Neuroscience is the study of the nervous system for understanding how the brain
regulates the body and behavior of an individual giving rise to his/her
consciousness. This has immensely contributed in the prevention and cure of
neurological and psychiatric disorders.
Our criminal justice system has been encouraging the admission of new types of
evidences which are the upshots of the latest scientific and technological
One of these newly admitted evidences is the neuroscientific evidence which has
created serious controversies as it is relatively new and inexperienced. This
tool can be used by the defense attorneys to reduce or even exculpate the
criminal responsibility of their clients.
This article analyses how conscious will of an individual is related to freedom
and responsibility while committing a crime and how this tool proves effective
in establishing and sometimes reducing the guilt of an offender. The article
focuses on the types of neuroscientific evidences and when they become material
[i]under the recognized legal parameters for examining criminal liability and
punishments. The article also focuses on the obstacles to the presentation of
this evidence at both trial and sentencing.
Science And Law: a brief history
Science in all forms has in recent times invaded the courtroom symposium whether
it is DNA testing, chemical tests, brain imaging and lie detection techniques,
psychiatric tests etc. The desire to use science in courtroom among the
attorneys has increased exponentially over the years. Science and law have
always exhibited love- hate relationship. The love part commences from the fact
that science helps in reducing the complexities of the law by providing greater
amount of certainty.
The hate part on the other hand emanates from the fact that science used by the
lawyers who are not well equipped in this field often leads to unreliability.
From the advent of Electro-encephalography (EEG) in 1930s to the Magnetic
Resonance Imaging (MRI) scans performed in 1970s, the discipline of neuroscience
has observed notable evolution.
In 1940, EEG was used for the first time in a case of a defendant suffering from
epilepsy. EEG measures various activities of the brain by placing electrodes on
various portions of head and then recording various electrical impulses
emanating in the nerve cells present in the outer region of the brain. After few
years again in 1981, Computed Tomography was introduced to scan the brain of
John Hickley who was charged with attempt to murder of President Ronald Raegan.
He was alleged to have been suffering from Schizophrenia. The indifference of
the legal system towards such incapacitated persons was debated by the defense
counsel. The judges of the district court admitted this evidence in order to
ensure maximum authenticity and subsequently found him not guilty by the reason
The data in the table above illuminates the fact that admissibility of
neuroscientific evidence has significantly elevated in recent years across
various countries with the U.S.A at the top of the list. However, there has been
great variation across different legal systems in deciding upon the
admissibility of this type of evidence in courtrooms and its impact on juristic
decisions, for instance it has led to decrease in detention time in the U.S.A in
contrast to that in Germany. Also, the intersection between the neuroscience and
law is crucial in order to reflect the use of these techniques for diagnosis,
risk assessment and treatment.
Admissibility Of Neuroscientific Evidences In Courts
Albeit, there has been significant increase in the inclination of the judges
towards the admissibility of this evidence, the neuroscientific evidence can
have mitigating effect only under some circumstances in criminal adjudication
especially at sentencing.
In order to make the evidences admissible into the
courts, how the attorneys should frame the claims and make them germane to the
criminal law doctrines is the question. The admissibility of the neuroscientific
evidence depends on the five types of neuroscience evidences. The first two are
weakly material at the trial while the last three are more likely to be relevant
both at trial and sentencing.
- Evidence of abnormality- evidence showing that defendant is suffering
from a neurological impairment e.g. Frontal Lobe Disorder (FLD). The brain
scan of the defendant done by using MRI technique can show that his frontal
lobe area of the brain ( associated with planning and decision making) and
the left side of the limbic system (associated with regulation of emotions)
exhibits reduction in volume.
It may seem on the very face that such
evidences are highly material; however the courts are reluctant to admit
these evidences most of the times. In a famous case, a Virginia school
teacher at the age of 37 suddenly developed interest in child pornography
and sexually propositioned his step daughter. It was found that he had
developed brain tumor and after the surgery his sexually motivated conduct
A case like this which establishes lucid and direct causative
link between the neurological defect and the crime is very unusual. In
majority of the cases this evidence fails to establish the causative link
between the abnormality and the crime; also it is very difficult to
ascertain the presence of the abnormality during the time of commission of
the crime and its significant contribution in the crime. This evidence is
rarely pertinent at trial and sentencing.
