BRAIN FUNCTION & CRIMINAL CULPABILITY
John McCluskey escaped from an Arizona prison in July, 2010. A few days later, he and two accomplices carjacked, shot, and burned the bodies of an Oklahoma couple in their 60s. McCluskey was convicted for the carjacking and two murders in federal court on Oct. 7, 2013. When it came time to sentence him, the jury had to choose between life in prison and the death penalty.
They failed to reach a unanimous decision on the death penalty, so he was sentenced to life without parole, primarily on the basis of the defense team’s argument that John McCluskey has a defective brain. The defense presented the results of several types of brain scans and various psychological tests, as well as testimony from neurologists and other experts. The defense argued that McCluskey’s brain abnormalities made him more impulsive and altered his emotional processing. They showed evidence of a stroke damaging the cerebellum, a region at the back of the brain best known for its role in balance and coordination. But the cerebellum has other roles as well, including the planning and controlling of behavior.
MRI scans also suggested that McCluskey’s superior frontal lobes are unusually small in relation to his overall brain volume, plus PET scans found hyperactivity in McCluskey’s frontal lobes and amygdala, a region involved in regulating emotion. The defense argued that a damaged amygdala will misinterpret danger signals and when excited, will issue false alarms that require intact frontal lobes to modulate. All in all, the PET scans found 10 areas that were less active than normal in McCluskey’s brain and 17 areas that were hyperactive, each one of which presumably could exert some positive or negative influence on his behavior.
Evidence of John McCluskey’s brain abnormalities presented by his defense team. Blue areas represent larger deviations from normal.
- Based on what we know about the brain and behavior, explain how the impaired regions of John McCluskey’s brain can be linked to aggression, violence and impulse control.
- Do you think that faulty neurobiology should be a mitigating factor in criminal trials? In other words, is a murderer with a defective frontal lobe in some way less guilty than a murderer with a healthy frontal lobe?
- Should John McCluskey (and similar cases in future) get a lighter sentence because his brain damage is not his fault, or should he get a harsher sentence, to prevent future crimes he seems bound to commit?
 This is a true case, modified from information found at: http://www.wired.com/wiredscience/2013/12/murder-law-brain/