                              In the
    United States Court of Appeals
                For the Seventh Circuit
                           ____________

No. 03-1067
CLYDE PIGGIE,
                                             Petitioner-Appellant,
                                  v.

ZETTIE COTTON,Œ
                                            Respondent-Appellee.
                           ____________
         Appeal from the United States District Court for the
          Northern District of Indiana, South Bend Division.
               No. 3:02cv0379—Allen Sharp, Judge.
                           ____________
SUBMITTED JULY 23, 2003—DECIDED SEPTEMBER 15, 2003ŒŒ
                     ____________


    Before CUDAHY, POSNER, RIPPLE, Circuit Judges.
  CUDAHY, Circuit Judge. Inmate Clyde Piggie appeals
from the denial of his petition for a writ of habeas corpus
under 28 U.S.C. § 2254 seeking relief from three convic-


Œ
  Zettie Cotton, the warden of the Pendleton Correctional Center
where Piggie is presently confined, has been substituted for
Daniel McBride as respondent pursuant to Fed. R. App. P.
43(c)(2).
ŒŒ
    After an examination of the briefs and the record, we have
concluded that oral argument is unnecessary. Thus, the appeal is
submitted on the briefs and the record. See Fed. R. App. P.
34(a)(2).
2                                                No. 03-1067

tions by the disciplinary board at Indiana’s Maximum
Control Facility. We affirm the district court’s judgment
except as to Piggie’s due process claim that he was denied
access to a videotape of the incident underlying his con-
viction for battery. As to that claim, we vacate and re-
mand for further proceedings.


                       Background
  Piggie’s three convictions stem from several acts of
insubordination during a two-day period in March 2001.
The first incident occurred on the afternoon of March 11,
when Piggie refused to return his food tray. Correctional
officer Sergeant Monzon approached Piggie’s cell and
ordered him to “cuff up.” As far as we can tell, such an order
meant for Piggie to place his hands through an opening in
his cell door so that he could be handcuffed and that
Monzon could enter the cell safely. According to Sergeant
Monzon, however, Piggie refused to comply with this or-
der. Piggie says that Sergeant Monzon did not open the
cuffport to his cell. Shortly thereafter a five-member
“extraction team” assembled outside Piggie’s cell. Piggie
again was ordered to cuff up, and again he refused. The
team, accompanied by an officer with a video camera, then
entered Piggie’s cell and attempted to restrain him. Piggie
resisted, allegedly shoving one of the officers, Officer Grott.
The following evening, on March 12, Piggie again refused
to return his food tray when ordered to do so by prison staff.
  Piggie was charged with “refusing to obey an order” for
defying both the March 11 order to cuff up and the March
12 order to return his food tray, and with “battery” for
pushing Officer Grott. Piggie denied all three charges,
requesting statements from numerous witnesses includ-
ing an inmate named Judge Merriweather. But, accord-
ing to a form prepared by Piggie’s screening officer,
Merriweather refused to provide a statement. Piggie also
No. 03-1067                                                3

asked that the prison’s Conduct Adjustment Board view
videotapes of the three incidents.
  The CAB found Piggie guilty of both refusing-to-obey
charges at a hearing on March 22, 2001, and imposed a 60-
day restriction on his telephone and recreation privileges.
The CAB heard Piggie’s battery case the following week
and found him guilty based on Officer Grott’s conduct re-
port and corroborating statements from the other mem-
bers of the extraction team. The CAB’s written decision
in the battery case also indicates that it reviewed the
videotape, but does not state what, if anything, the video-
tape revealed. The CAB recommended that 180 days of
Piggie’s good time credits be revoked and that he be
demoted from credit earning class I to III. Piggie ap-
pealed, but the administrative tribunals affirmed his
convictions. The prison superintendent did, however, reduce
Piggie’s punishment by increasing his credit-earning class
from class III to II.
  Piggie then filed this habeas corpus petition under § 2254,
claiming that the three disciplinary proceedings did not
comport with due process because (1) he was denied
the right to call inmate Merriweather as a witness; (2)
the CAB refused to view, or permit him access, to the
videotapes; (3) the evidence was insufficient to support
his convictions; and (4) the CAB committed these due
process violations in retaliation for his litigiousness. In
addition, Piggie moved to compel the state to produce
the videotapes and asked that the district court inspect
them in camera. The district court denied Piggie’s mo-
tions as premature, since the state had not yet responded
to the petition. After the state submitted its response, the
district court denied Piggie’s petition, concluding that his
challenge to the two refusing-to-obey convictions was
moot because the sanctions imposed had expired and, in
any event, the loss of telephone and recreation privileges
did not implicate a liberty interest protected by due pro-
4                                               No. 03-1067

cess. As for the battery conviction, which resulted in a
loss of earned good time and a reduction in credit-earn-
ing class, the court concluded that the CAB hearing sat-
isfied due process because the record revealed that
Merriweather had refused to provide a statement, and
that the CAB had examined the videotape, which Piggie
had no right to view himself because the Supreme Court
has never extended the rule of Brady v. Maryland, 373
U.S. 83 (1963), to prison disciplinary proceedings. The
court therefore did not require the state to submit the
tape for in camera review. Moreover, the court found
that “some evidence” supported the CAB’s finding that
Piggie committed battery.


