The Eighth Amendment does not forbid executing the mentally retarded; however, the three "special issues" a Texas jury is required to consider before imposing the death penalty did not adequately allow the jury in Penry's sentencing hearing to consider his alleged mental retardation as a mitigating factor.
Penry v. Lynaugh, 492 U.S.302 (1989), sanctioned the death penalty for mentally retarded offenders because the Court determined executing the mentally retarded was not "cruel and unusual punishment" under the Eighth Amendment. However, because Texas law did not allow the jury to give adequate consideration as a mitigating factor to Johnny Paul Penry's intellectual disability at the sentencing phase of his murder trial, the Court remanded the case for further proceedings. Eventually, Penry was retried for capital murder, again sentenced to death, and again the Supreme Court ruled, in Penry v. Johnson, 532 U.S.782 (2001), that the jury was not able to adequately consider Penry's intellectual disability as a mitigating factor at the sentencing phase of the trial. Ultimately, Penry was spared the death penalty because of the Supreme Court's ruling in Atkins v. Virginia, 536 U.S.304 (2002), which, while not directly overruling the holding in "Penry I", did give considerable negative treatment to Penry on the basis that the Eighth Amendment allowed execution of the mentally retarded.