17th Dec 2013
The use of neuroscience in the courtroom has increased dramatically in the past few years. According to Nita Farahany, a bioethicist at Duke University, the number of judicial opinions mentioning neuroscience evidence tripled between 2005 and 2011, from roughly 100 to more than 300. “It’s more prevalent than my numbers show,” Farahany said. That’s because most cases involving neuroscience evidence do not result in a written judicial opinion, and those that don’t are exceedingly difficult to find.
What are the common uses of neuroscience evidence in the courtroom and how is it influencing our legal system? Some uses that Farahany has found include establishing whether a defendant is competent to stand trial and mitigation during sentencing. Take the most recent turn of events in the McCluskey trial for example.
John McCluskey escaped from an Arizona prison in July, 2010. A few days later he and two accomplices carjacked Linda and Gary Haas, a vacationing Oklahoma couple in their 60s. McCluskey shot the couple inside the camping trailer they were towing behind their truck, and then set the trailer on fire with their bodies still inside. McCluskey was convicted for the carjacking and the two murders in federal court on October 7th. However on December 11, 2013 the jury charged with deciding his sentence announced it had been unable to come to a unanimous decision on the death penalty, meaning McCluskey will receive the lighter sentence of life without parole.
McCluskey’s defense team used neuroscience evidence in an attempt to convince the jury that McCluskey had several brain defects that, combined with other factors, contributed to his crimes and should be considered mitigating circumstances. The results of several types of brain scans and psychological tests were presented, as well as testimony from several neurologists and experts. According to Kent Kiehl, a neuroscientist at the Mind Research Network and University of New Mexico who was not involved in the case but observed several days of testimony, “What they found, in a nutshell, was a few structural abnormalities in his brain.” The defense argued that these abnormalities made McCluskey more impulsive and altered his emotional processing.
The prosecution countered the results, showing clear evidence that McCluskey was able to plan and control his behavior and exercise intent. They argued he didn’t lack volition, that he ran a drug circle in prison and had over 50 clients. In that time he was able to organize, procure, and deliver. His accounting books were found after his escape. Prosecutors also noted that he worked out and exercised for six months so he’d be able to run five miles through the desert after he escaped. Prosecutors questioned experts on cross-examination about what regions of the brain would be involved in planning and executing those types of behavior. The areas of the brain named by the experts (frontal lobes, the parietal lobes, corpus allosum) were the same areas that were supposed impaired in McCluskey. “It was a really great cross-examination about how just because he has these ‘holes’ in his head, he’s still able to plan and do careful accounting and all these other things,” Kiehl said.
While at this time it is not clear whether the brain scans and scientific evidence played a role in McCluskey receiving the lighter of the two sentences, there is reason to think it might have.
The other common use for neuroscience in the courtroom, and perhaps an even more telling one, is to establish ineffective assistance of counsel. A defendant may try to convince a judge to order a new trial or dismiss a case altogether because his attorney failed to investigate a neuroscience-based claim regarding his mental state.
What role does neuroscience play in shaping the future of legal policy decisions? Look for “Neuroscience in the Courtroom, Part Two: How Neuroscience Evidence is Influencing our Legal System.”