Lie Detector Test

Continued from https://cvshreejeev.wixsite.com/website/post/criminal-evidence

My apologies for the long gap after the publication of my last blog on "Criminal Evidence" on 22nd March 2021. There have been suggestions to make a YouTube channel and publish the content there in a video format. I want to know your thoughts on the same. If most of you think that it would help in creating a better understanding of the subject or in reaching a wider audience, I can think about the same. Request to please give your valuable suggestions in the comment box.

Lie Detector Test

Let us discuss here about proving the authenticity of oral statements and written documents.

First, we will talk about the methods used to prove the genuineness of signatures and documents.

GEQD: Apart from the various Central and State Forensic Labs, there is also an organization called the GEQD (Government Examiner of Questioned Documents). They would be able to prove the authenticity of signatures and handwriting, through document forensics. Though a real signature and a forged signature looks exactly the same to the normal eye, the force exerted by the writing instrument on the paper would be uneven and lacks smooth flow in the case of a forged signature. The age of the ink also determines the date when the signature was made. Scientific analysis of the age of the paper also determines whether the old paper is genuine or a new paper that looks like an old paper was used to appear as old. This can prove forgeries, alterations, damage to documents, or chain of document possession. It is when a document is under suspicion or in question, that it is sent to the GEQD.

Now let us talk about proving the authenticity of oral statements and various tests relating to them.

There are three tests viz. The Polygraph Test, Brain Mapping and Narco- Analysis. All these three are together classified as DDT (Deception Detection Test). It is useful for investigating agencies to unearth the concealed information about the case, which is known only to that particular person. However such information extracted from the person is not admissible in Court but can help the investigating agencies to know the truth of the crime. It is argued that it is much better than using 3rd-degree methods by the police to extract information. It is further argued that this will help in increasing the conviction rate and also help in more acquittals of innocent people. However, the Supreme Court has ruled that such tests cannot be taken without consent, from the point of view of human rights, ethical, legal, and constitutional perspectives.

Polygraph – This is also called the Lie Detector Test. The theory behind this test is that the person subjected to this will go into a hyperarousal state when questioned about the facts of the case. In a normal interrogation, the person can fake his outward appearance and answer with a straight face, but when subjected to a polygraph test, the changes in his body are picked up by the machine. A number of parameters like blood pressure, heartbeat rate, respiratory rate, skin conductance, and electromyography are recorded. A questionnaire is prepared in such a way that the person is asked very simple and familiar questions relating to his pleasant experiences in life, childhood, friends, etc. to make him feel at ease and suddenly a tricky question relating to his role in the case is asked, which will throw his senses out of sync in his hyperarousal state, if he is lying, and the same is captured by the machine, and then again continue with pleasant questions to relax him. Electromyography (EMG) is a medical technique to record the electrical activity produced by skeletal muscles. It is the skill of a polygraphist, the manner in which the questions are asked in a very friendly way and at what juncture should serious questions be asked and how to ask them. Later the questions and the polygraph test results are matched to arrive at a conclusion. However, a trained person or a pathological liar can beat a polygraph test. With breathing and relaxation exercises, yoga and meditation, etc., his hyperarousal symptoms can be controlled or suppressed. Hence it is not 100% reliable and cannot be used during the trial stage.

Narco-Analysis – It involves the intravenous administration of drugs such as sodium pentothal, sodium amytal, and scopolamine. It causes the person to slip into an anesthetic stage. In such a hypnotic condition, the person feels less inhibited and is likely to divulge more information which he or she may not usually have revealed in a conscious state. He or she may also reveal all his / her fantasies, impulses, instinctual drive, personal wishes, illusions, misinterpretations, conflicts, delusions, etc. The main drawback is that the answers are given in a hypnotic state of mind, and are not voluntary, and hence cannot be admitted in the Court as evidence. Secondly, it gives unrestricted access to the deeply private matters of his / her personal life which is not part of the investigation and can be misused.

Brain Mapping – Electrodes are placed on the surface of the skin covering the person’s head and face and the changes in the electrical field potentials produced by the sum of the neuronal activity in the brain are measured. The theory behind this is that the brain generates a unique brain-wave pattern when a person encounters a familiar stimulus. In India, the commonly used method is the “P300 waves test” or the “Brain electrical Activation Profile Test”. The person is shown pictures, videos, and sounds that are relevant to the criminal case along with other irrelevant pictures and words. In the case of guilty persons, the exposure to the material probes will lead to the emission of P300 wave components which will be recorded by the instruments. This generally throws light only on the memory or knowledge of the crime scene. But the drawback is that these facts can also be divulged by a bystander who witnessed the crime. Hence this cannot be used as evidence in the Court. However, it can prove to be a boon for an innocent person to prove that he or she has no memory of anything about the crime.

Conclusion: DDT which broadly comprises of Polygraph or Narco Analysis or Brain Mapping, has faced plenty of criticisms. The Supreme Court judgment on involuntary DDTs is that it has no place in the judicial process. On the contrary, it will disrupt proceedings, cause delays, and lead to numerous complications, which could have been easily avoided.

Contemporary DDT needs to undergo rigorous research in normative and pathological populations. Premature application of these technologies outside research settings should be resisted. The vulnerability of the techniques to countermeasures also needs to be explored. It is also important to know the sensitivity and specificity of these tests. There should be standard operating guidelines for conducting DDT. The recent Supreme Court judgment on DDT is admirable from the scientific, human rights, ethical, legal, and constitutional perspectives.

My next blog would be on the subject of “Guns & Laws”