PRECEDENTIAL

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

___________

No. 12-2621

___________

GABRIEL JOSEPH CARRERA, 

on behalf of himself and all others similarly situated

v.

BAYER CORPORATION; 

BAYER HEALTHCARE, LLC.,

 Appellants

 *(Amended Pursuant to the Clerk‟s Order of July 5, 2012)

_______________________

On Appeal from the District Court

for the District of New Jersey

D.C. Civil No. 2-08-cv-04716 

(Honorable Jose L. Linares)

______________

Argued April 16, 2013

Before: SCIRICA, SMITH and CHAGARES, Circuit Judges

(Filed: August 21, 2013)
2

Matthew R. Ford, Esq.

Christopher D. Landgraff, Esq.

Rebecca Weinstein Bacon, Esq. [ARGUED]

Bartlit, Beck, Herman, Palenchar & Scott

54 West Hubbard Street

Room 300

Chicago, IL 60654

Counsel for Appellants 

Caroline F. Bartlett, Esq.

Patton Boggs

One Riverfront Plaza

6

th Floor

Newark, NJ 07102

James E. Cecchi, Esq.

Lindsey H. Taylor, Esq.

Carella, Byrne, Cecchi, Olstein, Brody & Agnello

5 Becker Farm Road

Roseland, NJ 07068

Joe R. Whatley, Jr., Esq. [ARGUED]

Whatley, Drake & Kallas

1540 Broadway

37th Floor

New York, NY 10036

Counsel for Appellee 

John Beisner, Esq.

Skaden, Arps, Slate, Meagher & Flom

1440 New York Avenue, N.W.
3

Washington, DC 20005

Counsel for Amicus Curiae 

_________________

OPINION OF THE COURT

_________________

SCIRICA, Circuit Judge.

In this Fed. R. Civ. P. 23(f) appeal, Bayer 

Corporation and Bayer Healthcare contest the 

certification of a class of consumers who purchased 

Bayer‟s One-A-Day WeightSmart diet supplement in 

Florida. The sole issue on appeal is whether the class 

members are ascertainable. While this interlocutory 

appeal was pending, we decided Marcus v. BMW of 

North America, LLC, in which we held “[i]f class 

members are impossible to identify without extensive 

and individualized fact-finding or „mini-trials,‟ then a 

class action is inappropriate.” 687 F.3d 583, 593 (3d 

Cir. 2012). We explained that if class members cannot 

be ascertained from a defendant‟s records, there must 

be “a reliable, administratively feasible alternative,” 

but we cautioned “against approving a method that 

would amount to no more than ascertaining by 

potential class members‟ say so.” Id. at 594. In light of 

Marcus, we will vacate the class certification order and 

remand.

I.
4

Gabriel Carrera brings this class action against Bayer 

Corporation and Bayer Healthcare, LLC (“Bayer”), claiming 

that Bayer falsely and deceptively advertised its product OneA-Day WeightSmart. WeightSmart was promoted as a 

multivitamin and dietary supplement that had metabolismenhancing effects. The recommended daily dose was one 

tablet and prices ranged from about $8.99 for fifty tablets to 

about $16.99 for one hundred tablets. Bayer sold 

WeightSmart in retail stores, such as CVS, until January 

2007. Bayer did not sell it directly to consumers. Carrera 

alleges Bayer falsely claimed that WeightSmart enhanced 

metabolism by its inclusion of epigallocatechin gallate, a 

green tea extract.

Carrera initially sought to certify a nationwide class 

under Fed. R. Civ. P. 23(b)(3) bringing a claim under the 

New Jersey Consumer Fraud Act, as Bayer‟s headquarters is 

in New Jersey. The court denied certification, concluding that 

New Jersey law did not apply to out-of-state customers. This 

order is not before us on appeal.

Carrera then moved to certify a Rule 23(b)(3) class of 

Florida consumers under the Florida Deceptive and Unfair 

Trade Practices Act. One of Bayer‟s challenges to 

certification, and the issue on this appeal, is whether the class 

members are ascertainable. In this case, there is no dispute 

that class members are unlikely to have documentary proof of 

purchase, such as packaging or receipts. And Bayer has no 

list of purchasers because, as noted, it did not sell 

WeightSmart directly to consumers. 

