United States Court of Appeals

For the Eighth Circuit 

___________________________

No. 22-2348

___________________________ 

James Cody

 Plaintiff - Appellee

Vincent Grover; John Doe; John Roe

 Plaintiffs 

Michael Mosley; Diedre Wortham, on behalf of themselves and all others similarly 

situated; Callion Barnes; Eddie Williams; Jasmine Borden

 Plaintiffs - Appellees

v.

City of St. Louis, for and on behalf of Medium Security Institution

 Defendant - Appellant

____________

Appeal from United States District Court 

for the Eastern District of Missouri - St. Louis

____________ 

Submitted: January 10, 2024

Filed: June 3, 2024

____________ 
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Before SMITH, Chief Judge,1 GRUENDER and SHEPHERD, Circuit Judges. 

____________

SHEPHERD, Circuit Judge.

In this civil rights case, Plaintiffs seek damages for the allegedly inhumane 

conditions experienced at the City of St. Louis’s Medium Security Institution (MSI). 

To that end, Plaintiffs sought certification of classes of pre-trial and post-conviction 

detainees at MSI. After the district court denied their first motion to certify, 

Plaintiffs returned with new proposed classes and renewed their motion. The district 

court granted the renewed motion, and the City now appeals, challenging both the 

decision to certify and several of its procedural aspects. We reverse the certification 

of the classes and remand for proceedings consistent with this opinion.

I. 

The named Plaintiffs2 in this case are all former pre-trial or post-conviction 

detainees at MSI—a facility with a checkered past that closed in 2021 following 

action by St. Louis’s political leaders. Plaintiffs allege that they were subjected to 

inhumane conditions at MSI, in violation of the Eighth and Fourteenth Amendments. 

After suing the City for damages under 42 U.S.C. § 1983, they sought to represent 

classes of pre-trial and post-conviction detainees. Plaintiffs asserted that both 

categories of detainees were subjected to unconstitutionally poor physical conditions 

in the form of extreme temperatures, mold, faulty plumbing, and pest infestations, 

and unconstitutionally inadequate operations in the form of understaffing, 

inadequate recreation time, and the excessive use of force.

1

Judge Smith completed his term as chief judge of the circuit on March 10, 

2024. See 28 U.S.C. § 45(a)(3)(A).

2

James Cody, Jasmine Borden, Michael Mosley, Diedre Wortham, Callion 

Barnes, and Eddie Williams. 
-3- 

Plaintiffs first moved to certify four classes under Federal Rule of Civil 

Procedure 23(b)(3).

3

 Two were defined as all pre-trial and all post-conviction

detainees “who were or will be released from MSI on or after November 13, 2012.” 

And two were “heat” subclasses, defined as all members of the pre-trial and 

post-conviction detainee classes “who were assigned to a dorm, pod, or other area at 

MSI in which the internal temperature equaled or exceeded 88 degrees Fahrenheit.” 

While Plaintiffs’ motion to certify was pending, the City and Plaintiffs both 

filed motions to exclude from evidence at trial the opinions, testimony, and reports 

of the other’s experts concerning standards of care for prisons and the City’s 

compliance therewith. As relevant here, Plaintiffs sought to present the opinions of 

James Balsamo, an environmental health and safety consultant with experience 

investigating correctional institutions, and Eldon Vail, a former correctional 

administrator. Balsamo used City records and National Weather Service data to 

calculate heat indexes for MSI, covering the hottest months of 2016 and 2017. He 

opined about the risks that excessively high temperatures created for inmates, and 

how those risks were exacerbated by inmates’ underlying medical conditions or 

prescription medications. Vail opined about MSI’s policies and practices relating to 

facility conditions and compared them to standards set by national bodies. The City 

argued that Balsamo’s opinions should be excluded pursuant to Daubert4 because he 

relied on improper data in calculating the heat indexes and because he is not a 

medical doctor and is therefore not qualified to opine about medical risks posed by 

conditions at MSI. It also argued that Vail’s opinions about facility temperatures 

were based on Balsamo’s own unreliable opinions.

3

Plaintiffs also sought certification under Rule 23(b)(1), which the district 

court denied, and which is not at issue on appeal. See Wal-Mart Stores, Inc. v. 

