On April 28, the Supreme Court decided Cone v. Bell, No. 07-1114.
Gary Cone was convicted in 1982 of a double murder committed during an extended crime spree, and he was sentenced to death. His sole argument in defense and in mitigation of the death penalty was that he had committed the crimes while suffering from chronic amphetamine psychosis brought about by drug abuse.
Over the next ten years, Cone pursued a direct appeal and two petitions for post-conviction relief in the Tennessee court system. While his second petition was pending, he learned, as a result of a change in state law that made the prosecutors' files available to him for the first time, that evidence supporting his drug-related defense had been wrongfully withheld. But the state courts rejected his argument based on this fact, holding that the argument either had been raised and decided before or had not been raised and therefore had been waived.
Cone then filed a habeas corpus petition in federal court, arguing, among other grounds, that the suppression of the exculpatory or mitigating evidence violated his due-process rights under Brady v. Maryland, 373 U.S. 83 (1963). Although the Court of Appeals for the Sixth Circuit twice ordered a new sentence hearing on other grounds, and its decision was twice reversed by the Supreme Court, see Bell v. Cone, 535 U.S. 685 (2002), and Cone v. Bell, 543 U.S. 447 (2005), the court did not reach the merits of the Brady claim, holding that it was barred from doing so because the state courts' denial of relief had been based on the "independent and adequate state-law ground" of waiver.
The Supreme Court vacated the judgment and remanded. It first held, after extended review of the unusually confused post-conviction procedural record, that Cone's claim under Brady had not been waived in the state courts, and therefore the federal courts were not barred from considering the claim. It also held that, although the evidence of Cone's guilt was so overwhelming that the improperly-suppressed drug-abuse evidence would not have made a difference to his conviction, the jury might have considered it sufficient to mitigate the death penalty that was imposed. The Court therefore directed the federal district court to decide whether there was a reasonable probability that, if the evidence had been disclosed to Cone before trial, his sentence would have been different.
Justice Stevens delivered the opinion of the Court, in which Justices Kennedy, Souter, Ginsburg and Breyer joined. Chief Justice Roberts filed an opinion concurring in the judgment. Justice Alito filed an opinion concurring in part and dissenting in part. Justice Thomas filed a dissenting opinion in which Justice Scalia joined.