Carrera advanced two ways to ascertain the class: first,

by retailer records of online sales and sales made with store 
5

loyalty or rewards cards; second, by affidavits of class 

members, attesting they purchased WeightSmart and stating 

the amount they purchased. Bayer challenged this latter 

method on the ground that memories of putative class 

members will be unreliable. Bayer argued that, in Carrera‟s 

own deposition testimony, he failed to remember when he 

purchased WeightSmart and that he confused it with 

WeightSmart Advanced and other generic or similar products 

(none of which are part of this litigation). In response, Carrera 

produced a declaration of James Prutsman, who works for a 

company that verifies and processes class settlement claims, 

in which Prutsman stated there are ways to verify the types of 

affidavits at issue here and screen out fraudulent claims. 

The court certified the class, defined as all persons 

who purchased WeightSmart in Florida.

1

It characterized the

issue of ascertainability as one of manageability, stating 

“„speculative problems with case management‟” are

insufficient to prevent class certification. Carrera v. Bayer 

Corp., Civ. A. No. 08-4716, 2011 WL 5878376, at *4 (D.N.J. 

Nov. 22, 2011) (quoting Klay v. Humana, Inc., 382 F.3d 

1241, 1272-73 (11th Cir. 2004)). The court concluded Carrera 

had satisfied his burden, noting “that the claims involved will 

be relatively small and Plaintiff points to methods to verify 

claims.” Id. Bayer appealed. It contends Carrera has failed to 

demonstrate the class is ascertainable because there is no 

evidence that any retailer records show who purchased 

WeightSmart. Bayer also argues that the use of unverifiable 

affidavits to ascertain class members fails to comply with

 

1

The class definition does not include a class period. Bayer 

sold WeightSmart from December 2003 through January 

2007.
6

Rule 23 and violates its rights under the due process clause.

II.

The District Court had jurisdiction under 28 U.S.C. § 

1332(d). We have jurisdiction under 28 U.S.C. § 1292(e) and 

Fed. R. Civ. P. 23(f). “We review a class certification order 

for abuse of discretion, which occurs if the district court‟s 

decision rests upon a clearly erroneous finding of fact, an 

errant conclusion of law or an improper application of law to 

fact.” In re Hydrogen Peroxide Antitrust Litig., 552 F.3d 305, 

312 (3d Cir. 2008) (quotation omitted). “Whether an incorrect 

legal standard has been used is an issue of law to be reviewed 

de novo.” Id. (quotation omitted).

III.

In Marcus, we explained the concept of 

ascertainability at length for the first time. 687 F.3d at 592-

95. The claim in Marcus was that Bridgestone run-flat tires 

(“RFTs”) were defective because they were highly 

susceptible to flats; could only be replaced, not repaired; and 

were highly priced. Id. at 588. The district court certified a 

Rule 23(b)(3) class consisting of “any and all current and 

former owners and lessees of 2006, 2007, 2008, and 2009 

BMW vehicles equipped with run-flat tires manufactured by 

Bridgestone . . . and sold or leased in New Jersey whose Tires 

have gone flat and been replaced.” Id. at 590 (quotation and 

alterations omitted). The defendants appealed, and we vacated 

the order certifying the class.

Before turning to the explicit requirements of Rule 23

in Marcus, we addressed two “preliminary matters”: first, 
7

whether the class was clearly defined, and second, “whether 

the class must be (and, if so, is in fact) objectively 

ascertainable.” Id. at 591. We concluded the class was not 

clearly defined. At the least, the definition of the class was 

broader than intended and did not define the claims, issues, or 

defenses to be treated on a class-wide basis. Id. at 592.

Accordingly, we remanded the case for clarification of the 

class definition.

We then addressed ascertainability. We began by 

stating, “[m]any courts and commentators have recognized 

that an essential prerequisite of a class action, at least with 

respect to actions under Rule 23(b)(3), is that the class must 

be currently and readily ascertainable based on objective 

criteria.” Id. at 592-93 (citing cases). “If class members are 

impossible to identify without extensive and individualized 

fact-finding or „mini-trials,‟ then a class action is

inappropriate.” Id. at 593. We noted, “[s]ome courts have 

held that where nothing in company databases shows or could 

show whether individuals should be included in the proposed 

class, the class definition fails.” Id. (citing cases). 

