FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

OLEAN WHOLESALE GROCERY 

COOPERATIVE, INC.; BEVERLY 

YOUNGBLOOD; PACIFIC GROSERVICE,

INC., DBA Pitco Foods; CAPITOL 

HILL SUPERMARKET; LOUISE ANN 

DAVIS MATTHEWS; JAMES WALNUM;

COLIN MOORE; JENNIFER A. NELSON;

ELIZABETH DAVIS-BERG; LAURA 

CHILDS; NANCY STILLER; BONNIE 

VANDERLAAN; KRISTIN MILLICAN;

TREPCO IMPORTS AND 

DISTRIBUTION, LTD.; JINKYOUNG 

MOON; COREY NORRIS; CLARISSA 

SIMON; AMBER SARTORI; NIGEL 

WARREN; AMY JOSEPH; MICHAEL 

JUETTEN; CARLA LOWN; TRUYEN 

TON-VUONG, AKA David Ton; A-1

DINER; DWAYNE KENNEDY; RICK 

MUSGRAVE; DUTCH VILLAGE 

RESTAURANT; LISA BURR; LARRY 

DEMONACO; MICHAEL BUFF; ELLEN 

PINTO; ROBBY REED; BLAIR HYSNI;

DENNIS YELVINGTON; KATHY 

DURAND GORE; THOMAS E.

WILLOUGHBY III; ROBERT FRAGOSO;

SAMUEL SEIDENBURG; JANELLE 

ALBARELLO; MICHAEL COFFEY;

JASON WILSON; JADE CANTERBURY;

NAY ALIDAD; GALYNA 

No. 19-56514

D.C. No.

3:15-md-02670-

JLS-MDD

OPINION
2 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

ANDRUSYSHYN; ROBERT BENJAMIN;

BARBARA BUENNING; DANIELLE 

GREENBERG; SHERYL HALEY; LISA 

HALL; TYA HUGHES; MARISSA 

JACOBUS; GABRIELLE KURDT; ERICA 

PRUESS; SETH SALENGER; HAROLD 

STAFFORD; CARL LESHER; SARAH 

METIVIER SCHADT; GREG STEARNS;

KARREN FABIAN; MELISSA 

BOWMAN; VIVEK DRAVID; JODY 

COOPER; DANIELLE JOHNSON;

HERBERT H. KLIEGERMAN; BETH 

MILLINER; LIZA MILLINER; JEFFREY 

POTVIN; STEPHANIE GIPSON;

BARBARA LYBARGER; SCOTT A.

CALDWELL; RAMON RUIZ; THYME 

CAFE & MARKET, INC.; HARVESTERS 

ENTERPRISES, LLC; AFFILIATED 

FOODS, INC.; PIGGLY WIGGLY 

ALABAMA DISTRIBUTING CO., INC.;

ELIZABETH TWITCHELL; TINA 

GRANT; JOHN TRENT; BRIAN LEVY;

LOUISE ADAMS; MARC BLUMSTEIN;

JESSICA BREITBACH; SALLY 

CRNKOVICH; PAUL BERGER;

STERLING KING; EVELYN OLIVE;

BARBARA BLUMSTEIN; MARY 

HUDSON; DIANA MEY; ASSOCIATED 

GROCERS OF NEW ENGLAND, INC.;

NORTH CENTRAL DISTRIBUTORS,

LLC; CASHWA DISTRIBUTING CO. OF 

KEARNEY, INC.; URM STORES, INC.;

WESTERN FAMILY FOODS, INC.;

ASSOCIATED FOOD STORES, INC.;
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 3

GIANT EAGLE, INC.; MCLANE 

COMPANY, INC.; MEADOWBROOK 

MEAT COMPANY, INC.; ASSOCIATED 

GROCERS, INC.; BILO HOLDING, LLC;

WINNDIXIE STORES, INC.; JANEY 

MACHIN; DEBRA L. DAMSKE; KEN 

DUNLAP; BARBARA E. OLSON; JOHN 

PEYCHAL; VIRGINIA RAKIPI; ADAM 

BUEHRENS; CASEY CHRISTENSEN;

SCOTT DENNIS; BRIAN 

DEPPERSCHMIDT; AMY E.

WATERMAN; CENTRAL GROCERS,

INC.; ASSOCIATED GROCERS OF 

FLORIDA, INC.; BENJAMIN FOODS 

LLC; ALBERTSONS COMPANIES LLC;

H.E. BUTT GROCERY COMPANY;

HYVEE, INC.; THE KROGER CO.;

LESGO PERSONAL CHEF LLC; KATHY 

VANGEMERT; EDY YEE; SUNDE 

DANIELS; CHRISTOPHER TODD;

PUBLIX SUPER MARKETS, INC.;

WAKEFERN FOOD CORP.; ROBERT 

SKAFF; WEGMANS FOOD MARKETS,

INC.; JULIE WIESE; MEIJER 

DISTRIBUTION, INC.; DANIEL 

ZWIRLEIN; MEIJER, INC.; SUPERVALU 

INC.; JOHN GROSS & COMPANY;

SUPER STORE INDUSTRIES; W. LEE 

FLOWERS & CO. INC.; FAMILY 

DOLLAR SERVICES, LLC; AMY 

JACKSON; FAMILY DOLLAR STORES,

INC.; KATHERINE MCMAHON;

DOLLAR TREE DISTRIBUTION, INC.;

JONATHAN RIZZO; GREENBRIER 
4 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

INTERNATIONAL, INC.; JOELYNA A.

SAN AGUSTIN; ALEX LEE, INC.;

REBECCA LEE SIMOENS; BIG Y

FOODS, INC.; DAVID TON; KVAT

FOOD STORES, INC., DBA FOOD 

CITY; AFFILIATED FOODS MIDWEST 

COOPERATIVE, INC.; MERCHANTS 

DISTRIBUTORS, LLC; BROOKSHIRE 

BROTHERS, INC.; SCHNUCK 

MARKETS, INC.; BROOKSHIRE 

GROCERY COMPANY; KMART 

CORPORATION; CERTCO, INC.;

RUSHIN GOLD, LLC, DBA The Gold 

Rush; UNIFIED GROCERS, INC.;

TARGET CORPORATION; SIMONHINDI, LLC; FAREWAY STORES, INC.;

MORAN FOODS, LLC, DBA Save-ALot; WOODMAN’S FOOD MARKET,

INC.; DOLLAR GENERAL 

CORPORATION; SAM’S EAST, INC.;

DOLGENCORP, LLC; SAM’S WEST,

INC.; KRASDALE FOODS, INC.;

WALMART STORES EAST, LLC; CVS

PHARMACY, INC.; WALMART STORES 

EAST, LP; BASHAS’ INC.; WAL-MART 

STORES TEXAS, LLC; MARC 

GLASSMAN, INC.; WAL-MART 

STORES, INC.; 99 CENTS ONLY 

STORES; JESSICA BARTLING; AHOLD 

U.S.A., INC.; GAY BIRNBAUM;

DELHAIZE AMERICA, LLC; SALLY 

BREDBERG; ASSOCIATED 

WHOLESALE GROCERS, INC.; KIM 

CRAIG; MAQUOKETA CARE CENTER;
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 5

GLORIA EMERY; ERBERT &

GERBERT’S, INC.; ANA GABRIELA 

FELIX GARCIA; JANET MACHEN;

JOHN FRICK; PAINTED PLATE 

CATERING; KATHLEEN GARNER;

ROBERT ETTEN; ANDREW GORMAN;

GROUCHO’S DELI OF FIVE POINTS,

LLC; EDGARDO GUTIERREZ;

GROUCHO’S DELI OF RALEIGH;

ZENDA JOHNSTON; SANDEE’S 

CATERING; STEVEN KRATKY;

CONFETTI’S ICE CREAM SHOPPE;

KATHY LINGNOFSKI; END PAYER 

PLAINTIFFS; LAURA MONTOYA;

KIRSTEN PECK; JOHN PELS; VALERIE 

PETERS; ELIZABETH PERRON; AUDRA 

RICKMAN; ERICA C. RODRIGUEZ,

Plaintiffs-Appellees,

and

JESSICA DECKER; JOSEPH A.

LANGSTON; SANDRA POWERS;

GRAND SUPERCENTER, INC.; THE 

CHEROKEE NATION; US FOODS, INC.;

SYSCO CORPORATION; GLADYS,

LLC; SPARTANNASH COMPANY;

BRYAN ANTHONY REO,

Plaintiffs,

v.

