“ The singling out of particular defendants for the death penalty when their crimes are no more aggravated than those committed by numerous other defendants given lesser sentences is unacceptable. As Justice Brennan pointed out in his dissent in Pulley, comparative proportionality review, at the very least, "serves to eliminate some of the irrationality that currently surrounds imposition of a death sentence" and "can be administered without much difficulty by a court of statewide jurisdiction." ”

“ As we have often recognized, " [b] ecause of the uniqueness of the death penalty, . . . it [cannot] be imposed under sentencing procedures that creat [e] a substantial risk that it would be inflicted in an arbitrary and capricious manner." ”

“ Petitioner was convicted in California state court of first-degree murder and sentenced to death. On appeal, he argued that application of the death penalty in this case was arbitrary because it was excessive when compared with penalties imposed in similar cases. The California Supreme Court noted that petitioner "present [ed] an elaborate survey of published [California] Court of Appeal decisions to demonstrate the hypothesis that many first degree murderers of equal or greater culpability have received sentences less than death." ”