Cone v. Bell
The Court ruled that Tennessee's state courts had wrongly blocked federal review of a death-row inmate's claim that prosecutors hid evidence supporting his drug-addiction defense, because the state courts' stated reasons for refusing to hear the claim didn't actually apply.
On the merits, the Court found the hidden evidence would not have changed the jury's guilty verdict, but sent the case back so a lower court could decide whether that evidence might have changed the jury's decision to impose a death sentence.
How it got here: State postconviction courts denied Cone's suppressed-evidence claim; a federal district court and the Sixth Circuit held the claim procedurally barred, prompting Cone's appeal to the Supreme Court.
The Case in Depth
What happened
Gary Cone, a Vietnam veteran, was convicted of murdering an elderly couple during a 1980 Memphis crime spree and sentenced to death. His defense was that drug-induced psychosis made him legally insane. Years later, Cone discovered that prosecutors had withheld witness statements and police reports describing him as an obvious drug user around the time of the murders — evidence he argued would have bolstered his insanity defense and his case for a lesser sentence.
The question before the Court
Did prosecutors violate a death-row inmate's right to a fair trial by hiding evidence that might have backed up his drug-addiction defense and his plea for a lighter sentence?
The Court's answer
Partly — the Court ruled that Tennessee's state courts had no valid legal basis for refusing to consider Cone's claim that prosecutors hid evidence supporting his drug-addiction defense, so federal courts were free to review it. On the actual merits, the Court held the hidden evidence was too weak to have changed the jury's guilty verdict, since Cone's calm, deliberate behavior throughout his crime spree was inconsistent with legal insanity.
However, the Court found that lower courts had not properly considered whether the same evidence might have persuaded the jury to choose life imprisonment over death, since Tennessee's standard for mitigating evidence is far less demanding than its standard for insanity. The case was sent back to the district court to fully weigh whether the hidden evidence could have changed Cone's sentence.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
The ruling reinforces that state courts cannot block federal review of a suppressed-evidence claim by mistakenly claiming it was already decided or waived when it wasn't. It also clarifies that evidence can be too weak to affect a guilt verdict yet still strong enough to affect a death sentence, meaning courts must separately analyze both questions in death-penalty cases involving hidden evidence.
What changes now
The case returns to the federal district court, which must now decide, for the first time, whether the withheld evidence created a reasonable probability that at least one juror would have voted for a life sentence instead of death had it been disclosed. This is a final merits ruling on the procedural-bar and guilt-phase questions, but the sentencing-phase Brady claim remains open for further proceedings below.
What this does not decide
The Court did not decide whether Cone is actually entitled to a new sentencing hearing — only that the lower courts must more fully examine whether the withheld evidence could have changed the jury's sentencing decision. It also left open, for the lower courts, disputed questions about exhaustion and procedural default that Justice Alito raised.
Concurrences and dissents
Concurrence — Justice Roberts
Chief Justice Roberts agreed with vacating and remanding but stressed that the ruling rests on unusual facts and should not be read broadly. He emphasized the Court applied only the existing Kyles materiality standard to the specific facts, and cautioned that on remand courts should use constitutional standards, not ABA ethics rules, to judge the Brady claim.
Concurrence in part — Justice Alito
Justice Alito agreed the Sixth Circuit's procedural-default ruling rested on a mistaken premise and required a remand, but disagreed with the majority's unexplained conclusions that Cone had properly exhausted his claim and that the case should go back to the district court rather than the court of appeals. He would have left both issues for the Sixth Circuit to resolve on remand.
Dissent — Justice Thomas
Justice Thomas, joined by Justice Scalia, argued the Court of Appeals had already adequately addressed the sentencing-phase Brady claim and that Cone could not show a reasonable probability the withheld evidence would have changed his sentence given the overwhelming evidence of calculated, non-impaired behavior. He would have affirmed the Sixth Circuit's denial of relief entirely rather than remanding.
How the Court got there
The legal reasoning, step by step
- The Court applied the rule that federal habeas review of a state prisoner's claim is barred only when the state court's refusal to hear it rested on an independent and adequate state-law ground — meaning a state procedural rule genuinely applied and wasn't just tangled up with the federal claim.
- The state courts had said Cone's suppressed-evidence claim was barred because it had already been decided before. The Court found this premise false: the claim had never actually been ruled on in earlier proceedings, so there was nothing for the state courts to have already decided.
- Because a state court's mistaken belief that a claim was already decided does not create a procedural bar, and because the Tennessee appellate court never actually found the claim waived either, the Court concluded no valid state-law barrier blocked federal review.
- Turning to the merits, the Court applied the standard from Brady v. Maryland and Kyles v. Whitley: suppressed evidence is significant enough to require a new outcome only if there is a reasonable probability that disclosing it would have changed the result.
- Applying that standard to the guilt phase, the Court found Cone's own conduct before, during, and after the murders was too calculated and controlled to be explained by legal insanity, so the withheld evidence was not significant enough to undermine the guilty verdict.
- The Court then recognized that evidence can fail to change a guilt verdict while still being significant enough to affect a jury's sentencing decision, since Tennessee's standard for mitigating evidence was far less demanding than its standard for insanity, requiring separate analysis of the evidence's effect on the death sentence.
Doctrinal impact
Cases affected by this decision
Reaffirms Brady v. Maryland (373 U. S. 83)
The Court applied Brady's rule that suppressing favorable evidence violates due process when it is material to guilt or punishment.
Reaffirms Kyles v. Whitley (514 U. S. 419)
The Court used Kyles's test for whether withheld evidence undermines confidence in a verdict or sentence.
Reaffirms Coleman v. Thompson (501 U. S. 722)
The Court relied on Coleman's independent-and-adequate-state-ground doctrine to decide whether federal review was barred.
Reaffirms Ylst v. Nunnemaker (501 U. S. 797)
The Court used Ylst to explain that a state court's refusal to re-hear an already-decided claim creates no new procedural bar.