Admisibility Of Scientific Evidence Under Indian Laws In Criminal Justice System Of India

Reema Bhattacharya[1]


The paper is a deliberation on understanding the concept of scientific evidences and investigation on them. The concept in this paper is properly based to identify the problems in admissibility of scientific evidence in case of any doubts. Through the doctrinal method of research, the paper also contemplates on the constitutional provisions and constitutional validity of use of these scientific evidences in India through the reliability upon these tests; the modern litigation relies upon the testimony of experts and this testimony can play a dispositive role in litigation. In the researcher’s view, the various provisions of Indian statutes should be interpreted keeping in mind the changing circumstances of India, the advancement of crime and criminals, advancement of technology etc. Victims should not be deprived of their benefits just because of the reason that the laws of India are centuries old and the latest crimes are not specifically mentioned therein.

The advancement has been done a number of times, but here the researcher submits that despite of these amendments, courts are giving decision based on benefit of doubt in favor of accused only but not victim. This practice of courts creates a dissatisfaction among masses and delay in justice.

So, in view of researcher, the use of technology and various scientific evidences must be permitted by concerned authorities in checking increasing crime rates and to have a great impact on our Indian criminal justice system.

As technology is used to commit more sophisticated crimes, law enforcement officers and those in the legal system are increasingly using tech tools to combat crime. To keep the public safe and protect human lives, it’s important that the criminal justice industry use cutting-edge software, tracking systems, and more.

Those who study criminal justice today are at the forefront of life-saving technology. Here’s a look at some of the exciting technologies that are playing an important role in the criminal justice field today.


Like in every civilized society, in India too, a criminal justice system evolved. Socio-economic and political conditions prevailing during different phases of the history of India influenced its evolution. Accordingly, the objectives of the criminal justice and methods of its administration changed from time to time and from one period of history to another. To suit the changing circumstances the rulers introduced new methods and techniques to enforce law and administer justice.

Law is dynamic and not static and therefore, as society evolves, law has to be in consonance with the changing social order. Law is the instrument of societal change and the judiciary has the responsibility of interpreting the law for the greater good.[2]Therefore, it is clear that the judicial mind must stay in touch and keep in step with the advancement of humanity. To combat organized crime, its detection, investigation and prevention, methods have to be employed synchronously.[3] The process of thinking gives birth to both positive as well as negative ideas. Negative ideas in today’s transitional society are genesis of crimes, to deal with which, every civilized nation has a set of rules called ‘law’. The word ‘law’ literally means rule of action established by authority. Its origin can be traced back to the time when man, abandoning his individualistic way of life and his abodes on trees and in caves, came together to join hands with others of his race and decided on a ‘group’ living. Sociologists connect this grouping of individuals with the development of agriculture which compelled the man to socialize with his race and integrate efforts to cope with the needs of the agricultural revolution.[4]

Meaning of Scientific Evidence

Before putting into words, the term ‘scientific evidence’, it is imperative to identify the concepts of “Evidence” and “Science”. The term ‘evidence’ means “anything by which any alleged matter of fact is either established or disproved”. Whatsoever makes the controversial thing apparent and clear in the court of law is evidence. Where the question is whether the explosion took place before a fire occurred, the noise of the explosion and its flash are evident of it. Persons who saw the flash or heard the noise can give evidence of the fact of the explosion. Evidence can be in two forms i.e. oral and documentary, additionally; electronic records can be produced as evidence including video conferencing[5]. If the happening of a fact is recorded on anything apart from human memory, that record is an evidence of the happening. Evidence can be defined as any material which tends to persuade the court of the truth or probability of some fact asserted before it[6]. According to Webster dictionary, evidence is that which is legally submitted to a competent court or tribunal as a means of ascertaining the truth or otherwise of an alleged matter of fact under investigation[7].

Section 3 of Indian Evidence Act, 1872 defines evidence what “Evidence” means and includes:

  • All statements which the Court permits or requires to be made before it by witnesses, in relation to matters of fact under inquiry; such statements are called oral evidence;
  • All document including electronic records produced for the inspection of the Court, such statements are called documentary evidence”;

The section has not defined the term evidence in real sense but is rather a statement of what the term evidence includes, namely oral account of the happening of a fact given by those who have personally witnessed the happening and any document in which happening of the fact is recorded. Section 3 is just a statement of kinds of evidence. It tells us that evidence is of two types- Oral and Documentary, but this does not mean that there can be no other type of evidence. For instance if a judge inspects the scene of occurrence, it is regarded as evidence. Admissions, confessions, all are evidence though the Act does not regard them as relevant evidence. But even these are put under one category or the other. If any statement is given through mouth, then it is oral evidence and if anything is recorded, then it is documentary evidence.