We then explained the 

ascertainability requirement serves several 

important objectives. First, it eliminates serious 

administrative burdens that are incongruous 

with the efficiencies expected in a class action 

by insisting on the easy identification of class 

members. Second, it protects absent class 

members by facilitating the best notice 

practicable under Rule 23(c)(2) in a Rule 

23(b)(3) action. Third, it protects defendants by 
8

ensuring that those persons who will be bound 

by the final judgment are clearly identifiable.

Id. (citations and quotations omitted). 

We set forth why the “proposed class action raise[d]

serious ascertainability issues.” Id. Defendant BMW 

explained that it could not determine by its records which 

vehicles fit the definition of the class because it did not keep

records of which cars got fitted with Bridgestone RFTs, 

because some customers may have changed tires (of which

BWM had no record), and because BMW would not have 

known which customers experienced flat tires. Id. at 593-94. 

We stated that if plaintiff were to attempt to re-certify a class 

on remand, the court “must resolve the critical issue of 

whether the defendants‟ records can ascertain class members 

and, if not, whether there is a reliable, administratively 

feasible alternative.” Id. at 594. We cautioned “against 

approving a method that would amount to no more than 

ascertaining by potential class members‟ say so. For example, 

simply having potential class members submit affidavits that 

their Bridgestone RFTs have gone flat and been replaced may 

not be proper or just.” Id. (quotation omitted). “Forcing 

BMW and Bridgestone to accept as true absent persons‟ 

declarations that they are members of the class, without 

further indicia of reliability, would have serious due process 

implications.” Id.

IV.

A.

“A party seeking class certification must affirmatively 
9

demonstrate his compliance with” Rule 23. Wal-Mart Stores, 

Inc. v. Dukes, 131 S. Ct. 2541, 2551 (2011). “Class 

certification is proper only „if the trial court is satisfied, after 

a rigorous analysis, that the prerequisites‟ of Rule 23 are 

met.” Hydrogen Peroxide, 552 F.3d at 309 (quoting Gen. Tel. 

Co. of Sw. v. Falcon, 457 U.S. 147, 161 (1982)). “Frequently 

that „rigorous analysis‟ will entail some overlap with the 

merits of the plaintiff‟s underlying claim. That cannot be 

helped. „[T]he class determination generally involves 

considerations that are enmeshed in the factual and legal 

issues comprising the plaintiff‟s cause of action.‟” Dukes, 131 

S. Ct. at 2551-52 (alteration in original) (quoting Falcon, 457 

U.S. at 160). “Factual determinations necessary to make Rule 

23 findings must be made by a preponderance of the 

evidence.” Hydrogen Peroxide, 552 F.3d at 320.

These same standards apply to the question of 

ascertainability. Class ascertainability is “an essential 

prerequisite of a class action, at least with respect to actions 

under Rule 23(b)(3).” Marcus, 687 F.3d at 592-93. “[T]here 

is „no reason to doubt‟” that the “rigorous analysis” 

requirement “„applies with equal force to all Rule 23 

requirements.‟” Hydrogen Peroxide, 552 F.3d at 309 n.5

(quoting In re Initial Pub. Offering Sec. Litig., 471 F.3d 24, 

33 n.3 (2d Cir. 2006)). Accordingly, a plaintiff must show, by 

a preponderance of the evidence, that the class is “currently 

and readily ascertainable based on objective criteria,” 

Marcus, 687 F.3d at 593, and a trial court must undertake a 

rigorous analysis of the evidence to determine if the standard 

is met.

“A party‟s assurance to the court that it intends or 

plans to meet the requirements [of Rule 23] is insufficient.” 

Hydrogen Peroxide, 552 F.3d at 318. A plaintiff may not 
10

merely propose a method of ascertaining a class without any 

evidentiary support that the method will be successful. “„A 

critical need‟” of the trial court at certification “„is to 

determine how the case will be tried,‟” id. at 319 (quoting 

Fed. R. Civ. P. 23 advisory committee‟s note, 2003 

Amendments), including how the class is to be ascertained.

