This was not a case about the constitutionality of the death penalty in general as a cruel and unusual form of punishment. Instead, the Court examined a unique provision in Kansas' death penalty statute which compels a jury to sentence a defendant to death if the mitigating circumstances do not outweigh the aggravating circumtances. Thus, if a jury determined that the mitigating and aggravating circumstances were equal, it would nonetheless be commanded to impose the death penalty. The Kansas Supreme Court concluded that the statute's weighing equation violated the Eighth and Fourteenth Amendments of the United States Constitution because, "[i]n the event of equipoise, i.e., the jury's determination that the balance of any aggravating circumstances and any mitigating circumstances weighed equal, the death penalty would be required."
The defendant argued that "an equipoise determination reflects juror confusion or inability to decide between life and death or that the jury may use equipoise as a loophole to shirk its constitutional duty to render a reasoned, moral sentencing decision rest on an implausible characterization of the Kansas statute--that a jury's determination that aggravators and mitigators are in equipoise is not a decision, much less a decision for death. Justice Thomas disagreed writing, "Weighing is not an end, but a means to reaching a decision. Kansas' instructions clearly inform the jury that a determination that the evidence is in equipoise is a decision for death."
Justice David Souter's dissenting opinion, joined by Justices Breyer, Ginsburg and Stevens, dismisses the idea of a tie-breaker in favor of the death penalty as an absurdity. His opposition to the majority's position is best summarized in this paragraph:
In Kansas, when a jury applies the State's own standards of relative culpability and cannot decide that a defendant is among the most culpable, the state law says that equivocal evidence is good enough and the defendant must die. A law that requires execution when the case for aggravation has failed to convince the sentencing jury is morally absurd, and the Court's holding that the Constitution tolerates this moral irrationality defies decades of precedent aimed at eliminating freakish capital sentencing in the United States.
Souter pointed to the experience with the death penalty in Illinois, noting that the state had actually released more death row prisoners because they were later determined to be innocent than the actual number of death row prisoners executed. He writes:
When the Governor of Illinois imposed a moratorium on executions in 2000, 13 prisoners under death sentences had been released since 1977 after a number of them were shown to be innocent, as described in a report which used their examples to illustrate a theme common to all 13, of "relatively little solid evidence connecting the charged defendants to the crimes." (citations omitted) During the same period, 12 condemned convicts had been executed. Subsequently the Governor determined that 4 more death row inmates were innocent. (citations omitted) Illinois had thus wrongly convicted and condemned even more capital defendants than it had executed, but it may well not have been otherwise unique; one recent study reports that between 1989 and 2003, 74 American prisoners condemned to death were exonerated. (citations omitted)
Commentators are already speculating that the Court would have swung the other way narrowly had Justice Sandra Day O'Connor still been on the Court instead of Justice Alito. The Court actually re-heard arguments in this case so that Justice Alito could participate in the decision. You don't have to be an opponent of the death penalty to find fault with the majority's decision today. It seems that a jury should be convinced that the aggravating circumstances exceed the mitigating circumstances, not merely equal them, before a death sentence is compelled. If a majority of the Supreme Court justices have not detected there are iniquities in the criminal jutice system because of the uneven hand in which the death penalty is being applied across the country in capital murder cases, then they are completely out of touch with reality. By their ruling today, they have given a green light to more injustice and, in the words of Justice Souter, more "freakish capital sentencing."