                         Analysis
  As an initial matter, we decline Indiana’s invitation
to revisit our decision in Walker v. O’Brien, 216 F.3d 626
(7th Cir. 2000). Thus, although no certificate of appeal-
ability has been issued, we turn to the merits of Piggie’s
appeal.
  On appeal Piggie renews the arguments rejected by the
district court that his CAB hearing on the battery charge
did not satisfy due process. Piggie has a liberty interest
in earned-credit time and his credit-earning class, and
therefore was entitled to due process before either could
be taken away. Piggie v. McBride, 277 F.3d 922, 924 (7th
Cir. 2002). In the prison disciplinary context, due process
requires only that the prisoner receive advance written
notice of the charges, see Wolff v. McDonnell, 418 U.S. 539,
564 (1974), an opportunity to present testimony and
documentary evidence to an impartial decision-maker, id.
at 566, 570-71, and a written explanation for the discipline,
id. at 564, that is supported by “some evidence” in the
record, see Superintendent, Mass. Corr. Inst. v. Hill, 472
No. 03-1067                                               5

U.S. 445, 454-55 (1985); Webb v. Anderson, 224 F.3d 649,
652 (7th Cir. 2000).
  Piggie first insists that he was denied the right to call
Merriweather as a witness to defend against the battery
charge. Inmates have a due process right to call witnesses
at their disciplinary hearings when doing so would be
consistent with institutional safety and correctional goals,
Wolff, 418 U.S. at 566, but there is no right to call wit-
nesses whose testimony would be irrelevant, repetitive,
or unnecessary, Forbes v. Trigg, 976 F.2d 308, 317-18
(7th Cir. 1992). Indiana maintains that Piggie was not
denied the opportunity to call Merriweather as a witness—
Merriweather simply refused to cooperate. In support,
Indiana points to a form prepared by a screening offi-
cer indicating that Merriweather refused to provide a
statement. Piggie, however, submitted an affidavit from
Merriweather that directly contradicts this assertion.
Merriweather avers that he was asked to be a witness
in Piggie’s battery case, that he dated and signed the
appropriate form and returned it in his “mailbag,” and
that he never told the screening officer that he would
not provide a statement. Thus, we agree with Piggie that
whether or not Merriweather refused to cooperate is in
dispute.
  This controversy does not warrant further considera-
tion, however. Conspicuously absent from Merriweather’s
affidavit is any indication of what his testimony might
have been or how it would have aided in Piggie’s defense.
Nor does Piggie himself explain how Merriweather’s
testimony would have helped him. Therefore, even if
this factual dispute were to be resolved in Piggie’s favor,
we are unable to see how Piggie was harmed by the screen-
ing officer’s alleged conduct. See Powell v. Coughlin,
953 F.2d 744, 750 (2d Cir. 1991) (harmless error analysis
applies to prison disciplinary proceedings). Thus, the dis-
6                                               No. 03-1067

trict court properly denied relief on Piggie’s due pro-
cess claim relating to inmate Merriweather.
  Piggie next argues that the CAB refused to view, or
permit him to watch, the videotape of the cell extraction,
which, he says, would have shown that he did not hit
Officer Grott. Although Piggie is correct that the CAB
could not arbitrarily refuse to consider potentially exculpa-
tory evidence, see Piggie, 277 F.3d at 925, his assertion
that the CAB refused to do so here is speculative at best.
He says that a CAB member named Lieutenant Gambriel
who did not end up hearing his case watched the video-
tape, while the deciding CAB members did not. But the
CAB’s hearing report lists the videotape as evidence that
it considered; the CAB specifically checked the box next
to “physical evidence” relied on and wrote in “videotape.”
And during his administrative appeals Piggie admitted
that the CAB viewed the tape during his hearing, stating
that “S.G.T. Picken turned the videotape on for (10) seconds
then turned it off. Piggie objected to it. The CAB said
step out.” According to Piggie, the first ten seconds of the
video did not show the cell extraction, and the CAB did not
watch the rest of the tape. He does not, however, explain
how he has personal knowledge of what the CAB reviewed
after he was ushered from the room, and his conjecture
is insufficient to overcome the other evidence in the rec-
ord. See, e.g., Prewitt v. United States, 83 F.3d 812, 819
(7th Cir. 1996). The district court therefore did not err in
denying Piggie relief on this facet of his due process claim
concerning the videotape.
  However, Piggie also contends that having been ex-
cluded from the room, he was unable to show the CAB
where on the videotape to look and, thus, was precluded
from presenting evidence favorable to his defense. We
have held that the rule of Brady v. Maryland, 373 U.S. 83
(1963), requiring the disclosure of material exculpatory
evidence, applies to prison disciplinary proceedings. See
No. 03-1067                                                 7