B.

Ascertainability mandates a rigorous approach at the 

outset because of the key roles it plays as part of a Rule 

23(b)(3) class action lawsuit. First, at the commencement of a 

class action, ascertainability and a clear class definition allow 

potential class members to identify themselves for purposes 

of opting out of a class. Second, it ensures that a defendant‟s 

rights are protected by the class action mechanism. Third, it 

ensures that the parties can identify class members in a 

manner consistent with the efficiencies of a class action.

“„[T]he class-action device saves the resources of both 

the courts and the parties by permitting an issue potentially 

affecting every [class member] to be litigated in an 

economical fashion under Rule 23.‟” Falcon, 457 U.S. at 155 

(second alteration in original) (quoting Califano v. Yamasaki, 

442 U.S. 682, 701 (1979)). If a class cannot be ascertained in 

an economical and “administratively feasible” manner, 

Marcus, 687 F.3d at 594, significant benefits of a class action 

are lost. See id. at 593 (explaining ascertainability “eliminates

serious administrative burdens that are incongruous with the 

efficiencies expected in a class action” (quotation omitted)). 

Accordingly, a trial court should ensure that class members 

can be identified “without extensive and individualized factfinding or „mini-trials,‟” id., a determination which must be 
11

made at the class certification stage.

In this case, the ascertainability question is whether 

each class member purchased WeightSmart in Florida. If this 

were an individual claim, a plaintiff would have to prove at 

trial he purchased WeightSmart. A defendant in a class action 

has a due process right to raise individual challenges and 

defenses to claims, and a class action cannot be certified in a 

way that eviscerates this right or masks individual issues. See

McLaughlin v. Am. Tobacco Co., 522 F.3d 215, 231-32 (2d 

Cir. 2008) (rejecting a “fluid recovery” method of 

determining individual damages, in which aggregate damages 

would be based on estimates of the number of defrauded class 

members and their average loss), abrogated on other grounds 

by Bridge v. Phoenix Bond & Indem. Co., 553 U.S. 639 

(2008); see also Dukes, 131 S. Ct. at 2561 (rejecting a method 

of class certification in which a sample set of class members 

would be used to extrapolate average damages). A defendant 

has a similar, if not the same, due process right to challenge 

the proof used to demonstrate class membership as it does to 

challenge the elements of a plaintiff‟s claim. See Marcus, 687 

F.3d at 594 (“Forcing BMW and Bridgestone to accept as true 

absent persons‟ declarations that they are members of the 

class, without further indicia of reliability, would have serious 

due process implications.”). Ascertainability provides due 

process by requiring that a defendant be able to test the 

reliability of the evidence submitted to prove class 

membership.

The method of determining whether someone is in the 

class must be “administratively feasible.” Id. A plaintiff does 

not satisfy the ascertainability requirement if individualized

fact-finding or mini-trials will be required to prove class 
12

membership. Id. at 593. “Administrative feasibility means 

that identifying class members is a manageable process that 

does not require much, if any, individual factual inquiry.”

William B. Rubenstein & Alba Conte, Newberg on Class 

Actions § 3:3 (5th ed. 2011); see also Bakalar v. Vavra, 237 

F.R.D. 59, 64 (S.D.N.Y. 2006) (“Class membership must be 

readily identifiable such that a court can determine who is in 

the class and bound by its ruling without engaging in 

numerous fact-intensive inquiries.”).

The type of challenge to the reliability of evidence that 

is required will vary based on the nature of the evidence. For 

example, if Carrera produces retailer records that purport to 

list purchasers of WeightSmart, Bayer can challenge the 

reliability of those records, perhaps by deposing a corporate 

record-keeper.2In sum, to satisfy ascertainability as it relates 

to proof of class membership, the plaintiff must demonstrate 

his purported method for ascertaining class members is 

reliable and administratively feasible, and permits a defendant 

to challenge the evidence used to prove class membership.

V.

