Atkins , Adolescence and the Maturity Heuristic: Rationales for a Categorical Exemption for Juveniles from Capital Punishment

In Atkins v. Virginia, the U.S. Supreme Court held that mentally retarded people lacked a range of developmental capacities that were necessary to establish the higher threshold of culpability for the execution of murderers in the Court's death penalty jurisprudence. The Court emphasized that the impairments of mental retardation lead to a . . . special risk of wrongful execution. The Court had previously concluded that the limitations in developmental capacities that characterize mentally retarded defendants also characterize a significant proportion of adolescent offenders. These parallels invite an extension of the Atkins Court's reasoning to juveniles by highlighting the diminished capacity for culpability common to offenders of both groups. This Article addresses the logic and substance of an extension of Atkins to juveniles. Extending Atkins to juveniles requires analyses showing that: (a) many of the developmental characteristics that establish the diminished culpability of the mentally retarded also characterize adolescents, (b) the age-specific competencies for adolescents that define maturity and in turn culpability can be identified and then reliably measured, and (c) the age at which adolescents attain these competencies and when their developmental trajectory begins - that is, the age at which adolescent development measurably departs, both substantively and permanently, from the stable and flat developmental trajectories of the mentally retarded. The Article discusses recent evidence on the developmental capacities of adolescents showing that that many of the same deficits in cognitive and neuropsychological developmental that define retardation also are common markers of adolescence, and elements of immaturity long recognized in death penalty jurisprudence: diminished capacities to (a) understand and process information, (b) learn from experience and mistakes, engage in logical reasoning, (c) foresee the consequences of their actions, (d) control impulses, (e) understand the reactions of others, and (f) resist peer influence. Accordingly, the Article begins by decomposing the diagnostic category of retardation into specific dimensions of underdevelopment. Next, the Article analyzes the correspondence of these dimensions of underdevelopment among the retarded to legal standards about immaturity and culpability of adolescents. If children are in fact less formed developmentally than adults, they lack full capacity and therefore are less culpable than adults. Empirical research shows that a significant number of juveniles have a pattern of developmental and cognitive incapacities that places them well below the threshold of culpability that also exempts the mentally retarded under Atkins. In addition, adolescents will vary in the age when they realize these threshold developmental competencies that constitute maturity and in turn culpability, complicating attribution of full culpability to adolescents at the higher threshold set in death penalty jurisprudence. Recent evidence also suggests that brain development in areas controlling the developmental components of maturity may be incomplete at age 18 or beyond. The Article concludes because defendants with diminished competence and culpability, like the mentally retarded, are immature at age 18 and beyond, that there is sufficient evidence in social science to create a categorical exemption from capital punishment for adolescents who commit murders before the age of 18. The alternative - creating exempted categories such as the immature - invites disputes about how to reliably establish membership. Such classifications will be unreliable and inevitably suffer from the subjective risks of misdiagnosis, testing error, instrument unreliability, or other limits of behavioral science. To ignore the logic of Atkins elevates the risk of an erroneous attribution of cognitive and volitional maturity to a seemingly competent adolescent whose developmental reality may be exactly the opposite, raising the terrible risk of a death sentence where it is not deserved.