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

No. 06-2148
ESTEBAN MONTAÑO, DAVID MENDEZ, JULIO PERALES,
RICARDO RUIZ, and YESENIA MENDEZ,
                                               Plaintiffs-Appellants,
                                  v.


CITY OF CHICAGO, et al.,
                                               Defendants-Appellees.
                          ____________
             Appeal from the United States District Court
        for the Northern District of Illinois, Eastern Division.
           No. 97 C 8035—Samuel Der-Yeghiayan, Judge.
                          ____________
        ARGUED JUNE 7, 2007—DECIDED JULY 23, 2008
                          ____________


  Before BAUER, ROVNER, and SYKES, Circuit Judges.
  SYKES, Circuit Judge. This civil-rights suit against the
City of Chicago and several of its police officers is before
this court for the third time. The plaintiffs seek recovery
for injuries they received when police confronted and
forcibly arrested them during Mexican Independence
Day festivities in Chicago in September 1997. They
asserted numerous claims for relief against the City
and the individual officers under 42 U.S.C. § 1983 and
several state-law theories. The case has been before four
2                                               No. 06-2148

different district court judges and three appellate panels
and has a correspondingly long and complicated pro-
cedural history. We will simplify the litigation story
where we can.
   The last time the case was here, we vacated the dis-
trict court’s dismissal of the plaintiffs’ federal and state-
law claims as procedurally improper and remanded for
further proceedings. On remand, the district court again
dismissed the claims, this time as a sanction for abuse of
the judicial process, specifically, perjury by some of the
plaintiffs. The plaintiffs now appeal that order and also
seek review of two earlier orders granting: (1) mid-trial,
a Rule 50(a) judgment as a matter of law in favor of
six officers on certain of the false-arrest, excessive-force,
and unlawful strip-search claims under § 1983; and
(2) summary judgment in favor of the City on the plain-
tiffs’ claim under Monell v. Department of Social Services,

(1978), and in favor of seven officers on
various false-arrest and failure-to-intervene claims.
   We affirm in part and reverse in part. Summary judg-
ment was properly granted on the Monell claim and
the false-arrest and failure-to-intervene claims. As the
officers now concede, however, the entry of the Rule 50(a)
judgment was improper; with two exceptions discussed
below, there was sufficient evidence to submit those
claims to the jury. Finally, as to the claims that survived
the Rule 50(a) judgment but were mistried and later
dismissed as a sanction for perjury, we agree with the
plaintiffs that the imposition of this penalty was unwar-
ranted. The district court’s perjury findings were en-
tirely conclusory and failed to correspond to the legal
definition of perjury. The supposed instances of perjury
identified by the court—certain inconsistencies between
No. 06-2148                                              3

the plaintiffs’ deposition and trial testimony—amounted
to impeachment evidence but nothing more.


                     I. Background
  The plaintiffs allege flagrant mistreatment by Chicago
police officers during and after the celebration of
Mexican Independence Day in Chicago’s Little Village
neighborhood on September 14, 1997. The five plaintiffs
were forcibly arrested and jailed following an alterca-
tion between officers and several celebrants on the corner
of 25th and Whipple. The plaintiffs describe the incident
as a violent police-initiated beating followed by illegal
arrests and strip searches at the station house; the City
and the officers deny any wrongdoing. A more detailed
description of the incident (some of which was caught
on videotape by a bystander) and the detentions that
followed it can be found in our earlier opinion in this
case, Montaño v. City of Chicago, 

, 594-95
(7th Cir. 2004) (“Montaño I”), and will not be repeated
here. To understand the present appeal, however, we
think it necessary to recount the messy procedural
history of this long-running lawsuit.
  In November 1997 the plaintiffs filed a nine-count
complaint against 16 (later amended to 21) officers and
the City of Chicago. Five counts (excessive force, false
arrest, malicious prosecution, failure to intervene, and
conspiracy) were federal claims under 42 U.S.C. §§ 1983
and 1985, including a count against the City based on
Monell; the other four were related state-law claims. After
initially being assigned to Judge Aspen and then trans-
ferred to visiting Judge Moody in September 1998, the
case was transferred again in November 2000, this time
4                                                 No. 06-2148

