Deborah Denno quoted in National Geographic magazine regarding the use of genetics to inform criminal cases.
In 2011 Deborah Denno, a law professor at Fordham University, reported 33 recorded* instances of neuropsychiatric genetic evidence in criminal courts between 2007 and 2011. She had previously reported 44 instances between 1994 and 2007, suggesting that it’s becoming slightly more common. In almost every instance, genetic evidence was used as a mitigating factor in a death penalty case.
The genetic evidence in Denno’s reports tended to be fairly crude: a family history of a condition. But specific genetic tests are beginning to seep into court, too. In 2007, several psychiatrists and geneticists described their experiences presenting evidence at criminal trials related to two gene variants: a variant of monoamine oxidase A, which when mixed with child maltreatment increases the risk of violent behavior, and a variant of the serotonin transporter gene, which when mixed with multiple stressful life events ups the risk of serious depression and suicide. A couple of cases used these scientific links to argue that defendants didn’t have the mental ability to plan their crime in advance. But most of the time genetic evidence was used to mitigate sentences. In 2011, for example, an Italian court reduced a female defendant’s sentence from life in prison to 20 years based on genetic evidence and brain scans that supposedly proved “partial mental illness.”
*Most of Denno’s cases came from appellate courts because usually lower courts don’t have written opinions. So that means her numbers are almost certainly underestimates.
Read the entire National Geographic article.