BUMBLE BEE FOODS LLC; TRIUNION SEAFOODS, LLC, DBA 
6 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

Chicken of the Sea International, 

DBA Thai Union Group PCL, DBA 

Thai Union North America, Inc.; 

STARKIST CO.; DONGWON 

INDUSTRIES CO., LTD.; THAI UNION 

GROUP PCL,

Defendants-Appellants,

and

KING OSCAR, INC.; THAI UNION 

FROZEN PRODUCTS PCL; DEL 

MONTE FOODS COMPANY; TRI 

MARINE INTERNATIONAL, INC.;

DONGWON ENTERPRISES; DEL 

MONTE CORP.; CHRISTOPHER D.

LISCHEWSKI; LION CAPITAL 

(AMERICAS), INC.; BIG CATCH 

CAYMAN LP, AKA Lion/Big Catch 

Cayman LP; FRANCIS T.

ENTERPRISES; GLOWFISCH 

HOSPITALITY; THAI UNION NORTH 

AMERICA, INC.,

Defendants.

Appeal from the United States District Court

for the Southern District of California

Janis L. Sammartino, District Judge, Presiding

Argued and Submitted October 9, 2020

Pasadena, California

Filed April 6, 2021
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 7

Before: Andrew J. Kleinfeld, Andrew D. Hurwitz, and 

Patrick J. Bumatay, Circuit Judges.

Opinion by Judge Bumatay;

Partial Concurrence and Partial Dissent by Judge Hurwitz

SUMMARY*

Class Certification

The panel vacated the district court’s order certifying 

three classes in a multi-district antitrust case alleging a pricefixing conspiracy by producers of packaged tuna.

The panel held that statistical or “representative” 

evidence, finding classwide impact based on averaging 

assumptions and pooled transaction data, can be used to 

establish the “predominance” requirement of Fed. R. Civ. P. 

23(b)(3), under which a putative class must establish that 

“the questions of law or fact common to class members 

predominate over any questions affecting only individual 

members.” Agreeing with other circuits, the panel held that 

a district court must find by a preponderance of the evidence 

that the plaintiff has established predominance under Rule 

23(b)(3). The panel concluded that plaintiffs’ representative 

evidence could be used to establish predominance because 

plaintiffs’ evidence could have been used to establish 

liability in a class member’s individual suit by demonstrating 

the antitrust impact of their price-fixing claims; the 

* This summary constitutes no part of the opinion of the court. It 

has been prepared by court staff for the convenience of the reader.
8 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

representative evidence sufficiently linked plaintiffs’ 

injuries to their theory of antitrust violation; and plaintiffs’ 

use of averaging assumptions in their regression models did 

not defeat predominance.

The panel nonetheless concluded that the district court 

abused its discretion by not resolving the factual disputes 

necessary to decide the predominance requirement before 

certifying the classes. Accordingly, the panel vacated the 

district court’s order and remanded for the court to determine 

the number of uninjured parties in the proposed class based 

on the dueling statistical evidence, and only then to rule on 

whether predominance has been established.

Concurring in part and dissenting in part, Judge Hurwitz 

agreed with the majority’s conclusions that the district court, 

not the jury, must resolve factual disputes bearing on 

predominance; that a district court’s “rigorous analysis” of 

whether a putative class has satisfied Rule 23’s requirements 

should proceed by a preponderance of the evidence standard; 

and that the district court must conclude not that common 

issues could predominate at trial, but that they do 

predominate before certifying the class. Judge Hurwitz 

disagreed with the majority’s conclusion that, before 

certifying a class, the district court must find that only a de 

minimis number of class members are uninjured.

COUNSEL

Gregory G. Garre (argued) and Samir Deger-Sen, Latham & 

Watkins LLP, Washington, D.C.; Christopher S. Yates, 

Belinda S. Lee, and Ashley M. Bauer, Latham & Watkins 

LLP, San Francisco, California; John Roberti, Allen & 

Overy LLP, Washington, D.C.; Kenneth A. Gallo, Paul 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 9

Weiss Rifkind Wharton & Garrison LLP, Washington, D.C., 

for Defendants-Appellants.

Christopher L. Lebsock (argued), Michael P. Lehmann, 

Bonny E. Sweeney, and Samantha J. Stein, Hausfeld LLP,

San Francisco, California; Jonathan W. Cuneo (argued), Joel 

Davidow, and Blaine Finley, Cuneo Gilbert & Laduca LLP,

Washington, D.C.; Thomas H. Burt (argued), Wolf 

Haldenstein Adler Freeman & Herz LLP, New York, New 

York; Betsy C. Manifold, Rachele R. Byrd, Marisa C. 

Livesay, and Brittany N. Dejong, Wolf Haldenstein Adler

Freeman & Herz LLP, San Diego, California; for PlaintiffsAppellees.

Robert S. Kitchenoff, President, Committee to Support the 

Antitrust Laws, Washington, D.C.; Warren T. Burns and 

Kyle K. Oxford, Burns Charest LLP, Dallas, Texas; for 

Amicus Curiae Committee to Support the Antitrust Laws.

Ashley C. Parrish and Joshua N. Mitchell, King & Spalding 

LLP, Washington, D.C.; Anne M. Voigts and Quyen L. Ta, 

King & Spalding LLP, San Francisco, California; Steven P. 

Lehotsky and Jonathan D. Urick, U.S. Chamber Litigation 

Center, Washington, D.C.; for Amicus Curiae Chamber of 

Commerce of the United States.

Randy M. Stutz, American Antitrust Institute, Washington, 

D.C.; Ellen Meriwether, Cafferty Clobes Meriwether & 

Sprengal, Media, Pennsylvania; for Amicus Curiae 

American Antitrust Institute.

Scott L. Nelson and Allison M. Zieve, Public Citizen 

Litigation Group, Washington, D.C., for Amicus Curiae 

Public Citizen.
10 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

Corbin K. Barthold and Cory L. Andrews, Washington 

Legal Foundation, Washington, D.C., for Amicus Curiae 

Washington Legal Foundation.

OPINION

BUMATAY, Circuit Judge:

StarKist Company and Tri-Union Seafoods d/b/a 

Chicken of the Sea (collectively, “Defendants”),1 producers 

of packaged tuna, appeal an order certifying three classes in 

a multidistrict antitrust case alleging a price-fixing 

conspiracy. Defendants challenge the district court’s 

determination that Rule 23(b)(3)’s “predominance” 

requirement was satisfied by expert statistical evidence 

finding classwide impact based on averaging assumptions 

and pooled transaction data.

We ultimately conclude that this form of statistical or 

“representative” evidence can be used to establish 

predominance, but the district court abused its discretion by 

not resolving the factual disputes necessary to decide the 

requirement before certifying these classes. We thus vacate 

the district court’s order certifying the classes and remand 

for the court to determine the number of uninjured parties in 

the proposed class based on the dueling statistical evidence. 

Only then should the district court rule on whether 

predominance has been established.

1 As a result of Appellant Bumble Bee Foods LLC’s bankruptcy 

proceeding, appellate proceedings against Bumble Bee Foods have been 

held in abeyance due to the automatic stay imposed by 11 U.S.C. § 362. 

Dkt. No. 51.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 11

I. FACTUAL AND PROCEDURAL BACKGROUND

A. The Price-Fixing Conspiracy

Various purchasers of tuna products (“Plaintiffs”) 

brought this class action alleging a price-fixing conspiracy 

by Defendants, the three largest domestic producers of 

packaged tuna. Together, Defendants account for over 80% 

of all branded packaged tuna sales in the country. Plaintiffs 

allege that Defendants colluded to artificially inflate the 

prices of their tuna products by engaging in various forms of 

anti-competitive conduct, including agreeing to (1) fix the 

net and list prices for packaged tuna, (2) limit promotional 

activity for packaged tuna, and (3) exchange sensitive or 

confidential business information in furtherance of the 

conspiracy. There is little dispute over the existence of a 

price-fixing scheme. Soon after this action was commenced, 

the Department of Justice initiated criminal charges against 

Defendants for their price-fixing conspiracy. Bumble Bee 

and StarKist have since pleaded guilty to federal, criminal 

price-fixing charges, as have several of their current and 

former executives. Chicken of the Sea has also admitted to 

price fixing and agreed to cooperate with the federal 

investigation.

B. Certifying the Classes

Plaintiffs proposed three classes of purchasers who 

bought packaged tuna products between November 2010 

and December 2016.