Chavis v. Rowe, 643 F.2d 1281 (7th Cir. 1981). In Chavis,
we explained that the function of the Brady rule in prison
disciplinary proceedings, as in criminal cases, is twofold: to
insure that the disciplinary board considers all of the
evidence relevant to guilt or innocence and to enable the
prisoner to present his or her best defense. See id. at 1286.
Accordingly, an inmate is entitled to disclosure of mate-
rial, exculpatory evidence in prison disciplinary hearings
unless such disclosure would unduly threaten institutional
concerns. Id. at 1285-86; see also Piggie, 277 F.3d at
925; Campbell v. Henman, 931 F.2d 1212, 1214-15 (7th
Cir. 1991); Young v. Kann, 926 F.2d 1396, 1403 (3d Cir.
1991).
  The district court acknowledged this authority, but
concluded that Brady did not warrant disclosure of the
tape to Piggie because the Supreme Court had not held
that the Brady rule applied in prison disciplinary cases.
This was error. At one time this court had suggested that
prisoners challenging the decision of a disciplinary board
must find support in decisions of the Supreme Court
in order to obtain habeas corpus relief pursuant to 28
U.S.C. § 2254(d), see Sweeney v. Parke, 113 F.3d 716, 718-19
(7th Cir. 1997); Evans v. McBride, 94 F.3d 1062, 1065 (7th
Cir. 1996), and because the Supreme Court had not ex-
tended the Brady rule to prison disciplinary cases, Brady
could not provide a foundation for relief, see Gaither v.
Anderson, 236 F.3d 817, 819-20 (7th Cir. 2000) (per curiam).
But we have since held that prison disciplinary boards
are not “courts” for purposes of 28 U.S.C. § 2254(d), and
expressly disapproved of any language to the contrary
in Gaither, Sweeney, and Evans. See White v. Ind. Parole
Bd., 266 F.3d 759, 765-66 (7th Cir. 2001).
  Based on this erroneous conclusion, the district court,
without conducting an in camera review to evaluate
whether the video was, in fact, exculpatory as Piggie
claims or assessing whether the state had a legitimate
8                                              No. 03-1067

security reason to withhold the tape in any event, deter-
mined that Piggie was not entitled to view the videotape.
Piggie would not have been entitled to disclosure under
Brady if his viewing the tape would entail a security risk,
and we have had no trouble approving of non-disclosure
where prison officials have asserted a bona fide security
justification, for example, that if the inmate were permit-
ted to watch the tape, he might learn the location and
capabilities of the prison surveillance system, thus allow-
ing him to avoid detection in the future. Gaither, 236 F.3d
at 820. But here Indiana has not yet asserted that any
such risk to prison security would have resulted from
allowing Piggie to watch the tape of the cell extraction.
Rather, in its brief, Indiana simply states that “having the
offender excluded from the room is consistent with the
Department of Correction’s procedure of keeping security
tapes confidential.” We have never approved of a blanket
policy of keeping confidential security camera videotapes
for safety reasons, see id. at n.1, and the logistics of the
prison surveillance system are not at issue here because,
as Piggie points out, he knew he was being videotaped
during the extraction by an officer carrying a hand-held
camera. Thus, the state has not yet advanced any security
reason for withholding the tape.
  Nor can we say, on this record, that the CAB’s refusal
to give Piggie access to the videotape was harmless. Al-
though Brady compels only the disclosure of material
evidence that is favorable to the accused, see Gaither, 236
F.3d at 820; Rasheed-Bey v. Duckworth, 969 F.2d 357, 362
(7th Cir. 1992), the record here does not demonstrate
with any degree of certainty that the tape lacked exculpa-
tory value or was otherwise irrelevant. The CAB’s hearing
report is silent as to the contents of the tape, and a post-
hearing memorandum from Lieutenant Gambriel to
Piggie states that he “could not clearly see Offender
Piggie commit battery” on the video, which suggests, at
No. 03-1067                                                 9

least, that the tape was not inculpatory as to the battery. In
such a case, we have said that “[m]inimal due process
requires that the district court conduct an in camera re-
view . . . to determine whether or not exculpatory infor-
mation existed.” Campbell, 931 F.2d at 1215. But here, as
we noted previously, the district court did not order
the state to submit a copy of the videotape for in camera
review. Without some idea of what is on the tape, we
cannot evaluate the merits of Piggie’s claim that his de-
fense was hampered by not being given access to it.
  On remand, the district court should answer one, and
perhaps two, questions. First, did the state have a valid
security reason for failing to disclose the tape and, second,
if not, did the tape contain exculpatory information?
Finally, if the answer to this second question is affirma-
tive, was the error harmless?
  We therefore AFFIRM in part and VACATE and REMAND
in part for further proceedings consistent with this opinion.

A true Copy:
       Teste:

                        ________________________________
                        Clerk of the United States Court of
                          Appeals for the Seventh Circuit




                   USCA-02-C-0072—9-15-03