Dukes, 564 U.S. 338, 362 (2011) (“[I]ndividualized monetary claims belong in Rule 

23(b)(3).”). 

4

Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993). 
-4- 

Before ruling on the parties’ motions to exclude the expert testimony, the 

district court denied Plaintiffs’ motion to certify the four classes. It reasoned that 

certification was inappropriate because of the open-ended class periods and because 

it was undisputed that the City improved the conditions at MSI over that time, for 

example, by installing air conditioning and substantially reducing the prison

population. Moreover, the district court noted that the classes seemed to combine

Plaintiffs’ distinct complaints about the poor conditions and the use of excessive 

force: as the district court explained, different legal standards govern excessive force 

claims and conditions-of-confinement claims. Still, the district court “recognize[d]

that a more focused claim, covering a more discrete time period, on behalf of a more 

uniform class, may well be appropriate for class certification.” 

Responding to the district court’s concerns, Plaintiffs filed a renewed motion 

for class certification and proposed four new, more narrowly defined classes. The 

pre-trial and post-conviction classes were renamed as two “conditions” classes 

which, Plaintiffs argued, eliminated their excessive-force claims. The pre-trial and 

post-conviction heat subclasses were also narrowed to those detained in MSI’s 

dormitories only, and “on days where the ambient air temperature in St. Louis, 

Missouri equaled or exceeded 88 degrees Fahrenheit.” Plaintiffs argued this was an 

objective criterion for determining exposure to unconstitutionally hot conditions. 

Plaintiffs’ narrowed class definitions also set end dates: July 1, 2018 for the pre-trial 

and post-conviction conditions classes, and July 24, 2017 for the heat subclasses. 

The district court granted Plaintiffs’ renewed motion and certified the four 

new classes pursuant to Federal Rule of Civil Procedure 23(b)(3). It reasoned, in 

relevant part, that the new conditions classes were appropriate for certification 

because Plaintiffs’ renewed motion alleged that the conditions at MSI applied to 

them uniformly over a discrete period, meaning that class-wide proceedings would

generate common answers to the members’ claims. In doing so, the district court 

rejected the City’s contention that variations in the conditions faced by each member 

and in the length of exposure to those conditions precluded certification. With 

respect to the heat subclasses, the district court held that certification was 
-5- 

appropriate, in relevant part, because an Eighth Amendment violation may be proven 

by demonstrating exposure to excessive heat without adequate mitigation. 

Moreover, the district court explained that the proffered expert testimony from 

Balsamo concerning the dangers of high temperatures, and other common evidence 

of “sporadic and inconsistent” mitigation measures, would “help prove Plaintiffs’ 

uniform allegation that the City’s mitigation measures were, at best, haphazard and 

insufficient to reduce the danger posed by excessive heat.” The district court 

rejected the City’s argument that differences in the mitigation measures offered to 

class members—such as ice and cold showers—precluded certification. 

After certifying the four new classes, the district court ruled on the City’s and 

Plaintiffs’ respective Daubert motions. As relevant here, the district court agreed 

with the City that Balsamo’s heat indexes must be excluded because they were based 

on surface temperature data. However, the district court concluded that Balsamo 

was qualified to render an opinion regarding medical risks to inmates given his 

experience in public health. So too with his opinions regarding the excessive heat 

conditions at MSI, which were based on his observations of MSI’s ventilation, 

heating and cooling systems, and his own ambient air temperature readings. The 

district court excluded Vail’s opinions that relied on the surface temperature data but 

declined to exclude his remaining opinions, finding that the City’s challenges to their 

factual bases were best addressed through cross-examination.

The City timely petitioned this Court for permission to appeal the district 

court’s order certifying the classes, which we granted. See Fed. R. Civ. P. 23(f). 

The City now appeals, raising several points of error.

II. 

“A district court has ‘broad discretion’ to determine whether certification is 

appropriate. The district court’s rulings on questions of law are reviewed de novo 

and its application of the law is reviewed for an abuse of discretion. The district 

court’s factual findings are reversible only if clearly erroneous.” Stuart v. State Farm 
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Fire & Cas. Co., 910 F.3d 371, 375 (8th Cir. 2018) (citations omitted). “[T]he 

[district] court abuses its discretion if it commits an error of law.” Luiken v. 

