I spent the week before last doing jury service on a medical malpractice case. After decades immersed in fictional recreations of trials and courtrooms (what mystery editor hasn’t encountered barrelsful of successors to Perry Mason), it was enlightening to see how a real trial is conducted. Although this was not a criminal case, it brought to mind, for me, some recent developments in criminal law.

Back in 2010, when my AHMM counterpart and I were blogging on our website, I did a post about discoveries in neuroscience and speculated on how they might eventually affect the concept of personal responsibility for criminal acts. I decided to revisit that post and see what new information on the subject has become available over the past couple of years.

According to a November 2012 article in U.S. News and World Report, a survey from Duke University shows that “the number of cases in which judges have mentioned neuroscience evidence in their opinions increased from 112 in 2007 to 1,500 in 2011.” And defense attorneys are increasingly bringing medical evidence such as brain scans into court in cases ranging from murder to sex crimes. Having spent the better part of a week in a courtroom looking at medical diagrams, X-rays, charts, and records, I feel I might have experienced something of what the criminal trial of the future will look like. But the extent to which such medical evidence will—or ought to—affect jury verdicts in criminal cases will probably be a hotly debated subject for a long time to come.

When I posted on this subject in 2010, I had just seen a segment of an ABC Nightline Prime series called Secrets of Your Mind, in which evidence for a “murder gene”—actually several “murder genes”—was examined. According to one of the neuroscientists interviewed, James Fallon, scientific opinion is closing in on three factors that may be determinative of whether someone ends up becoming a violent criminal: 1) the existence of a brain defect in which the orbital cortex, the area of the brain now known to be the center for conscience, is “turned off”; 2) the presence of one or more of the ten genes known to put someone at high risk for violence; and 3) a childhood environment of abuse.

The first two of these factors—the biological ones—are the most controversial, but scientist Fallon was confronted with an unexpected confirmation of his research in his own family history. After discovering brain defects and the various genes associated with violence in a number of incarcerated murderers, Fallon learned—to his shock, I’d imagine—that he was descended from generations of murderers, including the notorious Lizzie Borden. And, perhaps more disturbing, a scan of his brain revealed the very same “turned off” orbital cortex that he had found in prison subjects, which, given his family history, certainly seems to lend credence to the theory that biological factors play a significant role in whether someone will commit violent acts.

On the other hand, Fallon himself is not a criminal, despite having the crucial brain defect and the genes associated with violence, so it might be tempting to think that in the end nothing can be made of this “hard” science in predicting how someone will in fact behave or, more importantly for our legal system, in relieving anyone of responsibility for criminal behavior. Many will still want to argue that what it all comes down to in the end is free will; that it may be harder for someone with such a condition of the brain, or for someone born with certain genes, to live a life without violence, but that they are, nevertheless, able to choose one path or the other.

I’m certainly not going to try to come down one way or the other on that question, but the very fact that more defense attorneys are bringing physiological evidence of a predisposition to violence into court should tell us that public opinion on this subject is changing. Lawyers choose their evidence according to what they think will convince a jury. One thing that impressed me at the end of the trial I just participated in was how interested the attorneys were in finding out why we members of the jury voted as we did, even down to details such as whether we liked it when one of the expert witnesses turned to face us as he testified. They were thinking ahead to other trials, keeping a finger on the pulse of the kind of people who will be deciding their future cases.

But enough about real trials; what interests me as a mystery editor is how crime and mystery writers will come to terms with what could turn out to be a profound change in the way we assign responsibility for crimes. It seems to me that a fundamental assumption behind the traditional mystery is that everyone has it in them to become a murderer. The fact that some commit such acts and others don’t—the way that “evil” enters into or is resisted in a life—is what the whole business of mystery writing seems to me to touch on in one way or another. And yet new scientific discoveries seem to be pointing in a different direction, telling us that we do not all start out alike. That some are born with brains that heavily predispose them to commit heinous crimes, and conversely that others are unlikely to commit such crimes no matter what circumstances confront them—and no matter what qualities they do or don’t cultivate in themselves.

Of course, deterministic theories of human behavior are nothing new, and free will is one of those concepts it’s probably impossible for a society to do entirely without. But I’d guess that at the very least, if the science connecting violent crime to certain brain defects holds up, there will be changes in how we view many of the perpetrators of violent acts. Perhaps we’ll punish less harshly those who were predisposed to crime by their physiology—even if we allow that they had a measure of choice.

Fiction is sometimes ahead of far-reaching changes in a society’s attitudes, but I haven’t encountered many mystery or crime stories that wrestle with this new science. Have you?—Janet Hutchings