to visiting Judge O’Meara. On September 25, 2001, the
court granted summary judgment to the City on the
Monell claim and to individual officers on many of the
federal claims.1 The court also relinquished jurisdiction
over the state-law claims, which the plaintiffs promptly
refiled in state court.
  The federal claims left standing—for use of excessive
force (against Officers Atilano, LaFrancis, Toolis, and
Lopez), false arrest (against Officers Atilano and
LaFrancis), and unlawful strip search (against Offi-
cers Maduzia and Lambert)—proceeded to jury trial in
November 2001 but got no further than the close of the
plaintiffs’ case-in-chief. The district court granted the
officers’ motion for judgment as a matter of law pursu-
ant to Rule 50 of the Federal Rules of Civil Procedure on all
but two counts. The court then declared a mistrial on the
two remaining counts: Montaño’s excessive-force claim
against Officer Lopez and Yesenia Mendez’s strip-search
claim against Officer Lambert. Before the two claims
could be retried, however, the court stayed the case
pending resolution of the state-court proceedings.
 In December 2001 the plaintiffs appealed the sum-
mary judgment and the Rule 50 judgment, but a motions


1
  Seven officers were granted summary judgment on all
claims based on their complete or partial lack of involvement
in the plaintiffs’ arrest and detention; all remaining officers
were granted summary judgment on the § 1983 and § 1985
claims for malicious prosecution, conspiracy, and denial of
medical treatment. Five officers (Zalewski, Predis, Skol,
Maresso, and Tamez) were also granted summary judgment
based on their qualified immunity from plaintiff Yesenia
Mendez’s false-arrest and excessive-force claims, and the false-
arrest claims of Julio Perales, Ricardo Ruiz, and David Mendez.
No. 06-2148                                                 5

panel of this court dismissed the appeal as premature.
Montaño v. City of Chicago, Nos. 01-4284 & 02-1034, Ct.
Order 2 (7th Cir. Mar. 20, 2002). The panel also dismissed
the plaintiffs’ challenge to the stay order because their
notice of appeal failed to specifically mention it. Id.; see
FED. R. APP. P. 3(c)(1)(B). Finally, the motions panel dis-
missed the officers’ untimely cross-appeal of the stay
order and the order declining supplemental jurisdiction
over the state-law claims. Montaño v. City of Chicago,
Nos. 01-4284 & 02-1034, Ct. Order 2-3 (applying Abbs
v. Sullivan, 

, 925 (7th Cir. 1992)). On March 19,
2002, the district court sua sponte dismissed the two re-
maining federal claims without prejudice pending resolu-
tion of the state-court proceedings. The court refused
the officers’ request to vacate that dismissal order and
the earlier order relinquishing supplemental jurisdiction
over the state-law claims. The officers appealed and a
different panel of this court addressed these issues in
Montaño I.
  The first order of business in Montaño I was to resolve
some thorny issues of appellate 

, 601. On the merits we sided with the officers
and vacated both the March 19 order dismissing the
surviving federal claims and the September 25 order
relinquishing jurisdiction over the state-law claims. 

The result was the reinstatement of Montaño’s
excessive-force claim, Yesenia Mendez’s strip-search
claim, and all of the state-law claims. We also ordered
the case reassigned on remand pursuant to Rule 36 of
the Circuit Rules of the U.S. Court of Appeals for the Seventh
Circuit. 

was reassigned to Judge Der-Yeghiayan. Ten
months later the officers moved for dismissal as a sanc-
6                                               No. 06-2148

tion against the plaintiffs and their attorney. They
claimed the plaintiffs committed perjury and fabricated
certain testimony, and their attorney knowingly offered
such testimony and engaged in other misconduct dur-
ing the jury trial. In addition to dismissal, the officers
sought an award of attorney’s fees and costs against
the plaintiffs’ attorney pursuant to 28 U.S.C. § 1927.
  Invoking its inherent power, the district court granted
the motion for dismissal, concluding that a “drastic
sanction is warranted . . . because if Plaintiffs’ fraud upon
the court were successful it would have had a tremendous
impact on the trial and . . . the lives of the [accused]
officers.” The court further noted that “[t]here was not
simply an isolated instance of perjury, but rather . . . a
coordinated effort by Plaintiffs to present a false version
of the events . . . to support their case.” Although the
judge dismissed what remained of the plaintiffs’ case,
he declined to sanction their attorney. Judge Der-
Yeghiayan was not convinced the attorney knew his
clients “were going to commit perjury,” noting that
“although guilty of some misconduct at trial, [plaintiffs’
counsel] cannot be held accountable for the perjury com-
mitted by Plaintiffs.”
  This appeal is from the district court’s final order dis-
missing the plaintiffs’ federal and state claims with preju-
dice. The plaintiffs also seek review of the court’s orders
granting summary judgment in favor of the City and
certain officers and granting the officers’ mid-trial
Rule 50(a) motion for judgment as a matter of law.


