(Slip Opinion)              OCTOBER TERM, 2008                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                       CONE v. BELL, WARDEN

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                  THE SIXTH CIRCUIT

   No. 07–1114. Argued December 9, 2008—Decided April 28, 2009
After the State discredited petitioner Cone’s defense that he killed two
  people while suffering from acute psychosis caused by drug addiction,
  he was convicted and sentenced to death. The Tennessee Supreme
  Court affirmed on direct appeal and the state courts denied postcon
  viction relief. Later, in a second petition for state postconviction re
  lief, Cone raised the claim that the State had violated Brady v. Mary
  land, 373 U. S. 83, by suppressing witness statements and police
  reports that would have corroborated his insanity defense and bol
  stered his case in mitigation of the death penalty. The postconviction
  court denied him a hearing on the ground that the Brady claim had
  been previously determined, either on direct appeal or in earlier col
  lateral proceedings. The State Court of Criminal Appeals affirmed.
  Cone then filed a petition for a writ of habeas corpus in Federal Dis
  trict Court. That Court denied relief, holding the Brady claim proce
  durally barred because the state courts’ disposition rested on ade
  quate and independent state grounds: Cone had waived it by failing
  to present his claim in state court. Even if he had not defaulted the
  claim, ruled the court, it would fail on its merits because none of the
  withheld evidence would have cast doubt on his guilt. The Sixth Cir
  cuit agreed with the latter conclusion, but considered itself barred
  from reaching the claim’s merits because the state courts had ruled
  the claim previously determined or waived under state law.
Held:
    1. The state courts’ rejection of Cone’s Brady claim does not rest on
 a ground that bars federal review. Neither of the State’s asserted
 justifications for such a bar—that the claim was decided by the State
 Supreme Court on direct review or that Cone had waived it by never
 properly raising it in state court—provides an independent and ade
2                             CONE v. BELL

                                  Syllabus

    quate state ground for denying review of Cone’s federal claim. The
    state postconviction court’s denial of the Brady claim on the ground it
    had been previously determined in state court rested on a false prem
    ise: Cone had not presented the claim in earlier proceedings and, con
    sequently, the state courts had not passed on it. The Sixth Circuit’s
    rejection of the claim as procedurally defaulted because it had been
    twice presented to the Tennessee courts was thus erroneous. Also
    unpersuasive is the State’s alternative argument that federal review
    is barred because the Brady claim was properly dismissed by the
    state postconviction courts as waived. Those courts held only that
    the claim had been previously determined, and this Court will not
    second-guess their judgment. Because the claim was properly pre
    served and exhausted in state court, it is not defaulted. Pp. 15–19.
       2. The lower federal courts failed to adequately consider whether
    the withheld documents were material to Cone’s sentence. Both the
    quantity and quality of the suppressed evidence lend support to
    Cone’s trial position that he habitually used excessive amounts of
    drugs, that his addiction affected his behavior during the murders,
    and that the State’s contrary arguments were false and misleading.
    Nevertheless, even when viewed in the light most favorable to Cone,
    the evidence does not sustain his insanity defense: His behavior be
    fore, during, and after the crimes was inconsistent with the conten
    tion that he lacked substantial capacity either to appreciate the
    wrongfulness of his conduct or to conform it to the requirements of
    law. Because the likelihood that the suppressed evidence would have
    affected the jury’s verdict on the insanity issue is remote, the Sixth
    Circuit did not err by denying habeas relief on the ground that such
    evidence was immaterial to the jury’s guilt finding. The same cannot
    be said of that court’s summary treatment of Cone’s claim that the
    suppressed evidence would have influenced the jury’s sentencing rec
    ommendation. Because the suppressed evidence might have been
    material to the jury’s assessment of the proper punishment, a full re
    view of that evidence and its effect on the sentencing verdict is war
    ranted. Pp. 20–26.
492 F. 3d 743, vacated and remanded.

  STEVENS, J., delivered the opinion of the Court, in which KENNEDY,
SOUTER, GINSBURG, and BREYER, JJ., joined. ROBERTS, C. J., filed an
opinion concurring in the judgment. ALITO, J., filed an opinion concur
ring in part and dissenting in part. THOMAS, J., filed a dissenting opin
ion, in which SCALIA, J., joined.
                        Cite as: 556 U. S. ____ (2009)                              1

                             Opinion of the Court

     NOTICE: This opinion is subject to formal revision before publication in the
     preliminary print of the United States Reports. Readers are requested to
     notify the Reporter of Decisions, Supreme Court of the United States, Wash
     ington, D. C. 20543, of any typographical or other formal errors, in order
     that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                   _________________

                                   No. 07–1114
                                   _________________


   GARY BRADFORD CONE, PETITIONER v. RICKY 

               BELL, WARDEN

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE SIXTH CIRCUIT

                                 [April 28, 2009] 


  JUSTICE STEVENS delivered the opinion of the Court.
  The right to a fair trial, guaranteed to state criminal
defendants by the Due Process Clause of the Fourteenth
Amendment, imposes on States certain duties consistent
with their sovereign obligation to ensure “that ‘justice
shall be done’ ” in all criminal prosecutions. United States
v. Agurs, 427 U. S. 97, 111 (1976) (quoting Berger v.
United States, 295 U. S. 78, 88 (1935)). In Brady v. Mary
land, 373 U. S. 83 (1963), we held that when a State sup
presses evidence favorable to an accused that is material
to guilt or to punishment, the State violates the defen
dant’s right to due process, “irrespective of the good faith
or bad faith of the prosecution.” Id., at 87.
  In this case, Gary Cone, a Vietnam veteran sentenced to
death, contends that the State of Tennessee violated his
right to due process by suppressing witness statements
and police reports that would have corroborated his trial
defense and bolstered his case in mitigation of the death
penalty. At his trial in 1982, Cone asserted an insanity
defense, contending that he had killed two people while
suffering from acute amphetamine psychosis, a disorder
2                      CONE v. BELL

                     Opinion of the Court

caused by drug addiction. The State of Tennessee discred
ited that defense, alleging that Cone’s drug addiction was
“baloney.” Ten years later, Cone learned that the State
had suppressed evidence supporting his claim of drug
addiction.
   Cone presented his new evidence to the state courts in a
petition for postconviction relief, but the Tennessee courts
denied him a hearing on the ground that his Brady claim
had been “previously determined,” either on direct appeal
from his conviction or in earlier collateral proceedings. On
application for a writ of habeas corpus pursuant to 28
U. S. C. §2254, the Federal District Court concluded that
the state courts’ disposition rested on an adequate and
independent state ground that barred further review in
federal court, and the Court of Appeals for the Sixth Cir
cuit agreed. Doubt concerning the correctness of that
holding, coupled with conflicting decisions from other
Courts of Appeals, prompted our grant of certiorari.
   After a complete review of the trial and postconviction
proceedings, we conclude that the Tennessee courts’ rejec
tion of petitioner’s Brady claim does not rest on a ground
that bars federal review. Furthermore, although the
District Court and the Court of Appeals passed briefly on
the merits of Cone’s claim, neither court distinguished the
materiality of the suppressed evidence with respect to
Cone’s guilt from the materiality of the evidence with
respect to his punishment. While we agree that the with
held documents were not material to the question whether
Cone committed murder with the requisite mental state,
the lower courts failed to adequately consider whether
that same evidence was material to Cone’s sentence.
Therefore, we vacate the decision of the Court of Appeals
and remand the case to the District Court to determine in
the first instance whether there is a reasonable probability
that the withheld evidence would have altered at least one
juror’s assessment of the appropriate penalty for Cone’s
                    Cite as: 556 U. S. ____ (2009)                   3

                         Opinion of the Court

crimes.
                             I
  On the afternoon of Saturday, August 10, 1980, Cone
robbed a jewelry store in downtown Memphis, Tennessee.
Fleeing the scene by car, he led police on a high-speed
chase into a residential neighborhood. Once there, he
abandoned his vehicle and shot a police officer.1 When a
bystander tried to impede his escape, Cone shot him, too,
before escaping on foot.
  A short time later, Cone tried to hijack a nearby car.
When that attempt failed (because the driver refused to
surrender his keys), Cone tried to shoot the driver and a
hovering police helicopter before realizing he had run out
of ammunition. He then fled the scene. Although police
conducted a thorough search, Cone was nowhere to be
found.
  Early the next morning, Cone reappeared in the same
neighborhood at the door of an elderly woman. He asked
to use her telephone, and when she refused, he drew a
gun. Before he was able to gain entry, the woman
slammed the door and called the police. By the time offi
cers arrived, however, Cone had once again disappeared.
  That afternoon, Cone gained entry to the home of 93
year-old Shipley Todd and his wife, 79-year-old Cleopatra
Todd. Cone beat the couple to death with a blunt instru
ment and ransacked the first floor of their home. Later,
he shaved his beard and escaped to the airport without
being caught. Cone then traveled to Florida, where he
was arrested several days later after robbing a drugstore
in Pompano Beach.
  A Tennessee grand jury charged Cone with two counts
——————
  1 From  the abandoned vehicle, police recovered stolen jewelry, large
quantities of illegal and prescription drugs, and approximately $2,400
in cash. Much of the cash was later connected to a grocery store rob
bery that had occurred on the previous day.
4                      CONE v. BELL

                     Opinion of the Court

of first-degree murder, two counts of murder in the perpe
tration of a burglary, three counts of assault with intent to
murder, and one count of robbery by use of deadly force.
At his jury trial in 1982, Cone did not challenge the over
whelming physical and testimonial evidence supporting
the charges against him. His sole defense was that he was
not guilty by reason of insanity.
  Cone’s counsel portrayed his client as suffering from
severe drug addiction attributable to trauma Cone had
experienced in Vietnam. Counsel argued that Cone had
committed his crimes while suffering from chronic am
phetamine psychosis, a disorder brought about by his drug
abuse. That defense was supported by the testimony of
three witnesses. First was Cone’s mother, who described
her son as an honorably discharged Vietnam veteran who
had changed following his return from service. She re
called Cone describing “how terrible” it had been to handle
the bodies of dead soldiers, and she explained that Cone
slept restlessly and sometimes “holler[ed]” in his sleep.
Tr. 1643–1645 (Apr. 20, 1982). She also described one
occasion, following Cone’s return from service, when a
package was shipped to him that contained marijuana.
Before the war, she asserted, Cone had not used drugs of
any kind.
  Two expert witnesses testified on Cone’s behalf. Mat
thew Jaremko, a clinical psychologist, testified that Cone
suffered from substance abuse and posttraumatic stress
disorders related to his military service in Vietnam. Ja
remko testified that Cone had expressed remorse for the
murders, and he opined that Cone’s mental disorder ren
dered him substantially incapable of conforming his con
duct to the law. Jonathan Lipman, a neuropharmacolo
gist, recounted at length Cone’s history of illicit drug use,
which began after Cone joined the Army and escalated to
the point where Cone was consuming “rather horrific”
quantities of drugs daily. App. 100. According to Lipman,
                    Cite as: 556 U. S. ____ (2009)                  5

                        Opinion of the Court

Cone’s drug abuse had led to chronic amphetamine psy
chosis, a disorder manifested through hallucinations and
ongoing paranoia that prevented Cone from obeying the
law and appreciating the wrongfulness of his actions.
   In rebutting Cone’s insanity defense the State’s strategy
throughout trial was to present Cone as a calculating,
intelligent criminal who was fully in control of his deci
sions and actions at the time of the crimes. A key compo
nent of that strategy involved discrediting Cone’s claims of
drug use.2 Through cross-examination, the State estab
lished that both defense experts’ opinions were based
solely on Cone’s representations to them about his drug
use rather than on any independently corroborated
sources, such as medical records or interviews with family
or friends. The prosecution also adduced expert and lay
testimony to establish that Cone was not addicted to drugs
and had acted rationally and intentionally before, during,
and after the Todd murders.
   Particularly damaging to Cone’s defense was the testi
mony of rebuttal witness Ilene Blankman, who had spent
time with Cone several months before the murders and at
whose home Cone had stayed in the days leading up to his
arrest in Florida. Blankman admitted to being a former
heroin addict but testified that she no longer used drugs
and tried to stay away from people who did. She testified
that she had never seen Cone use drugs, had never ob
served track marks on his body, and had never seen him
exhibit signs of paranoia.
   Emphasizing the State’s position with respect to Cone’s
——————
  2 The State also cast doubt on Cone’s defense by eliciting testimony

that Cone had enrolled in college following his return from Vietnam
and had graduated with high honors. Later, after serving time in
prison for an armed robbery, Cone gained admission to the University
of Arkansas Law School. The State suggested that Cone’s academic
success provided further proof that he was not impaired following his
return from war.
6                           CONE v. BELL

