Jay D. Aronson


Recent advances in the field of neuroscience, especially improved magnetic resonance imaging (MRI) techniques, are providing scientists and decision-makers with an increasingly complex understanding of how our brains develop from birth to adulthood. While these studies are still in their infancy, they have already made it clear that the brain typically continues to develop long after the point at which an individual becomes a legal adult (i.e., at age 18), and that the slow maturation process that plays out in the social context is mirrored by a slow maturation process at the neural level. Despite the tentative nature and unsettled meaning of this information (i.e., we do not yet understand the actual link between brain structure and behavior), neuroscience is increasingly implicated in long-standing debates about the treatment of juveniles in the criminal justice system and the extent to which adolescents can be held legally responsible for their acts. To date, the most notable example of this trend has been Roper v. Simmons, in which the Supreme Court banned the death penalty for offenders under the age of 18. The case revolved around the trial, sentencing, and habeas corpus petition of Christopher Simmons, who brutally murdered an elderly woman during the course of a burglary when he was 17 years old. The Court held that although the execution of juveniles was once considered acceptable in American society, a national consensus had emerged that such a punishment was cruel and unusual and, thus, in violation of the Eighth Amendment. The majority agreed with Simmons’ claim that adolescents do not possess the emotional, intellectual, or biological maturity necessary to be reliably classified among the worst offenders. Although adolescents should certainly be punished for their crimes, they should not pay the ultimate price for impulses that they were unable to control. Simmons’ argument was premised largely on new brain imaging evidence suggesting that the adolescent brain is not as well developed as the adult brain.