- Cause of effect evidence- this evidence tends to show that many
people with neurological impairment exhibit antisocial behavior i.e. most of
the criminals have FLD. It makes an earnest attempt to establish the fact
that it was not the offender but his brain which occasioned him to commit
the crime. But again this category of neurological evidence is no better
than the abnormality evidence as it too fails to provide as to how the
abnormality contributed to the commission of the crime, which is the
central question the law postulates to be answered.
- Effect of cause evidence- this evidence endeavors to show that violent
behavior is the effect of the neurological impairment i.e. people with FLD
are more likely to commit crimes. This category to some extent succeeds in
establishing the causative link between the violent behavior and
neurological impairment by comparing the prevalence of iniquitous behavior
among those with some neurological impairment to those lacking any of such
impairment. For instance, in a study it is found that the prevalence of
vicious behavior in persons with neurological defect is 10% higher than in
persons lacking such impairment; the data suggest that neurological
impairment predisposes people to commit crime.
However, the critics argue
that there is some or the other cause behind each crime, if the juries will
begin to mitigate or exculpate the punishment on the basis of these causes
then every criminal will try to manipulate the law in his favour. In some
cases where the defense attorney presents strong evidence that the criminal
behavior was the cause of neurological impairment, the prosecution will try
to point out the planning component of the crime, which will extirpate the
volitional impairment claim. The prosecutions can also emphasis the fact
that many people with these impairments do not commit such crimes thus
proving that control is possible. In short, the attorneys need to be
meticulous as though this category is better than the first two; it comes
with its own impediments.
- Impairments that are legally relevant- this type of evidence entails the
process behavioral study and gauging of the defendants ability to control,
plan, form intentions and various other germane enquiries made by the
neurologists. This differs from the simple evidence of abnormality as it
provides an insight into the defendant’s functioning. However, the degree of
impulsivity differs at different point of time and situations. It cannot be
said with certainty that the defendant shows same impulsivity at the time of
committing the crime.
- Impairments that law recognizes to be exculpatory- this is based on the
doctrine of “scientific stare decisis” which was laid down in the case of
Sears Vs Upton. According to this doctrine, if a 30 year old man’s and a
juvenile’s brain functions alike then the court shall evaluate their
culpability in the same manner. Synonymously, the criminality is more
proximately linked to the maturity of the brain than to the age of the
person. However, the attorneys should punctiliously frame this neuroscientific evidence as this evidence may indicate high recidivism risk.
The admissibility of neuroscience in order to evade criminal responsibility
is tremendously dependent upon the defensive arguments formulated by the defense
attorneys. There are four plausible arguments which can prove to be highly
germane by the judges. First one being the claim that 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.
A murderer shall not be responsible
for the killing if he has not acted from free will. Freedom and responsibility
of a criminal act entails more than just intention and will to do the act. Some
legal jurisdictions explicitly mandates conscious will as elements of crime.
For example a friend cooks soup with peanuts for a friend
who is allergic to peanuts. The cook was not negligent and his conscious goal
was to make the friend happy. The prosecutor’s argument that the cook had some
unconscious will to harm his friend will not hold him responsible as he had no
conscious control over such unconscious will. The antithetical view is that
there is always some connection between the brain and behavior.
This claim is
rarely befitted in the courts in determining criminal responsibility. The famous
“sleep walking case” in 1981 which drew much publicity in Arizona, in which the
defendant was charged with killing his wife with a kitchen knife by stabbing her
26 times. He claimed that he did not remember anything as he was sleeping at
that time. The jury found him not guilty on the ground lack of consciousness
during the commission of the crime.
The second legal defense tends to focus on the “mens rea”
element of the crime which is indispensable in establishing the criminal
responsibility. This requirement may vary between different jurisdictions over
time. The intention element is followed by the preparation and then the actus
reus component of the body of the crime. It is defined as commitment to a
plan of action. For the act to be intentional, the actor must know that he is
planning and performing the act. For establishing mens rea the prosecution needs
to show that the offender had relevant designs to accomplish his motive.