                         Opinion of the Court

alleged addiction, the prosecutor told the jury during
closing argument, “[Y]ou’re not dealing with a crazy per
son, an insane man. A man . . . out of his mind. You’re
dealing, I submit to you, with a premeditated, cool, delib
erate—and even cowardly, really—murderer.” Tr. 2084
(Apr. 22, 1982). Pointing to the quantity of drugs found in
Cone’s car, the prosecutor suggested that far from being a
drug addict, Cone was actually a drug dealer. The prose
cutor argued, “I’m not trying to be absurd, but he says he’s
a drug addict. I say baloney. He’s a drug seller. Doesn’t
the proof show that?” Id., at 107.3
   The jury rejected Cone’s insanity defense and found him
guilty on all counts. At the penalty hearing, the prosecu
tion asked the jury to find that Cone’s crime met the crite
ria for four different statutory aggravating factors, any
one of which would render him eligible for a capital sen
tence.4 Cone’s counsel called no witnesses but instead
rested on the evidence adduced during the guilt phase
proceedings. Acknowledging that the prosecution’s ex
perts had disputed the existence of Cone’s alleged mental
disorder, counsel nevertheless urged the jury to consider
Cone’s drug addiction when weighing the aggravating and
——————
  3 In his closing rebuttal argument, the prosecutor continued to press

the point, asserting: “There aren’t any charges for drug sales, but that
doesn’t mean that you can’t look and question in deciding whether or
not this man was, in fact, a drug user, or why he had those drugs. Did
he just have those drugs, or did he have those drugs and thousands of
dollars in that car? Among those drugs are there only the drugs he
used? How do we know if he used drugs? The only thing that we ever
had that he used drugs, period, is the fact that those drugs were in the
car and what he told people. What he told people. But according to
even what he told people, there are drugs in there he didn’t even use.”
Tr. 2068 (Apr. 22, 1982).
  4 The jury could impose a capital sentence only if it unanimously

determined that one or more statutory aggravating circumstances had
been proved by the State beyond a reasonable doubt, and that the
mitigating circumstances of the case did not outweigh any statutory
aggravating factors. Tenn. Code Ann. §39–2–203(g) (1982).
                     Cite as: 556 U. S. ____ (2009)                    7

                          Opinion of the Court

mitigating factors in the case.5 The jury found all four
aggravating factors and unanimously returned a sentence
of death.6
                            II
  On direct appeal Cone raised numerous challenges to
his conviction and sentence. Among those was a claim
that the prosecution violated state law by failing to dis
close a tape-recorded statement and police reports relating
to several trial witnesses. See App. 114–117. The Ten
nessee Supreme Court rejected each of Cone’s claims, and
affirmed his conviction and sentence. State v. Cone, 665
S. W. 2d 87 (1984).7 Cone then filed a petition for postcon
——————
   5 As defense counsel emphasized to the jury, one of the statutory miti

gating factors it was required to consider was whether “[t]he capacity of
the defendant to appreciate the wrongfulness of his conduct or to
conform his conduct to the requirements of the law was substantially
impaired as a result of mental disease or defect or intoxication which
was insufficient to establish a defense to the crime but which substan
tially affected his judgment.” §39–2404(j)(8).
   6 Specifically, the jury found Cone had committed one or more prior

felonies involving the use or threat of violence, see §39–2404(i)(2); the
murders had been committed for the purpose of avoiding, interfering
with, or preventing Cone’s lawful arrest or prosecution, see §39–
2404(i)(6); the murders were especially heinous, atrocious, or cruel in
that they involved torture and depravity of mind, see §39–2404(i)(5);
and Cone had knowingly created a risk of death to two or more persons,
other than the victim murdered, during his act of murder, see §39–
2404(i)(3). The Tennessee Supreme Court later observed that by
finding Cone guilty of murder in the first degree during the perpetra
tion of a burglary, the jury implicitly found the existence of an addi
tional statutory aggravating factor: that the murders occurred while
Cone was committing a burglary, §39–2404(i)(7). State v. Cone, 665
S. W. 2d 87, 94 (1984).
   7 In summarizing the trial proceedings the Tennessee Supreme Court

observed: “The only defense interposed on [Cone’s] behalf was that of
insanity, or lack of mental capacity, due to drug abuse and to stress
arising out of his previous service in the Vietnamese war, some eleven
years prior to the events involved in this case. This proved to be a
tenuous defense, at best, since neither of the expert witnesses who
8                            CONE v. BELL

                          Opinion of the Court

viction relief, primarily raising claims that his trial coun
sel had been ineffective; the Tennessee Court of Criminal
Appeals affirmed the denial of that petition in 1987. Cone
v. State, 747 S. W. 2d 353.
   In 1989, Cone, acting pro se, filed a second petition for
postconviction relief, raising myriad claims of error.
Among these was a claim that the State had failed to
disclose evidence in violation of his rights under the
United States Constitution. At the State’s behest, the
postconviction court summarily denied the petition, con
cluding that all the claims raised in it had either been
“previously determined” or “waived.” Order Dismissing
Petition for Post-Conviction Relief in Cone v. State, No. P–
06874 (Crim. Ct. Shelby Cty., Tenn., Jan. 2, 1990).8 At
that time, the court did not specify which claims fell into
which category.
   Cone appealed the denial of his petition to the Tennes
see Court of Criminal Appeals, asserting that the postcon
viction court had erred by dismissing 13 claims—his
——————
testified on his behalf had ever seen or heard of him until a few weeks
prior to the trial. Neither was a medical doctor or psychiatrist, and
neither had purported to treat him as a patient. Their testimony that
he lacked mental capacity was based purely upon his personal recita
tion to them of his history of military service and drug abuse.” Id., at
90.
   8 Under Tennessee law in effect at the time a criminal defendant was

entitled to collateral relief if his conviction or sentence violated “any
right guaranteed by the constitution of [Tennessee] or the Constitution
of the United States.” Tenn. Code Ann. §40–30–105 (1982); see also
§40–30–102. Any hearing on a petition for postconviction relief was
limited, however, to claims that had not been “waived or previously
determined.” See §40–30–111. A ground for relief was “previously
determined” if “a court of competent jurisdiction ha[d] ruled on the
merits [of the claim] after a full and fair hearing.” §40–30–112(a). The
claim was waived “if the petitioner knowingly and understandingly
failed to present it for determination in any proceeding before a court of
competent jurisdiction in which the ground could have been presented.”
§40–30–112(b)(1).
                    Cite as: 556 U. S. ____ (2009)                   9

                         Opinion of the Court

Brady claim among them—as previously determined
when, in fact, they had not been “previously addressed or
determined by any court.” Brief for Petitioner-Appellant
Gary Bradford Cone in No. P–06874, pp. 23–24, and n. 11.
In addition Cone urged the court to remand the case to
allow him, with the assistance of counsel, to rebut the
presumption that he had waived any of his claims by not
raising them at an earlier stage in the litigation. Id., at
24.9 The court agreed and remanded the case for further
proceedings.
  On remand counsel was appointed and an amended
petition was filed. The State once again urged the post
conviction court to dismiss Cone’s petition. Apparently
conflating the state-law disclosure claim Cone had raised
on direct appeal with his newly filed Brady claim, the
State represented that the Tennessee Supreme Court had
already decided the Brady issue and that Cone was there
fore barred from relitigating it. See App. 15–16.
  While that petition remained pending before the post
conviction court, the Tennessee Court of Appeals held for
the first time that the State’s Public Records Act allowed a
criminal defendant to review the prosecutor’s file in his
case. See Capital Case Resource Center of Tenn., Inc. v.
Woodall, No. 01–A–01–9104–CH–00150, 1992 WL 12217
(Jan. 29, 1992). Based on that holding, Cone obtained
access to the prosecutor’s files, in which he found proof
that evidence had indeed been withheld from him at trial.
Among the undisclosed documents Cone discovered were
statements from witnesses who had seen him several days
before and several days after the murders. The witnesses
described Cone’s appearance as “wild eyed,” App. 50, and
——————
  9 See Swanson v. State, 749 S. W. 2d 731, 734 (Tenn. 1988) (courts

should not dismiss postconviction petitions on technical grounds unless
the petitioner has first had “reasonable opportunity, with aid of coun
sel, to file amendments” and rebut presumption of waiver (internal
quotation marks omitted)).
10                          CONE v. BELL

                          Opinion of the Court

his behavior as “real weird,” id., at 49. One witness af
firmed that Cone had appeared “to be drunk or high.”
Ibid. The file also contained a police report describing
Cone’s arrest in Florida following the murders. In that
report, a police officer described Cone looking around “in a
frenzied manner,” and “walking in [an] agitated manner”
prior to his apprehension. Id., at 53. Multiple police
bulletins describing Cone as a “drug user” and a “heavy
drug user” were also among the undisclosed evidence. See
id., at 55–59.
   With the newly discovered evidence in hand, Cone
amended his postconviction petition once again in October
1993, expanding his Brady claim to allege more specifi
cally that the State had withheld exculpatory evidence
demonstrating that he “did in fact suffer drug problems
and/or drug withdrawal or psychosis both at the time of
the offense and in the past.” App. at 20. Cone pointed to
specific examples of evidence that had been withheld,
alleging the evidence was “exculpatory to both the jury’s
determination of petitioner’s guilt and its consideration of
the proper sentence,” and that there was “a reasonable
probability that, had the evidence not been withheld, the
jurors would not have convicted [him] and would not have
sentenced him to death.” Id., at 20–21.10 In a lengthy
affidavit submitted with his amended petition, Cone ex
plained that he had not raised his Brady claim in earlier
proceedings because the facts underlying it “ha[d] been
revealed through disclosure of the State’s files, which
occurred after the first post-conviction proceeding.” App.
18.
   After denying Cone’s request for an evidentiary hearing,
——————
  10 As examples of evidence that had been withheld, Cone pointed to

“statements of Charles and Debbie Slaughter, statements of Sue Cone,
statements of Lucille Tuech, statements of Herschel Dalton, and
patrolman Collins” and “statements contained in official police reports.”
App. 20.
                  Cite as: 556 U. S. ____ (2009)            11

                      Opinion of the Court

the postconviction court denied relief on each claim pre
sented in the amended petition. Many of the claims were
dismissed on the ground that they had been waived by
Cone’s failure to raise them in earlier proceedings; how
ever, consistent with the position urged by the State, the
court dismissed many others, including the Brady claim,
as mere “re-statements of previous grounds heretofore
determined and denied by the Tennessee Supreme Court
upon Direct Appeal or the Court of Criminal Appeals upon
the First Petition.” App. 22.
  Noting that “the findings of the trial court in post
conviction hearings are conclusive on appeal unless the
evidence preponderates against the judgment,” the Ten
nessee Court of Criminal Appeals affirmed. Cone v. State,
927 S. W. 2d 579, 581–582 (1995). The court concluded
that Cone had “failed to rebut the presumption of waiver
as to all claims raised in his second petition for post
conviction relief which had not been previously deter
mined.” Id., at 582 (emphasis added). Cone unsuccess
fully petitioned for review in the Tennessee Supreme
Court, and we denied certiorari. Cone v. Tennessee, 519
U. S. 934 (1996).
                               III
    In 1997, Cone filed a petition for a federal writ of habeas
corpus. Without disclosing to the District Court the con
trary position it had taken in the state-court proceedings,
the State acknowledged that Cone’s Brady claim had not
been raised prior to the filing of his second postconviction
petition. However, wrenching out of context the state
appellate court’s holding that Cone had “waived ‘all claims
. . . which had not been previously determined,’ ” the State
now asserted the Brady claim had been waived. App. 39
(quoting Cone, 927 S. W. 2d, at 581–582).
    In May 1998, the District Court denied Cone’s request
for an evidentiary hearing on his Brady claim. Lamenting
12                      CONE v. BELL

                      Opinion of the Court

that its consideration of Cone’s claims had been “made
more difficult” by the parties’ failure to articulate the state
procedural rules under which each of Cone’s claims had
allegedly been defaulted, App. to Pet. for Cert. 98a, the
District Court nevertheless held that the Brady claim was
procedurally barred. After parsing the claim into 11
separate subclaims based on 11 pieces of withheld evi
dence identified in the habeas petition, the District Court
concluded that Cone had waived each subclaim by failing
to present or adequately develop it in state court. App. to
Pet. for Cert. 112a–113a. Moreover, the court concluded
that even if Cone had not defaulted his Brady claim, it
would fail on its merits because none of the withheld
evidence would have cast doubt on Cone’s guilt. App. to
Pet. for Cert. 116a–119a. Throughout its opinion the
District Court repeatedly referenced factual allegations
contained in early versions of Cone’s second petition for
postconviction relief rather than the amended version of
the petition upon which the state court’s decision had
rested. See, e.g., id., at 112a.
   After the District Court dismissed the remainder of
Cone’s federal claims, the Court of Appeals for the Sixth
Circuit granted him permission to appeal several issues,
including the alleged suppression of Brady material.
Before the Court of Appeals, the State shifted its proce
dural default argument once more, this time contending
that Cone had “simply never raised” his Brady claim in
the state court because he failed to make adequate factual
allegations to support that claim in his second petition for
postconviction relief. App. 41. Repeating the District
Court’s error, the State directed the Court of Appeals’
attention to Cone’s pro se petition and to the petition
Cone’s counsel filed before he gained access to the prosecu
tion’s case file. Id., at 41–42, and n. 7. In other words,
instead of citing the October 1993 amended petition on
which the state court’s decision had been based and to
                 Cite as: 556 U. S. ____ (2009)          13