                      II. Discussion
 The plaintiffs argue that the extreme sanction of dis-
missal was unwarranted in this case because the instances
No. 06-2148                                                7

of perjury cited by the district court were merely ambigu-
ities or innocent discrepancies in certain aspects of their
testimony. They also argue the sanction unjustly
punished Yesenia Mendez and David Mendez, neither
of whom were accused of perjury in the officers’ motion
for sanctions. As to the two orders entered by Judge
O’Meara in 2001, the plaintiffs claim the court erred in
(1) granting summary judgment in favor of the City
and certain officers on some of the claims; and (2) en-
tering Rule 50(a) judgment as a matter of law in favor of
certain officers on the claims that went to trial. The plain-
tiffs seek a remand for a new trial before a different
district judge.
  The officers defend the entry of summary judgment, but
as to the claims that went to trial, now concede they
were not entitled to a Rule 50(a) judgment on all but two.
They maintain, however, that the entry of the Rule 50(a)
judgment was harmless error because Judge Der-
Yeghiayan would likely have dismissed those claims as a
sanction for perjury. The officers’ theory assumes the
propriety of the sanction order, which they also defend
on appeal, so we will address that matter first.


A. Dismissal Sanction
  A district court has inherent authority to sanction
conduct that abuses the judicial process. Chambers v.
NASCO, Inc., 

, 44-45 (1991); Dotson v. Bravo,

, 667 (7th Cir. 2003). The sanction imposed
should be proportionate to the gravity of the offense. Allen
v. Chi. Transit Auth., 

, 703 (7th Cir. 2003).
Though “particularly severe,” the sanction of dismissal
is within the court’s discretion. 

.
8                                                No. 06-2148

Our review is deferential. See Divane v. Krull Elec. Co.,

, 1025 (7th Cir. 1999) (noting the trial court’s
“intimate familiarity” with the relevant proceedings). The
imposition of a dismissal sanction is reviewed for abuse
of discretion, and underlying factual findings are re-
viewed for clear error. See 

.
  The plaintiffs suggest we review Judge Der-Yeghiayan’s
sanction order de novo. They argue that deference to
Judge Der-Yeghiayan’s findings and conclusions is inap-
propriate given that the sanctionable conduct alleged by
the officers occurred in 2001 while the case was before
Judge O’Meara. We need not address this subset of the
plaintiffs’ argument, however; the dismissal sanction
was improper even under the more deferential abuse-of-
discretion and clear-error standards.
   As a fraud on the court, perjury may warrant the sanc-
tion of dismissal. 

. We say “may”
because “one can imagine [perjury] cases in which a
sanction of dismissal would be excessive.” 

for a moment the question of whether the sanction
here was proportionate to the gravity of the offense, we
are confronted with the more immediate question of
whether the testimony that formed the basis of the dis-
trict court’s sanction order amounted to perjury in the
first place. In the federal criminal context, perjury is
defined as “false testimony concerning a material matter
with the willful intent to provide false testimony, rather
than as a result of confusion, mistake, or faulty memory.”
United States v. Dunnigan, 

, 94 (1993) (sum-
marizing the elements of 18 U.S.C. § 1621); see also United
States v. Dumeisi, 

, 582 (7th Cir. 2005). After
carefully reviewing the district court’s order and the
relevant portions of the record, we cannot agree that the
conduct cited by the district court satisfies this definition.
No. 06-2148                                                9

  The first flaw in the district judge’s reasoning is that
he failed to apply or even identify any legal definition
of perjury. The second is that he misinterpreted the in-
consistencies in the plaintiffs’ deposition and trial
testimony—inconsistencies of the sort that provide
fertile ground for vigorous impeachment but do not
support perjury findings—as a conspiracy among the
plaintiffs to fabricate testimony.
  The plaintiffs did not admit giving false testimony,
and the court did not mention any direct evidence that
plaintiffs knowingly lied under oath (there is none, as far
as we are aware). Instead, the court simply identified
six specific discrepancies between testimony given by
certain of the plaintiffs in deposition and the testimony
they gave at trial. We assume the court inferred from
these discrepancies that the plaintiffs intentionally lied
at either their depositions or at trial. The transcripts,
however, provide virtually no support for this inference.
True, the plaintiffs’ version of events at trial in 2001
were in certain respects out of sync with the story they
told in their 1999 depositions, but no evidence sug-
gests these inconsistences were willful, material falsehoods.
   The first discrepancy cited by the court involved plain-
tiff Ricardo Ruiz’s trial testimony that he saw arriving
police officers beat plaintiff Esteban Montaño after an
initial altercation between Montaño and other officers
beside a squad car. At his deposition Ruiz testified he
did not think he saw officers doing anything to Montaño
“after more police officers arrived.” These two state-
ments are not necessarily facially inconsistent—both
might be understood to imply that the alleged beating of
Montaño was over by the time the last backup officer
arrived. Moreover, there is simply no evidence to sup-
10                                                No. 06-2148

