According to Justice Souter's dissent in Kansas v. Marsh(126 S.Ct. 2516 ), the moral decision to impose the death penalty involves satisfying two criteria. First, the evidence should establish both the "details of the crime" and the "uniqueness of the individual defendant." Second, the evidence should establish that only the "worst of the worst" are eligible for the death penalty (page 2,543). Justice Souter argued that the Kansas statute, which requires imposition of the death penalty when the mitigating circumstances do not outweigh the aggravating circumstances, violates especially the second of these criteria, and therefore, is in violation of the reasoned moral judgment that the Eighth Amendment requires. Nonetheless, the U.S. Supreme Court upheld the Kansas death penalty scheme, overturning the decision against the statute that the Kansas Supreme Court reached (State v. Marsh, 102 P.3d 445 ).
A presumption of death?
The statute in question makes the death penalty mandatory in those cases in which a jury finds aggravating circumstances beyond a reasonable doubt and the state met its burden to demonstrate that mitigating factors do not outweigh aggravating circumstances.
The defendant, convicted of the first-degree murder of a woman andher young baby, argued that the statute created a presumption of death, requiring the death penalty in cases where the aggravating and mitigating circumstances were in "equipoise" (Kansas v. Marsh, 126 S.Ct. 2520). The majority found in favor of the state based upon State v. Walton (110 S.Ct. 3047 ), where the Supreme Court allowed Arizona to place the burden of proof on a defendant to prove that mitigating circumstances exist that call for leniency. Justice Thomas argued that the Kansas statute favored capital defendants compared with the Arizona law because it places the burden of proof on the state to show beyond a reasonable doubt that aggravators are not outweighed by mitigators. As long as the state's sentencing scheme narrows the range of eligibility for the death sentence and does not prevent the jury from considering any relevant mitigating circumstances, it has wide discretion in determining how jurors should balance aggravation and mitigation (Kansas v. Marsh, page 2,526).
Social science evidence
In his dissent, Justice Souter cited a number of social scientific studies, which showed the fallibility of the state's capital sentencing system. Several of the studies pointed to cases in which states released capital defendants because of lack of evidence, legal error or factual disagreements (i.e., mismatching DNA evidence). Souter pointed to the suspect accuracy of capital murder litigation when he concluded that mandating death in cases of a "tie" between aggravators and mitigators was a violation of rational, moral judgment.
However, Justice Scalia pointed to problems with the quality of the research in these studies and questioned whether evidence of defendants released before execution constitute errors of the system, or evidence demonstrating its ability to correct errors before they produce wrongful executions. In fact, Justice Scalia pointed out that abolitionists cannot point to a single case "in which it is clear that a person was executed for a crime he did not commit" (page 2,533). The argument concerning the quality of the scholarship on both sides of this debate should be of special interest to psychologists because a substantial portion of the scholarship comes from social science and psychological outlets.
The law of the land now permits states to make the death penalty mandatory in cases of equipoise, in which juries cannot decide whether mitigation outweighs aggravation beyond a reasonable doubt or whether aggravation outweighs mitigation. A program of empirical research that tests the consistency of jurors' deadlock findings will be of interest to state legislators and policy-makers charged with designing capital litigation schemes. For example, if decisions of equipoise are easily turned in one direction or the other, that would suggest that these are unstable outcomes and that a less equivocal standard might be preferable. If on the other hand, there are a class of case outcomes that consistently produce tied aggravating and mitigating factors, then the status of the equipoise is less suspect. Finally, psychological researchers interested in topics of procedural justice could ask some penetrating questions regarding the judgments of fairness that citizens make about a distribution of equipoise outcomes. While the product of this type of work may face serious obstacles in influencing the federal courts after Kansas v. Marsh, the findings could have significant impact in state legislatures.
"Judicial Notebook" is a project of APA's Div. 9 (Society for the Psychological Study of Social Issues).