Neuroscientist Michael S. Gazzaniga explains why some people may be born criminals.

A Neuroscientist Explains Why Some People May Be Born Criminals

A Neuroscientist Explains Why Some People May Be Born Criminals

The citizen’s guide to the future.
Nov. 15 2011 11:17 AM

Not Guilty by Reason of Neuroscience

Some people’s brains may doom them to a life of crime.

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While movies, books, and television portray crimes ending up in a courtroom where intention and many other circumstances are examined, very few criminal cases actually go to trial, only about 3 percent; most are plea bargained out. Once we step into the courtroom, the laboratory of judicial proceedings, neuroscience has an enormous amount to say about the goings-on. It can provide evidence that there is unconscious bias in the judge, jury, prosecutors, and defense attorneys; tell us about the reliability of memory and perception with implications for eyewitness testimony; and inform us about the reliability of lie detecting. Now it’s being asked to determine the presence of diminished responsibility in a defendant, predict future behavior, and determine who will respond to what type of treatment. It can even tell us about our motivations for punishment.

Robert Sapolsky, professor of psychology at Stanford, makes the extremely strong statement: “It’s boggling that the legal system’s gold standard for an insanity defense—M’Naghten—is based on 166-year-old science. Our growing knowledge about the brain makes notions of volition, culpability, and, ultimately, the very premise of a criminal justice system, deeply suspect.” The M’Naghten rules arose after the attempted assassination of British Prime Minister Robert Peel in 1843 and have been used to determine (with a few adjustments) criminal liability in regard to the insanity defense in most common law jurisdictions ever since. The British Supreme Court of Judicature, in answer to one of the questions posed to it by the House of Lords about the insanity law, responded:

“the jurors ought to be told in all cases that every man is presumed to be sane, and to possess a sufficient degree of reason to be responsible for his crimes, until the contrary be proved to their satisfaction; and that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong.”


The question that Sapolsky raises is: Given determinism, given that we are beginning to understand mental states, given we can track down which part of the brain is involved in volitional activity and that it may be impaired, and our growing knowledge that we can be specific about the existence of an impairment and what is causing it, will we view the defendant differently?

At stake in the arguments is the very foundation of our legal system, which holds a person responsible and accountable for his actions. The question is this: Does modern neuroscience deepen our ideas about determinism, and, with more determinism, is there less reason for retribution and punishment? Put differently, with determinism there is no blame, and, with no blame, there should be no retribution and punishment. This is the simmering idea that people are worried about. If we change our mind about these things as a culture, then we are going to change how we deal with this unfortunate aspect of human behavior involving crime and punishment.

Michael S. Gazzaniga is the director of the SAGE Center for the Study of the Mind at the University of California-Santa Barbara. He is the president of the Cognitive Neuroscience Institute and the founding director of the MacArthur Foundation’s Law and Neuroscience Project. His most recent book is Who’s in Charge?: Free Will and the Science of the Brain.