Domino’s Pizza, LLC, 705 F.3d 370, 372 (8th Cir. 2013). 

“To be certified as a class, plaintiffs must meet all of the requirements of Rule 

23(a) and must satisfy one of the three subsections of Rule 23(b). Rule 23(a) requires 

showing that the class meets requirements of ‘numerosity, commonality, typicality, 

and fair and adequate representation.’” Ahmad v. City of St. Louis, 995 F.3d 635, 

643 (8th Cir. 2021) (citations omitted). Certification under Rule 23(b)(3) requires 

the court to find “that the questions of law or fact common to class members 

predominate over any questions affecting only individual members, and that a class 

action is superior to other available methods for fairly and efficiently adjudicating 

the controversy.” Fed. R. Civ. P. 23(b)(3).

A.

First, we address the City’s argument that the district court abused its 

discretion in allowing Plaintiffs to renew their motion for class certification pursuant 

to Federal Rule of Civil Procedure 23(c)(1)(C). In short, the City faults the district 

court for entertaining the motion on an unchanged record and for citing Hargrove v. 

Sleepy’s LLC, 974 F.3d 467 (3d Cir. 2020), in support of its authority to reconsider 

the motion.

Rule 23(c)(1)(C) provides that “[a]n order that grants or denies class 

certification may be altered or amended before final judgment.” Fed. R. Civ. P. 

23(c)(1)(C). A district court’s grant of a motion to reconsider class certification is 

“a matter within the court’s broad discretion.” See In re Wholesale Grocery Prods. 

Antitrust Litig., 946 F.3d 995, 1004 (8th Cir. 2019). That “extends to requests, as 

here, to reconsider a prior class certification denial.” Id. A district court abuses its 

discretion in reconsidering a prior class certification denial “only if it ‘rests its 

conclusion on clearly erroneous factual findings or if its decision relies on erroneous 

legal conclusions.’” Id. (citation omitted). This is consistent with the approach in 
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other circuits. See, e.g., In re Initial Pub. Offering Sec. Litig., 483 F.3d 70, 73 (2d 

Cir. 2007) (allowing the petitioners to “return[] to the District Court to seek 

certification of a more modest class” and explaining that “District courts have ample 

discretion to consider (or to decline to consider) a revised class certification motion 

after an initial denial”).

Believing that we had not had occasion to pass upon these issues before, the 

district court cited Hargrove, 974 F.3d at 476, which held that Rule 23(c)(1)(C) 

“allows for multiple bites at the apple” and “does not impose an additional 

requirement on parties to prove a change in law or show new evidence to succeed 

on a renewed motion for certification.” This was no error, as Hargrove is consistent 

with the law in our circuit, as articulated by Wholesale Grocery. The City points to 

no clearly erroneous factual findings or conclusions of law in the district court’s 

decision to consider Plaintiffs’ renewed motion to certify. Accordingly, the district 

court did not abuse its discretion in entertaining the motion. Wholesale Grocery, 

946 F.3d at 1004.

B. 

Next, we address the City’s allegation that the district court erred in certifying 

the conditions classes and heat subclasses. The City asserts that the district court 

erred in describing the legal standard for conditions-of-confinement and heat-based 

claims and erred in failing to analyze Monell.

5

 The City asserts that the district court 

therefore erred in finding the commonality and predominance requirements satisfied 

despite Plaintiffs describing varied experiences at MSI.

“Commonality requires the plaintiff to demonstrate that the class members 

‘have suffered the same injury.’” Wal-Mart, 564 U.S. at 349-50 (citation omitted). 

“This does not mean merely that they have all suffered a violation of the same 

provision of law.” Id. at 350. Rather, “[t]heir claims must depend upon a common 

5

Monell v. Dep’t of Soc. Servs., 436 U.S. 658 (1978). 
-8- 

contention” which “must be of such a nature that it is capable of classwide 

resolution.” Id. Nor does this mean that Plaintiffs can prevail by raising common 

questions in droves. Id. Instead, class-wide proceedings should have the capacity 

to generate common answers that “drive the resolution of the litigation.” Id. (citation 

omitted). “Dissimilarities within the proposed class are what have the potential to 

impede the generation of common answers.” Id. (citation omitted).

