                               In the

    United States Court of Appeals
                 For the Seventh Circuit
                     ____________________
No. 16-2540
THOMAS R. SOCHA,
                                                Petitioner-Appellant,

                                 v.

REED A. RICHARDSON,
                                               Respondent-Appellee.
                     ____________________

         Appeal from the United States District Court for the
                   Eastern District of Wisconsin.
            No. 08-C-994 — Rudolph T. Randa, Judge.
                     ____________________

  ARGUED SEPTEMBER 6, 2017 — DECIDED NOVEMBER 3, 2017
                     ____________________

   Before WOOD, Chief Judge, and ROVNER and SYKES, Circuit
Judges.
     WOOD, Chief Judge. Thomas Socha has won two battles in
his effort to obtain relief from his Wisconsin conviction for
murder. See Socha v. Pollard, 621 F.3d 667 (7th Cir. 2010) (Socha
I); Socha v. Boughton, 763 F.3d 674 (7th Cir. 2014) (Socha II). He
is now hoping to win the war. Perhaps he would have been
able to do so, if federal courts had plenary authority to review
state-court criminal proceedings. But they do not. Especially
2                                                   No. 16-2540

since the enactment of the Antiterrorism and Effective Death
Penalty Act (AEDPA) in 1996, state prisoners seeking federal
habeas corpus relief have been required to overcome a set of
rules that, in the aggregate, require every benefit of the doubt
to be given to the state courts. Socha would like us to find that
the state prosecutor in his case violated the obligation recog-
nized in Brady v. Maryland, 373 U.S. 83 (1963), to disclose po-
tentially exculpatory evidence to him. But even though the
prosecutor indeed withheld potentially impeaching evidence
from Socha, the state courts concluded that there was no rea-
sonable probability that this evidence would have changed
the verdict. Because this conclusion was not so outlandish as
to be unreasonable, we must affirm the decision of the district
court refusing to issue the writ. See 28 U.S.C. § 2254(d).
                                I
   In November 2001, Socha and his acquaintances, Lance
Leonard and Victor Holm, each forged a stolen check. On
November 17, police officers began asking questions. They
went to Holm’s apartment, seeking Leonard, but Leonard was
not there. Holm agreed to go with them to the stationhouse,
where he admitted his forgery and said that Leonard had also
forged a check. Socha’s name did not come up.
    Accounts of what happened over the next few days differ.
But it is clear that Leonard moved from place to place, avoid-
ing contact with the police. On November 20, 2001, Holm and
his friend, Dennis Drews, drove Leonard from Berlin, Wiscon-
sin, 140 miles or so upstate to Crandon. They arrived at the
house of Holm’s brother, Vincent. Leaving Leonard behind
and armed with a shotgun, Holm, Drews, and Vincent left the
house and dug a grave. Back again at Vincent’s house, Holm
and Drews persuaded Leonard to go on an errand with them.
No. 16-2540                                                  3

The errand turned out to be a fateful one for Leonard. They
drove him to the grave they had just dug, murdered him, and
buried the body. Meanwhile, Socha was back in Berlin party-
ing with Holm’s girlfriend, Beth Mrazik, and making sure that
the two were seen in several bars. That night and early morn-
ing, Holm and Mrazik (and possibly Socha) exchanged mul-
tiple phone calls.
    In the days after November 20, news of the murder
quickly spread. Drews bragged about it to Mrazik, who told
a friend, who in turn informed the police. By December 6,
Holm and Drews were arrested. No one had yet implicated
Socha. That did not happen until a few months later when
Mrazik, Drews, and Holm alleged that Socha was involved in
the plan to kill Leonard. Eventually Mrazik, Drews, and Holm
entered into plea agreements with the state.
    In August 2002, Socha was tried for being a party to the
crime of first-degree intentional homicide. See Wis. Stat.
§§ 940.01, 939.05. The prosecution’s theory of the case identi-
fied Socha as the mastermind, who wanted Leonard dead pri-
marily to ensure that he did not reveal Socha’s drug-dealing
and only secondarily to keep him from telling the police about
the check-forgery scheme. The state presented testimony
from Holm and Drews that, with Socha, they decided that
Leonard had to die. Others testified to seeing the three men in
conversations in the days before the murder. There was also
testimony that Socha behaved suspiciously once the police be-
gan investigating the murder. After a two-day bench trial, the
judge found Socha guilty.
    Meanwhile, on April 11, 2002, the police had interviewed
Roy Swanson, Holm’s cellmate. While the recording and tran-
script of the interview were turned over to Holm’s counsel, a
4                                                   No. 16-2540