                     Opinion of the Court

which its order explicitly referred, the State pointed the
court to earlier, less developed versions of the same claim.
   The Court of Appeals concluded that Cone had proce
durally defaulted his Brady claim and had failed to show
cause and prejudice to overcome the default. Cone v. Bell,
243 F. 3d 961, 968 (2001). The court acknowledged that
Cone had raised his Brady claim. 243 F. 3d, at 969. Nev
ertheless, the court considered itself barred from reaching
the merits of the claim because the Tennessee courts had
concluded the claim was “previously determined or waived
under Tenn. Code Ann. §40–30–112.” Ibid.
   Briefly mentioning several isolated pieces of suppressed
evidence, the court summarily concluded that even if
Cone’s Brady claim had not been defaulted, the sup
pressed evidence would not undermine confidence in the
verdict (and hence was not Brady material) “because of
the overwhelming evidence of Cone’s guilt.” 243 F. 3d, at
968. The court did not discuss whether any of the undis
closed evidence was material with respect to Cone’s sen
tencing proceedings.
   Although the Court of Appeals rejected Cone’s Brady
claim, it held that he was entitled to have his death sen
tence vacated because of his counsel’s ineffective assis
tance at sentencing. See 243 F. 3d, at 975. In 2002, this
Court reversed that holding after concluding that the
Tennessee courts’ rejection of Cone’s ineffective
assistance-of-counsel claim was not “objectively unreason
able” within the meaning of the Antiterrorism and Effec
tive Death Penalty Act of 1996 (AEDPA). See Bell v. Cone,
535 U. S. 685, 699.
   In 2004, following our remand, the Court of Appeals
again entered judgment ordering a new sentencing hear
ing, this time based on the purported invalidity of an
aggravating circumstance found by the jury. Cone v. Bell,
359 F. 3d 785. Again we granted certiorari and reversed,
relying in part on the deferential standard that governs
14                          CONE v. BELL

                         Opinion of the Court

our review of state-court decisions under AEDPA. See
Bell v. Cone, 543 U. S. 447, 452–458 (2005) (per curiam).
  Following our second remand, the Court of Appeals
revisited Cone’s Brady claim. This time, the court divided
the claim into four separate subclaims: “(1) evidence re
garding [Cone’s] drug use; (2) evidence that might have
been useful to impeach the testimony and credibility of
prosecution witness Sergeant Ralph Roby; (3) FBI re
ports;[11] and (4) evidence showing that prosecution wit
ness Ilene Blankman was untruthful and biased.” 492 F.
3d 743, 753 (2007). Noting that it had previously found all
four subclaims to be procedurally defaulted, the court
declined to reconsider its earlier decision. See ibid. (citing
Cone, 243 F. 3d, at 968–970). At the same time, the court
reiterated that the withheld evidence “would not have
overcome the overwhelming evidence of Cone’s guilt in
committing a brutal double murder and the persuasive
testimony that Cone was not under the influence of
drugs.” 492 F. 3d, at 756. Summarily discounting Cone’s
contention that the withheld evidence was material with
respect to his sentence, the court concluded that the intro
duction of the suppressed evidence would not have altered
the jurors’ finding that Cone’s alleged drug use did not
“vitiate his specific intent to murder his victims and did
not mitigate his culpability sufficient to avoid the death
sentence.” Id., at 757.
  Judge Merritt dissented. He castigated the State not
only for withholding documents relevant to Cone’s sole
defense and plea for mitigation, but also for its “falsifica
——————
  11 In the course of federal habeas proceedings, Cone had obtained

access to files from the Federal Bureau of Investigation where he found
additional previously undisclosed evidence not contained in the state
prosecutor’s case file. The suppressed FBI documents make repeated
reference to Cone’s drug use and corroborate his expert’s representation
that he had used drugs during his prior incarceration for armed rob
bery. See id., at 26–28.
                 Cite as: 556 U. S. ____ (2009)           15

                     Opinion of the Court

tion of the procedural record . . . concerning the State’s
procedural default defense to the Brady claim.” Id., at
760. Over the dissent of seven judges, Cone’s petition for
rehearing en banc was denied. 505 F. 3d 610 (2007).
   We granted certiorari, 554 U. S. ___ (2008), to answer
the question whether a federal habeas claim is “proce
durally defaulted” when it is twice presented to the state
courts.
                              IV
   During the state and federal proceedings below, the
State of Tennessee offered two different justifications for
denying review of the merits of Cone’s Brady claim. First,
in connection with Cone’s amended petition for state
postconviction relief, the State argued that the Brady
claim was barred because it had been decided on direct
appeal. See App. 15–16. Then, in connection with Cone’s
federal habeas petition, the State argued that Cone’s claim
was waived because it had never been properly raised
before the state courts. See id., at 39. The District Court
and the Court of Appeals agreed that Cone’s claim was
procedurally barred, but for different reasons. The Dis
trict Court held that the claim had been waived, App. to
Pet. for Cert. 102a, while the Court of Appeals held that
the claim had been either waived or previously deter
mined, Cone, 243 F. 3d, at 969. We now conclude that
neither prior determination nor waiver provides an inde
pendent and adequate state ground for denying Cone
review of his federal claim.
   It is well established that federal courts will not review
questions of federal law presented in a habeas petition
when the state court’s decision rests upon a state-law
ground that “is independent of the federal question and
adequate to support the judgment.” Coleman v. Thomp
son, 501 U. S. 722, 729 (1991); Lee v. Kemna, 534 U. S.
362, 375 (2002). In the context of federal habeas proceed
16                      CONE v. BELL

                      Opinion of the Court

ings, the independent and adequate state ground doctrine
is designed to “ensur[e] that the States’ interest in correct
ing their own mistakes is respected in all federal habeas
cases.” Coleman, 501 U. S., at 732. When a petitioner
fails to properly raise his federal claims in state court, he
deprives the State of “an opportunity to address those
claims in the first instance” and frustrates the State’s
ability to honor his constitutional rights. Id., at 732, 748.
Therefore, consistent with the longstanding requirement
that habeas petitioners must exhaust available state
remedies before seeking relief in federal court, we have
held that when a petitioner fails to raise his federal claims
in compliance with relevant state procedural rules, the
state court’s refusal to adjudicate the claim ordinarily
qualifies as an independent and adequate state ground for
denying federal review. See id., at 731.
   That does not mean, however, that federal habeas re
view is barred every time a state court invokes a proce
dural rule to limit its review of a state prisoner’s claims.
We have recognized that “ ‘the adequacy of state proce
dural bars to the assertion of federal questions’ . . . is not
within the State’s prerogative finally to decide; rather,
adequacy ‘is itself a federal question.’ ” Lee, 534 U. S., at
375 (quoting Douglas v. Alabama, 380 U. S. 415, 422
(1965)); see also Coleman, 501 U. S., at 736 (“[F]ederal
habeas courts must ascertain for themselves if the peti
tioner is in custody pursuant to a state court judgment
that rests on independent and adequate state grounds”).
The question before us now is whether federal review of
Cone’s Brady claim is procedurally barred either because
the claim was twice presented to the state courts or be
cause it was waived, and thus not presented at all.
   First, we address the contention that the repeated pres
entation of a claim in state court bars later federal review.
The Tennessee postconviction court denied Cone’s Brady
claim after concluding it had been previously determined
                    Cite as: 556 U. S. ____ (2009)                 17

                        Opinion of the Court

following a full and fair hearing in state court. See Tenn.
Code Ann. §40–30–112(a) (1982). That conclusion rested
on a false premise: Contrary to the state courts’ finding,
Cone had not presented his Brady claim in earlier pro
ceedings and, consequently, the state courts had not
passed on it. The Sixth Circuit recognized that Cone’s
Brady claim had not been decided on direct appeal, see
Cone, 243 F. 3d, at 969, but felt constrained by the state
courts’ refusal to reach the merits of that claim on post
conviction review. The Court of Appeals concluded that
because the state postconviction courts had applied a state
procedural law to avoid reaching the merits of Cone’s
Brady claim, “an ‘independent and adequate’ state
ground” barred federal habeas review. 243 F. 3d, at 969.
In this Court the State does not defend that aspect of the
Court of Appeals’ holding, and rightly so.
   When a state court declines to review the merits of a
petitioner’s claim on the ground that it has done so al
ready, it creates no bar to federal habeas review. In Ylst
v. Nunnemaker, 501 U. S. 797, 804, n. 3 (1991), we ob
served in passing that when a state court declines to
revisit a claim it has already adjudicated, the effect of the
later decision upon the availability of federal habeas is
“nil” because “a later state decision based upon ineligibil
ity for further state review neither rests upon procedural
default nor lifts a pre-existing procedural default.”12
When a state court refuses to readjudicate a claim on the
ground that it has been previously determined, the court’s
——————
  12 With the exception of the Sixth Circuit, all Courts of Appeals to
have directly confronted the question both before and after Ylst, 501
U. S. 797, have agreed that a state court’s successive rejection of a
federal claim does not bar federal habeas review. See, e.g., Page v.
Frank, 343 F. 3d 901, 907 (CA7 2003); Brecheen v. Reynolds, 41 F. 3d
1343, 1358 (CA10 1994); Bennett v. Whitley, 41 F. 3d 1581, 1582 (CA5
1994); Silverstein v. Henderson, 706 F. 2d 361, 368 (CA2 1983). See
also Lambright v. Stewart, 241 F. 3d 1201, 1206 (CA9 2001).
18                          CONE v. BELL

                          Opinion of the Court

decision does not indicate that the claim has been proce
durally defaulted. To the contrary, it provides strong
evidence that the claim has already been given full consid
eration by the state courts and thus is ripe for federal
adjudication. See 28 U. S. C. §2254(b)(1)(A) (permitting
issuance of a writ of habeas corpus only after “the appli
cant has exhausted the remedies available in the courts of
the State”).
  A claim is procedurally barred when it has not been
fairly presented to the state courts for their initial consid
eration—not when the claim has been presented more
than once. Accordingly, insofar as the Court of Appeals
rejected Cone’s Brady claim as procedurally defaulted
because the claim had been twice presented to the Ten
nessee courts, its decision was erroneous.
  As an alternative (and contradictory) ground for barring
review of Cone’s Brady claim, the State has argued that
Cone’s claim was properly dismissed by the state postcon
viction court on the ground it had been waived. We are
not persuaded. The state appellate court affirmed the
denial of Cone’s Brady claim on the same mistaken ground
offered by the lower court—that the claim had been previ
ously determined.13 Contrary to the State’s assertion, the
——————
  13 As recounted earlier, Cone’s state postconviction petition contained
numerous claims of error. The state postconviction court dismissed
some of those claims as waived and others, including the Brady claim,
as having been previously determined. In affirming the denial of
Cone’s petition the Tennessee Court of Criminal Appeals summarily
stated that Cone had “failed to rebut the presumption of waiver as to
all claims raised in his second petition for post-conviction relief which
had not been previously determined.” Cone v. State, 927 S. W. 2d 579,
582 (1995). Pointing to that language, the State asserts that the
Tennessee Court of Criminal Appeals denied Cone’s Brady claim not
because it had been previously determined, but because it was waived
in the postconviction court proceedings. Not so. Without questioning
the trial court’s finding that Cone’s Brady claim had been previously
determined, the Court of Criminal Appeals affirmed the denial of
                     Cite as: 556 U. S. ____ (2009)                    19