Commonality is subsumed within the predominance requirement, Custom 

Hair Designs by Sandy v. Cent. Payment Co., 984 F.3d 595, 601 (8th Cir. 2020), 

which requires us to ask “whether proposed classes are sufficiently cohesive to 

warrant adjudication by representation,” Tyson Foods, Inc. v. Bouaphakeo, 577 U.S. 

442, 453 (2016) (citation omitted). This requires us “to give careful scrutiny to the 

relation between common and individual questions in a case.” Id. Individual 

questions are those where class members “will need to present evidence that varies 

from member to member.” Id. (citation omitted). Common questions are those 

“where ‘the same evidence will suffice for each member to make a prima facie 

showing [or] the issue is susceptible to generalized, class-wide proof.’” Id.

(alteration in original) (citation omitted).

“Under Monell, ‘[s]ection 1983 liability for a constitutional violation may 

attach to a municipality if the violation resulted from . . . an “official municipal 

policy.”’” Whitney v. City of St. Louis, 887 F.3d 857, 860 (8th Cir. 2018)

(alterations in original) (citations omitted).

Class certification is only proper if the district court conducts a “rigorous 

analysis” of Rule 23(a)’s requirements. Comcast Corp. v. Behrend, 569 U.S. 27, 33 

(2013) (citation omitted). And where, as here, certification is ordered pursuant to 

Rule 23(b)(3), the predominance requirement is “even more demanding” than the 

Rule 23(a) requirements. Id. at 34. A court therefore has a “duty to take a ‘close 

look’ at whether common questions predominate over individual ones.” Id. (citation 

omitted).
-9- 

1. 

In certifying the conditions classes, the district court concluded: 

Liability for all class members will depend on proof that the City had a 

policy or custom of detaining inmates in cells plagued with pest 

infestations, plumbing problems, and mold; that these conditions posed 

a substantial risk of serious harm to inmates; and that the City was 

deliberately indifferent to that risk.

The district court reasoned that, because Plaintiffs’ renewed motion alleged that 

these conditions applied to them in substantially uniform ways, class proceedings 

would generate common answers to the elements of their claims.

When describing this standard for liability, the district court relied on only 

one binding decision, Beaulieu v. Ludeman, 690 F.3d 1017 (8th Cir. 2012). 

Beaulieu concerned a challenge to several plaintiffs’ conditions of confinement, 

although they did not proceed as a class. Id. at 1021-23. There, when addressing 

the plaintiffs’ complaints of unsanitary prison conditions, we explained that they 

could establish a constitutional violation by showing that the conditions posed a 

substantial risk of serious harm to the plaintiffs, and that the defendants actually 

knew of, or were deliberately indifferent to, the plaintiffs’ health and safety. Id. at 

1045. 

We find two significant errors in the district court’s approach. First, the 

district court’s reliance on isolated language from a singular binding authority falls 

short of the “rigorous analysis” that must be performed before a court finds that 

certification is appropriate. Comcast, 569 U.S. at 33-34 (citation omitted). 

Moreover, the sole defendant in this matter is the City, and the district court’s order 

certifying the classes failed to analyze any theories of liability under Monell. See

Woodall v. Wayne Cnty., No. 20-1705, 2021 WL 5298537, at *6-8 (6th Cir. Nov. 

15, 2021) (reversing certification of Rule 23(b)(3) classes challenging prison strip 

searches, stating that different Monell theories have different elements, and that “[a] 
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proper analysis” under Rule 23(b)(3) must consider which elements of these claims 

“can be established on a class-wide basis”). A district court that fails to conduct the 

requisite rigorous analysis when certifying a class under Rule 23(b)(3) abuses its 

discretion. See IBEW Loc. 98 Pension Fund v. Best Buy Co., 818 F.3d 775, 779

(8th Cir. 2016). 