The first proposed class, called the Direct Purchaser 

Plaintiff (“DPP”) Class, consists of retailers who directly 

purchased packaged tuna products during the relevant 

period. In support of certification, the Plaintiffs submitted 

the expert testimony and report of econometrician 
12 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

Dr. Russell Mangum III. Dr. Mangum “primarily” relied on 

statistical evidence “in the form of a regression model which 

purports to prove that the price-fixing conspiracy harmed all, 

or nearly all, of the Class members.” First, Dr. Mangum 

calculated what the price for wholesale tuna would have 

been “but for” the alleged price fixing. To do so, he 

compared the prices during the period of the alleged pricefixing scheme to prices either before or after the alleged 

impacted period, while controlling for other factors that 

affect price differences. Comparing that but-for price to a 

“clean” benchmark period with no anticompetitive activity, 

Dr. Mangum concluded that the DPP Class was overcharged 

by an average of 10.28% because of the price fixing. Finally, 

assuming each class member experienced the same 10.28% 

average overcharge, Dr. Mangum ran a regression analysis 

and concluded that 1,111 out of 1,176 direct purchasers (or 

94.5%) were injured by Defendants’ actions.

The Defendants’ expert econometrician, Dr. John 

Johnson, posed several objections to Dr. Mangum’s 

methodology. First, Dr. Johnson contended that because 

Dr. Mangum used an average estimated overcharge, his 

model incorrectly assumed “every direct purchaser was 

injured—and necessarily in the same way.” Dr. Johnson 

instead calculated a unique overcharge coefficient for 604 

individual class members and concluded that only 72% paid 

an inflated price, meaning 28% of the class members 

suffered no injury at all. Second, Dr. Johnson argued that 

Dr. Mangum found “false positives” because his equation 

identified overcharges during the “clean” benchmark period 

by both Defendants and by packaged tuna sellers who are 

not Defendants. Additionally, Dr. Johnson claimed that 

Dr. Mangum relied on faulty economic assumptions. For 

example, Dr. Mangum’s report purportedly assumed that all 

Defendants would respond identically to changes in supply 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 13

and demand factors, and therefore costs would rise or fall 

identically across all producers. Dr. Johnson also 

commented that Dr. Mangum’s model failed a “Chow Test,” 

which examines the stability of coefficients among separate 

subgroups of a data set to determine if pooling them together 

to create an average is appropriate.

In rebuttal, Dr. Mangum noted that Dr. Johnson did not 

keep the average overcharge coefficient constant but rather 

allowed that coefficient to vary by customer. According to 

Dr. Mangum, this created too small sample sizes of 

customers with each coefficient, and this explained why 

Dr. Johnson was unable to create any results for some 

members of the DPP Class. Dr. Mangum claimed that, even 

under Dr. Johnson’s analysis, 98% of DPP customers were 

overcharged if those customers who showed no result 

whatsoever were excluded.2

The district court certified the class, concluding that the 

Defendants’ challenges to Dr. Mangum’s methods were 

“ripe for use at trial” but “not fatal to a finding of classwide 

impact.” In re Packaged Seafood Prod. Antitrust Litig., 

332 F.R.D. 308, 325 (S.D. Cal. 2019). The district court 

stressed that although Dr. Johnson’s “criticisms are serious 

and could be persuasive to a finder of fact . . . determining 

which expert is correct is beyond the scope” of a class 

certification motion. Id. at 328. The court instead thought 

the critical issue was to determine whether Dr. Mangum’s 

method is “capable of showing” impact on all or nearly all 

class members. Id. Because it was not persuaded that 

“Dr. Mangum’s model is unreliable or incapable of proving 

2 This is compared to Dr. Mangum’s view that 94% of DPP 

customers were overcharged if only statistically significant results were 

considered.
14 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

impact on a class-wide basis,” the court found predominance 

established for the DPP Class. Id.

For the next two proposed classes, Plaintiffs offered 

expert reports and testimony that proceeded similarly to 

Dr. Mangum’s statistical analysis. The Commercial Food 

Service Product (“CFP”) Class consists of those who 

purchased packaged tuna products of 40 ounces or more 

from six major retailers (Dot Foods, Sysco, US Foods, Sam’s 

Club, Wal-Mart, and Costco). The End Payer Plaintiffs 

(“EPP”) Class is defined as consumers who bought 

Defendants’ packaged tuna products in cans or pouches 

smaller than 40 ounces for end consumption from any of the 

six major retailers. Defendants’ expert, Dr. Laila Haider, 

objected to Plaintiffs’ experts’ methodology largely for the 

same reasons raised in opposition to the DPPs’ 

methodology, focusing on benchmark selection, averaging, 

and false positives. Finding only “subtle differences” 

between the methodologies of Plaintiffs’ experts’ and 

Defendants’ objections in these two classes and the DPP 

Class, the district court certified the CFP and the EPP 

Classes. Despite finding “potential flaws” in Plaintiffs’ 

experts’ methodology, the court nonetheless concluded it 

was “reliable and capable of proving impact” and that the 

jury could determine whether liability and damages were 

proven.

A motions panel granted Defendants’ petition for 

permission to appeal the class certification order under 

Federal Rule of Civil Procedure Rule 23(f) and 28 U.S.C. 

§ 1292(e).
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 15

II. LEGAL STANDARDS

A. Standard of Review

We review a district court’s decision to certify a class 

under Rule 23 for abuse of discretion and review the factual 

findings for clear error. Torres v. Mercer Canyons Inc., 

835 F.3d 1125, 1132 (9th Cir. 2016).

B. The Predominance Requirement

Class actions are “an exception to the usual rule that 

litigation is conducted by and on behalf of the individual 

named parties only.” Comcast Corp. v. Behrend, 569 U.S. 

27, 33 (2013) (simplified). To police this exception, Rule 23 

imposes “stringent requirements” for class certification. Am. 

Express Co. v. Italian Colors Rest., 570 U.S. 228, 234 

(2013). A party seeking class certification must first meet 

Rule 23(a)’s four requirements: numerosity, commonality, 

typicality, and adequacy of representation. Leyva v. Medline 

Indus., 716 F.3d 510, 512 (9th Cir. 2013); see Fed. R. Civ. 

P. 23(a). “To obtain certification of a class action for money

damages under Rule 23(b)(3),” a putative class must also 

establish that “the questions of law or fact common to class 

members predominate over any questions affecting only 

individual members.” Amgen Inc. v. Conn. Ret. Plans & Tr. 

Funds, 568 U.S. 455, 460 (2013); see Fed. R. Civ. P. 

23(b)(3). 

When considering whether to certify a class, it is 

imperative that district courts “take a close look at whether 

common questions predominate over individual ones.” 

Comcast, 569 U.S. at 34. The Supreme Court has made clear 

that district courts must perform a “rigorous analysis” to 

determine whether this exacting burden has been met before 

certifying a class. Id. at 35; Wal-Mart Stores, Inc. v. Dukes, 
16 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

564 U.S. 338, 350–51 (2011). This “rigorous analysis” 

requires “judging the persuasiveness of the evidence 

presented” for and against certification. Ellis v. Costco 

Wholesale Corp., 657 F.3d 970, 982 (9th Cir. 2011). Courts 

must resolve all factual and legal disputes relevant to class 

certification, even if doing so overlaps with the merits. WalMart, 564 U.S. at 351. A district court abuses its discretion 

when it fails to adequately determine predominance was met 

before certifying the class. See Valentino v. Carter-Wallace,

Inc., 97 F.3d 1227, 1234 (9th Cir. 1996).

C. The Burden of Proof for Predominance

Although we have not previously addressed the proper 

burden of proof at the class certification stage, we hold that 

a district court must find by a preponderance of the evidence 

that the plaintiff has established predominance under Rule 

23(b)(3). See In re Lamictal Direct Purchaser Antitrust 

Litig., 957 F.3d 184, 191 (3d Cir. 2020) (holding that district 

courts must find by a “preponderance of the evidence that 

the plaintiffs’ claims are capable of common proof at trial”); 

In re Nexium Antitrust Litig., 777 F.3d 9, 27 (1st Cir. 2015) 

(holding that plaintiffs must show “each disputed 

requirement has been proven by a preponderance of 

evidence”); Messner v. Northshore Univ. HealthSystem, 

669 F.3d 802, 811 (7th Cir. 2012) (“Plaintiffs bear the 

burden of showing that a proposed class satisfies the Rule 23

requirements, but they need not make that showing to a 

degree of absolute certainty. It is sufficient if each disputed 

requirement has been proven by a preponderance of 

evidence.”); Alaska Elec. Pension Fund v. Flowserve Corp., 

572 F.3d 221, 228 (5th Cir. 2009) (“[A]n issue of 

predominance must be established at the class certification 

stage by a preponderance of all admissible evidence.”) 

