My Genes Made Me Do It

My daughter is starting graduate school in neuroscience this fall. She has always recoiled from the idea of attending law school, but seems fascinated by the intersection of neuroscience and the law. This often plays out in the area of legal responsibility for criminal behavior "as neuroscience makes inroads into the courtroom, and presents guilt and innocence--not in terms of black and white--but in shades of gray."

This quotation comes from the last installment of a three-part series of articles written by Barbara Bradley Hagerty and forwarded to me by my daughter. The first article, "A Neuroscientist Uncovers A Dark Secret," describes the process by which neuroscientist James Fallon attempts to discover "how a killer's brain differs from yours and mine." His research showed that the orbital cortex, the part of the brain "involved with ethical behavior, moral decision-making and impulse control", displays little activity in people who are "'free-wheeling types or sociopaths.'"

The second article, "Inside A Psychopath's Brain: The Sentencing Debate," discusses the research of Kent Kiehl, an expert on psychopathy, who has done MRI scans of the brains of over 1,100 prisoners, about 20% of whom are psychopaths. Kiehl has found that in psychopaths, the "'emotional circuit,' involving the orbital cortex above the eyes and the amygdala deep in the brain," does not work in the same way it does in normal individuals. A psychopath may know the different between right and wrong, but can he make good decisions? And if he is physically incapable of making good decisions because his brain is abnormal, should he be held responsible for his actions?

The third article, "Can Your Genes Make You Murder?", describes a horrific murder committed by Bradley Waldroup in 2006. His defense attorney consulted William Bernet, a forensic psychiatrist, who evaluated Waldroup and analyzed his DNA. Bernet found that Waldroup has the "MAO-A gene--also known as the warrior gene because it has been associated with violence. ... Waldroup has the high-risk version of the gene." Bernet concluded that Waldroup's genetic composition coupled with the fact that he had suffered abuse as a child created a predisposition to violence; at Waldroup's trial, the judge permitted Bernet to testify "that these two factors help explain why Waldroup snapped that murderous night." The jury ultimately convicted Waldroup of voluntary manslaughter and second-degree murder, sparing him the death penalty; they believed that the murder was not a premeditated act.

The argument boils down to this. Some experts argue that a brain abnormality should not excuse a criminal act, but should go to mitigate the sentence; society should punish those who commit criminal acts, but not execute them. Other experts argue that it is irrelevant if someone's brain is abnormal, because, in the words of Jonathan Brodie, a psychiatrist, "'the brain does not dictate behavior.'" Steven Erickson, a forensic psychologist, goes even further and states that "' ... the law is not interested in brain abnormalities. The law is interested in whether or not someone at the time that the criminal act occurred understood the difference between right and wrong.'"