Evidence of a Genetic Defect May Lead to Lighter Judge-Imposed Sentencing

Both The New York Times and National Public Radio (NPR) report that a recent study suggests judges may impose lighter sentences in cases where a defendant, diagnosed as psychopathic, is genetically predisposed to violent behavior.

The study, carried about by researchers at the University of Utah and published in the journal Science, tasked 181 judges from 19 states with reading a fictional case file and sentencing the defendant. The fictional defendant, accused of beating a restaurant manager senseless with the butt of a gun, was identified in the case file as being diagnosed as a psychopath. All of the case files distributed were identical except that half of the files included expert testimony from a neurobiologist that the defendant had inherited a gene linked to violent behavior. In those files which included the neurobiologist’s testimony, judges, on average, imposed a sentence seven percent lighter than that imposed on the defendant in the file without the expert testimony.

However, experts, such as law and biological sciences professor Owen D. Jones of Vanderbilt, caution that results could differ in front of juries.  Further, evidence of a biological link to violence may be used by the prosecution to argue for harsher penalties because there is nothing to stop a defendant from being violent in the future.

But, as NPR reports, introduction of a biological basis can mean life or death for a client in a capital case because it may lessen culpability. Research by geneticist Han Brunner uncovered a link between a defect found in a gene known as MAOA (monoamine oxidase A) and the violent behavior of a number of men in a Dutch family who engaged in extremely violent behavior. Stephen Mobley, who was sentenced to death for robbing and shooting a restaurant manager later appealed his sentence on the grounds that his counsel was ineffective for failing to introduce evidence that he possessed the defective MAOA gene uncovered by Brunner and believed to be responsible for violent behavior. His death sentence was reduced to life. However, a later court overturned the ruling, finding that the brain evidence should not have been allowed.

While brain scans and other neurological evidence already is used in some cases, these studies highlight the potential for use of genetic evidence in mitigation, particularly salient in capital cases.  Vanderbilt University Pathology Laboratory Services in Tennessee performs this testing which requires only a client’s blood sample. More information can be found here, or contact Sarah Rackley to discuss this testing.

You can find the New York Times article here and the NPR article here.