port the conclusion that Ruiz lied about having seen
officers beat Montaño or suggesting that the altercation
never took place.2 Cf. 

(plaintiff
who admitted lying at his deposition committed perjury).
That Ruiz gave somewhat incongruous accounts of the
sequence, duration, and scope of the altercation is hardly
unusual; inconsistences of this sort are the prototypical
products of “confusion, mistake, or faulty memory.”

; see United States v. Griffin, 

, 1024 (7th Cir. 2002); United States v. Payne, 

, 292 (7th Cir. 1996). These inconsistencies
certainly bear on Ruiz’s credibility—the officers intro-
duced his deposition testimony as impeachment evi-
dence—but in the absence of other evidence of a delib-
erate falsehood do not permit the inference that Ruiz
committed perjury.
  The same holds true for the remaining testimonial
inconsistencies cited by the district court. Montaño
testified at trial that Officer Atilano hit him in the face or
head with a flashlight, yet stated in his deposition that
Officer Atilano tried but failed to hit him in the face after
striking him in the back. This is the sort of discrepancy
that juries routinely sort out; by itself, it does not sup-
port a conclusion that Montaño committed perjury.
Indeed, Montaño had an innocent explanation for
that discrepancy; he chalked it up to faulty memory,
testifying that it was only after his deposition that he


2
  Counsel for the plaintiffs told us at oral argument that the
bystander’s videotape that recorded part of the incident briefly
shows officers hitting Montaño, and the record also con-
tains color photographs of Montaño’s injuries taken after the
September 14, 1997 incident.
No. 06-2148                                              11

remembered being struck in the face by Officer Atilano.
Montaño’s faulty-memory claim hinges on his credibil-
ity—the province of the jury, not the court.
  On direct examination Montaño also denied punching
a police officer—an accusation he later admitted on cross-
examination. Here again, there is no direct evidence that
Montaño knowingly lied when he initially denied punch-
ing the officer. On direct examination, moments after
he denied throwing a punch, Montaño admitted that “one
of my hands got [sic] contact with one of the officers in
front of me.” He later conceded on cross-examination,
after being shown the videotape of the incident, that it
was actually a punch. This sequence of testimony may
tarnish Montaño’s credibility before the jury, but
standing alone is insufficient to support a perjury finding.
   The two testimonial discrepancies attributable to plain-
tiff Julio Perales also fall short of perjury. The first
involves an apparent conflict between his trial testimony
in which he stated that he saw officers “stomp” on plain-
tiff Ricardo Ruiz and his deposition testimony in which
he responded “No” to the question: “Other than [Ruiz
being pushed to the ground and placed in handcuffs],
did you see anything else done to [Ruiz]?” Perales never
affirmatively denied in his deposition that officers
“stomped” on Ruiz; there may or may not be an explana-
tion for his failure to mention that part of the incident at
his deposition. But even if unexplained, this discrepancy,
like the others cited by the district court, is standard-
fare impeachment evidence; it is not, without more,
proof of perjury.
 The second discrepancy involves Perales’s trial testi-
mony that he was strip-searched at the police station.
Confronted on cross-examination with a portion of his
12                                                No. 06-2148