Second, the district court erred in describing the standard for liability.6

 See

Luiken, 705 F.3d at 372. As an initial matter, we note that “[n]othing so amorphous 

as ‘overall conditions’ can rise to the level of cruel and unusual punishment when 

no specific deprivation of a single human need exists.” Wilson v. Seiter, 501 U.S. 

294, 305 (1991). “Some conditions of confinement may establish an Eighth 

Amendment violation ‘in combination’ when each would not do so alone, but only 

when they have a mutually enforcing effect that produces the deprivation of a single, 

identifiable human need . . . .” Id. at 304. Here, the certified class definitions 

referred to no specific conditions, let alone any mutually reinforcing combination of 

conditions: they were simply labeled “conditions” classes and defined membership 

with reference to dates of incarceration. 

The City’s liability for Plaintiffs’ conditions claims—concerning plumbing, 

mold, and pests—will turn on both the severity of the conditions each plaintiff faced, 

and the length of exposure to those conditions. Take plumbing, for instance. In 

Owens v. Scott County Jail, a detainee alleged unconstitutional conditions of 

confinement when he was forced to sleep less than two feet from a toilet, which 

6

We note, however, that the district court correctly explained the 

insignificance of the distinction between pre-trial and post-conviction detainees to 

the instant case. Although a convicted prisoner’s conditions of confinement “are 

subject to scrutiny under the Eighth Amendment . . . [,] a pretrial detainee[’s] . . . 

section 1983 claims are analyzed under the Fourteenth Amendment’s Due Process 

Clause instead of the Eighth Amendment.” Davis v. Oregon Cnty., 607 F.3d 543, 

548 (8th Cir. 2010). “This makes little difference as a practical matter, though: 

Pretrial detainees are entitled to the same protection under the Fourteenth 

Amendment as imprisoned convicts receive under the Eighth Amendment.” Id.

(citation omitted).
-11- 

would splash urine on him whenever used by his cellmate. 328 F.3d 1026, 1026-27 

(8th Cir. 2003) (per curiam). We held that when “reviewing the totality of 

circumstances of [the plaintiff’s] confinement . . . we focus on the length of his 

exposure to unsanitary conditions and how unsanitary the conditions were.” Id. at 

1027; see also Turner v. Mull, 784 F.3d 485, 491 (8th Cir. 2015) (collecting cases 

and holding that six-hour exposure to unsanitary conditions in transportation vehicle 

did not rise to Eighth Amendment violation). 

Or consider claims relating to mold. In Thurmond v. Andrews, we noted that 

“[w]hile prisoners certainly have an Eighth Amendment right to sanitary prison 

conditions[,] . . . the articulation of this broad right does not answer whether the 

presence of non-toxic environmental allergens are necessarily violative of this 

right.” 972 F.3d 1007, 1012 (8th Cir. 2020). Although we did not hold that “there 

can never be a case in which the presence of mold or another environmental allergen 

may give rise to unsanitary prison conditions that violate inmates’ Eighth 

Amendment rights,” we did hold that “the definition of the asserted constitutional 

right embraced by the district court—a right to sanitary prison conditions—was 

impermissibly broad.” Id. 

In Beaulieu, the principal case relied on by the district court, we expressly 

noted that the complained-of conditions “may be tolerable for a few days and 

intolerably cruel for weeks or months.” 690 F.3d at 1045 (citation omitted). 

Rejecting the plaintiffs’ complaints of unsanitary conditions, we held that they 

“produced no evidence as to the length of time that they were exposed to the 

unsanitary conditions.” Id. 

Plaintiffs resist this conclusion, arguing that “exposure to risk is what violates 

the Constitution” in a single-facility case like this. They rely primarily on our 

decision in Postawko v. Missouri Department of Corrections, 910 F.3d 1030 (8th 

Cir. 2018). There, we held that the commonality requirement was satisfied in a Rule 