In Pushpadevi M. Jatin v. M. L. Wadhwan,[8]Supreme Court has made it clear that where the evidence offered comes within the meaning of its definition, the court can act and need not concern itself with the method by which it was obtained. Sir Lawrence Jenkins, in Barinder Kumar Ghose v. Emperor[9] has observed that relevant evidence remains relevant despite the fact that it was not obtained by following proper procedure of law. “The Latin term scientia gave the birth to the term science, which means knowledge. It is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. In an older and closely related meaning, science also refers to a body of knowledge itself, of the type that can be rationally explained and reliably applied. In modern usage, science most often indicates to procedure of gaining knowledge, not only the knowledge itself. It is also frequently limited to those branches of study that tend to explain the phenomena of the material universe. On the other hand, science has also persisted to be used in a broad sense to symbolize reliable and teachable knowledge about a topic.” [10]

The term Science is used in the Indian Evidence Act, 1872 under Section 45 as:

“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”.

Scientific Evidence may be defined as fact or opinion evidence that purports to draw on specialized knowledge of science or to rely on scientific principles for its evidentiary value[11]. In simple terms, scientific evidence is evidence used in courts and which is arrived at by scientific or technical means[12]

Application of science in law is commonly known as Forensic Science. The area of its application is quite wide and comprehensive.[13] Forensic science has been defined as the application of the principle of medicine to the purpose of law. Forensic medicine deals almost entirely with crimes against the persons in which, medical examination and evidence are required. Forensic science is mostly an exercise of common sense, combined with the application of knowledge and experience already acquired in the study of other branches of medicine, surgery, obstetrics, etc. Its aim is to find out the truth. Its particular field of activity is judicial investigation, both civil and criminal. All medical work is of a responsible character, especially medico-legal work. In all the cases of crimes, involving the person, for example, murder, suicide, assault, sexual offences, traffic accident, poisoning etc., the help of a medical practitioner is sought by the police

The word ‘forensic’ is derived from a Latin term ‘forensis’, which means ‘of the forum’. In Rome, forum was the meeting place where civil and legal matters were discussed by those with public responsibility. Forensic science is the application of natural sciences to matters of the law. In practice, forensic science draws upon physics, chemistry, biology, and other scientific principles and methods. It is concerned with the recognition, identification, individualization, and evaluation of physical evidence. Literally, the word forensic means ‘something that belongs to courts of law’ but in common parlance, law and science contained together is called forensic science. It is the application of the methods and techniques of the basic sciences to legal issues.

Criminal Investigation Scenario

The object of criminal law is in terms of order- survival, security, maintenance of conditions which permit the society to progress, experience of higher values and finally the good life which subsumes all the ideals of the world; in which a democratic society moves.[14]

In a democratic country like India, the system of governance is based on the concept of ‘Rule of Law’ i.e. law is the supreme authority, all are equal before law and justice is to be achieved through it.[15]‘Rule of law’, which means that the law, and not the wishes of any individual,

governs the public affairs, presupposes a set of laws including criminal law to control the actions of the people as well as the State. The laws should be purposeful, public-welfare oriented, unambiguous and practicable. The laws, made in an autocratic manner without due consideration for social welfare, are liable to degenerate into an engine of oppression. Ambiguity or uncertainty in criminal law not only causes inconvenience and irritation to the people but may also create traumatic conditions for a man if the law enforcing agency resorts to arresting or detaining him, or seizing his property, under the pretext of a legal provision interpreted contrary to its spirit. Therefore, a well-defined criminal law is the foundation on which the whole structure of criminal justice system stands. It is the responsibility of the legislators to make the foundation strong by making criminal laws sound in all respects.[16] In the words of Justice S.R. Bannurmath, “The ultimate aim of criminal law is protection of right to personal liberty against invasions by others, protection of weak against strong, law abiding against law-less, peaceful against violent.” It would be correct to say that the human beings’ right to life and security has to be respected and protected otherwise it would defeat the very core of Rule of Law and would give rise to the ‘Law of Fishes’, the strong will swallow the weak.

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While all the branches of law govern every aspect of a man in a civilized society, yet criminal law is the one specific branch that has contact with an individual in his everyday routine. Yet, the position of Indian criminal law is not satisfactory[17]. Police has always been and remains the central agency of criminal justice system. In theory, the safety and liberty of the people depend upon the laws and the Constitution, but in practice the decisions of the legislature and the courts would remain merely on paper if there was no effective police to enforce them. The functioning of police is law in action. As a law enforcement agency, the police in all societies, developing or developed, has to preserve and protect the very basic needs of human survival and social intercourse, and when pushed to the rock bottom, this is what the criminal justice system has been all about. Having realized the importance of the instrumental role of the police in the society, the Gazetteer of India has concluded:

The creation and efficient operation of a modernized police force is essential to guarantee the ‘Rule of Law’ in the social structure of today.”[18]

The basis of the Indian criminal justice system is the investigation by the police. When an offence is brought to the note of police, it is their responsibility to investigate into the matter to find out who committed the crime, to ascertain the facts and circumstances, to collect and present a whole set of these to the court to find whether the accused is guilty or not.[19]

It is the duty of the police to apprehend the wrongdoer and present the case before the court of justice to meet the ends of justice.

