                             In the

    United States Court of Appeals
                For the Seventh Circuit
                    ____________________
No. 16-2159
RYAN DEKEYSER, et al.,
                                              Plaintiffs-Appellees,

                                v.

THYSSENKRUPP WAUPACA, INC., doing business as WAUPACA
 FOUNDRY, INC.,
                                    Defendant-Appellant.
                    ____________________

         Appeal from the United States District Court for the
                    Eastern District of Wisconsin.
    No. 1:08-cv-00488-WCG — William C. Griesbach, Chief Judge.
                    ____________________

      ARGUED APRIL 13, 2017 — DECIDED JUNE 22, 2017
                ____________________

   Before POSNER, MANION, and KANNE, Circuit Judges.
   POSNER, Circuit Judge. Before us is an appeal by the de-
fendant (Waupaca for short) in a class action suit brought
against it in a federal district court in Wisconsin on behalf of
a number of the workers that it employs in six foundries that
manufacture ductile and gray cast iron parts for use in the
automotive and other industries. Four of the six foundries
are located in Wisconsin, and the remaining two in Indiana
2                                                  No. 16-2159


and Tennessee. The suit alleges that Waupaca violated the
Fair Labor Standards Act, 29 U.S.C. §§ 201 et seq., by its long-
standing practice of not treating the time that its foundry
workers spend changing clothes and showering on-site at
the end of a foundry shift to be compensable “work” time.
The Act entitles employees to a minimum wage for each
hour they’re “employ[ed]” and a premium wage (1.5 times
their regular wage) for each hour they are “employ[ed]” be-
yond 40 hours in one work week. Id. §§ 206(a), 207(a). The
Act defines “employ” to mean “to suffer or permit to work,”
id. § 203(g), but does not define “work.” But an employee’s
activities at the beginning and end of a work shift may quali-
fy as compensable “work” if necessitated by the nature of
the work even if they are not required by a workplace poli-
cy, DeKeyser v. Thyssenkrupp Waupaca, Inc., 735 F.3d 568, 570–
71 (7th Cir. 2013) (DeKeyser I)—in other words if the activi-
ties are “an integral and indispensable part of the principal
activities for which [the workers] are employed.” Steiner v.
Mitchell, 350 U.S. 247, 256 (1956).
   The plaintiffs allege that they end their shifts covered in a
layer of “foundry dust,” which can irritate the skin and
cause lung disease if inhaled. Changing clothes and shower-
ing immediately after a shift, they argue, is indispensable to
reducing the risk that foundry work poses to their health.
The plaintiffs have also alleged violations of Wisconsin wage
law.
    The Fair Labor Standards Act authorizes collective ac-
tions by employees on behalf of “similarly situated” em-
ployees. 29 U.S.C. § 216(b). Unlike class actions under Fed.
R. Civ. P. 23, collective actions under the FLSA (which for
the sake of simplicity we’ll refer to as class actions—they are
No. 16-2159                                                   3


very similar to the more familiar Rule 23 class actions) re-
quire would-be members of the collectivity to opt in to (i.e.,
voluntarily join) the class. See Espenscheid v. DirectSat USA,
LLC, 705 F.3d 770, 771–72 (7th Cir. 2013). The district judge
in this case ruled that he would “conditionally certify” the
class since the plaintiffs showed a “reasonable basis” for be-
lieving that all the class members were similarly situated—
and then, after discovery, upon a motion by the defendant
for decertification the judge would determine whether the
plaintiffs who had opted in were, in fact, similarly situated
to the existing class members.
    After the district court in 2008 conditionally certified the
plaintiffs’ FLSA collective-action class (consisting of current
and former Waupaca foundry employees at any of the com-
pany’s six foundries), several hundred current and former
Waupaca employees from all three states opted in to the
lawsuit. Waupaca responded by moving to decertify the
class. At the same time the plaintiffs, deciding to proceed
with only Waupaca’s Wisconsin employees, moved to certify
a Rule 23 class just for their Wisconsin state-law claims and
so didn’t oppose the decertification of those Indiana and
Tennessee employees who had previously opted into the
FSLA class. The district judge agreed that a class action on
behalf of just the Wisconsin plaintiffs made sense and certi-
fied a class accordingly, denied Waupaca’s request to decer-
tify the entire FSLA class, and divided the FLSA class—
which included employees from Indiana and Tennessee as
well as from Wisconsin—into three subclasses, one for each
state. The judge then severed the claims of the Indiana and
Tennessee plaintiffs and transferred them to district courts in
their respective states, on the ground that they could be
more efficiently evaluated by such courts. Although this was
4                                                 No. 16-2159