23(b)(2) class action challenging various Missouri Department of Corrections 

policies regarding chronic Hepatitis C screening and care. Id. at 1033, 1038. The 
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class was defined as “[a]ll those individuals in the custody of MDOC, now or in the 

future, who have been, or will be, diagnosed with chronic [Hepatitis C], as that term 

is defined medically, but who are not provided treatment with direct acting antiviral 

drugs.” Id. at 1035-36. The plaintiffs’ claim was “that the failure of the 

[Department] to screen properly for a life-threatening disease and provide 

appropriate treatment exposes all inmates suffering from chronic [Hepatitis C] to the 

same unconstitutional injury.” Id. at 1038. The plaintiffs alleged that the screening 

and treatment procedures were “uniformly applied” to every incarcerated person 

who suffered or will suffer from Hepatitis C. Id. at 1040. The legal theory 

underlying the plaintiffs’ claim was that they “can show deliberate indifference in 

the level of care provided in different ways, including showing grossly incompetent 

or inadequate care, showing a defendant’s decision to take an easier and less 

efficacious course of treatment, or showing a defendant intentionally delayed or 

denied access to medical care.” Id. at 1038 (citation omitted). 

But here, the district court certified classes much less precisely 

defined—indeed, the only references to conditions in the certified classes are in the

names. Furthermore, the plaintiffs in Postawko alleged that the MDOC had six 

precise policies or customs. See id. at 1035 (listing policies). That is quite unlike 

Plaintiffs in the instant case, who, in their memorandum supporting their renewed 

motion to certify below, complained of undifferentiated “putrid physical 

conditions,” which they argued remedied “concerns of commonality and 

predominance” because they were limiting “the class’ allegation to only ‘poor 

physical conditions.’” In short, we do not agree that Postawko establishes the bare 

syllogism that exposure to risk amounts to a constitutional violation. While 

Plaintiffs now point to specific conditions on appeal like mold, plumbing, or pests, 

the conditions classes as certified are quite unlike the precisely defined class in 

Postawko, and are more like the “amorphous” overall-conditions claims that Wilson

disapproved of. 501 U.S. at 305.

Plaintiffs also cite a series of nonbinding authorities to suggest that their 

interpretation of single-facility cases is not only found in Postawko. The lone circuit 
-13- 

court opinion they cite, Mulvania v. Sheriff of Rock Island County, 850 F.3d 849 

(7th Cir. 2017), does not offer the support that they claim. In Mulvania, the Seventh 

Circuit, while ultimately affirming the denial of class certification on other grounds, 

held that the district court erroneously denied certification of a Rule 23(b)(3) class 

challenging a prison’s underwear policy on the basis that factual variances in the 

plaintiffs’ claims would affect the damages calculation. 850 F.3d at 858-59. This 

case establishes nothing more than the uncontroversial proposition that “[s]light 

variation in actual damages does not defeat predominance if there are common legal 

questions and common facts.” Custom Hair, 984 F.3d at 602. Here, the district court 

abused its discretion when it erroneously concluded that variations in the length of 

time of an individual plaintiff’s detention spoke only to damages, not liability.

 

Finally, the testimony of the named plaintiffs in this matter reveals that the 

classes, as presently defined, are not “sufficiently cohesive to warrant adjudication 

by representation.” Tyson Foods, 577 U.S. at 453 (citation omitted). Plaintiff 

Mosley was a pre-trial detainee for less than one month, whereas plaintiff Cody was 

a post-conviction detainee for approximately eight months. In its first order 

declining to certify the first four proposed classes, the district court stated that some 

plaintiffs complained of plumbing problems (such as Mosley), while others did not 

(such as Wortham and Williams). The City points to yet more supposed disparities 

on appeal, none of which Plaintiffs seriously dispute, and none of which the district 

court engaged with in its second order certifying the four new classes. While we do 

not hold that no class addressing Plaintiffs’ conditions complaints could ever be 

properly certified, we think that, as presently defined, “[d]issimilarities within the 

proposed class[es] . . . impede the generation of common answers.” Wal-Mart, 564 

U.S. at 350 (citation omitted). 

2. 