                          Opinion of the Court

Tennessee appellate court did not hold that Cone’s Brady
claim was waived.
  When a state court declines to find that a claim has
been waived by a petitioner’s alleged failure to comply
with state procedural rules, our respect for the state-court
judgment counsels us to do the same. Although we have
an independent duty to scrutinize the application of state
rules that bar our review of federal claims, Lee, 534 U. S.,
at 375, we have no concomitant duty to apply state proce
dural bars where state courts have themselves declined to
do so. The Tennessee courts did not hold that Cone
waived his Brady claim, and we will not second-guess
their judgment.14
——————
Cone’s postconviction petition in its entirety. Nothing in that decision
suggests the appellate court believed the Brady claim had been waived
in the court below.
  Similarly, while JUSTICE ALITO’s parsing of the record persuades him
that Cone failed to adequately raise his Brady claim to the Tennessee
Court of Criminal Appeals, he does not argue that the court expressly
held that Cone waived the claim. A review of Cone’s opening brief
reveals that he made a broad challenge to the postconviction court’s
dismissal of his petition and plainly asserted that the court erred by
dismissing claims as previously determined on direct appeal or in his
initial postconviction petition. See Brief for Petitioner-Appellant in No.
02–C–01–9403–CR–00052 (Tenn. Crim. App.), pp. 7, 14. The state
appellate court did not state or suggest that Cone had waived his Brady
claim. Rather, after commending the postconviction court for its
“exemplary and meticulous treatment of the appellant’s petition,” Cone,
927 S. W. 2d, at 581, the appellate court simply adopted without
modification the lower court’s findings with respect to the application of
Tenn. Code Ann. §40–30–112 to the facts of this case. The best reading
of the Tennessee Court of Criminal Appeals’ decision is that it was
based on an approval of the postconviction court’s reasoning rather
than on an unmentioned failure by Cone to adequately challenge the
dismissal of his Brady claim on appeal.
  14 Setting aside the state courts’ mistaken belief that Cone’s Brady

claim had been previously determined, there are many reasons the
state courts might have rejected the State’s waiver argument. The
record establishes that the suppressed documents which form the basis
for Cone’s claim were not available to him until the Tennessee Court of
20                          CONE v. BELL

                          Opinion of the Court

  The State’s procedural objections to federal review of the
merits of Cone’s claim have resulted in a significant delay
in bringing this unusually protracted case to a conclusion.
Ultimately, however, they provide no obstacle to judicial
review. Cone properly preserved and exhausted his Brady
claim in the state court; therefore, it is not defaulted. We
turn now to the merits of that claim.
                             V
  Although the State is obliged to “prosecute with ear
nestness and vigor,” it “is as much [its] duty to refrain
from improper methods calculated to produce a wrongful
conviction as it is to use every legitimate means to bring
about a just one.” Berger, 295 U. S., at 88. Accordingly,
we have held that when the State withholds from a crimi
nal defendant evidence that is material to his guilt or
punishment, it violates his right to due process of law in
violation of the Fourteenth Amendment. See Brady, 373
U. S., at 87. In United States v. Bagley, 473 U. S. 667, 682
(1985) (opinion of Blackmun, J.), we explained that evi
dence is “material” within the meaning of Brady when
there is a reasonable probability that, had the evidence
been disclosed, the result of the proceeding would have
been different. In other words, favorable evidence is sub
ject to constitutionally mandated disclosure when it “could
reasonably be taken to put the whole case in such a differ
——————
Appeals’ 1992 decision interpreting the State’s Public Records Act as
authorizing the disclosure of prosecutorial records. Soon after obtain
ing access to the prosecutor’s file and discovering within it documents
that had not been disclosed prior to trial, Cone amended his petition for
postconviction relief, adding detailed allegations regarding the sup
pressed evidence recovered from the file, along with an affidavit ex
plaining the reason why his claim had not been filed sooner. See App.
13, 18. The State did not oppose the amendment of Cone’s petition on
the ground that it was untimely, and it appears undisputed that there
would have been no basis under state law for doing so. See Brief for
Petitioner 7, n. 1.
                     Cite as: 556 U. S. ____ (2009)                   21

                          Opinion of the Court

ent light as to undermine confidence in the verdict.” Kyles
v. Whitley, 514 U. S. 419, 435 (1995); accord, Banks v.
Dretke, 540 U. S. 668, 698–699 (2004); Strickler v. Greene,
527 U. S. 263, 290 (1999).15
  The documents suppressed by the State vary in kind,
but they share a common feature: Each strengthens the
inference that Cone was impaired by his use of drugs
around the time his crimes were committed. The sup
pressed evidence includes statements by witnesses ac
knowledging that Cone appeared to be “drunk or high,”
App. 49, “acted real weird,” ibid., and “looked wild eyed,”
id., at 50, in the two days preceding the murders.16 It also
includes documents that could have been used to impeach
——————
  15 Although the Due Process Clause of the Fourteenth Amendment, as

interpreted by Brady, only mandates the disclosure of material evi
dence, the obligation to disclose evidence favorable to the defense may
arise more broadly under a prosecutor’s ethical or statutory obligations.
See Kyles, 514 U. S., at 437 (“[T]he rule in Bagley (and, hence, in
Brady) requires less of the prosecution than the ABA Standards for
Criminal Justice Prosecution Function and Defense Function 3–3.11(a)
(3d ed. 1993)”). See also ABA Model Rule of Professional Conduct
3.8(d) (2008) (“The prosecutor in a criminal case shall” “make timely
disclosure to the defense of all evidence or information known to the
prosecutor that tends to negate the guilt of the accused or mitigates the
offense, and, in connection with sentencing, disclose to the defense and
to the tribunal all unprivileged mitigating information known to the
prosecutor, except when the prosecutor is relieved of this responsibility
by a protective order of the tribunal”). As we have often observed, the
prudent prosecutor will err on the side of transparency, resolving
doubtful questions in favor of disclosure. See Kyles, 514 U. S., at 439;
United States v. Bagley, 473 U. S. 667, 711, n. 4 (1985) (STEVENS, J.,
dissenting); United States v. Agurs, 427 U. S. 97, 108 (1976).
  16 The State contends that the statements were made by witnesses

who observed Cone during and immediately after he committed robber
ies; therefore, it is not surprising that Cone appeared less than “se
rene.” See Brief for Respondent 46. Although a jury would have been
free to infer that Cone’s behavior was attributable to his criminal
activity, the evidence is also consistent with Cone’s assertion that he
was suffering from chronic amphetamine psychosis at the time of the
crimes.
22                          CONE v. BELL

                         Opinion of the Court

witnesses whose trial testimony cast doubt on Cone’s drug
addiction. For example, Memphis police officer Ralph
Roby testified at trial that Cone had no needle marks on
his body when he was arrested—an observation that
bolstered the State’s argument that Cone was not a drug
user. The suppressed evidence reveals, however, that
Roby authorized multiple teletypes to law enforcement
agencies in the days following the murders in which he
described Cone as a “drug user” and a “heavy drug user.”
See id., at 55–58.17 A suppressed statement made by the
chief of police of Cone’s hometown also describes Cone as a
serious drug user. See Cone, 243 F. 3d, at 968. And un
disclosed notes of a police interview with Ilene Blankman
conducted several days after the murders reveal discrep
ancies between her initial statement and her trial testi
mony relevant to Cone’s alleged drug use. App. 72–73. In
sum, both the quantity and the quality of the suppressed
evidence lends support to Cone’s position at trial that he
habitually used excessive amounts of drugs, that his ad
diction affected his behavior during his crime spree, and
that the State’s arguments to the contrary were false and
misleading.
  Thus, the federal question that must be decided is
whether the suppression of that probative evidence de
prived Cone of his right to a fair trial. See Agurs, 427
——————
   17 As the dissent points out, Roby did not testify directly that Cone

was not a drug user and FBI Agent Eugene Flynn testified that, at the
time of Cone’s arrest in Pompano Beach, Cone reported that he had
used cocaine, Dilaudid, and Demerol and was suffering from “slight
withdrawal symptoms.” See post, at 7, 11. See also Tr. 1916, 1920
(Apr. 22, 1982). It is important to note, however, that neither Flynn
nor Roby corroborated Cone’s account of alleged drug use. Taken in
context, Roby’s statement that he had not observed any needle marks
on Cone’s body invited the jury to infer that Cone’s self-reported drug
use was either minimal or contrived. See id., at 1939. Therefore,
although the suppressed evidence does not directly contradict Roby’s
trial testimony, it does place it in a different light.
                    Cite as: 556 U. S. ____ (2009)                  23

                         Opinion of the Court

U. S., at 108. Because the Tennessee courts did not reach
the merits of Cone’s Brady claim, federal habeas review is
not subject to the deferential standard that applies under
AEDPA to “any claim that was adjudicated on the merits
in State court proceedings.” 28 U. S. C. §2254(d). Instead,
the claim is reviewed de novo. See, e.g., Rompilla v.
Beard, 545 U. S. 374, 390 (2005) (de novo review where
state courts did not reach prejudice prong under Strick
land v. Washington, 466 U. S. 668 (1984)); Wiggins v.
Smith, 539 U. S. 510, 534 (2003) (same).
   Contending that the Federal District Court and Court of
Appeals adequately and correctly resolved the merits of
that claim, the State urges us to affirm the Sixth Circuit’s
denial of habeas relief. In assessing the materiality of the
evidence suppressed by the State, the Court of Appeals
suggested that two facts outweighed the potential force of
the suppressed evidence. First, the evidence of Cone’s
guilt was overwhelming. Second, the evidence of Cone’s
drug use was cumulative because the jury had heard
evidence of Cone’s alleged addiction from witnesses and
from officers who interviewed Cone and recovered drugs
from his vehicle.18 The Court of Appeals did not thor
oughly review the suppressed evidence or consider what
its cumulative effect on the jury would have been. More
over, in concluding that the suppressed evidence was not
material within the meaning of Brady, the court did not
distinguish between the materiality of the evidence with
respect to guilt and the materiality of the evidence with
respect to punishment—an omission we find significant.
   Evidence that is material to guilt will often be material
——————
  18 In pointing to the trial evidence of Cone’s drug use, the Court of

Appeals made no mention of the fact that the State had discredited the
testimony of Cone’s experts on the ground that no independent evi
dence corroborated Cone’s alleged addiction and that the State had
argued that the drugs in Cone’s car were intended for resale, rather
than personal use.
24                     CONE v. BELL

                     Opinion of the Court

for sentencing purposes as well; the converse is not always
true, however, as Brady itself demonstrates. In our semi
nal case on the disclosure of prosecutorial evidence, defen
dant John Brady was indicted for robbery and capital
murder. At trial, Brady took the stand and confessed to
robbing the victim and being present at the murder but
testified that his accomplice had actually strangled the
victim. Brady v. State, 226 Md. 422, 425, 174 A. 2d 167,
168 (1961). After Brady was convicted and sentenced to
death he discovered that the State had suppressed the
confession of his accomplice, which included incriminating
statements consistent with Brady’s version of events. Id.,
at 426, 174 A. 2d, at 169. The Maryland Court of Appeals
concluded that Brady’s due process rights were violated by
the suppression of the accomplice’s confession but declined
to order a new trial on guilt. Observing that nothing in
the accomplice’s confession “could have reduced . . .
Brady’s offense below murder in the first degree,” the
state court ordered a new trial on the question of punish
ment only. Id., at 430, 174 A. 2d, at 171. We granted
certiorari and affirmed, rejecting Brady’s contention that
the state court’s limited remand violated his constitutional
rights. 373 U. S., at 88.
   As in Brady, the distinction between the materiality of
the suppressed evidence with respect to guilt and punish
ment is significant in this case. During the guilt phase of
Cone’s trial, the only dispute was whether Cone was “sane
under the law,” Tr. 2040 (Apr. 22, 1982), as his counsel
described the issue, or “criminally responsible” for his
conduct, App. 110, as the prosecutor argued. Under Ten
nessee law, Cone could not be held criminally responsible
for the murders if, “at the time of [his] conduct as a result
of mental disease or defect he lack[ed] substantial capacity
either to appreciate the wrongfulness of his conduct or to
conform his conduct to the requirements of law.” Graham
v. State, 547 S. W. 2d 531, 543 (Tenn. 1977). Although we
                 Cite as: 556 U. S. ____ (2009)          25

                     Opinion of the Court

take exception to the Court of Appeals’ failure to assess
the effect of the suppressed evidence “collectively” rather
than “item by item,” see Kyles, 514 U. S., at 436, we never
theless agree that even when viewed in the light most
favorable to Cone, the evidence falls short of being suffi
cient to sustain his insanity defense.
   Cone’s experts testified that his drug addiction and
posttraumatic stress disorder originated during his service
in Vietnam, more than 13 years before the Todds were
murdered. During those years, despite Cone’s drug use
and mental disorder, he managed to successfully complete
his education, travel, and (when not incarcerated) function
in civil society. The suppressed evidence may have
strengthened the inference that Cone was on drugs or
suffering from withdrawal at the time of the murders, but
his behavior before, during, and after the crimes was
inconsistent with the contention that he lacked substan
tial capacity either to appreciate the wrongfulness of his
conduct or to conform his conduct to the requirements of
law. See Graham, 547 S. W. 2d, at 543. The likelihood
that the suppressed evidence would have affected the
jury’s verdict on the issue of insanity is therefore remote.
Accordingly, we conclude that the Sixth Circuit did not err
by denying habeas relief on the ground that the sup
pressed evidence was immaterial to the jury’s finding of
guilt.
   The same cannot be said of the Court of Appeals’ sum
mary treatment of Cone’s claim that the suppressed evi
dence influenced the jury’s sentencing recommendation.
There is a critical difference between the high standard
Cone was required to satisfy to establish insanity as a
matter of Tennessee law and the far lesser standard that a
defendant must satisfy to qualify evidence as mitigating in
a penalty hearing in a capital case. See Bell, 535 U. S., at
712 (STEVENS, J., dissenting) (“[T]here is a vast difference
between insanity—which the defense utterly failed to
26                         CONE v. BELL