Carrera contends the class is ascertainable. He points 

to two types of evidence that can be used to determine who is 

a class member. First, he argues the class can use records

from retailers, which purportedly track customers who make 

 

2 Although some evidence used to satisfy ascertainability, 

such as corporate records, will actually identify class 

members at the certification stage, ascertainability only 

requires the plaintiff to show that class members can be 

identified.
13

purchases online or who use loyalty cards. Second, he 

proposes using affidavits of class members attesting to their 

purchases of WeightSmart. We conclude that, based on the 

evidence produced below, neither method satisfies Carrera‟s 

burden to show the class is ascertainable.

A.

Carrera argues he will be able to show class 

membership using retailer‟s records of sales made with 

loyalty cards, e.g., CVS ExtraCare cards,

3

and records of 

online sales. Carrera points to a Federal Trade Commission 

(FTC) settlement with CVS regarding the sale of a 

supplement that was falsely advertised as boosting immune 

systems. The supplement was sold only at CVS. The FTC 

stated in its press release regarding the settlement that 

“[p]urchasers will be identified through the CVS ExtraCare 

card program and sales on cvs.com.” A1089. 

Bayer contends there is no evidence that any other 

retailer of WeightSmart has membership cards, that the FTC 

case is inapposite as it was a stipulated settlement in a nonRule 23 context,

4

in which some of the money paid might go 

to class members but did not have to, and that it is speculative 

 

3

ExtraCare cards are membership cards that offer customers 

discounts. A1091.

4

Settlement classes raise different certification issues than 

litigation classes. See Amchem Prods., Inc. v. Windsor, 521 

U.S. 591, 620 (1997). Accordingly, we question whether the 

FTC‟s proposals for identifying purchasers, made as part of a 

settlement (and a non-class action settlement at that), bear any 

relevance to the issue of ascertainability in this case. 
14

whether CVS or any other retailer‟s records will reveal 

customers who purchased WeightSmart.

The evidence put forth by Carrera is insufficient to 

show that retailer records in this case can be used to identify 

class members. Depending on the facts of a case, retailer 

records may be a perfectly acceptable method of proving 

class membership. But there is no evidence that a single 

purchaser of WeightSmart could be identified using records 

of customer membership cards or records of online sales.

There is no evidence that retailers even have records for the 

relevant period. The FTC‟s press release does not support a 

finding that these records can determine class membership on 

the facts of this case. Moreover, we have no evidence the 

FTC‟s method was successful.

B.

Carrera also contends the class is ascertainable using 

affidavits of class members. He advances three arguments.

First, due to the low value of the claims, class members will 

be unlikely to submit fraudulent affidavits. Second, because

Bayer‟s total liability will not depend on the reliability of the 

affidavits, the ascertainability requirement should be relaxed. 

Finally, a screening method such as the one described in the 

Prutsman Declaration will ensure any unreliable affidavits are 

identified and disregarded.

1.

Because the claims are of low value, Carrera argues it 

is less likely someone would fabricate a claim. He concedes it 

is unlikely customers would have retained a receipt, but 
15

asserts this is irrelevant to possible falsification. He contrasts 

the claims at issue here to those in Marcus, which involved 

more money and more complicated issues of fact as to 

whether an individual was a class member.

This argument fails because it does not address a core 

concern of ascertainability: that a defendant must be able to 

challenge class membership. This is especially true where the 

named plaintiff‟s deposition testimony suggested that 

individuals will have difficulty accurately recalling their 

purchases of WeightSmart.5 Cf. In re Phenylpropanolamine 

(PPA) Prods. Liab. Litig., 214 F.R.D. 614, 618-19 (W.D. Wa. 

2003) (concluding affidavits could not be used to ascertain a 

class because the named plaintiffs had difficulty remembering 

the products they bought that contained PPA). 

2.

Carrera also argues ascertainability is less important in 

this case because Bayer‟s total liability will be determined at 

trial, and will not increase or decrease based on the affidavits 

submitted. As noted, this is an action under the Florida 

Deceptive and Unfair Trade Practices Act (FDUTPA), Fla. 

Stat. § 501.201 et seq. “[A] consumer claim for damages 

under FDUTPA has three elements: (1) a deceptive act or 

unfair practice; (2) causation; and (3) actual damages.” 