slip-up in the prosecution’s office resulted in a failure to turn
them over to Socha. Consequently, Socha was not aware of the
Swanson interview until after his trial. In the interview, Swan-
son discussed his impressions of Holm. He commented that
“[a] lot of times [Holm is] still lying.” He recounted state-
ments exhibiting Holm’s lack of remorse about Leonard’s
death, saying at one point that he “should get a medal for kill-
ing [Leonard].” This was in marked contrast to the perfor-
mance Holm gave at trial, where he was wiping away tears in
supposed contrition. Swanson said that Holm had admitted
that he and Lance “were the ones who stole the checks in the
first place,” and even that Holm confessed that he had “killed
before in Arizona.” Swanson got the impression that Holm’s
accusation of Socha was concocted: Holm, he said, “talked to
his lawyer [who] said, well if you were coerced in any way, or
forced to say something, you know what I’m saying, do some-
thing against your will, you know, that’s a … Oh, and then all
of a sudden a big light bulb pops up on his head and says,
‘Oh, Mexican Mafia and Tom Socha … .’” Nonetheless, Swan-
son’s story was not entirely helpful for Socha. At one point
Swanson went so far as to say that “Tom’s a major player in
the murder.”
    Socha knew about the Swanson interview by the time he
filed his direct appeal and post-conviction motions. Among
other things, he argued that he was entitled to a new trial un-
der Brady because the prosecutor failed to disclose the Swan-
son transcript and recording. The circuit court, presided over
by the judge who had handled the trial, denied his post-con-
viction motions. On December 5, 2006, the Wisconsin Court of
Appeals affirmed the denial of all relief. It dispatched Socha’s
Brady claim in one paragraph, which characterized the Swan-
No. 16-2540                                                    5

son evidence as “inconsequential” and not “very exculpa-
tory.” The Wisconsin Supreme Court denied Socha’s petition
for review.
    Socha then turned to the federal court for habeas corpus
relief under 28 U.S.C. § 2254. The district court dismissed his
petition twice on timeliness grounds, and we reversed twice.
See Socha I, 621 F.3d at 673; Socha II, 763 F.3d at 688. At last
reaching the merits, the district court found no grounds sup-
porting issuance of the writ. We granted a certificate of ap-
pealability limited to the alleged Brady violation. See 28 U.S.C.
§ 2253(c).
                               II
    Socha is entitled to habeas corpus relief under Brady only
if he can show three things: first, that the evidence at issue
was favorable; second, that the evidence was suppressed; and
third, that it was material to his defense. United States v.
Walker, 746 F.3d 300, 306 (7th Cir. 2014). And it is not really
enough just to establish those points; instead, he must show
that the decision of the state courts with respect to the Brady
claim fails to meet the standards set out in AEDPA, 28 U.S.C.
§ 2254(d). AEDPA permits us to issue a writ of habeas corpus
only if the last state court’s decision on the merits (1) “was
contrary to, or involved an unreasonable application of,
clearly established Federal law, as determined by the Su-
preme Court of the United States”; or (2) “was based on an
unreasonable determination of the facts in light of the evi-
dence presented in the State court proceeding.” Id. We do not
lightly assume that the state court erred. Rhodes v. Dittmann,
783 F.3d 669, 674 (7th Cir. 2015). “[I]f we can posit arguments
or theories that could have supported the state court’s deci-
sion, and if fairminded jurists could disagree about whether
6                                                   No. 16-2540

