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The Use Of Lie Detectors In Criminal Justice In India

Crime refers to a prohibited act which violates the provisions of law, is detrimental and deleterious for the society, and is punishable under various provisions of law. The term crime has been derived from the Latin term crīmen which means 'charge' or 'cry of distress'. The Latin cognate has been derived from the ancient Greek term κρίμα, krima which referred to an intellectual mistake or an offence against the society, rather than a private or moral wrong.

William Blackstone, an English jurist, defined crime in his book, Commentaries on the Laws of England as "An act committed or omitted in violation of public law forbidding or commanding it."1.

Halsbury defined crime in his book Laws of England as "An unlawful act or default which is an offense against public and renders the person guilty of the act or default liable to legal punishment."2.

Criminal justice can be defined as the system though which crimes and criminals are identified, apprehended, judged, and punished.3. Criminal justice focuses on dispensing justice to those who have committed crimes. Criminal justice can be defined as an interdisciplinary subject which is comprised of three elements namely the law enforcement, the courts and the policing.

Criminal justice includes the crime that an offender commits, the law enforcement officers who arrested him for that crime, the court system that prosecutes and defends him, and how that offender is punished if he is convicted.4. All these agencies work together in order to establish the rule of law in the society.

Simply put criminal justice refers to the legal procedures and the courts that deal with crime, punish the offenders and dispense justice. The major purpose of criminal justice is to punish the offenders in accordance with the crimes they have committed, to ensure that those offenders do not further commit any such crime and to provide justice to those against whom crime has been committed by those offenders.

Lie Detectors
KN Bhat, the former additional solicitor general of India, writes: "In criminal cases when police resort to lie-detector tests it should be concluded that the investigation has reached a dead-end and other methods of discovering evidence or eliciting information, including procuring a confession, have failed."5.

The use of lie detectors in criminal justice has always been subjected to many debates, some say that it produces erroneous results and many human rights activists say that it is against the humanitarian law.

Lie detector or Polygraph is used to verify whether the statement given by the person is credible or not by measuring his pulse rate, heart rate, respiratory rate, etc. it is an instrument used to determine whether the suspect who is being questioned is giving true answers or not. The physical changes in the body of the suspect who is being questioned are studied by the examiner and accordingly it is incurred whether giving true answers or he is lying. It is a form of test where physiological changes are observed in the body to determine the authenticity of the answers given by the suspect.

Lie Detection And Human Rights
Every individual has the choice to give consent to undergo the Lie-Detection Test or not. If the suspect or the accused or the witness does not give a voluntary consent then the investigating authorities do not have the right to conduct this test. Lie detector test has been considered a violation of the provisions of the Human Rights. This test comes under the provision of 'torture' as provided under Article 1 of the United Nations Convention against Torture. The Human Rights Committee also forbids obtaining evidence from an individual through torture, force and duress.

The Mechanism
The lie detector test works on the basis of a psychological principle known as psychosomatic interaction which deals with minor physical changes in the body. The changes in the body could be that the heart rate or the pulse rate increase, there could be a change in the body temperature, etc. it is based on the principle that whenever a person lies, the fear of getting caught would bring about some changes in the body of that person and the lie detector would catch those changes and the investigating authority would get to know that the person is giving false statements.

The lie detector instrument is attached to the suspect who is being questioned in the following:
  1. To record the changes in the respiration patterns of the suspect, a pneumograph tube is strapped around the chest of the suspect and another around his abdomen.
  2. A regular blood pressure cuff is attached to his upper arm
  3. Electrodes are attached to the fingers through which a weak electric current is passed to measure the galvanic skin reflex.
  4. The body movements and pressure are measured through the chair, which is specially designed, on which the suspect is sitting.6.

The examiner asks the suspect some questions and the changes in his body are observed when he answers those questions. A few other things need to be ensured while conducting the test such as the examiner being given information about the suspect, maintaining silence in the examination room and the presence of only the examiner and the suspect in the room. To obtain better results general questions should be asked by the examiner whose answers can be given in Yes or No form.

Legal Provisions
The legal maxim maxim nemo tenetur se ipsum prodere means that no one is bound to accuse oneself the right against self incrimination was thus established which states that a suspect cannot be forced to be a witness against himself.

Article 20(3) of the Indian Constitution and Section 161 (2) of the Code of Criminal Procedure give the suspect rights against self-incrimination. Article 20 (3) of the Indian Constitution is based on the legal maxim nemo teneteur prodre accussare seipsum which states that no accused can be forced to be a witness against himself and that the burden of proof lies on the prosecution. It also provides that a man shall be presumed to be innocent until proved guilty. Therefore it can be said that the use of the Lie Detector test is a violation of the principle provided under Article 20(3) of the Indian Constitution.

Code Of Criminal Procedure:
  1. Section 53(1) of the Code of Criminal Procedure states "when a person is an arrest on a charge of committing an offence under such circumstances that there are reasonable grounds for believing that an examination of the person will afford, evidence as to the commission of an offence, it shall be lawful for a registered medical practitioner, acting at the request of the police officer snot below the rank of sub-inspector, and for any person acting in good faith in his aid and under his direction, to make such an examination of the person arrested as is reasonably necessary to determine if the facts which may afford such evidence, to use such force as is reasonably necessary for that purpose".

    This Section enables a medical practitioner to medically examine the accused when the police makes such request.
  2. Section 161 (2) of the Code of Criminal Procedure provides that "Every person shall be bound to answer truly all questions relating to such case put to him by such officer, other than questions the answers to which would have a tendency to expose him to a criminal charge or to a penalty or forfeiture."7.
This Section provides the accused the right to remain silent and a statement cannot be forcibly extracted from the accused.