                         Opinion of the Court

prove—and the possible mitigating effect of drug addiction
incurred as a result of honorable service in the military”).
As defense counsel emphasized in his brief opening state
ment during penalty phase proceedings, the jury was
statutorily required to consider whether Cone’s “capacity
. . . to appreciate the wrongfulness of his conduct or to
conform his conduct to the requirements of the law was
substantially impaired as a result of mental disease or
defect or intoxication which was insufficient to establish a
defense to the crime but which substantially affected his
judgment.” Tenn. Code Ann. §39–2–203(j)(8) (1982). It is
possible that the suppressed evidence, viewed cumula
tively, may have persuaded the jury that Cone had a far
more serious drug problem than the prosecution was
prepared to acknowledge, and that Cone’s drug use played
a mitigating, though not exculpating, role in the crimes he
committed.19 The evidence might also have rebutted the
State’s suggestion that Cone had manipulated his expert
witnesses into falsely believing he was a drug addict when
in fact he did not struggle with substance abuse.
    Neither the Court of Appeals nor the District Court fully
considered whether the suppressed evidence might have
persuaded one or more jurors that Cone’s drug addiction—
especially if attributable to honorable service of his coun
try in Vietnam—was sufficiently serious to justify a deci
sion to imprison him for life rather than sentence him to
death. Because the evidence suppressed at Cone’s trial

——————
  19 We agree with the dissent that the standard to be applied by the

District Court in evaluating the merits of Cone’s Brady claim on re
mand is whether there is a reasonable probability that, had the sup
pressed evidence been disclosed, the result of the proceeding would
have been different. See post, at 5. Because neither the District Court
nor the Court of Appeals considered the merits of Cone’s claim with
respect to the effect of the withheld evidence on his sentence, it is
appropriate for the District Court, rather than this Court, to do so in
the first instance.
                 Cite as: 556 U. S. ____ (2009)           27

                     Opinion of the Court

may well have been material to the jury’s assessment of
the proper punishment in this case, we conclude that a
full review of the suppressed evidence and its effect is
warranted.
                             VI
  In the 27 years since Gary Cone was convicted of mur
der and sentenced to death, no Tennessee court has
reached the merits of his claim that state prosecutors
withheld evidence that would have bolstered his defense
and rebutted the State’s attempts to cast doubt on his
alleged drug addiction. Today we hold that the Tennessee
courts’ procedural rejection of Cone’s Brady claim does not
bar federal habeas review of the merits of that claim.
Although we conclude that the suppressed evidence was
not material to Cone’s conviction for first-degree murder,
the lower courts erred in failing to assess the cumulative
effect of the suppressed evidence with respect to Cone’s
capital sentence. Accordingly, the judgment of the Court
of Appeals is vacated, and the case is remanded to the
District Court with instructions to give full consideration
to the merits of Cone’s Brady claim.
                                            It is so ordered.
                  Cite as: 556 U. S. ____ (2009)            1

              ROBERTS, C. J., concurring in judgment

SUPREME COURT OF THE UNITED STATES
                           _________________

                          No. 07–1114
                           _________________


   GARY BRADFORD CONE, PETITIONER v. RICKY 

               BELL, WARDEN

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE SIXTH CIRCUIT

                         [April 28, 2009] 


  CHIEF JUSTICE ROBERTS, concurring in the judgment.
  The Court’s decision is grounded in unusual facts that
necessarily limit its reach. When issues under Brady v.
Maryland, 373 U. S. 83 (1963), are presented on federal
habeas, they usually have been previously addressed in
state proceedings. Federal review is accordingly sharply
limited by established principles of deference: If the claim
has been waived under state rules, that waiver typically
precludes federal review. If the claim has been decided in
the state system, federal review is restricted in light of the
state court’s legal and factual conclusions. The unique
procedural posture of this case presents a Brady claim
neither barred under state rules for failure to raise it nor
decided in the state system.
  When it comes to that claim, the Court specifies that the
appropriate legal standard is the one we set forth in Kyles
v. Whitley, 514 U. S. 419, 435 (1995) (whether “the favor
able evidence could reasonably be taken to put the whole
case in such a different light as to undermine confidence
in the verdict”). See ante, at 20–21, 26, n. 19. I do not
understand the majority to depart from that standard, and
the majority certainly does not purport to do so.
  That leaves only application of the accepted legal stan
dard to the particular facts. It is highly unusual for this
Court to engage in such an enterprise, see Kyles, supra, at
2                        CONE v. BELL

              ROBERTS, C. J., concurring in judgment

458 (SCALIA, J., dissenting), and the Court’s asserted basis
for doing so in this case is dubious, see post, at 1, 4–5
(THOMAS, J., dissenting).
  In any event, the Court’s review of the facts does not
lead it to conclude that Cone is entitled to relief—only that
the courts below did not adequately consider his claim
with respect to sentencing. See ante, at 26 (“Neither the
Court of Appeals nor the District Court fully considered
whether the suppressed evidence” undermines confidence
in Cone’s sentence). The Court simply reviews the facts in
the light most favorable to Cone, concludes that the evi
dence does not undermine confidence in the jury’s deter
mination that Cone is guilty, but sends the case back for
“full consideration” of whether the same is true as to the
jury’s sentence of death. Ante, at 25–27.
  So this is what we are left with: a fact-specific determi
nation, under the established legal standard, viewing the
unique facts in favor of the defendant, that the Brady
claim fails with respect to guilt, but might have merit as
to sentencing. In light of all this, I see no reason to quar
rel with the Court’s ruling on the Brady claim.
  In considering on remand whether the facts establish a
Brady violation, it is clear that the lower courts should
analyze the issue under the constitutional standards we
have set forth, not under whatever standards the Ameri
can Bar Association may have established. The ABA
standards are wholly irrelevant to the disposition of this
case, and the majority’s passing citation of them should
not be taken to suggest otherwise. See ante, at 21, n. 15.
                    Cite as: 556 U. S. ____ (2009)                  1

                         Opinion of ALITO, J.

SUPREME COURT OF THE UNITED STATES
                             _________________

                            No. 07–1114
                             _________________


   GARY BRADFORD CONE, PETITIONER v. RICKY 

               BELL, WARDEN

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE SIXTH CIRCUIT

                           [April 28, 2009] 


   JUSTICE ALITO, concurring in part and dissenting in
part.
   We granted certiorari in this case to answer two ques­
tions:
     “1. Is a federal habeas claim ‘procedurally defaulted’
     because it has been presented twice to the state
     courts?
     “2. Is a federal habeas court powerless to recognize
     that a state court erred in holding that state law pre­
     cludes reviewing a claim?” Pet. for Cert. i.
   Both of these questions are based on a factually incor­
rect premise, namely, that the Tennessee Court of Crimi­
nal Appeals, the highest state court to entertain peti­
tioner’s appeal from the denial of his second petition for
state postconviction relief,1 rejected petitioner’s Brady2
claim on the ground that the claim had been previously

——————
  1 Because  the Tennessee Supreme Court denied discretionary review
of the decision of the Tennessee Court of Criminal Appeals decision
affirming the denial of petitioner’s second amended petition for post­
conviction relief, we must look to the decision of the latter court to
determine if the decision below was based on an adequate and inde­
pendent state ground. See Baldwin v. Reese, 541 U. S. 27, 30–32
(2004); O’Sullivan v. Boerckel, 526 U. S. 838, 842–843 (1999).
  2 Brady v. Maryland, 373 U. S. 83 (1963).
2                      CONE v. BELL

                      Opinion of ALITO, J.

decided by the Tennessee Supreme Court in petitioner’s
direct appeal. Petitioner’s argument is that the State
Supreme Court did not decide any Brady issue on direct
appeal, that the Tennessee Court of Criminal Appeals
erred in holding otherwise, and that the Sixth Circuit
erred in concluding that the Brady claim had been proce­
durally defaulted on this ground. Petitioner is quite cor­
rect that his Brady claim was not decided on direct appeal,
and the Court in the present case is clearly correct in
holding that a second attempt to litigate a claim in state
court does not necessarily bar subsequent federal habeas
review. See ante, at 8–9.
  But all of this is beside the point because the Tennessee
Court of Criminal Appeals did not reject petitioner’s Brady
claim on the ground that the claim had been previously
determined on direct appeal. Rather, petitioner’s Brady
claim was simply never raised before the Tennessee Court
of Criminal Appeals, and that court did not rule on the
claim at all.
  Because the Sixth Circuit’s decision on the issue of
procedural default rests on the same mistaken premise
that the Tennessee Court of Criminal Appeals rejected
petitioner’s Brady claim on the ground that it had been
previously determined, I entirely agree with the majority
that the Sixth Circuit’s decision on that issue cannot be
sustained and that a remand is required. I cannot join the
Court’s opinion, however, for two chief reasons.
  First, the Court states without explanation that “Cone
properly preserved and exhausted his Brady claim in the
state court” and that therefore the claim has not been
defaulted. Ante, at 20. Because Cone never fairly raised
this claim in the Tennessee Court of Criminal Appeals, the
claim is either not exhausted (if Cone could now raise the
claim in state court) or is procedurally defaulted (if state
law now provides no avenue for further review). I would
leave these questions for resolution in the first instance on
                 Cite as: 556 U. S. ____ (2009)            3

                      Opinion of ALITO, J.

remand.
  Second, the Court, again without explanation, remands
this case to the District Court, not the Court of Appeals. I
see no justification for this step.
                              I
  In order to understand the tangled procedural default
issue presented in this case, it is necessary to review the
far-from-exemplary manner in which the attorneys for
petitioner and respondent litigated the Brady claim in the
state courts.
  On direct appeal, petitioner did not raise any Brady
claim. As the Court notes, petitioner did claim that the
State had violated a state discovery rule by failing to
provide prior statements given by certain witnesses and
that therefore the testimony of these witnesses should
have been stricken. App. 114–117; State v. Cone, 665
S. W. 2d 87, 94 (Tenn. 1984). Although this claim con­
cerned the State’s failure to turn over information, it is
clear that this was not a Brady claim.
  The first appearance of anything resembling the claim
now at issue occurred in 1993 when petitioner’s experi­
enced attorneys filed an amendment to his second petition
for postconviction relief in the Shelby County Criminal
Court. This petition included a long litany of tangled
claims. Paragraph 35 of this amended petition claimed,
among other things, that the State had wrongfully with­
held information demonstrating that one particular prose­
cution witness had testified falsely concerning “petitioner
and his drug use.” App. 13–14. This nondisclosure, the
petition stated, violated not only the Fifth and Fourteenth
Amendments to the Constitution of the United States
(which protect the due process right on which Brady is
based) but also the Fourth, Sixth, and Eighth Amend­
ments to the United States Constitution and four provi­
sions of the Tennessee Constitution.
4                          CONE v. BELL

                         Opinion of ALITO, J.

   Two months later, counsel for petitioner filed an
amendment adding 12 more claims, including one (¶41)
alleging that the State had abridged petitioner’s rights by
failing to disclose evidence that petitioner suffered from
drug problems. Id., at 20. According to this new submis­
sion, the nondisclosure violated, in addition to the previ­
ously cited provisions of the federal and state constitu­
tions, five more provisions of the state constitution,
including provisions regarding double jeopardy, see Tenn.
Const., Art. I, §10, ex post facto laws, §11, indictment, §14,
and open courts, §17.
   The Shelby County Criminal Court was faced with the
task of wading through the morass presented in the
amended petition. Under Tenn. Code Ann. §40–30–112
(1990) (repealed 1995),3 a claim could not be raised in a
postconviction proceeding if the claim had been “previ­
ously determined” or waived. Citing the State Supreme
Court’s rejection on direct appeal of petitioner’s claim that
the prosecution had violated a state discovery rule by
failing to turn over witness statements, the State incor­
rectly informed the court that the failure-to-disclose­
exculpatory-evidence claim set out in ¶41 had been “previ­
ously determined” on direct appeal. App. 15–16. The
Shelby County Criminal Court rejected the claim on this
ground, and held that all of petitioner’s claims had either
been previously determined or waived. Id., at 22.
   Given the importance now assigned to petitioner’s
Brady claim, one might think that petitioner’s attorneys
would have (a) stressed that claim in the opening brief
that they filed in the Tennessee Court of Criminal Ap­
——————
   3 Tennessee law has since changed. Currently, the Tennessee Post-

Conviction Procedure Act bars any second postconviction petition, see
Tenn. Code Ann. §40–30–102 (2006), and permits the reopening of a
petition only under limited circumstances, §40–30–117. These restric­
tions apply to any petition filed after the enactment of the Post-
Conviction Procedure Act, even if the conviction occurred long before.
                     Cite as: 556 U. S. ____ (2009)                     5

                          Opinion of ALITO, J.

