When the Boston Marathon bombing occurred, Dzhokhar Tsarnaev was 19 years old. That means he could face the death penalty if convicted in the bombing.
If the bombing had occurred two years earlier, when he was 17, that wouldn't be possible. The Supreme Court banned the death penalty for juveniles in 2005.
In that case, the court received briefs from the American Medical Association, the nation's psychologists and psychiatrists, and other research groups, who said juveniles shouldn't be executed because their brains are still developing and they don't yet have all the wiring to make competent decisions, as adults do. We wouldn't indict a six-month-old baby for failing to walk, and we shouldn't administer the death penalty to an adolescent who hasn't yet developed a mature moral compass, the reasoning goes.
Dana Goldstein at The Marshall Project explores this issue in a short post that recaps a bit of the research on adolescent brains--indeed, she cites only one authority on the subject. And then, in a poorly executed attempt to provide the other side of the story, she quotes one other authority who says "societal factors" are "the most important contributors" to criminal behavior.
Goldstein doesn't explain either position well, but the larger problem is that acknowledging the importance of societal factors such as family stability and socioeconomic status does not say anything about the maturation of the human brain.
It's an obvious point that the condition of Tsarnaev's brain at the time of the bombing and his relationships with his family and friends could all be factors in how he behaved at the time of the bombing.
This piece does not provide the kind of "hiqh-quality journalism about the American criminal justice system" that The Marshall Project promises. Let's hope for a better explanation of nature, nurture, and the human brain in upcoming articles.