deposition testimony in which he denied being strip-
searched, Perales claimed he did not recall the search
until the day after the deposition. Although Perales’s
explanation strikes us as implausible, or at least more
convenient than persuasive, there is no other evidence to
suggest a deliberate falsehood. The discrepancy alone
is not enough to support a perjury finding.
  The final testimonial discrepancy cited by the district
court concerns David Mendez’s trial testimony about
the sequence of events at the jail after the plaintiffs
were arrested. Montaño claimed he was subjected to a
further beating at the jail. Mendez testified at trial that
he did not look at Montaño when officers returned him
to the lockup. At his deposition, however, he stated that
“at some point” he did look at Montaño but did not
notice anything different about him. David Mendez
attributed that inconsistency to confusion, explaining
that he interpreted “at some point” to mean “some time
later.” In the district court, the officers characterized this
discrepancy as further evidence of litigation “misconduct”
by the plaintiffs; the district judge found it was perjury.
We cannot agree. This sort of testimonial inconsistency
about whether and when Mendez saw a difference in
Montaño’s injuries is routine impeachment evidence;
it does not, by itself, support a finding that Mendez
committed perjury.
  There is a marked difference between a witness who
knowingly lies about a material matter and a witness
who is impeached with a prior inconsistent account of a
sudden and chaotic event that happened years ago. The
former is almost always perjury; the latter may be
the product of confusion, mistake, or faulty memory.
See 

; 

. Inconsis-
No. 06-2148                                                13

tent testimony may amount to perjury if the plaintiffs’
intent was to give false testimony on a material matter,
but the inconsistencies here do not themselves support
an inference of intent to testify falsely. There is no other
evidence to support a finding that these plaintiffs delib-
erately fabricated their testimony. The district court
seized on the fact that Montaño, Ruiz, Perales, and David
Mendez “met and discussed the events of September 14,
1997 on more than ten occasions prior to the trial.” But
when Ruiz was asked at trial whether the purpose of
those meetings was “to get your story straight about
what happened,” he denied it, setting up a routine cred-
ibility question for the jury. The district court cited no
other evidence to support its conclusion that the fore-
going inconsistent passages of testimony constituted
perjury; our own review of the record has disclosed none.
The district court’s perjury findings were clearly errone-
ous, and therefore its dismissal sanction was an abuse
of discretion.
  We note as an aside that even had the record shown
clear evidence of perjury by Montaño, Ruiz, Perales,
and David Mendez, the extreme sanction of dismissal
would be disproportionately severe as to Yesenia
Mendez, against whom no accusations of perjury were
ever leveled. See 

(sanction
should be “proportion[ate] to the gravity of the offense”).
Dismissing her case for the actions of the other four
plaintiffs was an abuse of discretion.3 In addition, large


3
  The district court also cited misconduct by the plaintiffs’
attorney—who repeatedly disobeyed a pretrial evidentiary
order forbidding mention of the video before it was admitted
                                                (continued...)
14                                                 No. 06-2148

portions of the other four plaintiffs’ trial testimony did not
contradict their deposition testimony. A jury could rea-
sonably conclude their testimony was a mix of fact and
fiction. See 

is not a reasonable inference
from a falsehood in one part of a witness’s testimony to
the falseness of the entire testimony.”). Where a wit-
ness’s testimony is “a compound of truth and falsity,”
the prudent course is to permit the jury to sort through
it; “[p]erjury is a circumstance to be weighed by the jury
in determining a witness’s credibility rather than a
ground for removing the issue of credibility from the
jury by treating the witness’s entire testimony as
unworthy of belief.” 

the case with
prejudice, however, the district judge took the credibility
question from the jury—and he did so on the basis of
a paper record from a trial that was (as we will discuss
in a moment) impermissibly cut short. The district court’s
sanction of dismissal with prejudice cannot stand.


B. Rule 50(a) Judgment
  The plaintiffs also claim the district court erred in
granting judgment as a matter of law in favor of six of


3
   (...continued)
at trial—as another reason why the plaintiffs’ claims should
be dismissed, although the court apparently considered this a
minor infraction compared to the plaintiffs’ perjury (it refused
to assess fees and costs under 28 U.S.C. § 1927). Having found
insufficient evidence to support the district court’s perjury
findings, we are unwilling to affirm the sanction of dismissal
based solely on the attorney’s misconduct. In this as in other
contexts, the punishment must fit the crime, Bolt v. Loy,

, 856 (7th Cir. 2000); outright dismissal with
prejudice for this sort of attorney misconduct is excessive.
No. 06-2148                                                15

the officers at the close of the plaintiffs’ case-in-chief.4
Rule 50 authorizes the entry of judgment as a matter of
law if “there is no legally sufficient evidentiary basis for
a reasonable jury to find for that party on that issue.” FED.
R. CIV. P. 50(a)(1) (2001). The officers now concede that
with the exception of two claims, the Rule 50(a) judg-
ment must be reversed. In this context, because “we
‘review judgments, not opinions,’ ” a defendant’s “conces-
sion that the district court erred by granting him judg-
ment [under Rule 50] . . . is enough to require reversal of
the Rule 50 judgment and remand for a new trial.” See
Acevedo v. Canterbury, 