(simplified); Teamsters Loc. 445 Freight Div. Pension Fund 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 17

v. Bombardier Inc., 546 F.3d 196, 202 (2d Cir. 2008) (“[We] 

hold that the preponderance of the evidence standard applies 

to evidence proffered to establish Rule 23’s requirements.”); 

see also Newberg on Class Actions, § 7:21 (5th ed.) (“The 

trend in recent cases has been a move . . . towards adoption 

of a preponderance of the evidence standard to facts 

necessary to establish the existence of a class.”).3

Aside from joining our sister circuits, employing a 

preponderance of the evidence standard supports the district 

court’s role as the gatekeeper of Rule 23’s requirements. See 

Wal-Mart, 564 U.S. at 351; Crutchfield v. Sewerage & 

Water Bd. of New Orleans, 829 F.3d 370, 375 (5th Cir. 2016) 

(holding the predominance inquiry envisions “what a class 

3 A number of district courts in our circuit have likewise applied a 

preponderance of the evidence standard to establish a class. See, e.g.,

Gomez v. J. Jacobo Farm Labor Contractor, Inc., 334 F.R.D. 234, 248

(E.D. Cal. 2019) (“Federal courts throughout the country require the 

movant to demonstrate by a preponderance of the evidence that class 

certification is appropriate.”); Martin v. Sysco Corporation, 325 F.R.D.

343, 354 (E.D. Cal. 2018) (“While Rule 23 does not specifically address 

the burden of proof to be applied, courts routinely employ the 

preponderance of the evidence standard.”); Valenzuela v. Ducey, 2017

WL 6033737, at *3 (D. Ariz. Dec. 6, 2017) (“[The preponderance of the 

evidence] standard appears to be the trend in federal courts and will be 

applied in this case.”) (simplified); Southwell v. Mortg. Inv’rs Corp. of 

Ohio, 2014 WL 3956699, at *1 (W.D. Wash. Aug. 12, 2014) (“[T]his 

Court finds itself in need of such a standard and chooses to align itself 

with the emerging trend in other districts towards the adoption of a 

preponderance of the evidence standard[.]”); Smilovits v. First Solar,

Inc., 295 F.R.D. 423, 427 (D. Ariz. 2013) (“[The preponderance] 

standard appears to be the trend in federal courts[.]”); Keegan v.

American Honda Motor Co., Inc., 284 F.R.D. 504, 521 n.83 (C.D. Cal.

2012) (“[D]efendants cite no Ninth Circuit authority that directs use of a 

preponderance standard in deciding class certification motions. Because 

that is the general standard of proof used in civil cases, however, the 

court applies it here.”).
18 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

trial would look like”). It best accords with the Supreme 

Court’s warning that class certification is “proper only if the 

trial court is satisfied, after a rigorous analysis, that the 

prerequisites of Rule 23(a) have been satisfied.” Wal-Mart 

Stores, 564 U.S. at 349–51 (emphasis added). And a 

preponderance standard is more faithful to Rule 23(b)(3)’s 

text, which provides that courts can certify a class “only if 

. . . the court finds that the questions of law or fact common 

to class members predominate” over individual ones. Fed. 

R. Civ. P. 23(b)(3) (emphasis added).

The preponderance standard also flows from the 

Supreme Court’s emphasis that the evidence used to satisfy 

predominance be “sufficient to sustain a jury finding as to 

[liability] if it were introduced in each [plaintiff’s] individual 

action.” Tyson Foods, Inc. v. Bouaphakeo, 136 S. Ct. 1036, 

1048 (2016) (emphasis added). Establishing predominance, 

therefore, goes beyond determining whether the evidence 

would be admissible in an individual action. Instead, a 

“rigorous analysis” of predominance requires “judging the 

persuasiveness of the evidence presented” for and against 

certification. Ellis, 657 F.3d at 982 (vacating class 

certification because the district court “confused the Daubert 

standard” for admissibility of expert evidence “with the 

‘rigorous analysis’ standard to be applied when analyzing” 

the Rule 23 factors).4

4 We acknowledge that Tyson Foods stated that once a district court 

finds representative evidence “admissible, its persuasiveness is, in 

general, a matter for the jury,” and class certification should only be 

denied if “no reasonable juror” could have found the plaintiffs’ 

representative evidence persuasive. 136 S. Ct. at 1049. But that 

discussion was in the context of a wage-and-hour class action where 

representative evidence is explicitly permitted to establish liability in 

individual cases. Id. (citing Anderson v. Mt. Clemens Pottery Co., 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 19

D. The Use of Representative Evidence

The acceptance of representative evidence at the class 

certification stage is nothing new. The Supreme Court has 

held that representative evidence can be relied on to establish 

a class, but it has also declined to adopt “broad and 

categorical rules governing” its use. Tyson Foods, 136 S. Ct. 

at 1049. Instead, whether a representative sample can 

“establish classwide liability” at the certification stage “will 

depend on the purpose for which the sample is being 

introduced and on the underlying causes of action.” Id. 

While consideration of representative evidence may be 

flexible, it must be scrutinized with care and vigor. See 

Comcast, 569 U.S. at 35 (rejecting the use of representative 

evidence to establish predominance); Wal-Mart, 564 U.S. 

328 U.S. 680, 687 (1946)). Such an evidentiary rule exists because 

defendants often fail to keep proper records of hours worked by 

employees. Id.; see also Lamictal, 957 F.3d at 191–92 (discussing how 

representative evidence is particularly appropriate in wage-and-hour 

suits since “a representative sample of employees may be the only 

feasible way to establish liability” in a wage-and-hour case due to the 

defendant’s own “inadequate record keeping”).

Given that representative evidence can be used to infer harm in 

individual wage-and-hour suits, Tyson Foods reasoned that 

representative evidence was presumptively usable at the class 

certification stage as well. See Tyson Foods, 136 S. Ct. at 1049; see also 

id. at 1046 (stating that representative evidence can be used to establish 

predominance if “each class member could have relied on that sample to 

establish liability if he or she had brought an individual action.”). But 

the “no reasonable jury” standard is cabined to wage-and-hour suits and 

doesn’t apply here. See Senne v. Kan. City Royals Baseball Corp.,

934 F.3d 918, 923, 947 & n.27 (9th Cir. 2019) (“Tyson expressly 

cautioned that this rule should be read narrowly and not assumed to apply 

outside of the wage and hour context.”).
20 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

at 350–51 (rejecting the use of representative evidence to 

establish commonality).

There is reason to be wary of overreliance on statistical 

evidence to establish classwide liability. Academic 

literature abounds observing that “judges and jurors, because 

they lack knowledge of statistical theory, are both overawed 

and easily deceived by statistical evidence.” United States 

v. Veysey, 334 F.3d 600, 604 (7th Cir. 2003).

5 If “highly 

consequential evidence emerges from what looks like an 

indecipherable” statistical model to most “non-statisticians,” 

it is “imperative that qualified individuals explain how the 

[model] works,” and courts must “ensure that it produces 

reliable information.” United States v. Gissantaner, — F.3d 

—, 2021 WL 834005, at *3 (6th Cir. 2021).6

Moreover, the use of representative evidence cannot 

“abridge, enlarge or modify [a plaintiff’s] substantive 

right[s].” See 28 U.S.C. § 2072(b). Otherwise, its use would 

5 See, e.g., Douglas H. Ginsburg & Eric M. Fraser, The Role of 

Economic Analysis in Competition Law (May 16, 2010) (“[Courts] 

almost certainly will not have the assistance of even one staff economist, 

nor will the judges likely be familiar with the economic concepts about 

the application of which [the parties] are debating.”); Laurence H. Tribe, 

Trial by Mathematics: Precision and Ritual in the Legal Process, 

84 Harv. L. Rev. 1329, 1342 n.40 (1971) (discussing how courts 

misunderstand and misapply statistical evidence); G. Alexander Nunn, 

The Incompatibility of Due Process and Naked Statistical Evidence, 

68 Vand. L. Rev. 1407 (2015) (discussing how the use of statistical 

evidence in certain circumstances can constitute a due process violation).

6 As Mark Twain famously popularized, “[t]here are three kinds of 

lies: lies, damn lies, and statistics.” See Mark Twain, Chapters from My 

Autobiography—XX, 186 N. Am. Rev. 465, 471 (1907). Although we 

welcome the use of statistical evidence when appropriate, it would be 

injudicious to swallow it uncritically.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 21

contravene the Rules Enabling Act. Id. Class actions are 

merely a procedural tool aggregating claims, Sprint 

Commc’ns Co. v. APPCC Servs., Inc., 554 U.S. 269, 291 

(2008), and Rule 23 “leaves the parties’ legal rights and 

duties intact and the rules of decision unchanged,” Shady 

Grove Orthopedic Assocs., P.A. v. Allstate Ins. Co., 559 U.S. 

393, 408 (2010) (plurality opinion). The use of 

representative evidence at the class certification stage must 

therefore be closely and carefully scrutinized, and “[a]ctual, 

not presumed, conformance” with Rule 23’s requirements is 

“indispensable.” Wal-Mart, 564 U.S. at 351 (simplified).

