This case requires us to address, for the second time in a decade and a half, whether it is permissible under the Eighth and Fourteenth Amendments to the Constitution of the United States to execute a juvenile offender who was older than 15 but younger than 18 when he committed a capital crime. In Stanford v. Kentucky, 492 U. S. 361 (1989), a divided Court rejected the proposition that the Constitution bars capital punishment for juvenile offenders in this age group. We reconsider the question.