The high court, reversing the Kansas Supreme Court, ruled 5-4 with Justice Clarence Thomas writing for the majority that the jury's weighing of factors during deliberations "is not an end but a means to reach an end."
The ruling upholds the death penalty in the case of Michael Lee Marsh, who was convicted of killing a woman and her daughter in 1996.
The law "does not create a general presumption in favor of the death penalty in the state of Kansas," Thomas said. "Rather, the Kansas capital sentencing system is dominated by the presumption that life is the appropriate sentence for a capital conviction."
Justice David Souter, in an opinion that pointed to recent exonerations in death penalty cases, called the Kansas law "obtuse by any moral or social measure."