not a final order, Waupaca has appealed to us from it under
Rule 23(f), which permits interlocutory appeals of class-
certification decisions.
   We analyze the two classes together. See Espenscheid v.
DirectSat USA, LLC, supra, 705 F.3d at 772. The plaintiffs ar-
gue that Waupaca should be ordered to give the class mem-
bers overtime pay and back pay for the time they have spent
or are spending on decontamination, as by changing out of
their work clothing and showering in the workplace locker
rooms immediately after their shifts. Not only does the de-
fendant not give these workers overtime pay (that is, pay
equal to 1.5 times of their normal pay) for the time they
spend on decontamination, it pays them nothing for this
time; it doesn’t even record the time, since it considers it
time spent in noncompensable activity. Although it ap-
proves of the workers’ taking the safety measures we’ve
mentioned, it refuses to pay them for the time they spend
taking them.
    Originally the district judge held that it was not a viola-
tion of the Fair Labor Standards Act for Waupaca not to pay
the workers for that time and so granted summary judgment
in favor of the defendant. The plaintiffs appealed, however,
and we reversed and remanded in DeKeyser I, supra, 735 F.3d
at 572, pointing out that decontamination might indeed be
required by the “nature of [the employees’] work,” and that
the district court had erred when it “ignored the ‘sharp dis-
pute’ in the evidence as to the health effects of chemical ex-
posure at Waupaca’s foundries and the impact, if any, that
showering and changing clothes would have on Waupaca
workers.” Id. at 570–71.
No. 16-2159                                                   5


   On remand the district judge ruled that the plaintiffs
would prevail if they “convince the finder of fact that chang-
ing clothes and showering at work will significantly reduce
the risk to the health of the employee.”
    Waupaca contends, though in tension with its encourag-
ing all its foundry workers to take the precautions noted,
that the plaintiffs haven’t met Rule 23’s requirement of iden-
tifying questions of fact common to the class because these
precautions do not reduce the risks of foundry work to the
health of all the workers by the same amount. Waupaca in-
sists that to prevail a plaintiff must provide an individual-
ized analysis of the chemicals that he is exposed to in the
foundry and provide information about his personal medical
background that will demonstrate that changing clothes and
showering on-site would indeed significantly reduce the risk
to his health.
    The company describes the plaintiffs’ evidence as “evi-
dence demonstrating that [the plaintiffs’] claims could not be
proven individually.” But that misunderstands both the
plaintiffs’ evidence and their evidentiary burden. Back in the
district court on remand from the earlier decision by our
court, the plaintiffs hired as an expert witness a certified in-
dustrial hygienist named Thomas Armstrong. He presented
evidence that changing out of one’s work clothes and show-
ering immediately after the standard 8-hour workday in a
foundry reduce an employee’s “foundry dust” skin contam-
ination twelve-fold and by doing so considerably reduce the
risk that such contamination poses to an employee’s health.
He opined that because foundry dust is distributed through-
out the plant any foundry worker could reduce his risk by
changing and showering immediately at the end of his shift.
6                                                 No. 16-2159


