Could the neuroscience of adolescence, including brain imaging suggesting that young adults remain susceptible to peer influence well into their twenties, be used as mitigating evidence that spares Dzhokhar Tsarnaev the death penalty for the Boston Marathon bombing? The Marshall Project raises that question, noting that his attorney, Judy Clarke, has shown an interest in applying brain research to the law. The Supreme Court cited brain development research in a 2005 case that abolished the juvenile death penalty and a 2010 ruling that ended mandatory life without parole for juveniles who have committed crimes other than homicide.
In 2013, Clarke said that most defendants in death penalty cases “have suffered from serious severe trauma, unbelievable trauma. We know that from brain research. Many suffer from severe cognitive development issues that affect the core of their being.” Laurence Steinberg of Temple University says that into a person’s twenties, the brain is still undergoing myelination, a process in which a white, fatty substance coats nerve fibers, gradually improving the brain's ability to make the neural connections necessary to plan ahead, weigh risks and rewards, and make complex decisions. Tsarnaev was 19 at the time of the Marathon bombing.