We now turn to the heat subclasses. In certifying the heat subclasses, the 

district court reasoned that “[i]t is well established [that] a violation of the Eighth 

Amendment (for post-conviction detainees) or of due process (for pretrial detainees) 
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can be established based on exposure to excessive heat without adequate mitigating 

measures.” It therefore concluded that liability would turn on “whether excessive 

heat constitutes a condition of confinement that poses a substantial risk of serious 

harm to the health of all inmates, whether the City’s mitigation efforts were 

adequate, and whether MSI officials were deliberately indifferent to that risk.” The 

district court acknowledged that Plaintiffs alleged that different mitigation measures 

were provided to some of them. This did not defeat predominance, the district court 

reasoned, because it spoke to the “uniform allegation that the City’s mitigation 

measures were, at best, haphazard and insufficient to reduce the danger posed by 

excessive heat.” 

The lone citation the district court offered to support this reasoning was Yates 

v. Collier, 868 F.3d 354 (5th Cir. 2017). There, the Fifth Circuit held that “[i]t is 

well-established in our circuit ‘that the Eighth Amendment guarantees inmates a 

right to be free from exposure to extremely dangerous temperatures without 

adequate remedial measures.’” Id. at 360. We do not agree with the district court

that Yates established a clear rule within our circuit, and Plaintiffs point us to no 

other authorities on appeal. And as with the conditions classes, we note that the 

district court conducted no analysis of the Monell theory underlying the heat 

subclass’s claims. See Woodall, 2021 WL 5298537 at *6. This falls short of the 

“rigorous analysis” that must be performed before a court finds that certification is 

appropriate. Comcast, 569 U.S. at 33-34 (citation omitted). The district court 

therefore abused its discretion. IBEW, 818 F.3d at 779. Should the district court 

entertain further motions to certify heat subclasses on remand, we leave it to the 

district court to conduct the requisite rigorous analysis in the first instance.

C. 

Separately, the City alleges that the district court erred in certifying the 

conditions classes because Plaintiffs are not adequate class representatives. Federal 

Rule of Civil Procedure 23(a)(4) requires that class representatives “will fairly and 

adequately protect the interests of the class.” This requirement “serves to uncover 
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conflicts of interest between named parties and the class they seek to represent.” 

Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 625 (1997). In practice, a court 

must ask whether “(1) the class representatives have common interests with the 

members of the class, and (2) whether the class representatives will vigorously 

prosecute the interests of the class through qualified counsel.” Paxton v. Union Nat’l

Bank, 688 F.2d 552, 562-63 (8th Cir. 1982). Here, the district court concluded, 

“based on the record and the conduct of counsel and parties throughout this 

litigation[,] that the named Plaintiffs’ interests are aligned with those of the putative 

classes and that their attorneys are competent to prosecute the action.” 

The City does not convince us that the district court’s conclusion was clearly 

erroneous. Stuart, 910 F.3d at 375. The City’s primary contention is that some 

named Plaintiffs do not seek damages, citing their deposition testimony. But the 

City’s first deposition reference is completely erroneous: the quoted language 

appears nowhere in Wortham’s deposition, and she states the exact opposite of what 

the City claims. When asked, “are you seeking money damages from the City of St. 

Louis in this case,” Wortham replied unequivocally, “Yes.” R. Doc. 139-2, at 31. 

Similarly, the City selectively quotes the deposition testimony of Barnes. Although 

Barnes stated that he was “not seeking any money,” he explained that he was 

“seeking damages for [his] civil rights being violated.” When counsel followed up 

and asked whether he was “seeking any money”—over one of several objections that 

the question had been asked and answered—Barnes replied that he was seeking 

money for civil rights violations. R. Doc. 139-3, at 39. Likewise, the City’s 

assertion that Cody was unclear about whether he sought damages is entirely 

unsupported by the record. Cody stated that he was “not doing this for money” and 

that this case “was never about [his] financial gain.” R. Doc. 139-6, at 38. Far from 

suggesting that he did not seek damages, Cody was clear that he simply did not know 

a specific amount that he was seeking from the City. R. Doc. 139-6, at 37-38. 

We also reject the City’s argument that adequacy is defeated because two of 

the named plaintiffs originally proceeded anonymously in this matter. Before 

certifying the classes, the district court granted Plaintiffs leave to amend their 
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complaint to add Barnes and Williams as plaintiffs. The City cites no authority 

demonstrating that this defeats the district court’s subsequent finding of adequacy: 

the lone authority cited, Capers v. National Railroad Passenger Corp., 673 F. App’x 

591 (8th Cir. 2016) (per curiam), concerned the timeliness of a plaintiff’s claim for 

statute-of-limitations purposes when she had initially proceeded anonymously. 

