What did the Supreme Court rule in Thompson v. Oklahoma (1988)?

In Thompson v. Oklahoma (1988), the Supreme Court ruled that the execution of individuals who were under the age of 16 at the time they committed their offenses is unconstitutional. This landmark decision is rooted in the Eighth Amendment's prohibition against cruel and unusual punishment. The Court recognized that executing someone who was not yet 16 years old at the time of their crime is disproportionate to their culpability and fails to align with evolving standards of decency in society. The ruling underscored a growing recognition of the developmental differences between juveniles and adults, highlighting that younger individuals may not possess the same level of moral culpability or capacity to understand the consequences of their actions. As a result of this decision, it became constitutionally impermissible to impose the death penalty on those who commit crimes while still considered juveniles, specifically those under the age of 16.