Rollins, Inc. v. Butland, 951 So. 2d 860, 869 (Fla. Dist. Ct. 

App. 2006). There is no requirement of actual reliance on the 

 

5 As mentioned, in his deposition testimony, Carrera was 

unable to remember when he purchased WeightSmart and 

confused WeightSmart with other products that are not part of 

this litigation.
16

deceptive act. See Fitzpatrick v. Gen. Mills, Inc., 635 F.3d 

1279, 1282-83 (11th Cir. 2011) (citing Davis v. Powertel, 

Inc., 776 So. 2d 971, 973 (Fla. Dist. Ct. App. 2000)). “[T]he 

question is not whether the plaintiff actually relied on the 

alleged deceptive trade practice, but whether the practice was 

likely to deceive a consumer acting reasonably in the same 

circumstances.” Davis, 776 So. 2d at 974.

Contending liability under the FDUTPA is not based 

on individual issues, Carrera argues that he can prove at trial 

that Bayer owes a refund for every purchase of 

WeightSmart.6Since Bayer‟s records show it sold 

approximately $14 million worth of WeightSmart in Florida, 

Carrera asserts Bayer‟s liability will be determined at trial to 

be $14 million—no more, no less. As a result, affidavits 

attesting to class membership will only be used to determine

to whom to pay the refund, and in what amount.

Under no circumstances, Carrera assures us, will Bayer 

pay any amount other than $14 million, even if a significant 

number of inaccurate claims are submitted and paid out. For 

example, if claims are made for more than $14 million, and 

inaccurate or false claims cannot be screened out, claimants 

will simply receive less than they are entitled to. And if too 

few claims are made, Carrera asserts the excess funds will not

be returned to Bayer but will go to an unclaimed property 

 

6 Bayer argues that if it is liable, its liability will be limited to 

refunding the premium consumers paid for WeightSmart 

based on its metabolism-enhancing claims. For purposes of 

this appeal, it makes no difference whether customers would 

be entitled to a full refund or merely a refund of this 

premium. 
17

fund. Carrera contrasts this situation with Marcus. In Marcus, 

there was no evidence of the total number of RFTs allegedly 

purchased in violation of the consumer protection laws. 

Accordingly, each claim submitted would have increased the 

amount of money the defendants would have had to pay. As a

result, the defendants had a more substantial interest in 

screening out false claims. Because Bayer‟s total liability 

cannot be so affected by unreliable affidavits, Carrera argues 

Bayer lacks an interest in challenging class membership.

Under Carrera‟s view, if fraudulent or inaccurate 

claims are paid out, the only harm is to other class members.

But ascertainability protects absent class members as well as 

defendants, Marcus, 687 F.3d at 593, so Carrera‟s focus on 

Bayer alone is misplaced. It is unfair to absent class members 

if there is a significant likelihood their recovery will be 

diluted by fraudulent or inaccurate claims. In this case, as we

discuss, there is the possibility that Carrera‟s proposed 

method for ascertaining the class via affidavits will dilute the 

recovery of true class members.

Bayer too has an interest in ensuring it pays only

legitimate claims. If fraudulent or inaccurate claims 

materially reduce true class members‟ relief, these class 

members could argue the named plaintiff did not adequately 

represent them because he proceeded with the understanding

that absent members may get less than full relief.7 When class 

members are not adequately represented by the named 

plaintiff, they are not bound by the judgment. See Hansberry 

 

7 We express no opinion on whether absent class members 

would be successful in arguing they were not adequately 

represented on this ground.
18

v. Lee, 311 U.S. 32, 42 (1940) (explaining that due process 

requires the interests of absent class members to be 

adequately represented for them to be bound by the 

judgment). They could then bring a new action against Bayer 

and, perhaps, apply the principles of issue preclusion to 

prevent Bayer from re-litigating whether it is liable under the 

FDUTPA. Bayer has a substantial interest in ensuring this 

does not happen. Accordingly, we reject Carrera‟s argument 

that the level of proof for ascertainability should be relaxed 

because Bayer‟s ultimate liability will not be based on the 

affidavits. 

3.

