In capital punishment cases, the jury must make an individualized determination of the appropriate sentence, considering factors that mitigate or aggravate the defendant's culpability. 118 When the Supreme Court ruled in Penry that the execution of the mentally retarded was not forbidden by the U.S. Constitution, it left to juries the responsibility to determine whether defendants with mental retardation who had been convicted of committing capital crimes should receive death sentences in light of the mitigating or aggravating factors present in each case. In so doing, the court accepted the risk that some people with mental retardation and, hence, with insufficient culpability, might be executed.119 As the late Supreme Court Justice William Brennan noted in his Penry dissent:
Indeed, offenders with mental retardation are often sentenced to death even when their defense counsel presents evidence of their disability to the jury. Our research suggests there are many reasons why the sentencing process leads to the imposition of death sentences on defendants with mental retardation. First, as noted above, few participants in criminal justice process -- including prosecutors, judges, defense attorneys, and juries -- understand the nature and significance of mental retardation.
Second, prosecutors are all too often more concerned with the professional or political ramifications of obtaining a "victory" -- a death sentence -- than with giving serious consideration to the ways mental retardation has affected the defendant's comprehension and conduct. Faced with pressure from the community and the victim's family, prosecutors do not want to appear to countenance an "excuse" or to let an offender "off too easy." During trials they vigorously challenge the existence of mental retardation as well as minimize its significance.121 They suggest that while a defendant may "technically" be considered retarded, he nonetheless has "street smarts," is "smart" enough to do the crime, and hence should receive the highest penalty. Prosecutors have also argued that the fact that a defendant may not be very smart makes him more dangerous and that this is an additional reason to impose the death penalty.
Third, judges are also at fault. They too are often ignorant about mental retardation, do not allow defense attorneys to present evidence of mental retardation adequately during a trial's penalty phase, or give juries confusing or incorrect instructions about mental retardation as a mitigating factor.
Fourth, when prosecutors insist on seeking the death penalty for mentally retarded offenders, jurors all too often comply. As James Ellis, a law professor and expert on mental retardation and the criminal justice system, has noted, "There's some kind of disconnect between people's moral understanding and the way the system of imposing the death penalty actually works."122 Faced with terrible crimes, jurors can fail to appreciate the difference between guilt and culpability and do not want to "condone" a murder. They see a defendant who looks normal, is not manifestly "crazy," and they do not grasp the profound yet subtle ways a person with retardation is limited in his capacity to understand the world around him and to act appropriately. They see a defendant who is not acting "remorseful" in the courtroom and they think it is because he is callous and heartless rather than understanding that a person with mental retardation may not fully comprehend what is happening. Finally, jurors can see mental retardation as an aggravating factor, i.e. they believe it portends the defendant's future dangerousness, and they are worried that if given a prison sentence he will one day be released to society and commit another violent crime. For many jurors, the aggravating factor of "future dangerousness" outweighs the mitigating factor of reduced culpability.
When the U.S. Supreme Court refused -- in the Penry decision -- to create a categorical exemption from the death penalty for persons with mental retardation, it left open the possibility that in individual cases a death sentence imposed on such a defendant might nevertheless violate the Eighth Amendment's ban on cruel and usual punishment. We are not, however, aware of cases subsequent to Penry in which a court has so ruled. Although courts have ordered retrials on Eighth Amendment grounds, they have done so when juries were not instructed to consider the potentially mitigating effects of a defendant's mental retardation. They have not otherwise overturned juries' decisions to impose death sentences on such defendants on Eighth Amendment grounds.
118 In some cases the sentencer is a judge.
119 Carol Steiker and Jordan Steiker, "Defending Categorical Exemptions to the Death Penalty: Reflections on the ABA's Resolutions concerning the Execution of Juveniles and Persons with Mental Retardation," 61 Law & Contemporary Problems 89 (1998).
120 Penry v. Lynaugh, 492 U.S. at 346 (Brennan, J. dissenting).
121 For an overview of strategies prosecutors may use when prosecuting a defendant with mental retardation, see William J. Edwards, "How to Demystify the Prosecution's Efforts of Minimizing the Severity of Your Client's Mental Retardation," presented at the State Bar of South Dakota Criminal Law Continuing Legal Education course on October 9, 1998 (on file at Human Rights Watch).
122 Mike Tolson, "Death sentence heightens debate over executing retarded," Houston Chronicle, February 12, 1995.