(3) of the Constitution as amounting to compelling them to be “witness” against themselves. The Court reasoned that in drafting Article 20(3), its framers intended to protect the accused from the hazards involved in self-incrimination, but did not intend to put obstacles in the way of an effective investigation and bringing criminals to justice. It was noted that, “to be a witness”, means imparting knowledge in respect of relevant fact, by means of oral statements, or statements in writing, by a person who has personal knowledge of the facts to be communicated to a Court. This depends on the accused’s own volition. Conversely, a “finger impressions or handwriting, in spite of efforts at concealing the true nature of it by dissimulation cannot, change their intrinsic character.” This is changeless, and verifiable. The Court reasoned that the content of a “statement”, on the other hand, is entirely within the control of the accused, and if it is self-incriminatory, then it is more likely that it is distorted or untrue. Thus, evidence of expert opinions conveyed via the compulsion to produce impressions, or handwriting, would not be barred by Article 20(3), though the same might be incriminatory.

In light of the two aforementioned cases, I would maintain that expert opinions on compelled polygraph results would not be inadmissible by virtue of Article 20(3), keeping our presumption of accuracy in mind. Relying on the Badwaik case, if such scientific tools are available, they must be utilized in the course of dispensing of justice, and not give way to evidentiary presumption. Similar to what was held in Kathi Kalu Oghad, a self-incriminatory statement attained through a compelled polygraph examination, would not be barred by Article 20(3) because it would be the expert opinion of the polygraph examiner that would incriminate the subject, who would be free to answer the questions posed to him in any way he pleases, and any attempt by authorities to compel a confession would be debunked by a reliable psycho-analytic test. The intrinsic nature of the truth would be brought out through the results, interpreted by the expert examiner. Thus, presuming the accuracy of such a test would grant the statements of the subject a changeless and verifiable nature that could not be concealed, much like a DNA test, or thumb impression, the same cannot be barred by the right against self-incrimination.

Thus, while the courts have been provided a powerful tool in being granted the admissibility of expert evidence, the same has been prudently exercised, insofar as the concerns discussed above. Courts have erred on the side of caution when discussing the admissibility of expert opinions regarding tests, the reliability of which has yet to be proved. However, if such tests did eventually gain a high level of accuracy, expert opinions on the same would have to be admitted in the interest of the dispensation of justice, for the reasons aforementioned.

[1] The Indian Evidence Act, 1872, s.45

[2] State of Himachal Pradesh v. Jai Lal (1999) 7 SCC 280 (India)

[3] United States v Scheffer 523 U.S. 303 (U.S.)

[4] The Indian Evidence Act, 1872, s.45

[5] Selvi v State of Karnataka (2010) 7 SCC 263 (India)

[6] Ranjitsingh v State of Maharashtra (2005) 5 SCC 294 (India)

[7] The Indian Evidence Act, 1872, s.73

[8] The Indian Evidence Act, 1872, s.47

[9] Nandlal Wasudeo Badwaik vs Lata Nandlal Badwaik & Anr (2014) 2 SCC 576 (India)

[10] State of Bombay v Kathi Kalu Oghad [AIR 1961 SC 1808] (India)

[11] The Indian Evidence Act, 1872, s.112

[12]Nandlal Wasudeo Badwaik vs Lata Nandlal Badwaik & Anr (2014) 2 SCC 576 (India)


Legal Maxim (April 19, 2021) Psycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns. Retrieved from
Psycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns.” Legal Maxim – April 19, 2021,
Legal Maxim March 16, 2021 Psycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns., viewed April 19, 2021,<>
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Psycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns.” Legal Maxim – Accessed April 19, 2021.
Psycho-analytic Tests in Trial Proceedings: Reliability and Constitutionality Concerns.” Legal Maxim [Online]. Available: [Accessed: April 19, 2021]

Author: Deviah P. Chinnappa

Organisation: 3rd Year Law Candidate, Jindal Global Law School

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