The Union Government has created its own central police organization for discharging certain specific duties such as investigation, vigilance, collection of intelligence and to assist the police forces of the states in certain situations such as elections, natural calamities, V.I.P. security, etc. Since the central police organizations play a definite role by assisting the state police forces and supplementing police functions, they play an important role under the criminal justice system. Brief descriptions of the major police establishments under the Central Government are given below:

Central Bureau of Investigation

The C.B.I. was created in 1963. Prior to that, the organization was known as Special Police Establishment, created and functioning under the Delhi Special Police Establishment Act, 1946. The functions of this organization were enlarged in 1963 covering, besides investigation of the role of National Central Bureau for India under the International Criminal Police Organization (INTERPOL), as also the Central Forensic Science Laboratory. The C.B.I. is the principal investigation agency of the Union Government and is concerned with the investigation of important cases of corruption, fraud, cheating, cases committed by organized gangs or professional criminals having inter-state or international ramifications. The C.B.I. derives its powers to investigate from the Delhi Special Police Establishment Act, 1946.[20]

Intelligence Bureau

The I.B. is the primary central agency of our country for collection of intelligence. Its network spreads all over India for the purpose of collecting intelligence relating to the security of the country and protection of foreign visitors. The I.B. maintains a close liaison with the similar establishments in states and advises them in matters of common interest.[21]

But this seldom happens in the present scenario. The reason behind this is that nowadays, the criminals have become classy, sophisticated, and hi-fi and are simply cutting-edge, as they are adopting new and enhanced techniques for commission of crimes. They hardly leave any sort of inkling or evidence at the crime site or otherwise and on the contrary, the country’s police and investigation agencies are still stuck on the longstanding tools and techniques for the investigation of crimes. Police often use third-degree torture to extract information as that is sometime is unethical under law. In many cases, they try to suppress the truth and make out fabricated cases for many reasons such as political influences or corruption, to name a few. Consequently, custodial atrocities and custodial deaths are on an increase with leaps and bounds and all this is nothing but a big blow on the ‘Rule of Law’. Also, where criminals leave no evidence of their alleged crimes, they escape punishments in the absence of direct proof sufficient enough to establish their guilt. Moreover, where victims turn hostile, there is no way left for the judiciary except to give the accused a benefit of doubt and set him free, which results in embodiment of criminals and loss of faith in the criminal justice system by the victim, victim’s family and society at large.

Getting released on bail is not a big deal these days and thereafter, the accused persons get released due to the aforementioned reasons. There are a lot of cases where an accused walked away freely for the want of evidence and the victim, who suffered trauma, watched helplessly. It was aptly held by Hon’ble Supreme Court in State of Punjab v. Karnail Singh,[22] a judge does not preside over a criminal trial to see no innocent man is punished, but also to see a guilty man does not escape. But the trial judge can only decide the matter based on the material presented before him. If investigation methods applied are not satisfactory, if witnesses turn hostile, if there is no evidence available, is the judge presiding over the trial left with any other option except to give the accused benefit of doubt, as law requires proof and corroboration beyond reasonable doubt?

Forensic science plays a vital role in crime detection. According to the Encarta World Dictionary, meaning of the word forensic, is “crime- solving relating to the application of science to decide questions arising from crime or litigation”. In the present scenario, forensic science can be said to be an important branch of jurisprudence. It is a potent and powerful weapon in the armory of administration of justice. It is here that we can seek the help of scientific evidence for effective delivery of justice as it combines both science and the law. We use a number of scientific techniques like DNA, asphyxia, epiphysis, etc. which have been discussed in the previous chapter. Here, in this chapter, the researcher has narrowed down the study to the use and admissibility of three specific techniques, namely Narco-Analysis, Polygraph and Brain-Mapping. The cardinal principle in applying scientific aids to investigation is the rule of fair play, unbiased approach and openness of mind from collection, evaluation analysis and use of these scientific evidences both by investigators and forensic experts.[23]

Narco-Analysis: Origin

The term Narco-analysis is derived from the Greek word ‘narke’ (meaning ‘anesthesia’ or ‘torpor’) and is used to describe a diagnostic and psychotherapeutic technique that uses psychotropic drugs. The term Narco-analysis was first used by Horseley. In 1922, the Narco Analysis test entered the mainstream when Robert House, a Texas obstetrician, used the drug scopolamine on two prisoners. This test was extensively used in the Nithari serial killing case. The two accused of the case, Mohinder Singh Pandher and Surendra Kohli, underwent the Narco Analysis test in Gujarat.[24]