With these background legal principles in mind, we turn 

to Defendants’ contentions on appeal.

III. DEFENDANTS’ CLAIMS

Defendants raise two challenges to the district court’s 

reliance on Plaintiffs’ representative evidence. First, 

Defendants argue that this type of representative evidence—

especially the use of averaging assumptions—cannot be 

used to establish predominance. Second, Defendants claim 

that, even if this type of evidence can show predominance, 

Plaintiffs’ econometric analysis does not in fact establish 

predominance because a significant percentage of the class 

may have suffered no injury at all under Plaintiffs’ experts’ 

statistical modeling. We consider each argument in turn.

A. Whether Plaintiffs’ Representative Evidence Can 

Establish Predominance

The threshold consideration is whether Plaintiffs’ 

representative evidence can be used to establish 

predominance. We believe this question raises several 

considerations.
22 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

First, we address whether the representative evidence 

could be used to establish liability in an individual suit. 

Tyson Foods, 136. S. Ct. at 1048. Second, we ensure that 

classwide liability is “capable of proof” through the

representative analysis. Comcast, 569 U.S. at 30. Finally, 

we assess whether the use of averaging assumptions masks 

the predominance question itself “by assuming away the 

very differences that make the case inappropriate for 

classwide resolution.” Tyson Foods, 136 S. Ct. at 1046.

We conclude that Plaintiffs’ representative evidence can 

prove the classwide impact element of Plaintiffs’ pricefixing theory of liability and, thus, may be used to establish 

predominance.

1. Plaintiffs’ Evidence Could Have Been Used to 

Establish Liability in a Class Member’s 

Individual Suit

To establish predominance, the representative evidence 

must be capable of use at trial in individual—not just class 

action—antitrust cases. See Tyson Foods, 136 S. Ct. at 1046 

(Representative evidence is permissible to establish 

predominance if “each class member could have relied on 

that sample to establish liability if he or she had brought an 

individual action.”). This is because plaintiffs and 

defendants cannot have “different rights in a class 

proceeding than they could have asserted in an individual 

action.” Id. at 1048. If the representative evidence could not 

be “relied on . . . to establish liability” in an “individual 

action,” id. at 1046, then it cannot establish predominance at 

the class certification stage.

The District Court held that to meet the predominance 

requirement on their antitrust claims, Plaintiffs had to 

establish: (1) the existence of an antitrust conspiracy; (2) the 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 23

existence of individual injury, also referred to as “antitrust 

impact,” as a result of the conspiracy; and (3) resultant 

damages. Packaged Seafood, 332 F.R.D. at 320; see 

1 McLaughlin on Class Actions § 5:33 (17th ed. 2020); see 

also In re New Motor Vehicles Canadian Exp. Antitrust 

Litig., 522 F.3d 6, 19 n. 18 (1st Cir. 2008).

Plaintiffs rely on their representative evidence to 

establish the “antitrust impact” of their price-fixing claims 

against the Defendants. Statistical evidence has long been 

used to prove antitrust impact in individual suits. To 

establish impact in any antitrust action, plaintiffs must 

“delineate a relevant market and show that the defendant 

plays enough of a role in that market to impair competition 

significantly.” Metro Indus., Inc. v. Sammi Corp., 82 F.3d 

839, 847–48 (9th Cir. 1996). Even in individual suits, doing 

so often requires comparing the actual world with a 

“hypothetical” world that would have existed “‘but for’ the 

defendant’s unlawful activities.” See LePage’s Inc. v. 3M, 

324 F.3d 141, 165 (3d Cir. 2003); see, e.g., MM Steel, L.P. 

v. JSW Steel (USA) Inc., 806 F.3d 835, 851–52 (5th Cir. 

2015) (holding that the district court didn’t abuse its 

discretion by using a “yardstick” calculation of damages in 

an antitrust suit where the individual plaintiffs did a but-for 

analysis by comparing their profits with “a study of the 

profits of business operations that are closely comparable to 

the plaintiff’s”).

In individual cases, constructing these “but-for” 

comparisons usually requires the use of statistical evidence. 

See Manual of Complex Litigation (Fourth) § 23.1, at pp. 

470–71 (“[S]tatistical evidence is routinely introduced . . . in 

antitrust litigation.”). And injury may be inferred from 

statistical evidence. See Zenith Radio Corp. v. Hazeltine 

Research, Inc., 395 U.S. 100, 125 (1969) (stating that 
24 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

antitrust impact can be inferred from “circumstantial 

evidence”); see also ABA Section of Antitrust Law, 

Econometrics: Legal, Practical, and Technical Issues 

§ 13.B.1.c. (2d ed. 2014) (discussing the use of regression 

models in antitrust actions).

Here, each class member could have relied on 

Dr. Mangum’s models to show classwide impact in each of 

their individual suits. By constructing a clean, “benchmark” 

period and comparing it to market price before and after the 

benchmark, Dr. Mangum created a “yardstick” comparison 

to isolate the “but-for” effect of the price-fixing conspiracy, 

similar to the type of evidence relied upon in individual 

antitrust actions. See, e.g., LePage’s Inc., 324 F.3d at 165; 

MM Steel, 806 F.3d at 851–52. And the regression analysis 

Dr. Mangum ran to calculate that 94% of the DPP Class 

suffered an injury is consistent with the use of regression 

models to prove price-fixing impact in other cases. See, e.g., 

In re Linerboard Antitrust Litig., 305 F.3d 145, 153 (3d Cir. 

2002) (affirming use of plaintiffs’ “multiple regression 

analysis” to prove “impact on a class-wide basis” in pricefixing suit). In short, Plaintiffs’ statistical evidence is not 

materially different than the type of evidence that would be 

used against Defendants in individual cases brought by each 

class member.

2. Plaintiffs’ Representative Evidence 

Sufficiently Links Their Injuries to Their 

Theory of Antitrust Violation

Plaintiffs’ representative evidence must also be 

consistent with their underlying theory of liability. Comcast,

569 U.S. at 35 (“[A]ny model supporting a plaintiff’s 

damages case must be consistent with its liability case, 

particularly with respect to the alleged anticompetitive effect 

of the violation.”). We have interpreted Comcast to require 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 25

that plaintiffs “show that their damages stemmed from the 

defendant’s actions.” Pulaski & Middleman, LLC v. Google, 

Inc., 802 F.3d 979, 987–88 (9th Cir. 2015) (simplified). Put 

another way, the evidence must be capable of linking the 

harm from the defendant’s conduct to the class members.

In this case, there is a sufficient nexus between Plaintiffs’ 

representative evidence and their price-fixing theory of 

liability. See Allied Orthopedic, 592 F.3d at 996. 

Dr. Mangum’s regression model can show antitrust impact 

by isolating the but-for effect of the price inflation 

attributable to Defendants’ alleged anticompetitive price list 

(the 10.28% average overcharge), and by using a regression 

model to calculate how much of the class would have been 

impacted by that overcharge. Plaintiffs thus present a 

“theory of injury and damages” that is “provable and 

measurable by an aggregate model relying on class-wide 

data.” In re Suboxone Antitrust Litig., 967 F.3d 264, 272 (3d 

Cir. 2020) (affirming representative evidence in an antitrust 

class action).

Accordingly, this is unlike cases where courts have 

disapproved of representative evidence. In Comcast, for 

example, the Court rejected representative evidence because 

the posited regression analysis showed common injury that 

did not track the plaintiffs’ underlying theory of liability. 

569 U.S. at 35–38. There, the plaintiffs’ regression model 

accounted for four different antitrust theories of harm, even 

though the district court had only allowed the plaintiffs to 

proceed on one of these theories. Id. at 31–32, 35. Such a 

model “failed to measure damages resulting from the 

particular antitrust injury on which” the class premised its 

claim and “identifie[d] damages that are not the result of the 

wrong” suffered by the certified class. Id. at 36–37. By 

contrast, here Plaintiffs’ regression models test only one 
26 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

theory of liability: the but-for impact of Defendants’ pricefixing conspiracy.

3. Plaintiffs’ Use of Averaging Assumptions 

Does Not Defeat Predominance

Defendants also argue that the representative evidence at 

issue here is categorically impermissible because Plaintiffs’ 

experts used averaging assumptions in their regression 

models. But the Supreme Court rejected “categorical 

exclusion” of representative evidence. Tyson Foods, 136 S. 

Ct. at 1046. Instead, Tyson approved the use of averaging 

assumptions so long as the statistical evidence was “reliable 

in proving or disproving the elements of the relevant cause 

of action.” Id.

The use of averaging assumptions in a regression 

analysis may be inappropriate “where [a] small sample size 

may distort the statistical analysis and may render any 

findings not statistically probative.” Paige v. California, 

291 F.3d 1141, 1148 (9th Cir. 2002). Indeed, Dr. Mangum’s 

rebuttal to Dr. Johnson’s testimony was that varying the 

overcharge value in his regression analysis resulted in too 

small sample sizes that were not statistically robust.