Finally, Carrera argues that a screening method such as 

the one described in the Prutsman Declaration will ensure that 

Bayer pays claims based only on reliable affidavits. In his 

declaration, James Prutsman states that he works at Rust 

Consulting, Inc., a firm that has administered class 

settlements for nearly 25 years. A992. He explains that Rust 

“employs numerous methods to detect claims that are 

submitted fraudulently.” A995. “For example, the firm runs 

programmatic audits to identify duplicate claims, outliers, and 

other situations. In addition, Rust has successfully utilized 

fraud prevention techniques where by [sic] the claim form 

offers claim options that do not reflect valid product 

descriptions, prices paid, geographic locations or 

combinations of such factors.” Id. “By providing claims 

options such as a very high pill count or significantly higher 

purchase price in this case, fraudulent claim filers would 

naturally be inclined to select options that they believe would 

increase their claim value. As such, techniques such as these 

can be used to effectively [eliminate] fraudulent claims.” Id.
19

Bayer maintains the Prutsman Declaration is 

insufficient to satisfy the reliability standard because it only 

addresses methods for allocating payment to a settlement 

class. This fact is important, according to Bayer, because 

there are different standards for approving a settlement class 

than for certifying a litigation class, and because Prutsman 

does not opine that his method would satisfy the standard for 

class certification. Bayer also argues that just because some 

defendants have agreed to use such techniques in 

administering a class settlement, it does not mean that it is 

sufficiently reliable.

The Prutsman Declaration does not show the affidavits 

will be reliable.8 Nor does it propose a model for screening 

claims that is specific to this case. And even if Prutsman 

produced a model that is specific to this case, we doubt

whether it could satisfy the ascertainability requirement. At 

this stage in the litigation, the district court will not actually 

see the model in action. Rather, it will just be told how the 

model will operate with the plaintiff‟s assurances it will be 

effective. Such assurances that a party “intends or plans to 

meet the requirements” are insufficient to satisfy Rule 23. 

Hydrogen Peroxide, 552 F.3d at 318; see also Comcast Corp. 

v. Behrend, 133 S. Ct. 1426, 1434 (2013) (rejecting 

 

8 Based on this conclusion, we do not need to reach Bayer‟s 

argument that the District Court erred by considering the 

Prutsman Declaration, which was produced with Carrera‟s 

reply brief in support of its motion for class certification. 

Accordingly, we will deny Bayer‟s motion to supplement the 

appellate record, which relates solely to this issue.
20

contention that Rule 23 is satisfied by an assurance that the 

plaintiffs can produce a damages model capable of measuring 

damages caused by a specific theory of antitrust impact). 

Carrera has suggested no way to determine the reliability of 

such a model. For example, even if a model screens out a 

significant number of claims, say 25%, there is probably no 

way to know if the true number of fraudulent or inaccurate 

claims was actually 5% or 50%.9

As Marcus was decided after the trial court certified 

the class, Carrera should have another opportunity to satisfy 

the ascertainability requirement. Accordingly, we will afford 

Carrera the opportunity to submit a screening model specific 

to this case and prove how the model will be reliable and how 

it would allow Bayer to challenge the affidavits. Mere 

assurances that a model can screen out unreliable affidavits

will be insufficient.

10

VI.

 

9 Carrera‟s ability to meet the ascertainability requirement 

using a screening model is further in doubt due to his inability 

to clearly remember his purchases of WeightSmart, although 

the District Court did not determine whether his testimony 

was reliable. It would appear that the less reliable a class 

member‟s memory is, the more reliable any screening method 

would have to be.

10 Bayer also argues that because the statute of limitations 

will bar some claims, the class cannot be ascertained. Because 

the class is defined as all purchasers of WeightSmart in 

Florida, whether an individual‟s claim is barred by the statute 

of limitations is not an aspect of ascertainability in this case. 
21

For the foregoing reasons, we will vacate the District 

Court‟s order certifying the class action and remand for 

further proceedings consistent with this opinion. Because

Marcus was decided after the court‟s certification of the class, 

Carrera should be allowed to conduct further, limited 

discovery on the issue of ascertainability and afforded another 

opportunity to satisfy the ascertainability requirement.