Using an offender’s genetic data in an attempt to explain or excuse violent or impulsive criminal behavior has become increasingly common in the courtroom. In a new review, however, researchers have found that this strategy has not been very effective thus far in terms of convincing judges and juries that defendants should not be held accountable for their actions.
Although researchers have certainly established an association between gene variants and criminal behavior, the exact link is still unclear. And many people remain unconvinced that this factor alone is strong enough to excuse someone for poor behavior.
For example, the combination of low activity in the MAOA gene (found on the X chromosome) and a history of childhood maltreatment has been associated with a greater number of convictions for violent crime. Still, the link between the gene’s activity, environmental factors, and criminal behavior remains unknown.
In addition, using genetic data to excuse a criminal’s behavior can trigger contradictory feelings among jury members.
“A judge and jury may find defendants are less responsible because of a genetic factor,” said Paul Appelbaum, M.D., at Columbia University Medical Center, “but also feel that they are more likely to re-offend because they can’t control themselves due to the genetic effect.”
These two ideas end up canceling each other out, negating any effect this evidence would have had on the assignment of blame and punishment.
Furthermore, it is argued by many that genetic information alone is not enough to decrease responsibility for behavior. For instance, the law requires that defendants must show limited rationality (e.g., due to insanity) or have a reason for reduced behavioral control (e.g., mental disability or young age) for the courts to reduce responsibility or shorten a sentence.
“Ongoing use of behavioral genetic data in the criminal courts may depend on the success of future research elucidating the mechanisms of genetic effects on behavior and responsibility,” said Appelbaum, “as well as how these genetic explanations relate to legal standards for responsibility in the criminal arena. ”
“Until that evidence is forthcoming,” he said, “the use of behavioral genetic data in the criminal justice system is likely to diminish. For the time being, at least, not relying on genetic evidence in criminal courts may result in fairer outcomes at every level.”
Appelbaum led that study with Nicholas Scurich, Ph.D., at the University of Californa, Irvine. Their paper was recently published in the journal Nature Human Behaviour.