those arguments or theories are inconsistent with Supreme
Court holdings,” we must deny the petition. Kidd v. Lemke, 734
F.3d 696, 703 (7th Cir. 2013).
    Socha contends that we should review the decision of the
Wisconsin Court of Appeals, the last state court to consider
his Brady claim, de novo because it was not “on the merits.” But
this fails to give the state appellate court its due. Its Brady
analysis addresses the prosecutor’s failure to turn over “notes
of a sheriff’s deputy” who interviewed Swanson. Socha thinks
that the “notes” to which it refers are not the same as the
Swanson interview, but instead are notes that an officer took
during Socha’s trial. That dispute is immaterial, because the
state appellate court’s opinion also refers to “Swanson’s inter-
view” and contains a quote from the interview transcript. We
grant that the court’s Brady discussion was brief, but AEDPA
does not require full-blown analysis. The state court did
enough to earn the deference commanded by AEDPA. See
Harrington v. Richter, 562 U.S. 86, 98–100 (2011).
                               A
     With the proper perspective in mind, we turn to the mer-
its. The first question is whether the Swanson interview was
the type of favorable material that engages the prosecutor’s
duty to turn over evidence. The Wisconsin Court of Appeals
disputed Socha’s assertion that the Swanson interview was
“very exculpatory.” The court was right, if “exculpatory”
means only something that suggests innocence. But the Brady
duty reaches impeachment evidence as well. United States v.
Bagley, 473 U.S. 667, 676 (1985); Holland v. City of Chicago, 643
F.3d 248, 255 (7th Cir. 2011). Indeed, a prosecutor must share
impeachment evidence with the defense even if the evidence
partly inculpates the defendant. As the Supreme Court put it
No. 16-2540                                                       7

in Strickler v. Greene, 527 U.S. 263, 282 n.21 (1999), “Brady’s dis-
closure requirements extend to materials that, whatever their
other characteristics, may be used to impeach a witness” (cit-
ing Bagley, 473 U.S. at 676); see also United States v. Rivas, 377
F.3d 195, 199 (2d Cir. 2004) (holding impeachment evidence
was subject to Brady though it had “an inculpatory and an ex-
culpatory effect”).
    Socha’s attorney could have used the Swanson interview
for impeachment. It contained statements that directly contra-
dicted Holm’s testimony (for example, Holm’s comment that
he should get a medal for killing Leonard rebuts the remorse
he described and showed on the witness stand). If Socha had
had access to the interview before the trial, he could have used
it to cross-examine Holm. See Wis. Stat. § 906.13. This is so
even though, for some lines of questioning, Socha would have
been stuck with Holm’s answers, since the transcript would
have been inadmissible as extrinsic evidence on collateral
matters. See Wis. Stat. § 906.08(2). Whether Socha’s counsel for
strategic reasons may have elected not to use the interview
because of the inculpatory statements is a matter of specula-
tion. The point of Brady is to leave that decision with defense
counsel, not to allow the prosecutor to withhold impeach-
ment or direct evidence because she guesses that the defense
would pass on the chance to use it. The Swanson interview
was impeachment evidence falling within Brady’s ambit, and
it was unreasonable for the Wisconsin Court of Appeals to
conclude otherwise. See Bagley, 473 U.S. at 676–77.
                                 B
   That is not enough to win the day for Socha, however. The
next issue is whether the prosecution “suppressed” the Swan-
8                                                   No. 16-2540

son interview. Evidence is considered impermissibly with-
held if “(1) the prosecution failed to disclose the evidence be-
fore it was too late for the defendant to make use of the evi-
dence, and … (2) the evidence was not otherwise available to
the defendant through the exercise of reasonable diligence.”
Harris v. Kuba, 486 F.3d 1010, 1015 (7th Cir. 2007) (citation
omitted).
    The Wisconsin Court of Appeals recognized that the pros-
ecution did not provide the “notes” from the interview to So-
cha prior to his trial. In this Court, the state notes that the
prosecutor’s failure to disclose was inadvertent. That may be
so, but the Supreme Court held in Giglio v. United States, 405
U.S. 150, 154 (1972), it makes no difference “whether the non-
disclosure was a result of negligence or design, it is the re-
sponsibility of the prosecutor.” The state also suggests that we
should make something of the fact that the prosecutor shared
the transcript and recording with Holm’s counsel. But any
such sharing is neither here nor there. Brady does not exempt
a prosecutor from disclosure when the prosecutor has given
evidence to a co-defendant—especially an adversarial co-de-
fendant, as Holm surely was. It is also unrealistic to expect
defense counsel to ask for the transcript of an interview he
knows nothing about. While Socha had received a police re-
port vaguely mentioning a separate interview of Swanson on
a different date, the record is devoid of evidence that he knew
about Swanson’s April 11 statements to Holm. See Boss v.
Pierce, 263 F.3d 734, 740 (7th Cir. 2001) (access to a witness
does not per se mean a reasonably diligent defense lawyer has
access to all the witness’s knowledge). Furthermore, the state
previously conceded that this evidence, if material, would
need to be disclosed to Socha. Tr. 7/7/2005, R. 106–10, at 86–87;
see Crivens v. Roth, 172 F.3d 991, 997 (7th Cir. 1999) (grounding
No. 16-2540                                                    9