History of Novel Scientific and Technical Tools of Instigation with Reference of the Frye Case and Dubert Case: The history of the admissibility of scientific testimony involves two very instructive and interesting cases that illustrate the difficulties that courts have had in determining the standard for admissibility of novel scientific evidence. Prior to 1923 in the United States, most courts treated scientific evidence the same as any other type. The rules governing the admissibility of evidence were derived from the Common Law. There was no codification of specific rules. In 1923, the landscape changed for novel scientific evidence, owing to a murder case in Washington, D.C. James Frye was on trial for murder. As part of his case, he sought to have introduced the result of a test that utilized a machine that could be considered the forerunner of today‘s polygraph. He claimed that the result of the test helped to prove that he was innocent. The prosecution objected to the admission of his novel evidence, and the judge agreed. On appeal, the court upheld the trial judge‘s decision. In effect, the appeal court stated that, with respect to novel scientific evidence, just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages, is difficult to define.[25]

Somewhere in this twilight zone the evidence force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field to which it belongs. Thus, the slandered for novel scientific or technical evidence that came out of this decision was that before a new scientific technique could be introduced in court, the underlying principle that governed it, must have achieved general acceptance within the particular field to which it belongs.

One important issue was not decided by the court, i.e. what constitutes general acceptance. In fact, this issue has never been clearly decided. It has come to mean, more or less by default, that the technique and principles should have been published in a peer reviewed journal or other equivalent exposure to the field the federal courts and about half of the States used the Frye case as the yardstick to evaluate the admissibility of new scientific techniques.

During that time, a number of novel scientific techniques were subject to Frye challenges in various courts. They included Voiceprint Spectrograph, Blood Spatter Pattern Analysis, Polygraph analysis, and even DNA Typing techniques. On, January 2, 1975, the Congress, for the first time, approved an evidence code[26]

The Narco Analysis Test is also known as Lie Detector Testing (LDT) or Truth System Testing (T.S.T). In this test, probes are attached to various nerves ending by passing a serum through the blood. Slowly the person goes into an unconscious state and speaks about the things that are present in his/her mind.

What is a Narco Analysis test?

The Narco Analysis test is a kind of a psychological test. A drug named sodium pentothal is given with slow IV (An IV infusion is a controlled administration of medication into your bloodstream over time) and the stage of the patient is monitored over the period of the test. The patient develops a dissociative state during the test. The original personality of the patient severs the association with his consciousness. In this test, the inhibition of the patient fades, because in a stage of consciousness, he can suppress what he does not wish to release, but in the dissociative state, the patient effortlessly expresses the truth or suppressed information of his sub-conscious mind.

If the patient wants to keep the truth in the stage of inhibition while being conscious is when that the Narco Analysis test is done. The narcosis state of the brain is produced with the help of this test and hence, the extraction of the truth is projected. It is a kind of a dissociative test.

A constant monitoring of blood pressure, pulse, or ECG (the pattern of cardiograph) of the patient or accused is carried out as part of the test after injecting sodium pentothal, which is administered intravenously along with dextrose over a period of three hours, with the help of anesthetist. The reaction in the patient starts within minutes of medication. The use of sodium pentothal sometimes sedates the patient and puts them to sleep. But it is mandatory to maintain the level of consciousness and keep the patient in a drowsy state.

Need for the Narcoanalysis Test

In a nutshell, during the last few years, the field of criminology has expanded rapidly. Thus, there is a need for a detecting deception test and to improve the efficacy of the investigation, when the accused are not coming forward with the truth and to have a further clue in the matter for further investigation of the crime and truth and to apprehend the real culprit by getting some clue after the test. The conducting of Narco analysis is in the process of collection of evidence by the investigating agency. The scientific test helps the investigating agency in the collection of the hidden evidences and to prove the guilt or innocence of the accused, as the modern scientific test helps to protect the society too from the third-degree methods of the Police officers.

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Uses of Narco Analysis in Criminal Investigation

By looking at the present pathetic condition of society regarding criminals, crime rate and affected innocent people, it seems to be right time to check the ways with which this can be reduced. It can be possible by giving rich technology to the investigation agencies and Narco analysis is one of them.

To facilitate the investigating agencies, there is need to provide an option of scientific tools which can be applied when there is absolute darkness, to discover evidence. The traditional method of extracting truth by torture is very heinous which violates the rights of individuals and is also blot to the society.

The process is only harmful to the body when the doses are very high but which is only injected in the presence of experts. The questions framed by the specialized person and expertise of the process are such that there is very less possibility to tell a lie, as indicated by many foreign and Indian writers.

The evidence extracted through this process may be denied as reliable but it can be used to get an admissible evidence, to corroborate with other evidence or in support of other evidence.

A mere questioning of a person by a police officer while the person is suspected in a crime and the same is a voluntary statement cannot be treated as incriminatory. As in the Abu Salem Case, he disclosed many important information and his involvement of crime.