, 723 (7th Cir. 2006)
(citation omitted).
   More specifically, the officers concede that the plain-
tiffs presented sufficient evidence that, if believed, would
permit a reasonable jury to find in their favor on the
following claims: Montaño’s false-arrest claim against
Officers Atilano and LaFrancis; Montaño’s excessive-
force claims against Officers Atilano and Toolis; the
excessive-force claims of Ruiz and David Mendez
against Officer Lopez; the excessive-force claims of
Montaño, Ruiz, and David Mendez against Officer


4
  The court’s written Rule 50 order, dated November 19, 2001,
only names five officers (LaFrancis, Atilano, Toolis, Ferrer,
and Maduzia), but it is clear from the court’s oral statements
that Rule 50 judgment was also granted in favor of Officer
Lopez on David Mendez’s and Ruiz’s excessive-force claims.
We suspect the reason Lopez’s name is omitted from the
November 19 order was because Montaño’s excessive-force
claim against Lopez survived the Rule 50 order (later to be
dismissed as a sanction for perjury), and thus Lopez, unlike
the other five officers, was only awarded partial judgment as
a matter of law under Rule 50.
16                                             No. 06-2148

Ferrer; and the strip-search claims of Montaño, Ruiz, and
Perales against Officer Maduzia. We accept the con-
cession and agree that the Rule 50(a) judgment entered
on these claims must be reversed.
  The exceptions are these: Montaño’s excessive-force
claim against Officer LaFrancis based on an alleged episode
of hair-pulling and David Mendez’s strip-search claim
against Officer Maduzia. As to the latter, David Mendez
conceded he was not subjected to a strip search. As to the
former, the plaintiffs did not cite to record evidence or
otherwise develop their argument on appeal that judg-
ment as a matter of law on this claim was improper. See
Estate of Moreland v. Dieter, 

, 759 (7th Cir.
2005) (We need not “scour the record” for evidence to
support a party’s argument on appeal; perfunctory or
underdeveloped arguments are waived.). Accordingly,
we affirm the Rule 50(a) judgment on these two claims.


C. Summary Judgment
   Finally, the plaintiffs claim the district court erred in
granting summary judgment for the City on the Monell
claim and in favor of seven officers on certain false-
arrest and failure-to-intervene claims. We review de novo
a grant of summary judgment, Payne v. Pauley, 

, 770 (7th Cir. 2003), which is appropriate where the
pleadings, depositions, and other documentary evid-
ence show “no genuine issue as to any material fact and
that the movant is entitled to judgment as a matter of
law.” FED. R. CIV. P. 56(c). Because the City and the
officers were the moving parties, we construe the evid-
ence and any reasonable inferences in favor of the plain-
tiffs. 

.
No. 06-2148                                             17

    1. Claims Against Individual Officers
   Ruiz, Perales, and David Mendez claimed Officers
Atilano and LaFrancis lacked probable cause to arrest them
on suspicion of drinking alcohol in a public way, a
local ordinance violation. CHICAGO, ILL., CODE § 8-4-030
(1999). Because the existence of probable cause is an
absolute defense to a § 1983 false-arrest claim, Mustafa v.
City of Chicago, 

, 547 (7th Cir. 2006), summary
judgment is proper if the record establishes that “at the
moment the arrest was made[,] . . . the facts and circum-
stances within [the officers’] knowledge . . . were suf-
ficient to warrant a prudent [person] in believing”
Ruiz and Mendez committed the offense of drinking in a
public way. Beck v. Ohio, 

, 91 (1964) (defining
probable cause). The undisputed evidence establishes
that the two officers had probable cause to believe Ruiz,
Perales, and Mendez were drinking in the public way.5
  Ruiz admitted he was holding a bottle of beer in the
vicinity of 25th and Whipple when Officers Atilano and
LaFrancis slowly drove west past the intersection. Mendez
also admitted he was holding a bottle of beer when the
two officers turned around and made a second slow
pass of the intersection (this time with their flashlights
on), and that the intersection and a nearby stoop were
strewn with empty beer bottles. An eyewitness also
testified that she saw Ruiz, Mendez, and Perales
standing in the street with beer bottles. All this corrobo-