However, the defense attorney can show 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. If these
defense arguments prevail, the criminal responsibility diminishes to a great
extent. The famous case of Andrea Yates, the women who drowned her five children
in the bath tub in 2001. She had been suffering from a very severe postpartum
depression and schizophrenia. She was not found guilty by the courts by reason
of her mental incapacity.
The third possible legal defense is associated with insanity. The
earliest case on this matter is that of R. Vs Arnold in 1724 decided by
the English court. He was acquitted by the jury pointing him out to be a madman
who is exempted from punishment and that he was no more than an infant and such
a man should never be an object of punishment.
In the famous case of Daniel M’Naghten in 1840, from which the famous M’Naghten rule was derived; Daniel
M’Naghten who was charged with murder of Sir Robert Peel, the private secretary
of the then Prime Minister of England, was acquitted on the ground of insanity.
Their lordship observed that every man is presumed to be sane to be held
responsible for his crime until contrary is proved. In order to establish this
defense it must be clearly proved that at the time of committing the offense the
accused was incapable of understanding both the nature and the consequences of
the said act by the reason of mental impairment.
However, such mental and
volitional impairment should be a serious one to be recognized by the jury as a
defense. If a little knowledge about the consequences and the nature of the
criminal act is proved by the prosecution, this defensive argument fails.
As stated above, use of neuroscience evidences in courtroom symposium has
increased tremendously, but with this blooming advancement lays various queries
which need to be addressed. The language of law and the language of neuroscience
are stupendously different. The experts of both fields must together develop a
set of rules in order to gauge when a particular defendant’s neurological
profile conforms to the legal requirements. These rules must be prudently
examined as they being too liberal will set free the guilty and they being too
strict will make the innocent to suffer.
As this field is new and inexperienced, Neurolaw scholarship among the lawyers
and juries should be ameliorated by spending more time with the experts of this
field wrestling with the types of evidence useful in the courts. Experts should
be appointed to explain these evidences to the juries who are naïve in this
field. This is crucial because the responsibility to examine the facts and to
devise any judgment based on these facts is upon the judges hence the judgment
should not be an erroneous one.
The double-edged sword dilemma which is characterized as indicative of high
risks must also be addressed. The neurological evidence is often exploited by
the prosecution when it indicated that the offender poses high future risks to
the general public.
But anecdotally, the defense attorneys are clearly concerned
about this fact. However with all these issues and challenges, neuroscience can
be helpful in reforming the present retributively driven system, by both
preventing as well as rehabilitating the offender. Neuroscience experts would
focus on risks and treatment thus uprooting the cause behind such antisocial
- Christopher Slobogin, “Neuroscience nuance: dissecting the relevance of
neuroscience in adjudicating criminal culpability.” Journal of law and
Biosciences, 577-593 (2017).
- Deborah W. Denno, “The Myth of the Double-Edged Sword: An Empirical
Study of Neuroscience Evidence in Criminal Cases” Boston college law review,
Volume 56, Issue 2, Article 3 (2015).
- U.S. v. Hinckley, 525F.Supp. 1342 [D.D.C. 1981].
- Eyal Aharoni, Chadd Funk, Walter Sinnott-Armstrongand Michael Gazzaniga,
“Can Neurological Evidence Help Courts Assess Criminal Responsibility?
Lessons from Law and Neuroscience, University of California.
- Paul Catley and Lisa Claydon, “The use of neuroscientific evidence in
the courtroom by those accused of criminal offenses in England and Wales.”
Journal of Law and the Biosciences, 510–549, Advance Access Publication [14
- Andrea L. Glenn, Adrian Raine, “Neurocriminology: Implications for the
Punishment, Prediction and Prevention of Criminal Behaviour” Neuroethics
- Rex vs. Arnold (1724).
- R v M'Naghten (1843) 8 E.R. 718; (1843) 10 Cl. & F. 200.
- The Honorable Jed S. Rakoff, “ Science and the Law: Uncomfortable
- Francis X. Shen, “Neuroscientific evidence as instance replay” Journal
of law and the Biosciences, volume3 issue 2, 343-349 (2016).