The head of Drafting Committee of the National Criminal Justice System Policy, Prof. N.R. Madhavan, also recommended for the utilization of scientific method in investigation process in India.[27]


Polygraph is another important scientific tool of investigation. Polygraph is popularly known as lie detector and sometimes referred to as a psycho-physiological detection. It is an instrument which measures and records physiological actions of the human body as for instance, blood-pressure of the subject, his pulse rate, respiratory system, skin conductivity while the subject is asked questions relating to the crime and he answers them. The polygraph tests measures all the natural changes caused by autonomic nervous system during questioning. The autonomic nervous system changes are beyond the reasonable control of an individual and hence, autonomic nervous system response changes transpire when the subject tries to tell a lie. Polygraph is a device that records simultaneously tracing of several different pulsations, as arterial and venous pulse waves, and the apex beat of heart[28]. According to Science and Technology encyclopedia, “Lie Detector” is a device intended to detect an involuntary physiological response that all persons exhibit when lying, but never when telling the truth.

In the US Federal agencies, a Polygraph test is also referred to as a ‘Psychological Detection of Deception‖’ or PDD examination. There is no Indian legislation which defines Polygraph, but United States Employees Protection Act of 1988 defines the term Polygraph which means an instrument which-

  1. Records continuously visually, permanently and simultaneously as minimum instrumentation tendered;
  2. Is used, or the result of which are used, for the purposes of rendering a diagnostic opinion regarding the honesty or dishonesty of an individual.[29]

On the other hand, usually in India, the suspects who are being taken by police or other security agencies to the forensic labs for detection of lies and deception, and where it is said that such person is being taken for Narco-Analysis test, generally also put to Polygraph test, but it is not the strict rule. The Polygraph test is so old that it had diminished the credibility in the minds of general public, therefore the police in the West seldom publicly say that the culprit is being taken for polygraph test (rather they say and mention Narco-Analysis test in India). The most significant requirement of a yogin is speaking truth. Truth is the emperor of intrinsic worth. Truth is the ultimate asset. The essence of the Vedas is Truth. Have power over passions constitutes the real meaning of truth. Truth is virtue. Virtue is light, and light is pleasure. Ahimsa, brahmacharya, transparency, fairness, harmony, pardon, peace are forms of truth. Impartiality, self-discipline, humility, patience, decency, repudiation, deliberation, self-respect, strength, sympathy, and refraining from harm are the various forms of truth. All the above virtues, although apparently dissimilar, have but one and the same form, namely, truth. All these hold up truth and strengthen it. When the path of truth is crushed, the entire additionally also is done. When the root is watered, all the branches are automatically watered.[30]

Origin of Polygraph Test

The origin of the Polygraph test has been traced back to the efforts of Lombroso, a criminologist who experimented with a machine that measured blood pressure and pulse rate to assure the honesty of the person suspected of criminal conduct.[31]

Since the dawn of civilization, mankind has sought ways to distinguish truthfulness from lying in those individuals who are suspected of criminal wrongdoing. Various inventive techniques for the verification of truth and the detection of deception have been tried over the centuries, many of these being ridiculous and cruel. Despite their crudeness, each technique was based on the assumption that some form of physiological reaction occurred within a person when confronted with certain stimuli regarding a specific event under investigation, and that this physiological reaction would, in turn, be manifested in certain recognizable external symptoms that were indicative of honesty or deception.[32]

Polygraphy i.e. the science of truth verification based upon psycho physiological analogues is barely 100 years old. In 1730, British novelist Daniel Defoe wrote an essay titled “An Effectual Scheme for the Immediate Preventing of Street Robberies and suppressing all Other Disorders of the Night,” wherein he recommended that taking the pulse of a suspicious fellow was a practical, effective and humane method for distinguishing truthfulness from lying. Defoe’s was an early and insightful suggestion to employ medical science in the fight against crime.[33]

In 1878, Science first came to the aid of the truth seeker through the research of Italian physiologist Angelo Mosso. It was then that Mosso used an instrument called a plethysmograph in his research on emotion and fear in subjects undergoing questioning and he studied the effects of these variables on their cardiovascular and respiratory activity. Mosso studied blood circulation and breathing patterns and how they changed under certain stimuli. The use of the plethysmograph revealed periodic undulations or waves in a subject’s blood pressure caused by the respiratory cycle in response to certain stimuli. Angelo Mosso was the first scientist to report on experiments in which he observed that a person’s breathing pattern changed under certain stimuli, and that this change, in turn, caused variations in their blood pressure and pulse rate.[34]

Although not for the purpose of detecting deception, Sir James Mackenzie, M.D., constructed the clinical Polygraph in 1892, an instrument to be used for medical examinations with the capability to simultaneously record undulated line tracings of the vascular pulses (radial, venous and arterial), by way of a stylus onto a revolving drum of smoked paper.[35]

Until the end of the 19th century, no measuring device for the detection of deception had ever been used. The first use of a scientific instrument designed to measure physiological responses for this purpose came in 1895 when Italian physician, psychiatrist and pioneer criminologist Cesare Lombroso modified an existing instrument called a hydroshygmograph and used this modified device in his experiments to measure the physiological changes that occurred in a crime suspect’s blood pressure and pulse rate during a police interrogation.