peals, (b) pointed out the lower court’s clear error in con­
cluding that this claim had been decided in the direct
appeal, and (c) explained that information supporting the
claim had only recently come to light due to the production
of documents under the State’s public records act. But
counsel did none of these things. In fact, the Brady claim
was not mentioned at all.
  Nor was Brady cited in the reply brief filed by the same
attorneys. The reply brief did contain a passing reference
to “the withholding of exculpatory evidence,” but the brief
did not elaborate on this claim and again failed to mention
that this claim had never been previously decided and was
supported by newly discovered evidence.4
  The Tennessee Court of Criminal Appeals affirmed the
decision of the lower state court, but the appellate court
made no mention of the Brady claim, and I see no basis for
concluding that the court regarded the issue as having
been raised on appeal.
  Appellate courts generally do not reach out to decide
issues not raised by the appellant. Snell v. Tunnell, 920
F. 2d 673, 676 (CA10 1990); see Powers v. Hamilton Cty.
Public Defender Comm’n, 501 F. 3d 592, 609–610 (CA6
2007); see also Galvan v. Alaska Dept. of Corrections, 397
F. 3d 1198, 1204 (CA9 2005) (“Courts generally do not
decide issues not raised by the parties. If they granted
relief to petitioners on grounds not urged by petitioners,

——————
   4 After referring to a long list of claims (not including any claim for

the failure to disclose exculpatory evidence), the reply brief states:
“[I]t is clear that meritorious claims have been presented for adjudica­
tion. These claims have not been waived and a remand for a hearing is
essential in order to enable Mr. Cone to present evidence and prove the
factual allegations, including those relating to his claims of ineffective
assistance of counsel, Petition ¶¶15, 16, 44, R–67, 71 and 141 and of the
withholding of exculpatory evidence. Petition ¶41, R–139.” Reply Brief
of Petitioner-Appellant in No. 02–C–01–9403–CR–0052, p. 5 (emphasis
added) (hereinafter Reply Brief).
6                          CONE v. BELL

                          Opinion of ALITO, J.

respondents would be deprived of a fair opportunity to
respond, and the courts would be deprived of the benefit of
briefing” (footnote omitted)). Nor do they generally con­
sider issues first mentioned in a reply brief. Physicians
Comm. For Responsible Medicine v. Johnson, 436 F. 3d
326, 331, n. 6 (CA2 2006); Doe v. Beaumont Independent
School Dist., 173 F. 3d 274, 299, n. 13 (CA5 1999) (Garza,
J., dissenting); Doolin Security Sav. Bank, F. S. B. v.
Office of Thrift Supervision, 156 F. 3d 190, 191 (CADC
1998); Boone v. Carlsbad Bancorporation, Inc., 972 F. 2d
1545, 1554, n. 6 (CA10 1992). And it is common to prac­
tice for appellate courts to refuse to consider issues that
are mentioned only in passing. Reynolds v. Wagner, 128
F. 3d 166, 178 (CA3 1997) (citing authorities).
   The Tennessee Court of Criminal Appeals follows these
standard practices. Rule 10(b) of that court states quite
specifically: “Issues which are not supported by argument,
citation to authorities, or appropriate references to the
record will be treated as waived in this court.” The court
has applied this rule in capital cases, State v. Dellinger, 79
S. W. 3d 458, 495, 497, 503 (Tenn. 2002) (appendix to
majority opinion); Brimmer v. State, 29 S. W. 3d 497, 530
(1998), and in others. See, e.g., State v. Faulkner, 2001
WL 378540 (Tenn. Crim. App., Sept. 10, 2001) (73-year
sentence for first-degree murder). And in both capital and
noncapital cases, the court has refused to entertain
arguments raised for the first time in a reply brief. See
State v. Gerhardt, 2009 WL 160930 (Tenn. Crim. App.,
Jan. 23, 2009) (capital case); Carruthers v. State, 814 S. W.
2d 64, 68 (Tenn. Crim. App. 1991) (capital case); Cammon
v. State, 2007 WL 2409568, *6 (Tenn. Crim. App., Aug. 23,
2007) (noncapital case).5 Thus, unless the Tennessee
——————
  5 In a footnote in his reply brief, petitioner stated that he was not

waiving any claim presented in the court below and asked the appellate
court to consider all those claims. See Reply Brief 3, n. 1. But the
                    Cite as: 556 U. S. ____ (2009)                  7

                         Opinion of ALITO, J.

Court of Criminal Appeals departed substantially from its
general practice, that court did not regard petitioner’s
Brady claim as having been raised on appeal.
   In the decision now under review, the Sixth Circuit held
that “[t]he Tennessee courts found that Cone’s Brady
claims were ‘previously determined’ and, therefore, not
cognizable in [his] state post-conviction action.” 492 F. 3d
743, 756 (2007). In my judgment, however, there is no
basis for concluding that the Tennessee Court of Criminal
Appeals thought that any Brady issue was before it. A
contrary interpretation would mean that the Tennessee
Court of Criminal Appeals, disregarding its own rules and
standard practice, entertained an issue that was not men­
tioned at all in the appellant’s main brief and was men­
tioned only in passing and without any development in the
reply brief. It would mean that the Tennessee Court of
Criminal Appeals, having chosen to delve into the Brady
issue on its own, ruled on the issue without even mention­
ing it in its opinion and without bothering to check the
record to determine whether in fact the Brady issue had
been decided on direct appeal. Such an interpretation is
utterly implausible, and it is telling that the majority
in this case cites no support for such an interpretation in
the opinion of the Tennessee Court of Criminal Appeals’
opinion.
   The Sixth Circuit’s decision on the question of proce­
dural default rests on an erroneous premise and must
therefore be vacated.
                           II
  I also agree with the Court that we should not affirm
the decision below on the ground that the Brady claim
lacks substantive merit. After its erroneous discussion of
——————
Tennessee Court of Criminal Appeals has specifically held that claims
may not be raised on appeal in this manner. See Leonard v. State, 2007
WL 1946662, *21–*22 (Tenn. Crim. App., July 5, 2007).
8                          CONE v. BELL

                          Opinion of ALITO, J.

procedural default, the Sixth Circuit went on to discuss
the merits of petitioner’s Brady claim. In its 2001 opinion,
the Court of Appeals recognized that the prosecution’s
Brady obligation extends not only to evidence that is
material to guilt but also to evidence that is material to
punishment. See Cone v. Bell, 243 F. 3d 961, 968 (2001)
(citing Pennsylvania v. Ritchie, 480 U. S. 39, 57 (1987)).
But neither in that opinion nor in its 2006 opinion did the
court address the materiality of the information in ques­
tion here in relation to petitioner’s punishment. See 492
F. 3d, at 756 (“A review of the allegedly withheld docu­
ments shows that this evidence would not have overcome
the overwhelming evidence of Cone’s guilt in committing a
brutal double murder and the persuasive testimony that
Cone was not under the influence of drugs” (emphasis
added)). Therefore, despite the strength of the arguments
in JUSTICE THOMAS’ dissent, I would leave that question to
be decided by the Sixth Circuit on remand.
                             III
   The Court, however, does not simply vacate and remand
to the Sixth Circuit but goes further.
   First, the Court states without elaboration that peti­
tioner “preserved and exhausted his Brady claim in the
state court.” Ante, at 20. As I have explained, petitioner
did not fairly present his Brady claim in his prior appeal
to the Tennessee Court of Criminal Appeals, and therefore
that claim is either unexhausted or procedurally barred.
If the State is not now foreclosed from relying on the
failure to exhaust, see 28 U. S. C. §2254(b)(3), or on proce­
dural default,6 those questions may be decided on remand.
——————
  6 Unlike exhaustion, procedural default may be waived if it is not

raised as a defense. Banks v. Dretke, 540 U. S. 668, 705 (2004) (allow­
ing for waiver of “procedural default” “based on the State’s litigation
conduct” (citing Gray v. Netherland, 518 U. S. 152, 166 (1996))). Here,
it appears that the State has consistently argued that petitioner’s
                   Cite as: 556 U. S. ____ (2009)                 9

                        Opinion of ALITO, J.

   Second, the Court remands the case to the District
Court rather than the Court of Appeals. A remand to the
District Court would of course be necessary if petitioner
were entitled to an evidentiary hearing, but the Court
does not hold that an evidentiary hearing is either re­
quired or permitted. In my view, unless there is to be an
evidentiary hearing, there is no reason to remand this
case to the District Court. If the only purpose of remand is
to require an evaluation of petitioner’s Brady claim in
light of the present record, the District Court is not in a
superior position to conduct such a review. And even if
such a review is conducted in the first instance by the
District Court, that court’s decision would be subject to de
novo review in the Court of Appeals. 492 F. 3d, at 750;
Cone v. Bell, 243 F. 3d, at 966–967 (CA6 2001); see United
States v. Graham, 484 F. 3d 413 (CA6 2007); United States
v. Miller, 161 F. 3d 977, 987 (CA6 1998); United States v.
Phillip, 948 F. 2d 241, 250 (CA6 1991). Accordingly, I see
no good reason for remanding to the District Court rather
than the Court of Appeals. And if the majority has such a
reason, it is one that it has chosen to keep to itself.
                       *   *     *
  For these reasons, I would vacate the decision of the
Court of Appeals and remand to that court.




——————
Brady claim was procedurally defaulted, but the State’s supporting
arguments have shifted. Whether the question of procedural default
described in this opinion should be entertained under the particular
circumstances here is an intensely fact-bound matter that should be
left for the Sixth Circuit on remand.
                 Cite as: 556 U. S. ____ (2009)            1

                    THOMAS, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

                         No. 07–1114
                         _________________


   GARY BRADFORD CONE, PETITIONER v. RICKY 

               BELL, WARDEN

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF 

            APPEALS FOR THE SIXTH CIRCUIT

                        [April 28, 2009] 


   JUSTICE THOMAS, with whom JUSTICE SCALIA joins,
dissenting.
   The Court affirms Gary Cone’s conviction for beating an
elderly couple to death with a blunt object. In so doing,
the majority correctly rejects Cone’s argument that his
guilty verdict was secured in violation of his rights under
Brady v. Maryland, 373 U. S. 83 (1963). The majority
declines, however, to decide whether the same evidence
that was insufficient under Brady to overturn his convic
tion provides a basis for overturning his death sentence.
The majority instead remands this question to the District
Court for further consideration because it finds that the
Court of Appeals engaged in a “summary treatment” of
Cone’s Brady sentencing claim. See ante, at 25–27.
   I respectfully dissent. The Court of Appeals’ allegedly
“summary treatment” of Cone’s sentencing claim does not
justify a remand to the District Court. Cone has failed to
establish “ ‘a reasonable probability that, had the evidence
been disclosed to the defense, the result of the [sentencing]
proceeding would have been different,’ ” Kyles v. Whitley,
514 U. S. 419, 435 (1995) (quoting United States v. Bagley,
473 U. S. 667, 682 (1985) (opinion of Blackmun, J.)). As a
result, I would affirm the judgment of the Court of Ap
2                           CONE v. BELL

                         THOMAS, J., dissenting

peals. 1
                                I
   This case arises from a crime spree 28 years ago that
began with Cone’s robbery of a jewelry store in Memphis,
Tennessee, and concluded with his robbery of a drugstore
in Pompano Beach, Florida. Along the way, Cone shot a
police officer and a bystander while trying to escape the
first robbery, attempted to shoot another man in a failed
carjacking attempt, unsuccessfully tried to force his way
into a woman’s apartment at gunpoint, and murdered 93
year-old Shipley Todd and his 79-year-old wife, Cleopatra.
When he was tried on two counts of first-degree murder in
1982, Cone’s sole defense was that he did not have the
requisite intent to commit first-degree murder because
he was in the grip of a chronic amphetamine psychosis.
The jury rejected the defense and convicted Cone of both
murders.
   At sentencing, the Tennessee jury found beyond a rea
sonable doubt that four statutory aggravating factors
applied to Cone’s offense: (1) Cone had been convicted of
one or more previous felonies involving the use or threat of
violence; (2) he had knowingly created a great risk of
death to two or more persons other than the victim during
his act of murder; (3) the murder was especially heinous,
atrocious or cruel in that it involved torture or depravity of
mind; and (4) the murder was committed for the purpose
of avoiding a lawful arrest. Tr. 2151–2152 (Apr. 23, 1982);
see also State v. Cone, 665 S. W. 2d 87, 94–96 (Tenn.


