492 U.S. 302 (1989), argued 11 Jan. 1989, decided 26 June 1989; O’Connor announced the judgment of the Court and delivered the opinion of the Court, which was joined in part and dissented to in part by the other justices. Penry held that the application of the death penalty to persons who are mentally retarded but not legally insane does not violate the Eighth Amendment prohibition against cruel and unusual punishments. The Court also held, however, that jurors in a capital case must be given the opportunity to consider mitigating evidence and to provide a “reasoned moral response” to that evidence in rendering its sentencing decision.
Penry was mildly to moderately mentally retarded, probably from birth but possibly as a result of childhood beatings. Though but a child in mental age and maturity, he was found legally sane and competent to stand trial and was sentenced to death for rape and murder.
Because the Texas jury was not specifically instructed that it could consider mitigating circumstances in deciding whether or not to apply the death penalty, the Supreme Court reversed. The Court, per Justice Sandra Day O’Connor, held that “the jury must be able to consider and give effect to any mitigating evidence relevant to a defendant's background, character, or the circumstances of the crime” (p. 328).
The Court held, however, that the execution of a mildly or moderately retarded person was not automatically barred by the Eighth Amendment, whether viewed in light of the attitudes of its framers or interpreted in accordance with society's evolving attitudes toward crime and punishment. The Court's decision did not affect its previous decision, in Ford v. Wainwright (1986), that execution of an insane person was prohibited by the Eighth Amendment.