In 1906, Sir James Mackenzie refined his clinical Polygraph of 1892 when he devised the clinical ink Polygraph with the help of Lancashire watchmaker, Sebastian Shaw. This instrument used a clockwork mechanism for the paper-rolling and time marker movements and it produced ink recordings of physiological functions that were easier to acquire and to interpret. Interestingly, it has been written that the modern Polygraph is really a modification of Dr. Mackenzie’s clinical ink Polygraph.[36] In 1914, Italian psychologist Vittorio Benussi discovered a method for calculating the quotient of the inhalation to exhalation time as a means of verifying the truth and detecting deception in a subject. Using an Anemograph, a device that recorded a subject’s breathing patterns, Benussi conducted experiments regarding the respiratory symptoms of lying. He concluded that lying caused an emotional change within a subject that resulted in detectible respiratory changes that were indicative of deception.[37]

Dr. William Moulton Marston, an American attorney and psychologist, is credited with inventing an early form of the Lie Detector when, in 1915, he developed the discontinuous systolic blood pressure test which would later become one component of the modern Polygraph. Dr. Marston’s technique used a standard blood pressure cuff and a stethoscope to take intermittent systolic blood pressure readings of a suspect during questioning for the purpose of detecting deception.[38]

How is a Polygraph Test Conducted?

The Polygraph is a pneumatically operated device, which concurrently records changes in a subject’s blood pressure, pulse, respiration rate and depth, psycho galvanic skin reflex (skin resistance to electrical current) and in some cases, the muscular activity. When a subject is put to the ‘Polygraph’ test (Lie-detector test) the machine reflects and records only the subjects’ physiological responses to the questions asked by the operator who then interprets the Polygraph and determines whether the subject is lying or otherwise. The instrument in fact, records the sign of internal stress accompanying deception. All polygraph tests involve the measurement of physiological responses (usually, respiration, palmar sweating, and cardiovascular activity) with an instrument while the subject is asked a series of questions. Polygraph tests begin with an interview during which the examiner psychologically prepares the subject for the test. Once collected, the physiological data are usually evaluated by the examiner. Failed law enforcement examinations are often followed by an intense interrogation designed to force the subject to confess to the crime in question. However, substantial differences exist between the various polygraph tests in the character of the pretest interview, in the structure of the question series, and in the assessment of the physiological data.[39]

During the Polygraph test, an expert and skilled examiner will make assessment of the following procedure –

  1. An assessment of examiner’s emotional state;
  2. Medical fitness of the examinee;
  3. To identify overly responsive behavior specialized tests be conducted;
  4. To asses overly responsive behavior specialized test be conducted;
  5. To do factual analysis of case information and
  6. To do pre-test interview and detail review of question.[40]

In Polygraph process three aspects of human physiology are tested i.e.

  1. Pneumograph tracing
  2. Electro dermal activity tracing, and
  3. Cardio vascular tracing.

The first relate to respiration, the second to skin conductor or skin resistance and the third with blood volume and pulse rate.[41]

Result After Polygraph Testing

The result of the test is obtained on a chart known as Polygram. The following changes are noted carefully, suppression in respiration and increase of blood pressure after the reply, decrease in blood pressure, behaviour breathing, slowing of pulse rate and the course of blood pressure.

Polygraph does not directly detect whether the person is speaking truth or is deceiving but the examiner carefully analyzes the pattern of arousal responses and on that basis, veracity of the individual is inferred. This inference or assessment is called ‘diagnosis’ of truthfulness or deception. In India, since 1974 at Central Forensic Science Laboratory, New Delhi more than 3000 polygraph tests have been conducted.

Brain Finger Printing Tests

In brain finger printing text, words, pictures or sounds describing the salient features of crime are flashed on a video screen attached to a computer to the suspect, along with other irrelevant information that would be equally plausible for an innocent subject. Items which are known only to the person who has committed the crime creates a brain waves that is absorbed by patented head band and recorded by EEG. The brain emits a specific brain response if only the record of the crime is stored in the brain. This response appears when the brain recognizes the correct relevant items shown, and there is an absence of response if it fails to recognize the item.

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Brain Mapping is one more valuable scientific tool for investigation of crimes. Brain Mapping is also known as Late Positive Complex or P3 or P300.

P300 Test: When the brain recognizes a person or a sound, it generates a particular type of electric wave and this wave is called P300. In modern times, it is recognized as a reliable forensic tool in investigation of facts by the government. In the field of neurology, visual and auditory evoked potential tests are generally used.[42]

It is a component of averaged brain potentials. In this test no questions are asked from the accused. The accuracy of Brain Mapping is almost 100%. Brain Mapping is a response of the brain to a stimulus which is shown to the subject. In 1965, scientists were working on the research of Event Related Potentials and it was discovered by Sutton and his colleagues. It is a very robust Event Related Potential. As soon as it recognizes the stimuli, it sends the reaction within 300 milliseconds of seeing the stimuli. If the person is attentive to the stimuli, its response would be the fastest. If more time is taken for making decision, more time is spent for the responses of P300. Its latency shows the amount taken by it in arriving at a decision.[43]

Constitutional Validity of the Scientific Evidence

Admissibility of scientific evidence has attracted a serious debate in India especially post Selvi v. State of Karnataka[44] case wherein Hon’ble Supreme Court has held that narco-analysis, Brain-mapping and polygraph tests cannot be conducted without the consent of accused person. Admissibility of scientific evidence involves some important questions relating to basic rights that are available to accused under various provisions of law in India. A major problem in India is that we always look at provisions of law through the view-point of accused and we totally forget the pain, misery and trauma of a victim and victim’s family. There are various provisions, if given interpretation keeping in mind the changed scenario, would make scientific evidence admissible in court of law without any amendment.