——————
   1 Because I would affirm on the basis of the Court of Appeals’ alterna

tive holding below, I do not reach the issues of procedural default
resolved by the majority. See United States v. Atlantic Research Corp.,
551 U. S. 128, 141, n. 8 (2007); Ayotte v. Planned Parenthood of North
ern New Eng., 546 U. S. 320, 332 (2006); Ardestani v. INS, 502 U. S.
129, 139 (1991).
                    Cite as: 556 U. S. ____ (2009)                   3

                        THOMAS, J., dissenting

1984). Tenn. Code Ann. §39–2-203(i) (1982).2 Cone ar
gued to the jury at sentencing that his “capacity . . . to
appreciate the wrongfulness of his conduct or to conform
his conduct to the requirements of the law was substan
tially impaired as a result of mental disease or defect or
intoxication which was insufficient to establish a defense
to the crime but which substantially affected his judg
ment.” See §39–2-203(j)(8). But the jury found that nei
ther this, nor any other mitigating factor, outweighed the
aggravating factors. The jury, as required by Tennessee
law, unanimously sentenced Cone to death. See §39–2
203(g).
   For almost three decades, Cone’s case has traveled
through the Tennessee and federal courts. This Court has
twice reversed decisions from the Court of Appeals that
invalidated Cone’s conviction and sentence. See Bell v.
Cone, 535 U. S. 685 (2002); Bell v. Cone, 543 U. S. 447
(2005) (per curiam). On remand from this Court’s latest
decision, the Court of Appeals directly considered whether
a handful of police reports, law enforcement bulletins, and
notes that were allegedly withheld from Cone’s trial attor
neys could have changed the result of Cone’s trial or sen
tencing. And, for the second time, the Court of Appeals
held that there was not a “ ‘reasonable probability’ ” that
the evidence would have altered the jury’s conclusion “that
Cone’s prior drug use did not vitiate his specific intent to
murder his victims and did not mitigate his culpability
sufficient to avoid the death sentence.” 492 F. 3d 743, 757
(CA6 2007). The Court of Appeals, therefore, held that
neither Cone’s conviction nor his sentence was invalid.
——————
  2 The Tennessee Supreme Court later concluded that the record in

Cone’s case was doubtful as to evidence supporting the second circum
stance given the lapse in time between the initial events of the escape
and the Todd murders. Cone, 665 S. W. 2d, at 95. The court, however,
determined that the existence of the other three factors rendered any
possible error in this factor harmless beyond a reasonable doubt. Ibid.
4                       CONE v. BELL

                     THOMAS, J., dissenting

See ibid.; Cone v. Bell, 243 F. 3d 961, 968 (CA6 2001). We
should affirm the Court of Appeals and put an end to this
litigation.
                               II
    According to the majority, the Court of Appeals’ decision
affirming Cone’s death sentence is too “summary,” ante, at
25, and the facts are such that, on further examination,
Cone “might” be able to demonstrate that it is “possible”
that the contested evidence would have persuaded the jury
to spare his life, ante, at 25–26. On this reasoning, the
majority remands the case directly to the District Court
for “full consideration [of] the merits of Cone’s [sentencing]
claim.” Ante, at 27. I disagree on all counts. Remanding
the sentencing issue to the District Court is an “unusual
step” for this Court to take. House v. Bell, 547 U. S. 518,
557 (2006) (ROBERTS, C. J., concurring in judgment in part
and dissenting in part). Furthermore, in this case, it is a
step that is legally and factually unjustified. There is not
“ ‘a reasonable probability that, had the evidence been
disclosed to the defense, the result of the proceeding would
have been different.’ ” Kyles, 514 U. S., at 433–434 (quot
ing Bagley, 473 U. S., at 682 (opinion of Blackmun, J.)).
                            A
  The majority’s criticism of the Court of Appeals’ alleg
edly “summary treatment” of the sentencing question is
misplaced. Before the Court of Appeals, Cone dedicated
eight pages of his opening brief to arguing that the impli
cated evidence was material to his guilt or innocence, but
spent only one paragraph arguing its materiality to his
death sentence. See Brief for Appellant in No. 99–5279
(CA6), pp. 40–48. The Court of Appeals’ focus on the guilt
phase, rather than the sentencing phase, simply followed
Cone’s lead. See 492 F. 3d, at 755 (“In his most recent
brief, claiming that his receiving the withheld evidence
                     Cite as: 556 U. S. ____ (2009)                     5

                         THOMAS, J., dissenting

would have resulted in a different sentence, Cone has
made only conclusory arguments”).3        There is nothing
defective about a judicial decision that summarily rejects
an abbreviated legal argument, especially where, as here,
the burden of proving the materiality of the contested
evidence was on Cone.4
                             B
  In remanding this matter to the District Court, the
majority makes two critical errors—one legal and one
factual—that leave the false impression that Cone’s Brady
claim has a chance of success. First, the majority states
that “[i]t is possible that the suppressed evidence” may
have convinced the jury that Cone’s substance abuse
played a mitigating role in his crime and “[t]he evidence
might also have rebutted the State’s suggestion” that
Cone’s experts were inaccurately depicting the depth of his
drug-induced impairment. Ante, at 26 (emphasis added);
see also ante, at 26–27 (remanding “[b]ecause the evidence
suppressed at Cone’s trial may well have been material to
the jury’s assessment of the proper punishment in this
case” (emphasis added)). But, as the majority implicitly
——————
  3 The assertion by the majority, ante, at 26, n. 19, and JUSTICE ALITO,

ante, at 8 (opinion concurring in part and dissenting in part), that the
Court of Appeals did not address the merits of the sentencing issue at
all is flatly wrong. See 492 F. 3d, at 757 (rejecting Cone’s Brady claim
because the proffered evidence would not have altered the jury’s con
clusion “that Cone’s prior drug use did not vitiate his specific intent to
murder his victims and did not mitigate his culpability sufficient to
avoid the death sentence” (emphasis added)).
  4 The majority does not attempt to justify its remand by contending

that it is necessary because the record is insufficient to decide the
claim. Nor could it persuasively contend a remand is necessary so that
the District Court can hold an evidentiary hearing. Such a hearing
would shed no additional light on the trial proceedings or the relative
impeachment value of the withheld documents. Cone himself agrees
that “this Court should resolve the merits of [his] Brady claim.” Reply
Brief for Petitioner 24; see also Brief for Respondent 26–27.
6                       CONE v. BELL

                     THOMAS, J., dissenting

acknowledges, see ante, at 26, n. 19, this is not the correct
legal test for evaluating a Brady claim: “The mere possibil
ity that an item of undisclosed information might have
helped the defense, or might have affected the outcome of
the trial, does not establish ‘materiality’ in the constitu
tional sense.” United States v. Agurs, 427 U. S. 97, 109–
110 (1976) (emphasis added).
   Rather, this Court has made clear that the legal stan
dard for adjudicating such a claim is whether there is a
“reasonable probability” that the jury would have been
persuaded by the allegedly withheld evidence. Kyles,
supra, at 435; Bagley, supra, at 682 (opinion of Blackmun,
J.). It simply is not sufficient, therefore, to claim that
“there is a reasonable possibility that . . . testimony might
have produced a different result . . . . [P]etitioner’s burden
is to establish a reasonable probability of a different re
sult.” Strickler v. Greene, 527 U. S. 263, 291 (1999) (em
phasis in original). To satisfy the “reasonable probability”
standard, Cone must show that “the favorable evidence
could reasonably be taken to put the whole case in such a
different light as to undermine confidence” in the jury’s
sentencing determination. Kyles, supra, at 435. The
Court must view the record “as a whole,” Sawyer v.
Whitley, 505 U. S. 333, 374 (1992) (STEVENS, J., concur
ring in judgment), and determine whether the absence of
the disclosure prevented Cone from receiving “ ‘a trial
resulting in a [sentence] worthy of confidence.’ ” Strickler,
supra, at 290 (quoting Kyles, 514 U. S., at 434).
   In the context of this case, for Cone to establish “ ‘a
reasonable probability that, had the evidence been dis
closed to the defense, the result of the [sentencing] pro
ceeding would have been different,’ ” id., at 435, he must
not only demonstrate that the withheld evidence would
have established that he was substantially impaired as a
result of drug abuse or withdrawal; Cone also must estab
lish that the addition of the allegedly withheld evidence
                      Cite as: 556 U. S. ____ (2009)                     7

                         THOMAS, J., dissenting

ultimately would have led the jury to conclude that any
mitigating factors (including substantial impairment)
outweighed all of the established aggravating factors. See
Tenn. Code Ann. §39–2-203(g).5
   Second, the majority incorrectly claims that to prevail
on his Brady claim, Cone must demonstrate simply that
the withheld evidence supported the inference that he
“was impaired by his use of drugs around the time his
crimes were committed.” See ante, at 21. This is factually
inaccurate because there was already significant evidence
of Cone’s drug use at trial. To establish that the allegedly
withheld evidence would reasonably have had any impact
on his case, Cone must instead show that the evidence
would have supported his claim of substantial mental
impairment from drug use.
   There was extensive evidence at trial that supported the
inference that Cone was not only a longstanding drug
user, but that he was in fact using drugs at the time of his
crimes. The State itself presented significant evidence on
this point. For example, it presented proof that officers
found marijuana cigarette butts, empty drug vials, and
loose syringes in the car that Cone abandoned immedi
ately after the jewelry store robbery. Tr. 1505–1509 (Apr.
19, 1982). The State also did not challenge testimony from
Cone’s mother that Cone used drugs. Id., at 1647, 1648–
1653 (Apr. 20, 1982). And, most tellingly, the State intro
duced evidence that Cone was abusing three drugs—
——————
  5 The majority asserts that the standard under Tennessee law for

demonstrating mental defect or intoxication as a mitigating factor at
sentencing is “far lesser” than the standard for demonstrating insanity
in the guilt phase of a criminal trial. Ante, at 25. But the mitigating
factor still requires a showing that Cone’s mental capacity was “sub
stantially impaired” as a result of mental defect. Tenn. Code Ann. §39–
2-203(j)(8). In any event, the only authority cited by the majority for its
assertion that the standard is “far” lesser than that for insanity is
JUSTICE STEVENS’ lone dissent in a prior appeal in this case. Ante, at
25.
8                           CONE v. BELL

                         THOMAS, J., dissenting

cocaine, Dilaudid, and Demerol—at the time of his arrest
and was suffering “slight withdrawal symptoms” from
them. Id., at 1915–1916, 1920 (Apr. 22, 1982). As the
Court of Appeals explained, “[i]t would not have been news
to the jurors, that Cone was a ‘drug user.’ ” 492 F. 3d, at
757.6
   In contrast, what was contested by the State during
trial was Cone’s defense that his drug use was so signifi
cant that it caused him to suffer from extreme ampheta
mine psychosis at the time of the murders. One of Cone’s
expert witnesses, a neuropharmacologist, testified that by
the summer of 1980, when the crimes occurred, Cone was
ingesting “ferociously large doses” of drugs and that his
increasing tolerance and use of amphetamines caused a
chronic amphetamine psychosis. Tr. 1736–1737, 1744–
1747, 1758–1759 (Apr. 21, 1982). The expert further
testified that if a person with chronic amphetamine psy
chosis were to go into withdrawal, he could suffer extreme
mood swings, “a crashing depression,” and a state of weak
ness so severe that “he could barely lift himself.” Id., at
1857–1859. In this expert’s view, these symptoms could
cause a person to “lose his mind.” Id., at 1859.
   The State contradicted that testimony with significant
——————
    6 Althoughthere were two occasions during closing arguments where
prosecutors intimated that Cone was not a drug user, see Tr. 2014–
2015, 2068 (Apr. 22, 1982), the State’s argument otherwise consistently
focused on the real issue in the case: that Cone was not so significantly
affected by his drug use around the time of his crimes that he was “out
of his mind” or “drug crazy” during the critical days of August 1980.
See id., at 2023–2024, 2071–2084. The majority’s focus on two brief
excerpts from the State’s closing argument fails to faithfully view the
record “as a whole” for purposes of a Brady analysis. See Sawyer v.
Whitley, 505 U. S. 333, 374 (1992) (STEVENS, J., concurring in judg
ment); see also Strickler v. Greene, 527 U. S. 263, 290–291 (1999)
(finding no reasonable probability of a different result even when
prosecutor’s closing argument relied on testimony that could have been
impeached by withheld material).
                 Cite as: 556 U. S. ____ (2009)            9

                    THOMAS, J., dissenting

evidence that Cone did not act like someone who was “out
of his mind” during the commission of his crimes. Rather,
the State argued, Cone behaved rationally during his
initial Tennessee robbery, his subsequent escape, his
flight from Tennessee to Florida after the Todd murders,
his Florida robbery, and his subsequent arrest. See, e.g.,
id., at 2074–2084 (Apr. 22, 1982). To substantiate this
argument, the State called FBI Special Agent Eugene
Flynn to the stand. Agent Flynn testified that, when
captured, Cone coherently detailed his travel from Ten
nessee to Florida, explained his efforts to evade detection
by shaving his beard and buying new clothes, and initi
ated negotiations for a plea bargain. Id., at 1918–1921.
The State also presented testimony from a friend of
Cone’s, Ilene Blankman, that she saw no indication that
Cone was under the influence of drugs or severe with
drawal in the days immediately following the murder of
the Todds. Id., at 1875–1876, 1882–1883 (Apr. 21, 1982).
   Viewing the record as a whole, then, it is apparent that
the contested issue at trial and sentencing was not
whether Cone used drugs, but rather the quantity of
Cone’s drug use and its effect on his mental state. Only if
the evidence allegedly withheld from Cone was relevant to
this question whether Cone suffered from extreme am
phetamine psychosis or other substantial impairment
would the evidence have been exculpatory for purposes of
Brady. See Order Denying Motion for Evidentiary Hear
ing and Order of Partial Dismissal, Cone v. Bell, No. 97–
2312–M1/A (WD Tenn., May 15, 1998), App. to Pet. for
Cert. 119a, n. 9 (explaining that “the issue at trial was not
whether Cone had ever abused any drugs (he clearly had),
but whether he was out of his mind on amphetamines at
the time of the murders”); Tr. 2115–2116 (Apr. 23, 1982).
                          III
  With the legal and factual issues correctly framed, it
10                     CONE v. BELL

