People Kill People: Neuroscience in the Courtroom

It’s the GOP’s favorite saying when the left wing broaches gun statistics and murder rates: Guns don’t kill people, people kill people. Only recently has this been taken to a new extreme: Brains don’t kill people, people kill people; or at least that’s what mitigating prosecutors of most murder trials would try to tell you… A neuroscientist would laugh.

As Dr. Ruben Gur, a neuropsychologist specializing in brain imaging, so eloquently explained in his discussion on the use of neuroscience in the courtroom, we are our brains. To say that brains don’t kill people but people kill people would be paradoxical. The problem is that not every brain operates on the same level with normal cognitive function and, as we know, people’s behavior is a direct product of their cognitive processes. It is precisely this reason that neurological evidence should be employed as evidence in the mitigation portion of murder trials. I say ‘should’ because despite the use of Stone Age psychoanalytic tests – first laid out by the outdated Freud – and testimony from psychologists and psychiatrists, neurological evidence derived from brain imaging such as fMRI, DTI, and PET scans has not yet found its place in the legal system. 

Let me digress. Deborah Denno, a professor of law at Fordham University is currently conducting research on cases from the last two decades that have had a neuroscience component to them. Though incomplete, her research thus far has come to several conclusions: (1) neurological evidence is almost always brought up in death penalty cases, (2) it is usually applied as mitigating evidence rather than in determining culpability of the criminal and (3) it is used nearly explicitly by defense attorneys and opposed by prosecutors.  It meets opposition she claims, for several reasons – historic abuse of neuroscience, ignorance of the law among scientists, ignorance of science among lawyers, its possibility as a double edge sword, and its undue influence on juries. Denno refutes these sources of debate on the grounds that her current data and conclusions render these concerns unfounded. She has seen no proof that these sources of debate arise when neurological evidence is used properly. What she has seen is that time and time again testimony from psychological “experts” relying on outdated forms of psychoanalytic theory is allowed as evidence both in determining guilt as well as deciding on punishment. Time and time again the so-called evidence has been skewed and unreliable, giving neuroscience a bad reputation as evidence. 

The instances are far and few between where neuroscience has been appropriately applied in the courtroom, but there are rare cases such as those which Dr. Gur works on that pave the way for the use of this evidence in the future. It takes a lawyer that has done their homework to give Gur a call but neurological evidence can play an important role in the outcome of mitigation. DTI can show significant decreases in grey matter, fMRI can show brain functionality in cognitive tasks, PET scans can show active parts of the brain during times of stress versus rest and these ‘pretty pictures’ – as the prosecution would have them called – can demonstrate to a judge or a jury that the defendant simply wasn’t dealing with a full deck. To be clear, this evidence is not being used to say a criminal isn’t at fault; people do in fact kill people. However, this evidence can allow for less severe punishments than the death sentence for criminals that have impaired cognitive function and less ability to control their behaviors. 

As technology continues to improve, the tools used to gather neurological evidence are only getting more and more precise in providing data about the brain – data that is used to diagnose disease, operate on people’s brains, and prescribe medication. If this science is so precise and the points of opposition against its use in the courtroom are moot, evidence founded in brain imaging should be acceptable for submission when determining sentencing in capital cases. It is vital that the justice system acknowledge the way in which neuroscience sheds light on the human experience and adjust current policies to make room for it in the courtroom.