Neuroscience is the study of the nervous system in order to understand the regulation of body and behaviour by the brain. Advance medical science is capable of identifying deception by shooting infrared beams through convict’s head. This is done by placing them in a magnetic resonance imaging machine and using scanners to track their eyeballs. This technique is used by many countries such as United States in the hope of producing fruitful investigations to counter terrorism. Highly promising yet unproved technique has stirred up quiet some controversy relating to its admissibility in courts.

Indian criminal justice system has always encouraged admission of evidence that upheld the latest development in science and technology.  Earlier scientific techniques of DNA testing, brain imaging, chemical tests, psychiatric tests, etc has been accepted as evidence which have helped in providing certainty and hence reduced the complexity of the law. However it also sows a seed of unreliability when used by lawyers who are not familiar with this field.

Admissibility of neuroscientific evidence has significantly increased in recent years across various countries. However, different legal systems have come up with their own variation regarding the admissibility of this type of evidence in courtrooms and its impact on juristic decisions. The admissibility of the neuroscientific evidence depends on the type of neuroscience evidences, which are:

  1. Evidence of neurological abnormality- Evidence such as brain scan showing that defendant is suffering from a neurological impairment e.g. Frontal Lobe Disorder (FLD), which hampers the function of brain associated with planning and decision making. In a famous case of Virginia, a school teacher after developing brain tumour showed sudden interest in child pornography. Though in such cases it is difficult to ascertain the presence of the abnormality during the time of commission of the crime and its significant contribution in the crime, the courts generally admit it, even though such evidence is considered weak.

The intersection between the neuroscience and law is crucial in order to reflect the use of these techniques for diagnosis, risk assessment and treatment. The admissibility of neuroscience in order to evade criminal responsibility is highly dependent upon the defensive arguments. There are four plausible arguments which are considered relevant by the judges, which are:

  1. Defendant’s act was involuntary. This requires the proof of lack of conscious control over the body as in the case of sleepwalking or epilepsy. For example a friend while sleep walking cooks brownies with walnuts for a friend who is allergic to walnuts. The prosecutor cannot argue that the cook had some unconscious will to harm his friend as he had no conscious control over such unconscious will.
  2. Absence of “mens rea” during commission of crime. For establishing mens rea the prosecution needs to show that the offender had relevant preparation to accomplish his motive. However, such proof can be rebutted by the defence attorney by showing through various brain imaging techniques that the defendant’s brain has certain functional impairments due to which it is not possible for the defendant to form and commit to plans of action.
  3. Legal defence associated with insanity. The earliest case on this matter is that of R. v. Arnold in 1724 . The court held that every man is presumed to be sane to be held responsible for his crime until contrary is proved. In order to establish this defence it must be clearly proved that at the time of committing the offence the accused was incapable of understanding both the nature and the consequences of the said act by the reason of mental impairment.

Admissibility of neuroscience evidences in Indian courtrooms has rapidly increased, however its advancement presents several obstacles as well as this field is new and inexperienced and is often exploited by the prosecution. The experts of both fields must come together to develop a set of rules in order to gauge when a particular defendant’s neurological profile conforms to the legal requirements.


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