Also, the first principle interpretation is that the words of an enactment should be given their ordinary and natural meaning because whatever was the intention of legislature, has been expressed by it through words. If the language of a statute is plain, the only duty of court is to give effect of to it[45]. In this regard, the legal maxim, ut res magis valeat quam pereat, is also worth mentioning. According to this maxim, where alternate constructions are possible, the court must give effect to that interpretation which will help in smooth working of the system rather than that construction which will be responsible for putting unnecessary hindrances in the way of statute for which it has been exacted. As far as possible, all the words used in the statute must be given meaning, as the legislature is not expected to use unnecessary words. Superfluous or insignificant words are not used by the makers of a statute.[46]

Therefore, various provisions of Indian statutes should be interpreted keeping in mind the changed circumstances of India, the advancement of crimes and criminals, advancement of technology etc. Accused persons should not get benefit for the simple reason that Indian laws are centuries old and latest crimes have not been specifically mentioned therein. No doubt, statutory laws have been amended ‘n’ number of times but the researcher humbly submits that despite the amendments, courts give decision based on benefit of doubt in favour of accused. This practice of courts is creating dissatisfaction among masses and is emboldening the criminals. In view of the researcher, courts should permit use of latest technology by concerned authorities to check increasing crime rate.

The Constitution of India is a product of the intense research and consideration of a body of distinguished spokespersons of the people who wanted to make better the existing system of administration.[47] The framers of the Indian Constitution were not writing on a clean slate. They had before them the working of the government under the Government of India Acts of 1919 and 1935. While framing the Constitution, they also kept in mind geographical necessities, historical precedents and our cultural and social diversities. It, therefore, would be in the fitness of things[48] to study and interpret every provision of the Constitution keeping in mind the needs of India. Articles of the Indian Constitution related with the topic of research are discussed in detail as follows:

Article 20(3) Self – Incrimination: Clause (3) of Article 20 of the Indian Constitution talks about self-incrimination. It provides “No person accused of any offence shall be compelled to be a witness against himself”. This clause is based on the legal maxim nemo tenetur prodere accussare seipsum, which means that no man is bound to accuse himself.[49] Making any statement that has the possibility of exposing the accused to criminal prosecution either at present or in future is not permitted under the Constitution. This provision is inspired from the 5th Amendment of the United States Constitution that prohibits the government from forcing any person to produce any sort of evidence that would incriminate that person. This immunity is available to every person against whom formal accusation has been framed.[50] The scope of this immunity has, prima facie, been widened by our Supreme Court by interpreting the word ‘witness’ to comprise both oral and documentary evidence which is likely to support a prosecution against him. Such evidence however should be in the nature of communication[51]. Also, this protection is available against testimonial compulsion. This protection cannot be claimed by a person if, at the time of making the statement, he was not an accused. Moreover, it is immaterial that he becomes accused thereafter[52]. Article 20(3) is not applicable in cases where any sort of recovery is made, be that an object or evidence, from the possession of a person. General statements given by any person at some regular inquiry or investigation without formal charges being framed against accused would not attract Article 20(3) even if that statement turns out to be incriminatory at some later stage[53]. In the case of Pakhar Singh and Anr. v. State[54] , “The word ‘witness’ must be understood in its natural sense, i.e. as referring to a person who furnishes evidence. Indeed, every positive volitional act which furnishes evidence is testimony”. The statement or information given by the accused to the police during investigation is evidence. Statements made under Narco analysis do not fulfil the above three ingredients at the same time thus, Narco analysis should be outside the purview of Article 20(3).


The decision made in Selvi v. State of Karnataka is inflexible and full of errors. It seems all the contentions in favour of narco-analysis, polygraph and brain mapping were not thoroughly considered by the court. The court did not take into consideration the problems being faced by the investigating authorities while solving cases. If every tool of investigation is seen as violative of Article 20 (3) and Article 21 then the police authorities will be left with no other option than to resort to custodial violence. There has been an urge that novel and scientific tools of investigation should be embraced. However, in such a scenario, cooperation was expected from the court. In cases where no direct evidence is available, it becomes extremely difficult for the investigating authorities to detect crime. The court should have kept room for the use of scientific techniques at least in blind cases. The benefit is always enjoyed by the criminal. The court has discussed the rights and privileges available to the accused. No attention has been paid to the victim and the society at large. Such types of judgements encourage the criminals. They play with the law. They use sophisticated means in commission of crimes. They leave no clue of their crime. Hence, they are rarely put behind the bars. The courts should allow the use of modern techniques in crime investigation. In blind cases, no miracle is going to happen. Every case will meet the fate of Selvi v. State of Karnataka. Kavita is still mourning her husband’s death. Kavita is still awaiting justice

[1] Reema Bhattacharya, Ph.D Scholar , Amity Law School, Amity University, Noida.

