Polygraph tests, known as the “lie detector test,” are common in forensic science DDT (deception detection test), in which evidence is collected through several psychological processes. With this test, you examine whether the investigator or forensic expert deduces such a psychological state from the subject that it becomes easy to verify whether the person is telling the truth or lying. Etymologically, the term polygraph test refers to a process in which certain physiological actions are recorded. According to Webster`s Legal Dictionary, a polygraph is a device used to measure certain involuntary bodily reactions, such as blood pressure and sweat, from which an opinion is derived as to whether or not the person being tested is telling the truth.2 Not a single Indian law gives meaning or defines the term “polygraph”. but the United States Employees Polygraph Protection Act. 1988 defines the term “polygraph” as an instrument that (a) continuously records, visually, permanently, and simultaneously changes in cardiovascular, respiratory and electrodermal patterns as minimum instrumentation standards; and (b) is used or the results thereof are used to provide a diagnostic opinion about a person`s honesty or dishonesty.3 In addition, U.S. federal authorities have referred to the polygraph as a “psychological detection of deception” or PDD examination. Not only in criminal cases but also in civil cases, such tests are not admissible, although the court may order a medical examination under sections 151, 75 (e) and Ordinance 26, Rule 10-A of the Code of Criminal Procedure, but in Selvi v. State of Karnataka, the court used the term criminal or other, which also excludes civil cases. The court heard a petition from a certain Khanna virus, which challenged a court order ordering him to undergo a lie detector test and provide police with biometric passwords for his electronic devices. As a defendant in the sandalwood drug scandal, Khanna claimed in his petition that the “unintentional use of the techniques denounced” was a restriction of his “personal freedom” and a flagrant violation of his privacy and his “right to self-incrimination.” Narco-analysis, lie detector testing, brain mapping were declared ultra vires with the basic structure of the constitution after the interpretation of various legal provisions and violated the principle of natural justice.
Its administration violates various fundamental rights enshrined in Article 20(3) (right to self-incrimination) and Article 21 (right to life and personal liberty). This includes the right to remain silent during the criminal investigation, as guaranteed in Nandini Sathpathy v. P.L.Dani.[9] This case made clear that the forced intrusion into a person`s mind by carrying out these tests violates the legitimacy of the constitutional right to silence. As we know, theoretically everything seems simple, but in practice it is quite difficult to implement. The same problem is associated with all these deception detection tests. Let`s take a look at the problem you might encounter while running this test. Measured changes in physiological responses Therefore, the polygraph test cannot be considered as evidence. But according to sections 45 and 45A of the Indian Evidence Act, 1872.
That is, the court can seek the opinion of an expert in any field required for the case. Things like foreign law, science, art, handwriting identity, fingerprints, where the judge has limited knowledge. Then it is useful to get the expert`s opinion to pursue the case. The polygraph test cannot be considered as evidence, but the court may consider it as an expert report under section 45A of the Evidence Act. And the polygraph test can also help advance the investigation for police officers. The theory behind this test is that if a subject (person) lies to the questions asked by the examiner, his body produces physiological responses different from those of the normal course, which would be detected by the examiner by noting measurements such as heart rate, blood pressure, respiratory rate, skin conductance and electromyography, since few instruments to record these measurements adhere to the subject. The central debate stemming from DDT is its legitimacy to use inhumane degrading methods to confess to the crime. The questioning of the accused plays a decisive role in the preservation of evidence. If the accused remains silent and does not answer questions from the investigating authorities, to what extent can the investigating authorities compel or compel the accused to disclose information? In a civilized world, police torture to obtain information about the crime is unacceptable.
Even in court, a confession made to a police officer is not valid. Now the question is: “Can the police use DDT to extract information from the accused”? Many support the view that such tests often help investigative authorities in times of ever-increasing crime, but others dismiss them as a flagrant violation of constitutional provisions. This view examines the views of the previous court, the recent Supreme Court decision, and the scientific basis for DDT. The test works on a psychological principle known as psychosomatic interaction. The principle deals with minor physical changes that occur in a human body. The changes are such as the change in breathing such as heavy breathing, galvanic resistance of the skin, change in blood pressure or pulse, muscle pressure, finger pulse, change in body temperature. Whenever a person lies or fakes a statement, that person will be afraid of being caught and will cling to their emotions, which will lead to a mental disorder in that person. All these reactions lead to psychological changes in that person`s body. With all due respect to the Supreme Court`s decisions on the legality or illegality of lie detector tests, some questions remain unanswered. The court left open the likelihood of incorrect use of these tests, as it made a narrow exception that, if the test is performed with the subject`s voluntary consent to the test, it can be used as evidence in court.
But the dilemma is that even if the person is well informed with the consequences of their consent and then voluntarily gave consent, then it cannot be said that consent was given voluntarily. This is a problematic attitude. The instrument (polygraph/lie detector) records changes in the suspect/interviewee`s body. It records changes such as abdominal breathing, galvanic resistance of the skin[2], changes in blood pressure and pulse, and some other aspects. The new model of the polygraph instrument also records muscle movement in the subject`s body.