5
  Perales also claims three other officers arrested him for
disorderly conduct without probable cause. Because we find
that Officers Atilano and LaFrancis had probable cause to
believe Perales was drinking in the public way, however,
we need not separately address this claim.
18                                             No. 06-2148

rates Officer LaFrancis’s statement that when she and
Officer Atilano got out of the squad car (immediately
after making the second pass), they approached a noisy,
apparently intoxicated group of celebrants at the corner
of 25th and Whipple. While many in the group fled upon
the approach of the police, five men who remained
were ordered to put down their beer bottles and place
their hands on the squad car. Ruiz and Perales were
among those five, and Mendez was arrested nearby a
short time later. Officer Atilano also said all three men
were arrested after being seen holding a beer in the
public way, although he did not see Montaño holding
a beer.
  Most important for summary-judgment purposes, none
of these plaintiffs deny holding a beer in view of at least
two officers. The undisputed evidence easily establishes
probable cause to arrest Ruiz, Mendez, and Perales for
drinking in a public way. Summary judgment on these
claims was properly granted.
  Yesenia Mendez also brought a false-arrest claim against
Officers Zalewski and Predis. She claimed the two
officers lacked probable cause to arrest her for dis-
orderly conduct, but her claim is deficient in two
respects. First, the uncontradicted evidence shows that
Officer Predis—Officer Zalewski’s partner—did not
participate in the arrest; he was working crowd control
and first had contact with Mendez when he helped
Zalewski transport her to the squad car after her arrest.
Second, the uncontradicted evidence also establishes
that (1) a crowd had gathered after the initial altercation
at the squad car; (2) Yesenia Mendez repeatedly com-
plained to (and in one instance yelled at) Zalewski
about the treatment of her husband (David Mendez) and
No. 06-2148                                                19

brother (Montaño); (3) Zalewski unsuccessfully ordered
Mendez to leave the scene despite threats of arrest; and
(4) Zalewski believed Mendez was aggravating an al-
ready chaotic and hazardous situation. At the very
least, this is enough to confer qualified immunity, a
defense Zalewski successfully pursued on summary
judgment. See Purtell v. Mason, 

, 621 (7th
Cir. 2008).
  Officers Kusar and Matual were also entitled to sum-
mary judgment on the plaintiffs’ failure-to-intervene
claims. More specifically, the plaintiffs alleged (1) Officer
Kusar failed to stop Officer Toolis from choking Montaño
with a flashlight; and (2) Officer Matual failed to stop
Officer Ferrer from driving the police van in such an
erratic manner as to injure the plaintiffs. While an officer
has a duty under § 1983 “to intervene to prevent a
false arrest or the use of excessive force if the officer is
informed of the facts that establish a constitutional vio-
lation and has the ability to prevent it,” Morfin v. City
of East Chicago, 

, 1001 (7th Cir. 2003), the
plaintiffs have not produced sufficient evidence that either
officer “had reason to know . . . excessive force was
being used . . . and . . . had a realistic opportunity to
intervene to prevent the harm from occurring.” Yang v.
Hardin, 

, 285 (7th Cir. 1994).
  As to Officer Kusar, none of the evidence cited by the
plaintiffs—namely, Montaño’s deposition and the
officers’ statement of undisputed facts—mention that
Kusar was even involved in Montaño’s arrest. While the
officers concede that Kusar may have aided in the arrest,
they deny he did anything improper, and under Rule 56.1
of the Local General Rules of the U.S. District Court for the
Northern District of Illinois, the plaintiffs’ “mere disagree-
20                                              No. 06-2148

ment with the movant’s asserted facts is inadequate
[to defeat summary judgment] if made without reference
to specific supporting material.” Smith v. Lamz, 

, 683 (7th Cir. 2003); see also Behrens v. Pelletier,

, 309 (1996) (“On summary judgment . . . the
plaintiff can no longer rest on the pleadings . . . .”). The
scant record materials referenced in the plaintiffs’ plead-
ings do not mention Kusar. As such, they were not
enough to avert summary judgment.
  As to Officer Matual, the evidence establishes only that
he was a passenger in the police van driven by Officer
Ferrer. The plaintiffs have cited no evidence that Matual
knew Ferrer was intentionally injuring the plaintiffs in
the back of the van or that he had a realistic opportunity
to prevent the alleged harm. 

. That
Matual was a passenger in the van does not by itself
permit the inference that he “was informed of the facts
that establish a constitutional violation and had the
ability to prevent it.” 