Here, we see no issue with Plaintiffs’ use of averaging 

assumptions in its regression models. Dr. Mangum averaged 

the overcharge calculation using Defendants’ own data, and 

then used that average in a regression model to calculate 

what percentage of the class was impacted. Presuming the 

reliability of Plaintiffs’ statistical methodology (which we 

discuss later), the representative evidence can show that 

virtually all class members suffered an injury due to 

Defendants’ alleged wrongdoing.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 27

According to Defendants, Plaintiffs’ averaging 

assumptions papered over the very individualized 

differences that make classwide resolution of this case 

inappropriate. Defendants stress that “innumerable 

individualized differences” among the class members make 

it impossible to show class-wide impact through “common 

proof.” For instance, direct purchasers often individually 

negotiate prices, and the prices retailers actually pay may 

vary based on purchasing power, retail price strategy, and 

other factors. Some retailers may have even sold 

Defendants’ tuna products as a loss leader to drive customers 

to their stores. Defendants also contend that these averaging 

assumptions are even more inappropriate when applied to 

the indirect-purchaser class, which contains “even more 

disparate” class members, including millions of individuals 

who bought billions of tuna products from “countless stores 

across the country over a four-year period.”

But even assuming the existence of these individualized 

differences, a higher initial list price as a result of 

Defendants’ price-fixing scheme could have raised the 

baseline price at the start of negotiations and could have 

affected the range of prices that resulted from negotiation.

Even Walmart, which as the largest retailer in the country 

would have had the strongest bargaining power of any class 

member, was shown to have suffered overcharges as a result 

of Defendants’ conduct. This relieves concerns that the class 

members were not “similarly situated,” and would allow the 

“reasonable inference of class-wide liability.” See Tyson 

Foods, 136 S. Ct. at 1045 (citations omitted).

Moreover, even if class members suffered individualized 

damages that diverged from the average overcharge 

calculated by Plaintiffs’ expert, “the presence of 

individualized damages cannot, by itself, defeat class 
28 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

certification under Rule 23(b)(3).” Leyva, 716 F.3d at 514. 

Indeed, we have consistently distinguished the existence of 

injury from the calculation of damages. See Vaquero, 

824 F.3d at 1155; Senne, 934 F.3d at 943. Consequently, 

individualized damages calculations do not, alone, defeat 

predominance—although, as we discuss below, the presence 

of class members who suffered no injury at all may defeat 

predominance.

*****

Because this type of representative evidence can be used 

to prove injury in individual antitrust suits, is consistent with 

Plaintiffs’ underlying cause of action, and doesn’t 

necessarily mask a lack of predominance, we hold it is 

permissible to rely on Plaintiffs’ representative evidence at 

the class certification stage.

B. Whether the District Court Must Rule on the 

Presence of Uninjured Class Members

Even if Plaintiffs’ representative evidence could be used 

to satisfy predominance, we cannot embrace their 

conclusions and averaging assumptions uncritically. 

Statistical evidence is not a talisman. Courts must still 

rigorously analyze the use of such evidence to test its 

reliability and to see if the statistical modeling does in fact 

mask individualized differences.

As stated earlier, reliability is the touchstone for 

establishing predominance through representative sampling. 

See Tyson Foods, 136 S. Ct. at 1046. It is thus necessary for 

courts to consider “the degree to which the evidence is 

reliable in proving or disproving” whether a common 

question of law or fact predominates over the class members. 

Id. (emphasis added); see also Vaquero, 824 F.3d at 1155. 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 29

To do so, courts must “resolve any factual disputes necessary 

to determine whether” predominance has in fact been met.

Ellis, 657 F.3d at 982–84. In other words, the threshold 

predominance determination cannot be outsourced to a jury. 

Lamictal, 957 F.3d at 191 (“[T]he court must resolve all 

factual or legal disputes relevant to class certification[.]”) 

(simplified).

When considering if predominance has been met, a key 

factual determination courts must make is whether the 

plaintiffs’ statistical evidence sweeps in uninjured class 

members. As the district court recognized, Plaintiffs “must 

establish, predominantly with generalized evidence, that all 

(or nearly all) members of the class suffered damage as a 

result of Defendants’ alleged anti-competitive conduct.” 

Packaged Seafood, 332 F.R.D. at 320 (simplified). If a 

substantial number of class members “in fact suffered no 

injury,” the “need to identify those individuals will 

predominate.” In re Asacol Antitrust Litig., 907 F.3d 42, 53 

(1st Cir. 2018); see Halvorson v. Auto-Owners Ins. Co., 

718 F.3d 773, 779 (8th Cir. 2013). If injury cannot be 

proved or disproved through common evidence, then 

“individual trials are necessary to establish whether a 

particular [class member] suffered harm from the [alleged 

misconduct],” and class treatment under Rule 23 is 

accordingly inappropriate. In re Rail Freight Fuel 

Surcharge Antitrust Litig.-MDL No. 1869, 725 F.3d 244, 252 

(D.C. Cir. 2013); see also Tyson Foods, 136 S. Ct. at 1045.7

7 The presence of uninjured parties in a certified class also raises 

serious standing implications under Article III. The federal court system 

is reserved only for those that have suffered an injury. See Lujan v. Defs. 

of Wildlife, 504 U.S. 555, 566 (1992). To that end, standing requires 

each plaintiff provide “a factual showing of perceptible harm.” Id. A
30 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

In this case, the district court abused its discretion in 

declining to resolve the competing expert claims on the 

reliability of Plaintiffs’ statistical model. Defendants’ expert 

provided testimony and alternative statistical modeling that 

suggested Plaintiffs’ data was methodologically flawed and 

was unable to show impact for up to 28% of the class—not 

5.5%, as Plaintiffs’ expert insists. Rather than resolving the 

dispute, however, the district court merely considered 

whether Plaintiffs’ statistical evidence was “plausibly 

reliable” and otherwise left determination of this question to 

the jury. It concluded that “determining which expert is 

correct is beyond the scope” of class certification and was 

“ultimately a merits decision” for the jury to decide.8

But resolving this dispute is of paramount importance to 

certification of the class. If Plaintiffs’ model indeed shows 

that more than one-fourth of the class may have suffered no 

class action should be no different. See Tyson Foods, 136 S. Ct. at 1053 

(Roberts, C.J., concurring) (“Article III does not give federal courts the 

power to order relief to any uninjured plaintiff, class action or not.”). 

Accordingly, as the Fifth Circuit recently expressed, we are skeptical that 

Article III permits certification of a class where “[c]ountless unnamed 

class members lack standing.” Flecha v. Medicredit, Inc., 946 F.3d 762, 

768 (5th Cir. 2020). But we do not reach this issue because, as we lay 

out, class certification fails under Rule 23(b)(3), which is dispositive of 

the matter. In re Hyundai & Kia Fuel Economy Litig., 926 F.3d 539, 565 

n.12 (9th Cir. 2019).

8 Courts cannot relocate the predominance inquiry to the merits 

stage of the trial. Rule 23 requires this determination be made at the pretrial stage. And for good reason. Suppose the jury ultimately decides 

Defendants’ expert is right and Plaintiffs’ model sweeps in 28% 

uninjured class members. Too late: the damage has been done. By then, 

Defendants would have possibly weathered years of litigation at untold 

costs, only to discover that the case never should have reached the merits 

at all. Rule 23’s objective—that only cases suitable for class 

adjudication be certified—would have been effectively undermined.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 31

injury at all, the district court cannot find by a preponderance 

of the evidence that “questions of law or fact common to 

class members predominate over any questions affecting 

only individual members.” Fed. R. Civ. P. 23(b)(3).

Rule 23(b)(3)’s choice of wording matters. The word 

“common” means “belonging to or shared . . . by all 

members of a group.”9 Meanwhile, “predominate” means 

“to hold advantage in numbers or quantity.”10 Similarly, 

when used as a noun, the word “predominance” means “the 

state of . . . being most frequent or common.”11 Thus, Rule 

23(b)(3) requires that questions of law or fact be shared by 

substantially all the class members, and these common 

questions must be superior in strength or pervasiveness to 

individual questions within the class.

If 28% of the class were uninjured, common questions of 

law or fact would not be shared by substantially all the class 

members, nor would they prevail in strength or 

pervasiveness over individual questions. This would raise 

concerns that Plaintiffs’ experts’ use of average assumptions 

did mask individual differences among the class members, 

9 Common, Merriam-Webster’s Collegiate Dictionary (11th ed. 

2007).