As for the City’s argument that variations in Plaintiffs’ length of detention and 

the conditions complained of defeats adequacy—an argument presented without 

citations to legal authority—we consider it waived. See Milligan v. City of Red 

Oak, 230 F.3d 355, 360 (8th Cir. 2000) (per curiam) (“[I]nasmuch as [appellant’s]

brief does not support his assertion with any argument or legal authority, he has 

waived the issue and we do not address it.”). The City also waived its argument that 

adequacy is defeated by the Prison Litigation Reform Act (PLRA). In resisting 

Plaintiffs’ renewed motion to certify the narrowed conditions classes, the City did 

not raise a PLRA argument, so the district court did not consider it when granting 

the motion. Although we doubt whether it would have merit, the City could have 

raised a PLRA argument at that stage of proceedings if it had so desired, given that

it previously raised the contention in resisting Plaintiffs’ first motion to certify in the 

context of the superiority requirement. See Heuton v. Ford Motor Co., 930 F.3d 

1015, 1022 (8th Cir. 2019) (holding that the appellant waived an “argument because 

he did not raise it before the district court”); cf. Nerness v. Johnson, 401 F.3d 874, 

876 (8th Cir. 2005) (per curiam) (explaining that “the [PLRA’s] exhaustion 

requirement does not apply to plaintiffs who file § 1983 claims after being released 

from incarceration”). 

D. 

Finally, we reject the City’s argument that the district court procedurally erred 

in its handling of the Daubert motions and its order certifying the classes. The City’s 

primary contention is that the district court did not conduct a rigorous Daubert

analysis in its order certifying the classes. That contention is predicated on the City’s 

claim that In re Zurn Pex Plumbing Products Liability Litigation, 644 F.3d 604 (8th 
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Cir. 2011), established an obligation for district courts to conduct a “tailored” or 

“focused” Daubert analysis when certifying a class. We disagree. Zurn merely held 

that a district court did not err in conducting a “focused Daubert analysis” over the 

“exhaustive and conclusive” analysis the appellant suggested was necessary. Id. at 

611-14. Zurn expressly recognized that “[t]he main purpose of Daubert exclusion is 

to protect juries from being swayed by dubious scientific testimony. That interest is 

not implicated at the class certification stage where the judge is the decision maker.” 

Id. at 613. 

Fatal to the City’s contention is the fact that “[a] district court’s Daubert

inquiry need not take any specific form, . . . so long as the court has an adequate 

record on which to base its ruling.” Miller v. Baker Implement Co., 439 F.3d 407, 

413 (8th Cir. 2006). Here, the district court issued its order ruling on the Daubert

motions promptly after issuing its order certifying the classes. While the City 

complains that there was no admissible evidence in the record to support a finding 

of common exposure to risk from heat, the argument is beside the point. “[A] court’s 

inquiry on a motion for class certification is ‘tentative,’ ‘preliminary,’ and ‘limited.’” 

Zurn, 644 F.3d at 613 (citations omitted). Because “class certification decisions are 

generally made before the close of merits discovery, the court’s analysis is 

necessarily prospective and subject to change and there is bound to be some 

evidentiary uncertainty.” Id. (citation omitted). The ultimate admissibility of an 

expert’s opinion is therefore a red herring at the class-certification stage.

To the extent that the City raises further arguments on this issue, we will not 

“do [the City’s] work for it by developing the argument[s] and putting flesh on [their] 

bones,” Sturgis Motorcycle Rally, Inc. v. Rushmore Photo & Gifts, Inc., 908 F.3d 

313, 324 (8th Cir. 2018), and so we decline to consider them. We find no abuse of 

discretion in the district court’s decision to rule on the Daubert motions shortly after 

class certification. Stuart, 910 F.3d at 375. 
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III. 

For the foregoing reasons, we reverse the certification of the four classes and 

remand for proceedings consistent with this opinion.

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