Dr. Armstrong acknowledged that there wasn’t enough in-
formation to quantify the precise risks associated with
changing and showering on-site, as opposed to at home
(particularly because ethics rules forbid testing of known
carcinogens on humans), but emphasized the reduction in
risk associated with using a “dirty side/clean side” shower
and locker-room system, by which he meant a configuration
that allows employees to shed their work clothes on one side
of the shower facility, shower in the middle, and dress in
street clothes on the other side. Such a system could hardly
be replicated in the household bathrooms of Waupaca em-
ployees, and it would reduce the risk of employees’ carrying
contaminants such as silica dust and manganese into their
vehicles and homes, where they would endanger themselves
and their families, especially children and elders.
    Waupaca’s rebuttal, hinted at earlier, is that the health
risks must vary across workers because of different expo-
sures to chemicals and different medical histories of differ-
ent workers and that as a result some workers may derive no
significant health benefits from showering and changing
clothes right after the end of the work day in the foundry,
and therefore should not be entitled to be paid for the time
they spend doing so. But the company has not identified any
such workers. Nor has it challenged Dr. Armstrong’s expert
testimony as inadmissible under Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993), and his report im-
plies that the reduction in risk from conducting the decon-
tamination activities at work would dwarf any variation in
risk based on particular individual exposures or medical his-
tory. Whether a jury will credit Dr. Armstrong’s report is a
separate question, but the district court did not err in con-
cluding that the plaintiffs have produced common evidence
No. 16-2159                                                    7


tending to prove their common assertion, as Rule 23 and sec-
tion 216(b) require.
    One more issue remains to be considered. Waupaca ar-
gues that the district court erred by severing the FLSA
claims of the plaintiffs from Indiana and Tennessee who had
opted in to the lawsuit and transferring those claims to their
respective home districts. Although the district court’s plan
to sever and transfer was laid out in the district court’s class
certification order, Rule 23(f) appeals are limited to “those
issues related to [the] class certification decision.” Andrews v.
Chevy Chase Bank, 545 F.3d 570, 576 n. 2 (7th Cir. 2008). It’s
true that the non-Wisconsin plaintiffs had been conditionally
certified, so in a sense the district court “decertified” them
from the FLSA class. But Waupaca doesn’t challenge that as-
pect of the order by arguing that the Indiana and Tennessee
plaintiffs should be added back into the FSLA class; it simp-
ly wants the claims of the non-Wisconsin plaintiffs dis-
missed. The district court’s plan to sever and transfer the
non-Wisconsin plaintiffs to their home districts does not
bear on the soundness of the class certification decision for
the Wisconsin plaintiffs, so Waupaca cannot challenge it on a
Rule 23(f) appeal, and did not obtain certification to appeal
under 28 U.S.C. § 1292(b). See Union Oil Co. of California v.
John Brown E & C, 121 F.3d 305, 311 (7th Cir. 1997). In any
event there was nothing wrong with what the district court
did—28 U.S.C. § 1404(a) gives a district court discretion to
transfer a civil action to any other district or division where
it might have been brought if the transfer is “for the conven-
ience of parties and witnesses, [and] in the interest of jus-
tice.”
8                                                  No. 16-2159


   Unfortunately the end of this protracted litigation, which
began in June 2008—almost nine years ago—is not yet in
sight. The district court has certified the plaintiff class, now
limited to Wisconsin plaintiffs, under Rule 23 and section
216(b), but has yet to determine whether the time spent
changing clothes and showering is indeed “work” time
compensable under the FLSA or, if it is, what damages the
members of the plaintiff class are entitled to, to compensate
them for Waupaca’s failure to have paid them for that time.
Those determinations presumably will require a trial. For
now we simply affirm the district court’s certification deci-
sion.
                                                     AFFIRMED.
No. 16-2159                                                   9

    MANION, Circuit Judge, concurring. Before us on appeal is
a district court order granting Rule 23 class certiﬁcation for
Wisconsin opt-ins at four Waupaca foundries located within
the Eastern District of Wisconsin and partially granting the
defendant’s motion to decertify the FLSA class for opt-ins
outside Wisconsin. I write separately for two reasons. First,
I reiterate my concerns about permitting class certiﬁcation in
this case, and to examine the plaintiﬀs’ legal theory which
enables the Wisconsin claims to move forward on a class-wide
basis. Second, I would like to caution against overreading
today’s majority as an endorsement of a novel sever-and-
transfer procedure not before this court.
    As I noted in dissent the last time this case was on appeal,
and as the majority notes today, this is an old case. DeKeyser
v. Thyssenkrupp Waupaca, 735 F.3d 568, 572 (7th Cir. 2013).
Many employees have undoubtedly left Waupaca, and it will
be extraordinarily diﬃcult to identify which former
employees spent how much, if any, uncompensated time
donning and doﬃng. Individual cases would be hard enough
to prove, and determining damages for an “average” worker
will likely be next to impossible. This high evidentiary
burden is compounded by the legal theory underlying the
commonality of the class. Plaintiﬀs have a common claim
under Rule 23 and the FLSA only to the extent that they were
all potentially harmed by Waupaca foundries so inundated
with cupola dust that “the only reasonable thing” for each
worker to do, “given the potential of exposure to materials
known to be dangerous, is to shower and change clothes at
work.” DeKeyser v. Thyssenkrupp Waupaca, Inc., No. 08-C-0488
(E.D. Wis. March 31, 2016). As the district court further noted,
“the jury or other factﬁnder will not be required to accept
Plaintiﬀ’s expert’s opinion with respect to the dangerousness
10                                                         No. 16-2159