10 Predominate, Merriam-Webster’s Collegiate Dictionary; see also 

Predominate, Oxford English Dictionary, 

https://www.oed.com/view/Entry/149893 (defining “predominate” as 

“[t]o have or exert controlling power; to be of greater authority or 

influence, to be superior”).

11 Predominance, Merriam-Webster’s Collegiate Dictionary; see 

also Predominance, Oxford Online English Dictionary, 

https://www.oed.com/view/Entry/149888 (defining “predominance” as 

“preponderance, prevalence; prevailing or superior influence, power, or 

authority”).
32 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

such as bargaining power, negotiation positions, and 

marketing strategies.

Although we have not established a threshold for how 

great a percentage of uninjured class members would be 

enough to defeat predominance, it must be de minimis. Even 

though “a well-defined class may inevitably contain some 

individuals who have suffered no harm,” Torres, 835 F.3d 

at 1136, the few reported decisions involving uninjured class 

members “suggest that 5% to 6% constitutes the outer limits 

of a de minimis number,” In re Rail Freight Fuel Surcharge 

Antitrust Litig., 934 F.3d 619, 624–25 (D.C. Cir. 2019) 

(simplified) (finding no predominance where 12.7% of class 

members were conceded to be uninjured by plaintiffs’ own 

expert). The First Circuit reversed certification where the 

district court had concluded that “around 10%” of the 

proposed class was uninjured. See In re Asacol, 907 F.3d 

at 47, 51–58. And even the district court recognized that the 

inclusion of 28% uninjured class members would 

“unquestionably” defeat predominance. Packaged Seafood, 

332 F.R.D. at 325. Contrary to the dissent’s suggestion, we 

do not adopt a numerical or bright-line rule today.12 But 

under any rubric, if Plaintiffs’ model is unable to show 

impact for more than one-fourth of the class members, 

predominance has not been met.13 While we do not set the 

12 The dissent also claims that we ignore Ninth Circuit case law. 

Dissent at 36. Not so. We agree with Torres v. Mercer Canyons Inc., 

835 F.3d 1125, 1136 (9th Cir. 2016) that the mere presence of some noninjured class members does not defeat predominance, but we hold that 

the number of uninjured class members must be de minimis. As Torres

stated, the “existence of large numbers of class members” who were 

never exposed to injurious conduct may defeat predominance. Id.

13 This is over double the percentage of uninjured class members 

considered sufficient to defeat predominance in In re Rail Freight 
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 33

upper bound of what is de minimis, it’s easy enough to tell

that 28% would be out-of-bounds.

The district court’s gloss over the number of uninjured 

class members was an abuse of discretion. Rule 23(b)(3) 

requires courts “to make findings about predominance and 

superiority before allowing the class.” Wal-Mart, 564 U.S. 

at 363 (emphasis added). Deferring determination of 

classwide impact effectively “amounts to a delegation of 

judicial power to the plaintiffs, who can obtain class 

certification just by hiring a competent expert.” West v. 

Prudential Sec., Inc., 282 F.3d 935, 938 (7th Cir. 2002). If 

“savvy crafting of the evidence” were enough to guarantee 

predominance, there would be little limit to class 

certification in our modern world of increasingly 

sophisticated aggregate proof.” See Richard A. Nagareda, 

Class Certification in the Age of Aggregate Proof, 84 N.Y.U. 

L. Rev. 97, 103 (2009). In Ellis, we vacated the district 

court’s certification of a class for the failure to resolve 

“critical factual disputes” in a “battle of the experts” 

regarding commonality. 657 F.3d at 982, 984. So too here, 

the district court failed to resolve the factual disputes as to 

how many uninjured class members are included in 

Plaintiffs’ proposed class—an essential component of 

predominance.

Plaintiffs emphasize that the district court stated its 

inquiry went beyond a Daubert analysis and that the court 

recognized it was required to determine whether the expert 

evidence was “in fact persuasive.” The district court even 

walked through the strengths and weaknesses of the experts’ 

(12.7%), almost triple the percentage disapproved of in In re Asacol

(10%), and around five times greater than the percentages at issue in the 

district courts cited (5–6%).
34 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

competing testimony. Yet despite acknowledging there 

were “potential flaws” in the Plaintiffs’ expert’s 

methodology, the district court made no finding. A district 

court that “has doubts about whether the requirements of 

Rule 23 have been met should refuse certification until they 

have been met.” Brown v. Electrolux Home Prods., Inc., 

817 F.3d 1225, 1233–34 (11th Cir. 2016) (simplified).14

Despite admirably and thoroughly marshaling the 

evidence in this difficult case, the district court needed to go 

further by resolving the parties’ dispute over whether the 

representative evidence swept in only 5.5% or as much as 

28% uninjured DPP Class members. The district court also 

needed to make a similar determination for the other putative 

classes. Deciding this preliminary question is necessary to 

determine whether Plaintiffs have established 

predominance.

IV. CONCLUSION

Accordingly, we vacate the district court’s order 

certifying the classes and remand with instructions to resolve 

the factual disputes concerning the number of uninjured 

14 Compounding these concerns, the burden of persuasion may have 

been improperly shifted to Defendants to affirmatively disprove the 

claims made by Plaintiffs’ expert. In certifying the classes, the district 

court reasoned that “Defendants have not persuaded the Court that 

Dr. Mangum’s model is unreliable.” Packaged Seafood, 332 F.R.D. 

at 326. Additionally, the district court concluded that the predominance 

requirement was met because Defendants had not shown that Plaintiffs’ 

models were “glaringly erroneous.” Id. But the “party seeking class 

certification has the burden of affirmatively demonstrating that the class 

meets the requirements of [Rule] 23.” Mazza v. Am. Honda Motor Co., 

666 F.3d 581, 588 (9th Cir. 2012).
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 35

parties in each proposed class before determining 

predominance.15

VACATED and REMANDED.

HURWITZ, Circuit Judge, concurring in part and dissenting 

in part:

The majority is faithful to the plain text of Rule 23 in 

concluding that the district court, not a jury, must resolve 

factual disputes bearing on predominance. See Fed. R. Civ. 

P. 23(b)(3) (permitting a class action to be maintained if “the 

court finds that the questions of law or fact common to class 

members predominate over any questions affecting only 

individual members”) (emphasis added). I also agree with 

the majority that a district court’s “rigorous analysis” of 

whether a putative class has satisfied Rule 23’s requirements 

should proceed by a preponderance of the evidence standard. 

See Ellis v. Costco Wholesale Corp., 657 F.3d 970, 982 (9th 

Cir. 2011). And, the majority correctly holds that the 

question for the district court is not whether common issues 

could predominate at trial; the court must determine that they 

do predominate before certifying the class. See Comcast 

Corp. v. Behrend, 569 U.S. 27, 34 (2013). I therefore agree 

that remand is required.

I part company, however, with the majority’s conclusion 

that, before certifying a class, the district court must find that 

only a “de minimis” number of class members are uninjured. 

15 Pursuant to Federal Rule of Appellate Procedure 39(a) and Ninth 

Circuit General Order 4.5(e), each party shall bear its own costs on 

appeal.
36 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

The text of Rule 23 contains no such requirement, nor do our 

precedents. The majority’s effective amendment of Rule 23 

not only ignores our case law but also circumvents the 

established process for modifying a Rule of Civil 

Procedure—study and advice from the relevant committees, 

followed by the consent of the Supreme Court and 

Congress’s tacit approval. See Rules Enabling Act, 

28 U.S.C. § 2072; Shady Grove Orthopedic Assocs., P.A. v. 

Allstate Ins. Co., 559 U.S 393, 407 (2010) (describing the 

Supreme Court’s rulemaking power). I therefore 

respectfully dissent from Part III.B of the majority opinion.1

I

As an initial matter, our caselaw squarely forecloses the 

majority’s approach. The critical question is not what 

percentage of class members is injured, but rather whether 

the district court can economically “winnow out” uninjured 

plaintiffs to ensure they cannot recover for injuries they did 

not suffer. See Torres v. Mercer Canyons, Inc., 835 F.3d 

1125, 1137 (9th Cir. 2016). If the district court can ensure 

that uninjured plaintiffs will not recover, their mere presence 

in the putative class does not mean that common issues will 

1 The majority also notes that “[a]cademic literature abounds 

observing that ‘judges and jurors, because they lack knowledge of 

statistical theory, are both overawed and easily deceived by statistical 

evidence.’” Op. at 20 (quoting United States v. Veysey, 334 F.3d 600, 

604 (7th Cir. 2003)). But even assuming that academic literature does 

so “abound,” see Op. at 20, n.5, that doesn’t establish that Article III 

judges in general, or the distinguished district judge in this case, are so 

easily fooled. The cited literature is, for better or worse, based on the 

observations of the authors, not on a rigorous scientific survey of the lack 

of knowledge of statistical theory by district judges (or even federal 

appellate judges).
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 37

not predominate. See Yokoyama v. Midland Nat’l Life Ins. 