[2] Philosophy propounded by Jeremy Bentham and John Stout  Mills

[3] Nathuni Yadav v. State of Bihar (1998)9 SCC 238.

[4] B. M. Mittal, Text Book of Forensic Science (1899).

[5] State of Maharashtra v. Praful B. Desai (2003) 4 SC 601

[6] Avtar Singh, Principles of the Law of Evidence 6, (19th ed. Allahabad: Central Law Publications, 2011).

[7] Jhala and Raju, Medical Jurisprudence 19, (6th ed. Lucknow: Eastern Book Company, 1997).

[8] Pushpadevi M. Jatin v. M. L. Wadhwan AIR 1987 SC 1748.

[9] Barinder Kumar Ghose v. Emperor ILR (1910) 37 Cal 467

[10] Science, (November 19, 2019),

[11] Satyendra K. Kaul and Mohd. H.Zaidi, Narcoanalysis, Brain Mapping, Hypnosis and Lie Detector Tests in Interrogation of Suspect 911, (Allahabad: Alia Law Agency, 2008).

[12] Ishita Chatterjee, Techno-legal aspects of Scientific Evidence 16, (Allahabad: Central Law Publications, 2012).

[13] Som Dutt Vasudeva, The Science and the Crime, criminal Law Journal 238, (2006).

[14] Justice Hall

[15] C. K. Takwani, Lectures on Administrative Law 25, (9th ed. Lucknow: Eastern Book Company, 2012).

[16] Rule Of Law, Dicey

[17] Peter Bret, An Inquiry into Criminal Guilt 51.5 cal. L. Rev. 1031-1036 (1963).

[18] The Gazetteer of India, Vol. IV, pp. 424-28

[19] S.R. Bannurmath, “Narco-analysis, Brain- Mapping- Legal Implications with Reference to Right to Silence”, unpublished report, Karnataka Section of International Commission of Jurists 2, 2007

[20] The Gazetteer., loc. cit

[21] Ibid

[22] State of Punjab v. Karnail Singh (2003) 11 SCC 271

[23] R. P. Sharma, Truth Detecting Techniques Vis-à-vis Physical Evidence, 4 Karnataka Law Journal, 33 (2007).

[24] Article by Chitra Pandey

[25] International Journal of Pure and Applied Mathematics, 128.

[26] Ibid

[27] Ajay Kr. Barnwal1 Dr.S.N.Ambedkar, Narco-analysis Test: An analysis of various Judgements of Indian Judiciary 19.10.1 IOSR-JHSS 52, 55 (2014).

[28] Taber’s Medical Dictionary (17th edition,1553).

[29] International Journal of Pure and Applied Mathematics, (137).

[30] Polygraph test and its reliability, (November 19, 2019),

[31] Pratibha Banergee, Violation of human rights through scientific techniques,  CriLJ 108, (2013).

[32] Timeline History of Polygraph Test, (November) http://

[33] Ibid.

[34] Ibid

[35] Ibid.

[36] Ibid.

[37] Ibid.

[38] Ibid.

[39] Charles R. Honts and Mary v. Perry, Polygraph Admissibility: Changes and Challenges, 16 Law and Human Behavior 358 (1992).

[40] Supra 32, 594.

[41] Ibid.594.

[42] Textbook on medical jurisprudence and Toxicology 118, (edition 2018).

[43] Satyendra Kumar Kaul, 249

[44] Selvi v. State of Karnataka AIR 2010 SC 1974

[45] T. Bhattacharyya, The Interpretation of Statutes 10, (6th ed. Allahabad: Central Law Agency, 2006).

[46] Ibid 55.

[47] Durga Das Basu, Introduction to the Constitution of India 2, (21st ed. Gorgaon: LexisNexis, 2013).

[48] Narender Kumar, Constitutional Law of India 6, (6th ed. Faridabad : Allahabad Law Agency, 2007).

[49] ibid 283.

[50] M.P. Sharma v. Satish Chandra, AIR 1954, SC 300.

[51] Durga Das Basu, Introduction to the Constitution of India 114, (21st ed. Gorgaon: LexisNexis, 2013).

[52] State of Bombay v. Kathi Kalu Qghad, AIR 1961 SC 1808.

[53] Veera v. State of Maharashtra, AIR 1976 SC 1167

[54] Pakhar Singh and Anr. v. State 1958 CriLJ 1084.