Should murderous psychopaths be punished less severely if their behavior can be blamed on brain differences or genes? Or, conversely, should their sentence be longer precisely because their biology makes them even more intractable and dangerous than other criminals?
A new study published in Science explored these questions by asking judges to impose a prison term on a hypothetical convict. When the judges were initially told that the offender was a psychopath, they tended to consider it an aggravating factor in sentencing, but when they heard additional expert testimony that biological factors could explain the guilty man’s behavior, they saw that information as mitigating and handed down a shorter sentence.
The impact of such expert testimony depended in part on whether the biological arguments came from the defense or the prosecution — it influenced judges’ reasoning more when it was delivered by the defense. But, overall, judges still levied lengthy sentences for the crime and viewed the convict as morally and legally responsible for his behavior: they reduced prison time only by a year, from 13.93 years on average to 12.83, when considering brain or genetic explanations for the convict’s behavior.