. Summary
judgment on this claim was therefore properly granted.


  2. The Monell Claim Against the City
  While a municipality is not vicariously liable under
§ 1983 for the acts of its employees, a constitutional depri-
vation may be attributable to a municipality “when execu-
tion of a government’s policy or custom . . . inflicts the
injury.” 

; Schlessinger v. Salimes,

, 522 (7th Cir. 1996). “In other words, to
maintain a [Monell] claim against a municipality, one
must establish the requisite culpability (a “policy or
custom” attributable to municipal policymakers) and the
requisite causation (the policy or custom was the “moving
No. 06-2148                                                21

force” behind the constitutional deprivation).” Gable v.
City of Chicago, 

, 537 (7th Cir. 2002); see Bd. of
the Co. Comm’rs v. Brown, 

, 404 (1997) (“The
plaintiff must also demonstrate that, through its deliberate
conduct, the municipality was the ‘moving force’ behind
the injury alleged.”). The plaintiffs have produced insuffi-
cient evidence of any actionable policy on the part of the
City of Chicago or its police department, as well as insuf-
ficient evidence that the City was deliberately indifferent
to any widespread constitutional violations by its officers.
  To establish a municipal policy for § 1983 purposes,
plaintiffs must show either (1) an express policy that,
when enforced, causes a constitutional deprivation; or
(2) that the constitutional injury was caused by a person
with final policymaking authority. 

.
The plaintiffs claim the City had an express policy
of condoning excessive force. For support they cite a
decision of the Chicago Police Board that overturned
the suspension of an officer who used a flashlight to
strike a suspect who died shortly thereafter. In that deci-
sion the Police Board concluded the force the officer used
was not excessive because (1) the suspect may have
attacked the officer with a board; (2) the officer feared
for his safety; (3) the suspect died from a cardiac arrhyth-
mia caused by Thorazine and the strain of resisting arrest;
and (4) the officer did not injure the suspect’s brain or
skull. In other words, the Board concluded that the
force used in that specific case was justified. This hardly
establishes a general policy of condoning the use of
excessive force.
  The plaintiffs also argue that City policymakers were
deliberately indifferent to the need for an “early warning”
system to preemptively remove “problem officers” from
22                                              No. 06-2148

the street. To establish municipal “custom” for § 1983
purposes, the plaintiff must show “a widespread prac-
tice that, although not authorized by written law or
express municipal policy, is so permanent and well
settled as to constitute a custom or usage with the force
of law.” 

. Because a municipality is
only liable for deliberate conduct, the plaintiffs must also
show that City policymakers were “deliberate[ly]
indifferen[t] as to [the custom’s] known or obvious con-
sequences.” 

(quotation marks
omitted). “Deliberate indifference” is a “stringent stand-
ard of fault.” 

see also Frake v. City of Chicago,

, 782 (7th Cir. 2000) (stating that a finding
of deliberate indifference requires a showing that
policymakers “were aware of a substantial risk” of a
constitutional violation and “failed to take appropriate
steps to protect [plaintiffs] from a known danger”).
  The plaintiffs’ evidence of deliberate indifference to
“problem officers” is limited to Officer Lopez; this
cannot establish a “widespread practice that . . . is so
permanent and well settled as to constitute a custom or
usage.” 

. The plaintiffs also point to
portions of a 1994-1995 Police Board report noting that
multiple appeals by officers accused of excessive force
unnecessarily prolonged the disposition of internal disci-
plinary proceedings. Rather than establishing deliberate
indifference, this report reflects the Board’s deliberate
attempt to improve (or at least identify) problems in the
police department’s system of adjudicating excessive-
force claims. In short, the plaintiffs presented insufficient
evidence of deliberate indifference to avoid summary
judgment on this claim.
No. 06-2148                                            23

                    III. Conclusion
  For the foregoing reasons, we REVERSE the district
court’s dismissal of the plaintiffs’ claims as a sanction;
those claims are reinstated and REMANDED to the district
court for further proceedings consistent with this opin-
ion. We REVERSE IN PART the district court’s order
granting Rule 50(a) judgment as a matter of law in favor
of certain officers, but AFFIRM IN PART with respect
to David Mendez’s strip-search claim against Officer
Maduzia and Montaño’s excessive-force claim against
Officer LaFrancis. We AFFIRM the district court’s order
granting summary judgment in favor of the City and
certain officers. Circuit Rule 36 shall apply upon remand.




                  USCA-02-C-0072—7-23-08