The Indian Evidence Act, 1872:
  1. Section 3 (1) of the Indian Evidence Act states the definition of "Evidence" as � (1) All statements which the court permits or requires to be made before it by witnesses, in relation matter of fact under inquiry;
  2. Section (2) All documents including electronic records produced for the inspection of the court; Such documents are called documentary evidence.

Hence, the statements obtained from the Polygraph or the Lie Detector test or any Narcotics Test cannot be treated as evidence as they the same are not included in the definitions give in Section 3 of The Indian Evidence Act.
  • Section 45 of the Indian Evidence Act, 1872.
    Opinions of experts.�When the Court has to form an opinion upon a point of foreign law or of science or art, or as to identity of handwriting [or finger impressions], the opinions upon that point of persons specially skilled in such foreign law, science or art, [or in questions as to identity of handwriting] [or finger impressions] are relevant facts. Such persons are called experts.8
This Section provides that experts have to be consulted in order to decide upon a point in the case where identity of handwriting of finger impressions is involved or other such aspects of science in involved.

Selvi Vs. State Of Karnataka
AIR 2010 SC 1974, (2010) 7 SCC

In 2004, Selvi and others filed a criminal appeal and subsequent appeals were filed in the years 2005, 2006 and 2007 and 2010. The Supreme Court then allowed a special leave petition to be filed in cases where it was challenged that the suspects, the accused and the witnesses involved in the investigation were subjected to the Narco-analysis tests, Brain Electrical Activation Profile (BEAP), Functional Magnetic Resonance Imaging (FMRI) and Polygraph tests without obtaining the consent of those on whom these tests were conducted.

The constitutionality of these tests to gather evidence was questioned. The Polygraph or the Lie Detector test catches the minor changes which happen in the body of the suspect or the accused on whom the test is being conducted and accordingly the examiner determines whether the suspect or the accused is giving true answers or he or she is lying to the questions being asked.

Issues Raised:
  1. The first issue that was raised in this case was whether these tests were constitutionally valid or not?
  2. The second issue that was raised was whether these tests violated the right against self-incrimination provided under the provisions of Article 20(3) of the Indian Constitution and Section 161(2) of the Code of Criminal Procedure?
  3. The third issue was whether these tests if conducted without the consent of the suspect or the accused or the witness violate the provision of 'personal liberty' as provided under Article 21 of the Indian Constitution?

The petitioners argued that conducting these tests without the consent of the suspect, accused or the witness violated the right of 'personal liberty' guaranteed under Article 21 of the Indian Constitution. They further argued that these tests violated the right against self-incrimination which was guaranteed as per the provisions of Article 20(3) of the Indian Constitution and Section 161(2) of the Code of Criminal Procedure. The petitioners also argued that the results obtained from these tests could not be scientifically verified hence could not be relied upon.

On the other hand the respondent argued that the information obtained by the investigating authorities through these tests could be used to gather other evidence and prevent crimes. Also these tests did not physically harm the suspect or the accused or the witness on whom these tests were conducted and only helped in gathering evidence. The provisions of the Code of Criminal Procedure and The Indian Evidence Act were also referred according to which it was the duty of all the citizens to cooperate with the investigating authorities.

The Supreme Court held that no individual could be subjected to the tests above mentioned without his consent and with force as the same violated the right of 'personal liberty' guaranteed under Article 21 of the Indian Constitution. However, the court also held that where these tests were conducted voluntarily, appropriate safeguards had to be ensured.

The bench also stated that even if these tests were conducted with the consent of the suspect or the accused or the witness, the results of those tests would still not be considered as evidence by themselves as the suspect or the accused or the witness who underwent the test was unable to exercise conscious control on the responses he or she gave while undergoing the test. However, the information which was subsequently discovered while conducting the tests with the consent of the person on whom the test was conducted could be admitted as per Section 27 of The Indian Evidence Act.

The court further held that the guidelines provided by the National Human Rights Commission for the Administration of Polygraph Test (Lie Detector Test) had to be adhered to and appropriate safeguards had to be followed while conducting these tests.

The question on the constitutionality of the Lie-Detector Tests is still unanswered. The Supreme Court has left the choice to use this test open to the investigating authorities, the only limitation is that the Lie-Detector Test has to be administered with the voluntary consent of the suspect or the accused or the witness on whom the test is being conducted. However, the results of this test are still not yet considered scientifically valid and verifiable.

The Polygraph test of the Lie-Detector test verifies the statement given by the person who is undergoing the test by determining the physiological changes in his body. The results of this test can be manipulated by the accused if he is able to control his emotions and physiological changes and thus do not have scientific validity.

The Lie-Detector test also has drawbacks of being considered violative of the right to 'personal liberty' as provided under Article 21 of the Indian Constitution as well as opposing the right against self-incrimination as provided under Article 20(3) of the Indian Constitution and Section 161(2) of the Code of Criminal Procedure.

  1. Crime,, (Visited on 21 July,2022).
  2. Supra 1.
  3. What is Criminal Justice?,, (Visited on 27 July, 2022).
  4. Criminal Justice and Criminology,, (Visited on 22 July, 2022
  5.  Kedar Nagarajan, Why Are Lie-Detector Tests Still Being Used In Criminal Investigations?,, (Visited on 22 July, 2022).
  6. Thota Raghavendra, Polygraphy Test And Its Legal Admissibility In India, (Visited on 22 July, 2022).
  7. Code of Criminal Procedure 1973,, (Visited on 23 July, 2022).
  8. The Indian Evidence Act 1872,, (Visited on 23 July, 2022).
Written By: Akshita Tandon - 4th Year Law Student, University Institute of Legal Studies, Panjab University, Chandigarh,

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