U.S. Supreme Court · 2005
Roper v. Simmons
543 U.S. 551 (2005)
Holding
Held that the Eighth and Fourteenth Amendments forbid imposition of the death penalty on offenders who were under 18 when their crimes were committed (overruling Stanford v. Kentucky). The Court relied on three developmental differences that diminish juvenile culpability: a lack of maturity and underdeveloped sense of responsibility, producing impetuous and ill-considered conduct; greater vulnerability to negative influences and peer pressure; and a character that is not yet well formed and more transitory.
Claims this case relied on
Adolescents have a diminished capacity for self-regulation and impulse control relative to adults; the neural systems supporting cognitive control and behavioral inhibition mature gradually across adolescence and do not reach adult levels until the late teens to early twenties.
Evidence strength: HighScientific consensus: Established· adolescent self-regulation / impulse controlAdolescents are more susceptible than adults to peer influence and to external pressure or coercion, with susceptibility greatest in mid-adolescence; the mere presence of peers measurably increases adolescents' risk-taking and shifts their decisions toward immediate rewards.
Evidence strength: HighScientific consensus: Established· adolescent social influence / coercionAdolescent personality and character are still forming and are not reliable indicators of fixed adult character; most adolescents who engage in antisocial behavior, including serious offending, desist as they mature, so adolescent conduct is a poor predictor of irretrievable depravity.
Evidence strength: HighScientific consensus: Established· adolescent personality development / desistance