                    THOMAS, J., dissenting

becomes clear that Cone cannot establish a reasonable
probability that admission of the evidence—viewed either
individually or cumulatively—would have caused the jury
to alter his sentence.
                             A
                             1
  Cone first argues that he was improperly denied police
reports that included witness statements regarding Cone’s
behavior around the time of his crime spree. The first
statement was given by a convenience store employee,
Robert McKinney, who saw Cone the day before he robbed
the Tennessee jewelry store. When asked whether Cone
appeared “to be drunk or high on anything,” McKinney
answered, “[w]ell he did, he acted real weird . . . he just
wandered around the store.” App. 49. But McKinney
subsequently clarified that Cone “didn’t sound drunk” and
that the reason Cone attracted his attention was because
he “wasn’t acting like a regular customer”; he was “just
kinda wandering” around the store. Motion to Expand the
Record in No. 97–2312–M1 (WD Tenn.), Exh. 2, pp. 3, 4.
Contrary to the majority’s assertion, this interview is not
convincing evidence “that Cone appeared to be ‘drunk or
high’ ” when McKinney saw him. Ante, at 21. McKinney’s
clarification that he had characterized Cone’s behavior as
“weird” because Cone appeared to be killing time rather
than acting like a normal shopper undermines the impli
cation of McKinney’s earlier statement that Cone looked
“weird” because he might have been drunk or on drugs.
Thus, there is little chance that McKinney’s statement
would have provided any significant additional evidence
that Cone was using drugs, let alone provide sentence
changing evidence that he was substantially impaired due
to amphetamine psychosis.
  The second statement was given by Charles and Debbie
Slaughter, who both witnessed Cone fleeing from police
                  Cite as: 556 U. S. ____ (2009)           11

                     THOMAS, J., dissenting

after the jewelry store robbery and reportedly told police
that he looked “wild eyed.” App. 50. Cone had just robbed
a jewelry store, shot a police officer and a bystander, and
was still fleeing from police when seen by the Slaughters.
It is thus unlikely that their observation of a “wild eyed”
man would have been interpreted by the jury to mean that
Cone “was suffering from chronic amphetamine psychosis
at the time of the crimes,” ante, at 21, n. 16, rather than to
mean that Cone looked like a man on the run.
   The third statement is contained in a police report
authored by an officer who helped apprehend Cone after
the Florida drugstore robbery. He reported that he saw a
suspect “at the rear of Sambos restaurant. Subject was
observed to be looking about in a frenzied manner and also
appeared to be looking for a place to run.” App. 53. Noth
ing in this police report either connects Cone to drug use
or appears otherwise capable of altering the jury’s under
standing of Cone’s mental state at the time of the crimes.
It certainly makes perfect sense that Cone was “looking
about in a frenzied manner,” ibid.; he had just robbed a
drugstore and was about to engage in a gun battle with
police in order to evade arrest. The police officer’s descrip
tion of Cone’s appearance under these circumstances thus
does not “undermine confidence” in Cone’s sentence.
Kyles, 514 U. S., at 435.
                             2
  The next category of documents that Cone relies upon to
establish his Brady claim are police bulletins. Some of the
bulletins were sent by Memphis Police Sergeant Roby to
neighboring jurisdictions on the day of the Todd murders
and the day after. The bulletins sought Cone’s apprehen
sion and alternatively described him as a “drug user” or a
“heavy drug user.” App. 55–58. Cone asserts that he
could have used these bulletins to impeach Sergeant
Roby’s trial testimony that the sergeant did not see any
12                         CONE v. BELL

                        THOMAS, J., dissenting

track marks when visiting Cone in jail a week later. Tr.
1939 (Apr. 22, 1982). Cone’s reasoning is faulty for two
key reasons. First, Sergeant Roby never testified that
Cone was not a drug user. His only trial testimony on this
point was simply that he observed no “needle marks” on
Cone’s arm when taking hair samples from him a few days
after Cone’s apprehension. Ibid. Second, the bulletins
establish only “that the police were initially cautious
regarding the characteristics of a person who had commit
ted several heinous crimes.” App. to Pet. for Cert. 119a, n.
9. The bulletins would not have tended to prove that the
fugitive Cone was, in fact, a heavy drug user—let alone
“out of his mind” or otherwise substantially impaired due
to amphetamine psychosis—at the time of his crimes.7
                              3
  Cone also argues that material was withheld that could
have been used to impeach Ilene Blankman’s testimony
that Cone did not appear to be high or in withdrawal when
she helped him obtain a Florida driver’s license during his
efforts to evade arrest in Florida. Tr. 1875–1882 (Apr. 21,
1982). But he again fails to meet the standard for excul
patory evidence set by Brady.
  Cone first points to police notes of a pre-trial interview
with Blankman, which did not reflect the statement she
gave at trial that she saw no track marks on Cone’s arm.
App. 72–73. But Blankman was questioned at trial about
——————
   7 Alert bulletins sent by the FBI similarly identified Cone as a “be

lieved heavy drug user” or a “drug user.” App. 62–70. Cone argues
that these bulletins could have been used to impeach FBI Agent Flynn’s
testimony about Cone’s arrest in Florida. The bulletins would not have
constituted material impeachment evidence, however, for the second
reason identified above. In addition, the bulletins would not have
contradicted any of FBI Agent Flynn’s testimony; he in fact stated at
trial that Cone reported using three drugs and was undergoing mild
drug withdrawal when he was captured in Florida. Tr. 1915–1916
(Apr. 22, 1982).
                  Cite as: 556 U. S. ____ (2009)            13

                     THOMAS, J., dissenting

her failure to initially disclose this fact to police, Tr. 1903
(Apr. 21, 1982), so the jury was fully aware of the omis
sion. Disclosure of the original copy of the police notes
thus could not have had any material effect on the jury’s
deliberations. Moreover, the missing notes also recorded a
damning statement by Blankman that Cone “never used
drugs around” her and she “never saw Cone with drug
paraphernalia.” App. 73. Thus, it is difficult to accept
Cone’s argument that he would have benefited from the
introduction of notes from Blackman’s pretrial interview.
If anything, these police notes would have undermined his
mitigation argument.
   Cone next relies on a report that describes a woman’s
confrontation with the prosecution team and Blankman at
a restaurant during trial. During the encounter, the
woman accused Blankman of lying on the stand in order to
frame Cone for the murders. Id., at 74–75. The report
indicates that the prosecutors politely declined the
woman’s numerous attempts to discuss the merits of the
case and that Blankman said nothing. Id., at 75. Nothing
about this encounter raises doubts about Blankman’s
credibility.
   Last, Cone points to “correspondence in the district
attorney’s files suggest[ing] that the prosecution had been
unusually solicitous of [Blankman’s] testimony.” Brief for
Petitioner 45. But the correspondence was completely
innocuous. One of the notes, sent in response to Blank
man’s request for a copy of her prior statement, expressed
to Blankman that her “cooperation in this particular
matter is appreciated.” App. 76. The prosecutor then sent
a letter to confirm that Blankman would testify at trial.
Id., at 77. And finally, after trial, the prosecutor sent a
note to inform Blankman of the verdict and indicate that
they “certainly appreciate[d] [her] cooperation with [them]
in the trial of Gary Bradford Cone.” Id., at 78. There is
nothing about these notes that “tend[s] to prove any fact
14                     CONE v. BELL

                    THOMAS, J., dissenting

that is both favorable to Cone and material to his guilt or
punishment.” App. to Pet. for Cert. 116a.
                               B
   Viewing the record as a whole, Cone has not come close
to demonstrating that there is a “reasonable probability”
that the withheld evidence, analyzed individually or cu
mulatively, would have changed the result of his sentenc
ing. Much of the impeachment evidence identified by
Cone is of no probative value whatsoever. The police
bulletins do not contradict any of the trial testimony; the
restaurant encounter was innocuous; and the correspon
dence sent by prosecutors to Blankman does not under
mine her testimony or call Cone’s mental state into doubt.
If the remaining evidence has any value to Cone, it is
marginal at best. There was testimony that Blankman
did not initially tell police that Cone lacked track marks.
See Tr. 1903 (Apr. 21, 1982). McKinney clarified in his
statement that Cone’s activity in the store was consistent
with a person killing time, not the use of drugs or alcohol.
And the behavior described by the Slaughters and the
Florida police officer is more naturally attributable to the
circumstances of Cone’s flight from the police than to any
inference that Cone was “out of his mind” or otherwise
substantially impaired due to amphetamine psychosis.
   Countering the trivial value of the alleged Brady mate
rial is the clear and overwhelming evidence that during
Cone’s crime spree, he was neither sufficiently insane to
avoid a conviction of murder nor substantially impaired by
his drug use or withdrawal-related psychosis. There was
substantial evidence that Cone carefully planned the
jewelry store robbery and was calm in carrying it out, Tr.
at 974–976, 1014 (Apr. 16, 1982), 1350–1352 (Apr. 17,
1982), 1501 (Apr. 19, 1982), 2075 (Apr. 22, 1982); that he
successfully eluded police after engaging them in a shoot
out, id., at 1053–1064 (Apr. 16, 1982); that, after hiding
                 Cite as: 556 U. S. ____ (2009)           15

                    THOMAS, J., dissenting

overnight, he concocted a ruse to try to gain illegal entry
to a residence, id., at 1205–1208 (Apr. 17, 1982); that he
murdered the Todds after they declined to cooperate with
his efforts to further elude police, id., at 1681 (Apr. 20,
1982); that he took steps to change his appearance at the
Todd residence and then successfully fled to Florida, id., at
1918–1919 (Apr. 22, 1982); that he arrived in Florida
exhibiting no signs of drug use or severe withdrawal, id.,
at 1875–1882 (Apr. 21, 1982); that he obtained false iden
tification in a further effort to avoid apprehension, id., at
1881–1882, and that he denied any memory lapses and
described undergoing only minor drug withdrawal when
police arrested him, id., at 1919–1920 (Apr. 22, 1982).
Given this wealth of evidence, there is no “reasonable
probability” that the jury would have found that Cone was
entitled to the substantial impairment mitigator had the
evidence he seeks been made available to him.
   And even if Cone could have presented this evidence to
the jury at sentencing and established an entitlement to
this mitigator, he still has not demonstrated a reasonable
probability that it would have outweighed all of the aggra
vating factors supporting the jury’s death sentence. See
id., at 2151–2154 (Apr. 23, 1982). In its decision on direct
appeal, the Tennessee Supreme Court was well aware of
the evidence regarding the “degree and extent of [Cone’s]
drug abuse.” Cone, 665 S. W. 2d, at 90. As part of its
required independent review of whether the mitigation
evidence was sufficiently substantial to outweigh the
aggravating factors, see Tenn. Code Ann. §39–2-205, the
Tennessee court nevertheless concluded that the sentence
was “not in any way disproportionate under all of the
circumstances, including the brutal murders of two elderly
defenseless persons by an escaping armed robber who had
terrorized a residential neighborhood for twenty-four
hours.” 665 S. W. 2d, at 95–96. None of Cone’s proffered
evidence places that conclusion, made by both the jury and
16                     CONE v. BELL

                    THOMAS, J., dissenting

the Tennessee Supreme Court, “in such a different light as
to undermine confidence” in Cone’s sentence. Kyles, 514
U. S., at 435; see also Strickler, 527 U. S., at 296.
                            IV
  This Court should not vacate and remand lower court
decisions based on nothing more than the vague suspicion
that error might be present, or because the court below
could have been more clear. This is especially so where, as
here, the record before the Court is adequate to evaluate
Cone’s Brady claims with respect to both the guilt and
sentencing phases of his trial. The Court’s willingness to
return the sentencing issue to the District Court without
any firm conviction that an error was committed by the
Court of Appeals is inconsistent with our established
practice and disrespectful to the lower courts that have
considered this case. Worse still, the inevitable result will
be years of additional delay in the execution of a death
sentence lawfully imposed by a Tennessee jury. Because I
would affirm the judgment below, I respectfully dissent.
