A lie detector (popularly referred to as a polygraph test) measures several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions. The Polygraph is based on the principle of psychosomatic interaction of an individual means that psychologically, a change takes place in a person who consciously holds his feelings.

The first attempt to develop a scientific instrument to detect truth or deception was made as early as 1895 by Lombroso. It was basically designed to record blood pressure and changes in the pulse rate. It is conducted by various probes attached to the body of the person who is interrogated by an expert. The variations in the pulse rate, the heart rate, the skin conductance, the blood pressure etc. are measured. In the very beginning, a baseline for this psychological characteristic is established by asking questions whose answers the investigator knows.

In Ramchandra Reddy v State of Maharashtra, case while discussing on polygraph test the Hon’ble Court said that- “The lie detector test is an examination which is conducted by various probes attached to the body of the person who is interrogated by the Expert.”

Before conducting the polygraph test, there are some steps which the examiner has to prepare the subject and himself are to be followed.

• Go through the background of the case
• Formulate questionnaire based on the background of the case
• Apprise the subject on the objectives of the test, the nature of instrument, its various attachments and recordings.

The Questioning Techniques in Polygraph Test

The questioning part though takes only a few minutes, require repetition to get consistent results on the chart. The questions asked are brief to elicit responses in ‘yes’ or ‘no’ form. The time interval between each question is about 15 to 20 seconds. Generally, the polygraph examiner practices three types of questioning techniques- irrelevant questions, control questions and peak of tension questions.

Irrelevant– in relevant questioning technique, several irrelevant questions are framed which have no bearing on the case or involvement of the subject in a crime under investigation. The relevant questions are interposed in-between irrelevant questions, which have a direct bearing on the case, and are likely to draw stressed response from a guilty subject.

Control questions are interspersed among the relevant and irrelevant questions. They do not directly relate to the crime under investigation, but to a similar situation in which his answer may have a feeling of concern with respect to either its truthfulness or its accuracy.

Peak of tension questions is framed when some of the important details of the offence in question are not made known to the subject. The test questions in this case are framed in such a way that only one question will have bearing upon the matter under investigation and all other coming close to the guilty knowledge. The series of questions framed are first read to the subject and later they are administered with the instrument attached. During the first reading if the subject has no knowledge or information on the pertinent question put to him then no tension is built up. But if he has the knowledge then as the question approaches he is likely to experience the tension and hence the term ‘peak of tension.’

Polygraph Test-Indian Scenario 

The main legal provisions which govern the expert evidence (LIE DETECTOR TEST), are in Indian Constitution, Code of Criminal Procedure; 1973, Indian Evidence Act; 1872.

The Indian Constitution is the Article 20 (3). It states, “No person accused of an offence can be compelled to be a witness against himself”. The constitutional bench of the Supreme Court held that the above type of clue materials become evidence only after their evaluation and the evaluation instead of helping the prosecution may help the accused. It can be seen in the case State of Bombay v Kathi Kalu, threatened with being forcibly subjected to the lie detector tests by the police, persons petitioned the Bombay High Court to pronounce such methods illegal and violation of their fundamental rights. The Court had to decide whether forcing the petitioners to undergo these tests would violate their right to silence and compel them to furnish evidence against themselves. While declining the petitioner’s claims and allowing the police to subject people to these tests, the judgment makes certain far reaching pronouncements which it is respectfully submitted, are legally wrong, contrary to authority and logically unconvincing. In the course of the judgment distinction between a “statement” (made before a police officer) and “testimony” (made under oath in court). Court held that the right against self-incrimination applies only to court proceedings and not to police interrogations.

On May 5, 2010 the Supreme Court of India in Smt. Selvi vs. State of Karnataka declared brain mapping, Lie Detector tests and Narco analysis to be unconstitutional, violating Article 20 (3) of Fundamental Rights. These techniques cannot be conducted forcefully on any individual and requires consent for the same. When they are conducted with consent, the material so obtained is regarded as evidence during trial of cases according to Section 27 of the Evidence Act.

In the Criminal Procedure Code, the legislature has guarded a citizen’s right against self-incrimination. Section 161(2) states that every person 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 charge, penalty or forfeiture. Evidently, it has been left to the person being interrogated to decide whether the answer to a question would be self-incriminating and, if so, to withhold that answer and keep silent.

In Nandini Sathpathy’s case, the petitioner (A former chief minister of Orissa) had complained that she was being prosecuted for her refusal to answer police questions about a corruption case lodged against her. She claimed that her assertion of silence and refusal to answer questions was well within her rights under Article 20(3) and Section 161(2) Criminal Procedure Code prosecuting her for silence, she argued amounted to compelling her to make self incriminating statements. It was held that no one could forcibly extract statements from the accused that have the right to keep silent during the course of interrogation or investigation. Freedom to tell lies is not within the protection of this clause.

Another Act which comes for the constitutional validity of lie detector test is The Indian Evidence Act– (sec.45). This is the most important section of the Act vis-à-vis polygraph. It states “when a court has to form an opinion upon a point of foreign law or of science or art, or as to the identity of handwriting or finger impressions, the opinion upon that point, of persons specially skilled in such foreign law, science or art or in questions as to the identity of handwriting or finger impressions are relevant facts. Such persons are called experts.” There has been a lot of confusion about what constitutes science. By Supreme Court Judgment State v Chaudhary has not only eliminated the absurdity relating to typescript identification but is has also provided the guideline for the induction of new types of scientific evidence. The question arises here that who is experts then. Section 45 indicates that who are experts or in another words as Specially Skilled persons. Special skill has not been defined but by convention is it acquired through Basic education, Training, Experience, Research, and Participation in scientific gatherings. The second most important section relating to expert evidence is Section 73 of Indian Evidence Act. This section specifies what comparison material for disputed handwriting signatures or seals (or for finger prints) can be utilized by courts. Section 46 is about Facts bearing upon opinions of experts. Section 51 is about grounds of opinion when relevant. Section 159 is about Refreshing Memory.  Evidence Act plays an important role in the Constitutional Validity of polygraph. Especially Section 45 and section 46 is a key. We can see that here lot of emphasis has been given on experts and few cases are enshrined in our constitution in which judges have taken use of experts. As every coin has two sides it had demerits too but experts can be given some power so that they can reveal justice and truth from the criminals.

Conclusion

Forensic Science plays an important role in criminal investigation by establishing the presence or absence of link between crime, the criminal, the victim, the place and time of occurrence. In modern scientific age, its need is more pressing due to social change, wide hiding facilities, ultra modern technical knowledge, wide field of activities which are conducive for criminality and more neglected prosecution. In Polygraph, inferences are drawn from physiological responses of the subject though no direct reliance is placed on verbal responses. This test should also be treated as personal testimony since they are a means of imparting personal knowledge about relevant facts. Results obtained through involuntary administration of any of the impugned tests come within the scope of testimonial compulsion, thereby attracting protective shield of Article 20(3).

Lawz Bureau