Sandra Day O'Connor

“ The impairment of a mentally retarded offender's reasoning abilities, control over impulsive behavior, and moral development in my view limits his or her culpability so that, whatever other punishment might be appropriate, the ultimate penalty of death is always and necessarily disproportionate to his or her blameworthiness and hence is unconstitutional. ”

“ There is a second ground upon which I would conclude that the execution of mentally retarded offenders violates the Eighth Amendment: killing mentally retarded offenders does not measurably further the penal goals of either retribution or deterrence. "The heart of the retribution rationale is that a criminal sentence must be directly related to the personal culpability of the criminal offender." ”

“ The common law prohibition against punishing "idiots" for their crimes suggests that it may indeed be "cruel and unusual" punishment to execute persons who are profoundly or severely retarded and wholly lacking the capacity to appreciate the wrongfulness of their actions. Because of the protections afforded by the insanity defense today, such a person is not likely to be convicted or face the prospect of punishment. ”

“ Underlying Lockett and Eddings is the principle that punishment should be directly related to the personal culpability of the criminal defendant. If the sentencer is to make an individualized assessment of the appropriateness of the death penalty, "evidence about the defendant's background and character is relevant because of the belief, long held by this society, that defendants who commit criminal acts that are attributable to a disadvantaged background, or to emotional and mental problems, may be less culpable than defendants who have no such excuse." ”

“ While a national consensus against execution of the mentally retarded may someday emerge reflecting the "evolving standards of decency that mark the progress of a maturing society," there is insufficient evidence of such a consensus today. ”

“ Lack of culpability as a result of mental retardation is simply not isolated at the sentencing stage as a factor that determinatively bars a death sentence; for individualized consideration at sentencing is not designed to ensure that mentally retarded offenders are not sentenced to death if they are not culpable to the degree necessary to render execution a proportionate response to their crimes. ”

“ The term mental retardation, as commonly used today, embraces a heterogeneous population, ranging from totally dependent to nearly independent people. Although all individuals so designated share the common attributes of low intelligence and inadequacies in adaptive behavior, there are marked variations in the degree of deficit manifested and the presence or absence of associated physical handicaps, stigmata, and psychologically disordered states. ”

“ In light of the inherent problems with the mental age concept, and in the absence of better evidence of a national consensus against execution of the retarded, mental age should not be adopted as a line-drawing principle in our Eighth Amendment jurisprudence. ”

“ When Johnny Penry is resentenced, absent a change in Texas law there will be nothing to prevent the jury, acting lawfully, from sentencing him to death once again-even though it finds his culpability significantly reduced by reason of mental retardation. ”

“ Since mentally retarded offenders as a class lack the culpability that is a prerequisite to the proportionate imposition of the death penalty, it follows that execution can never be the "just desserts" of a retarded offender, id., at 801, 102 S.Ct., at 3379, and that the punishment does not serve the retributive goal, see Stanford, 492 U.S., at 404, 109 S.Ct., at 2993 (BRENNAN, J., dissenting) ("A punishment that fails the Eighth Amendment test of proportionality because disproportionate to the offender's blameworthiness by definition is not justly deserved") . ”

“ In our view, the finality concerns underlying Justice Harlan's approach to retroactivity are applicable in the capital sentencing context, as are the two exceptions to his general rule of nonretroactivity. See Teague, supra, 489 U.S., at 311-313, 109 S.Ct., at 1075-1077.
As we indicated in Teague, " [i] n general . . . a case announces a new rule when it breaks new ground or imposes a new obligation on the States or the Federal Government." ”

“ The consideration of mental retardation as a mitigating factor is inadequate to guarantee, as the Constitution requires, that an ndividual who is not fully blameworthy for his or her crime because of a mental disability does not receive the death penalty. ”

“ As the types of murders for which the death penalty may be imposed become more narrowly defined and are limited to those which are particularly serious or for which the death penalty is particularly appropriate as they are in Georgia by reason of the aggravating-circumstance requirement, it becomes reasonable to expect that juries-even given discretion not to impose the death penalty-will impose the death penalty in a substantial portion of the cases so defined. ”

“ This Court subsequently held that the Eighth Amendment, as a substantive matter, prohibits imposing the death penalty on a certain class of defendants because of their status, Ford v. Wainwright, supra, 477 U.S., at 410, 106 S.Ct., at 2602 (insanity) , or because of the nature of their offense, Coker v. Georgia, 433 U.S. 584, 97 S.Ct. 2861, 53 L.Ed.2d 982 (1977) (rape) (plurality opinion) . In our view, a new rule placing a certain class of individuals beyond the State's power to punish by death is analogous to a new rule placing certain conduct beyond the State's power to punish at all. ”

“ In discerning those "evolving standards," we have looked to objective evidence of how our society views a particular punishment today. See Coker v. Georgia, supra, at 593-597, 97 S.Ct., at 2866-2869; Enmund v. Florida, 458 U.S. 782, 788-796, 102 S.Ct. 3368, 3371-3376, 73 L.Ed.2d 1140 (1982) . The clearest and most reliable objective evidence of contemporary values is the legislation enacted by the country's legislatures. We have also looked to data concerning the actions of sentencing juries. Enmund, supra, at 794-796, 102 S.Ct., at 3375-3376; Thompson v. Oklahoma, 487 U.S. 815, 831, 108 S.Ct. ”

“ The "mental age" concept may underestimate the life experiences of retarded adults, while it may overestimate the ability of retarded adults to use logic and foresight to solve problems. Ibid. The mental age concept has other limitations as well. ”

“ Rather than creating the risk of an unguided emotional response, full consideration of evidence that mitigates against the death penalty is essential if the jury is to give a " 'reasoned moral response to the defendant's background, character, and crime.' " Franklin, 487 U.S., at 184, 108 S.Ct., at 2333 (O'CONNOR, J., concurring in judgment) (quoting California v. Brown, 479 U.S., at 545, 107 S.Ct., at 841 (O'CONNOR, J., concurring) ) . ”

“ And the very factors that make it disproportionate and unjust to execute the mentally retarded also make the death penalty of the most minimal deterrent effect so far as retarded potential offenders are concerned. ”

“ But at present, there is insufficient evidence of a national consensus against executing mentally retarded people convicted of capital offenses for us to conclude that it is categorically prohibited by the Eighth Amendment. ”

“ See, e.g., American Law Institute, Model Penal Code ¬ß 4.01, p. 61 (1985) ("A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law") ”