of working in Waupaca’s foundries.” The plaintiﬀs have thus
committed themselves to the claim that all workers in the four
Wisconsin plants were put in equal danger from the cupola
dust. So whether a worker did a night shift on the factory
ﬂoor or oﬃce work during the day, plaintiﬀs have raised class
claims certiﬁable under the FLSA and Rule 23. I thus agree
with the majority that the part of the district court order
granting class certiﬁcation for the Wisconsin claims was
proper. 1
    But I caution against reading today’s decision as an
endorsement of the irregular procedure employed in the case
cited by the plaintiﬀs, Medina v. Happy’s Pizza Franchise, LLC,
No. 10 C 3148 (N.D. Ill. Feb. 3, 2012). In this case, the district
judge only partially decertiﬁed the Tennessee and Indiana
groups of opt-ins because the theory of certiﬁcation for those
two subclasses will likely be substantially diﬀerent from the
class certiﬁed for the Wisconsin plaintiﬀs. Those two
subclasses will have leave to amend their complaints. The
single decertify-sever-and-transfer order employed in
Medina, by contrast, would often result in the district judge
stepping outside his role as an adjudicator between two
parties. Here, FLSA subclasses are distinguished solely on the
basis of the state residency of the plaintiﬀs.
    Thus while it probably would be an abuse of discretion to
partially decertify FLSA claims and immediately transfer those
actions in a manner unsupported by the statute, that is not
what is happening here. District judges retain “wide

1
  I do not think that Waupaca’s compliance with OSHA’s mandate that
they simply recommend that their employees change clothes and shower
is really not “in tension” with its central argument that doing so was not
necessary to safely working at their foundries.
No. 16-2159                                                    11

discretion to manage collective actions.” Alvarez v. City of
Chicago, 605 F.3d 445, 449 (7th Cir. 2010). Further, civil actions
may be transferred under 28 U.S.C. § 1404(a) for “the
convenience of the parties and witnesses [where it is] in the
interest of justice.” In this case, there has not yet been a
transfer order. These claims are going back to the district
court, where an amended complaint will be ﬁled for each
subclass of claims.      On remand, the district judge and
defendants will have a ﬁrst bite at the apple in determining
whether there are suﬃciently pleaded allegations to sustain a
cause of action for this subclass, and whether the subclass is
certiﬁable under the FLSA or Rule 23. If the district judge
determines that these cases can go forward, or decides to
certify or transfer these cases, there will be additional
opportunities to appeal. All that is before us now is the partial
decertiﬁcation order: all we have decided is that the
Tennessee and Indiana subclasses do not have suﬃcient
claims in common with the Wisconsin subclass to proceed as
a single action. We have not decided that the Tennessee or
Indiana subclasses have suﬃcient internal coherence to
themselves be certiﬁable as classes. Such a decision, best left
for the Tennessee or Indiana district courts, is down the road.
    Undoubtedly, this case is a mess, and has gone on for far
too long. While I concur that it was not an abuse of discretion
to certify the Wisconsin plaintiﬀs under Rule 23, or to partially
decertify the Indiana and Tennessee plaintiﬀs under the
FLSA, I caution against overreading today’s majority as an
endorsement of a novel procedure for avoiding local bars to
relief.