its finding that evidence was withheld in part on the state’s
concession that Brady required disclosure). Clearly estab-
lished Supreme Court law requires the conclusion that the
Swanson interview was “suppressed” as Brady uses the term.
                               C
    That brings us to materiality. Evidence is “material” under
Brady “only if there is a reasonable probability that, had the
evidence been disclosed to the defense, the result of the pro-
ceeding would have been different.” Bagley, 473 U.S. at 682.
“A ‘reasonable probability’ is a probability sufficient to under-
mine confidence in the outcome.” Id. Impeachment evidence
is not material if it is “merely cumulative.” United States v.
Dweck, 913 F.2d 365, 371 (7th Cir. 1990). Additional evidence
describing a co-conspirator’s criminal nature may not be ma-
terial when the witness’s credibility has already been im-
pugned. See United States v. Ervin, 540 F.3d 623, 632 (7th Cir.
2008). This is particularly true when the witness who would
be impeached by the evidence at issue was not the only one
to testify about the existence of a conspiracy. See id.
    The Wisconsin Court of Appeals found, as the state trial
court had done, that the Swanson interview was “inconse-
quential.” It first noted that the Swanson interview included
both inculpatory and exculpatory information. Had the excul-
patory portions been introduced into evidence, it is a safe bet
that the state would have introduced the inculpatory state-
ments, such as the one labeling Socha as a “major player” in
the murder. For what it is worth (which may not be very
much), the state judge who conducted the bench trial ruled on
the post-conviction motion that this interview would not have
changed his mind.
10                                                No. 16-2540

    Second, it is not as if the Swanson interview provided the
only fodder for impeaching Holm. To the contrary, there was
ample impeachment evidence against him, including his sig-
nificant criminal history and his guilty plea to the offense of
murder.
    Third, and most importantly, Holm’s testimony was not
the only evidence of Socha’s involvement in the conspiracy.
Even if Holm was the state’s star witness, his testimony did
not stand alone. Other witnesses provided ample evidence to
support a guilty verdict. Most damaging is Drews’s testimony.
He said things such as “[a]nd between me and Victor and
Thomas … Socha and Beth, we decided that Lance needed to
die,” and “See, I remember Tom being there when the deci-
sion was made to kill Lance.” Mrazik testified that she over-
heard Socha say that if they were planning to kill someone
(which she understood meant Leonard), they should use
buckshot. A bartender witnessed a meeting among Socha,
Holm, Drews, and Mrazik at a time just before the murder,
when Socha was allegedly out of town. They fell silent every
time she drew near.
     The state also presented a significant amount of evidence
that Socha acted suspiciously after the police began investi-
gating. A friend testified that Socha got “upset” about Leon-
ard’s murder and was considering leaving town. Mrazik tes-
tified to threats Socha made to her and to Holm. A friend con-
firmed that during one of these encounters, Socha confronted
Holm with a gun. Given the incriminating material in the in-
terview and the significant amount of evidence pointing to
Socha’s guilt aside from Holm’s testimony, the Wisconsin
No. 16-2540                                                  11

Court of Appeals reasonably concluded that any Brady viola-
tion that occurred was not material, in that it did not under-
mine the court’s confidence in the verdict.
                              III
    It is always regrettable to see a failure to comply with an
obligation as basic as the Brady rule, which is hardly new.
Nevertheless, the question before us is only whether the Wis-
consin Court of Appeals acted unreasonably when it found
that the evidence in question was not, on this record, material.
Its conclusion was not unreasonable, and so we AFFIRM the
judgment of the district court denying Socha’s petition for a
writ of habeas corpus.