Co., 594 F.3d 1087, 1089 (9th Cir. 2010).

The plain text of Rule 23 requires only that “questions of 

law or fact common to the class predominate over any 

questions affecting only individual members.” Fed. R. Civ. 

P. 23(b)(3) (emphasis added). The noun “predominant” 

means “[m]ore powerful, more common, or more 

noticeable.” Predominant, Black’s Law Dictionary (11th ed. 

2019). In Rule 23(b)(3), the subject of the verb 

“predominate” is “common questions of law or fact.” The 

Rule therefore simply instructs the district court to determine 

whether common questions exceed others. See Pavelic & 

LeFlore v. Marvel Ent. Grp., 493 U.S. 120, 123 (1989) 

(applying statutory interpretation maxims to a Federal Rule 

of Civil Procedure); see also Weyerhauser Co. v. U.S. Fish 

and Wildlife Serv., 139 S. Ct. 361, 368 (2018) (reading 

statutory text “[a]ccording to the ordinary understanding of 

how adjectives work” to determine how the statute 

“modif[ies] nouns”).

We have therefore stressed that “[t]he potential existence 

of individualized damage assessments . . . does not detract 

from the action’s suitability for class certification.” 

Yokoyama, 594 F.3d at 1089; see also Advisory Comm. Note 

to 1966 Amendment, Rule 23 (“It is only where this 

predominance exists that economies can be achieved by 

means of the class-action device. In this view, a fraud 

perpetrated on numerous persons by the use of similar 

misrepresentations may be an appealing situation for a class 

action, and it may remain so despite the need, if liability is 

found, for separate determination of the damages suffered by 

individuals within the class.”). In Levya, for example, we 

stated that although “plaintiffs must be able to show that 

their damages stemmed from the defendant’s actions that 
38 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

created the legal liability,” the presence of putative class 

members “allegedly entitled to different damage awards” did 

not defeat predominance. Levya v. Medline Indus., 716 F.3d 

510, 513–14 (9th Cir. 2013); see also Vaquero v. Ashley 

Furniture Indus., Inc., 824 F.3d 1150, 1155 (9th Cir. 2016), 

Pulaski & Middleman, LLC v. Google, Inc., 802 F.3d 979, 

988 (9th Cir. 2015) (holding that Comcast did not disturb 

Yokoyama). Even in a properly certified class, “[d]amages 

may well vary, and may require individualized calculations.” 

Senne v. Kansas City Royals Baseball Corp., 934 F.3d 918, 

943 (9th Cir. 2019).

Most importantly, we have held that because “even a 

well-defined class may inevitably contain some individuals 

who have suffered no harm,” the same approach governs 

even if there are uninjured plaintiffs. Torres, 835 F.3d at 

1136–37. Rather, the presence of some plaintiffs not harmed 

by the defendants’ conduct merely highlights the “possibility 

that an injurious course of conduct may sometimes fail to 

cause injury.” Id. at 1136. And, no Ninth Circuit case 

imposes a cap on the number of uninjured plaintiffs as a 

prerequisite to class certification.

Our settled law is consistent with the basic principles 

underlying Rule 23. A class plainly may be certified solely 

on discrete issues. See Fed. R. Civ. P. 23(c)(4). So, in the 

case before us, the district court could well certify a class on 

liability, followed by a more narrowly defined class (or even 

individual trials, if necessary) on damages. As the majority 

recognizes, there is little dispute the defendants engaged in 

an antitrust conspiracy. I perceive no bar in Rule 23 to 

certifying a liability class, while leaving open which 

members of the class suffered damage from the defendants’ 

illegal conduct.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 39

As the Fifth Circuit has recognized, the predominance 

inquiry focuses on “what a class trial would look like.” 

Crutchfield v. Sewerage & Water Bd. of New Orleans, 

829 F.3d 370, 375 (5th Cir. 2016). The crucial question, left 

to the district court’s sound discretion, is whether “common 

questions present a significant aspect of the case and they 

can be resolved for all members of the class in a single 

adjudication.” True Health Chiropractic, Inc. v. McKesson 

Corp., 896 F.3d 923, 931 (9th Cir. 2018). Certification 

should fail only when the individual questions “threaten to 

become the focus of the litigation.” Torres, 835 F.3d 

at 1142.

II

A numerical cap on uninjured class members is not very 

helpful to district courts analyzing predominance. To be 

sure, a large percentage of uninjured plaintiffs may raise 

predominance concerns. See In re Asacol Antitrust Litig., 

907 F.3d 42, 53–54 (1st Cir. 2018). Our cases plainly 

recognize that concern. See Torres, 835 F.3d at 1142.

But, as written, the Rule is not categorical with respect 

to the number of uninjured plaintiffs. If the questions of law 

or fact about whether a defendant breached a legal duty to a 

class are common, and identifying the uninjured members 

would be relatively simple, there is likely no reason to deny 

Rule 23 certification on liability. For example, if a 

telecommunications company were alleged to have 

erroneously charged many California customers double rates 

for certain interstate calls, a district court could certify a 

class of all the company’s California customers even if an 

expert testified that only 80 percent of them were likely to 

have made the calls in question. Determining who did, 

which likely could be done from available records, could be 

left to a damages stage.
40 OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS

This variation among cases is why we review decisions 

on class certification for abuse of discretion. Torres,

835 F.3d at 1132. We give the district court “noticeably 

more deference” when it certifies a class than when it denies 

certification. Abdulla v. U.S. Sec. Assocs., Inc., 731 F.3d 

952, 956 (9th Cir. 2013) (cleaned up). That deference is 

appropriate because Rule 23 certification is at bottom a trial 

management decision; it simply allows the class litigation to 

continue under the district court’s ongoing supervision. The 

district court retains the power to alter or amend a class 

certification order at any time before final judgment. Fed. 

R. Civ. P. 23(c)(1)(C).

I recognize that one of our sister Circuits has suggested 

that “5% to 6%” is the “outer limit[]” of an acceptable 

number of uninjured class members. In re Rail Freight Fuel 

Surcharge Antitrust Litig., 934 F.3d 619, 625 (D.C. Cir. 

2019).2 While disclaiming any particular numerical cap, the 

majority suggests that something between 5 and 10 percent 

approaches the outer limit. Op. at 32. But this effectively 

rewrites Rule 23. If the Supreme Court finds that approach 

wise, after the usual input and recommendations from the 

advisory committees, and Congress does not see fit to act to 

the contrary, then so be it. But we should not legislate from 

the appellate bench based on our personal concerns with the 

class action device. Under the Rule as currently written, we 

should instead leave fact-based decisions on predominance 

2 Although the First Circuit has adopted a “de minimis” rule, it has 

defined it in “functional terms,” asking whether there is a “mechanism 

that can manageably remove uninjured persons.” Asacol Antitrust Litig., 

907 F.3d at 53–54 (cleaned up). That rule corresponds in practical 

application to Ninth Circuit precedent. See Torres, 835 F.3d at 1137.
OLEAN WHOLESALE GROCERY COOP. V. BUMBLE BEE FOODS 41

and case management to the sound discretion of the district 

courts.

Nor is a “de minimis” rule necessary to address Article 

III concerns. “[O]nly the representative plaintiff need allege 

standing at the motion to dismiss and class certification 

stages.” Ramirez v. TransUnion LLC, 951 F.3d 1008, 1023 

(9th Cir. 2020). Class members “must satisfy the 

requirements of Article III standing at the final stage of a 

money damages suit when class members are to be awarded 

individual monetary damages.” Id. at 1017 (emphasis 

added). To be sure, Torres instructs the district court to 

“winnow out” uninjured class members, 835 F.3d at 1137, 

but their presence at the certification stage is not a barrier to 

standing. Put simply, the de minimis rule is a solution in 

search of a problem.

III

Defendants may well be correct that Plaintiffs’ data was 

“methodologically flawed and was unable to show impact 

for up to 28% of the class.” Op. at 30. And, in the exercise 

of its discretion, the district court might find that such a large 

percentage of uninjured class members means that common 

issues of law or fact do not predominate in this case. But, by 

the same measure, the district court could find that Plaintiffs’ 

aggregated proof could establish liability to a predominant 

portion of the class, and that uninjured members could be 

identified in future (perhaps non-class) proceedings. 

Because the majority removes from the district court the 

broad discretion Rule 23 provides and instead replaces it 

with a “de miminis” requirement found nowhere in the Rule 

or our precedents, I respectfully dissent from Part III.B.3 of 

the majority opinion.