The predominance inquiry under Rule 23(b)(3) has never been comfortable terrain for plaintiffs. But since Comcast Corp. v. Behrend, 569 U.S. 27 (2013), it has become the central battleground in most contested class certifications. Comcast's core holding — that a damages model must be consistent with the plaintiff's liability theory — sounds almost obvious in retrospect, yet its application has created genuinely divergent outcomes in the lower courts. This post maps the Comcast holding, the corrective provided by Tyson Foods, Inc. v. Bouaphakeo, 577 U.S. 442 (2016), and the Eleventh Circuit's application of both.
I. The Predominance Standard: Doctrinal Context
Rule 23(b)(3) permits class certification when "the court finds that the questions of law or fact common to class members predominate over any questions affecting only individual members, and that a class action is superior to other available methods for fairly and efficiently adjudicating the controversy." Fed. R. Civ. P. 23(b)(3).
Amchem Products, Inc. v. Windsor, 521 U.S. 591 (1997), established that predominance is "far more demanding" than Rule 23(a)'s commonality requirement. Where commonality asks merely whether there is a common question, predominance asks whether common questions — those that can be resolved with generalized proof applicable across the class — predominate over individual ones in driving the litigation.
The standard does not require every question to be common; it requires that the "most significant" questions be susceptible to classwide resolution. A class may properly include members who sustained different amounts of harm, so long as the determination of liability is common.
II. Comcast Corp. v. Behrend: The Holding
A. Facts and Lower Court Rulings
Respondents in Comcast Corp. v. Behrend, 569 U.S. 27 (2013) were cable television subscribers who alleged that Comcast's "clustering" strategy — acquiring cable systems in the Philadelphia DMA and swapping systems outside the region for competitor systems within it — violated the Sherman Act by eliminating competition and sustaining supra-competitive prices.
The district court accepted only one of four proposed liability theories: that Comcast's clustering deterred "overbuilder" competition. It then certified the class after finding that respondents' damages expert, Dr. James McClave, had produced a regression model that calculated classwide damages attributable to Comcast's anticompetitive conduct generally — without isolating damages attributable to the overbuilder-deterrence theory specifically. The Third Circuit affirmed, declining to scrutinize the damages model because doing so would "reach the merits" at the certification stage.
B. The Supreme Court's Reversal
In a 5–4 decision authored by Justice Scalia, the Supreme Court reversed. The Court held:
"A model purporting to serve as evidence of damages in this class action must measure only those damages attributable to [the accepted liability] theory. If the model does not even attempt to do that, it cannot possibly establish that damages are susceptible of measurement across the entire class for purposes of Rule 23(b)(3)."
Comcast, 569 U.S. at 35.
The Court's reasoning rested on two propositions:
- The same analytical principles govern Rule 23(a) and 23(b). Courts may — and must — "probe behind the pleadings" when analyzing certification, even if doing so requires merits analysis. Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338 (2011), is the controlling precedent on this point.
- The damages model must be consistent with the liability case. At the certification stage (as at trial), "any 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." Id. at 35 (citation omitted). A model that measured damages across all four liability theories could not support certification where only one theory was viable.
C. The Dissent's Limiting Principle
Justices Ginsburg and Breyer, joined by Justices Sotomayor and Kagan, wrote a significant dissent contesting both the merits of the majority's approach and its reach. The dissent argued:
- The case should have been dismissed as improvidently granted because Comcast forfeited its Daubert objection.
- The majority's ruling "breaks no new ground" on the predominance standard and "should not be read to require, as a prerequisite to certification, that damages attributable to a classwide injury be measurable 'on a class-wide basis.'"
The dissent's limiting principle has been influential: lower courts, including the Eleventh Circuit, have read Comcast as applying primarily where (1) the district court accepted only a subset of the plaintiff's liability theories, and (2) the damages model was specifically designed to measure damages across all theories. Where both liability and damages are susceptible to classwide proof without the Comcast mismatch problem, the dissent suggests the holding should not apply.
III. Tyson Foods, Inc. v. Bouaphakeo: Representative Proof and Statistical Evidence
Tyson Foods, Inc. v. Bouaphakeo, 577 U.S. 442 (2016) provided an important counterweight to Comcast's limiting effect on class certification. The case involved Iowa pork processing plant workers who claimed Tyson violated the FLSA and Iowa wage law by failing to compensate them for time spent donning and doffing protective gear.
Because Tyson failed to record donning-and-doffing time, the plaintiffs relied on an industrial relations expert's study — Dr. Kenneth Mericle's videotaped observations of donning and doffing activities — to produce average time estimates of 18 minutes per day (cut and retrim departments) and 21.25 minutes per day (kill department). These averages were added to each employee's timesheets to generate classwide overtime hours.
A. The Holding: Representative Proof May Suffice
Writing for a 6–2 majority, Justice Kennedy held that the use of a representative sample to establish classwide liability is permissible when:
- The sample would be admissible in an individual suit. If each class member could have individually relied on the Mericle study to prove donning-and-doffing time in an individual FLSA action, the same evidence is not rendered improper merely because the claim is brought on behalf of a class.
- The representative sample is the only feasible means of proof. Tyson's own failure to record donning-and-doffing time created the evidentiary gap that the representative study was designed to fill. Tyson "cannot litigate this class action on the merits, then use the specter of damages to undo the certification order."
- The use of the sample is not merely formulaic or arbitrary. Statistical sampling must be reliable and must measure what it purports to measure. The sample is evaluated under the same Daubert standards applicable to expert evidence generally.
Tyson Foods, 577 U.S. at 455–58.
B. Tyson Foods' Scope and Its Interaction with Comcast
Tyson Foods does not override Comcast. The two decisions are in tension on the question of how much methodological imprecision is tolerable in a classwide damages model, but they can be synthesized:
- **Comcast requires alignment between liability theory and damages model.** Where the court has limited liability to a specific theory, the damages model must measure damages attributable to that specific theory.
- **Tyson Foods permits representative proof when individualized proof is infeasible and the sample is reliable.** Where the defendant's own recordkeeping failures make exact individual measurement impossible, a statistically valid sample may substitute.
The key battleground after Tyson Foods is whether the representative evidence could have been used in an individual case — the "individual action" test. If no individual class member could have relied on the statistical model alone to establish their specific damages, the model may not be used to certify a class.
IV. Eleventh Circuit Applications
The Eleventh Circuit has applied the Comcast framework in a range of class certification contexts:
A. FDUTPA Class Actions
In Carriuolo v. General Motors Co., 823 F.3d 977 (11th Cir. 2016), the court affirmed certification of a FDUTPA class under Rule 23(b)(3). The claim involved inaccurate window sticker safety ratings for certain Cadillac CTS vehicles. The Eleventh Circuit, per Judge Marcus, held that the FDUTPA's objective deception standard — whether a reasonable consumer would be deceived — was susceptible to classwide resolution. Crucially, the damages model (market value diminution) was consistent with the liability theory (the sticker ratings were uniformly false across the class), satisfying Comcast's alignment requirement.
B. The Comcast Mismatch Problem in the Eleventh Circuit
Where plaintiffs' damages models have not aligned with accepted liability theories, the Eleventh Circuit has applied Comcast to decertify or deny certification. The court has emphasized that Comcast requires courts to conduct a "rigorous analysis" at certification — not to defer to the plaintiff's framing of the damages case.
Practitioners in the Eleventh Circuit should structure damages models with Comcast in mind from the earliest stages of a case:
- Identify all viable liability theories before engaging the damages expert. If only a subset of the plaintiff's theories is likely to survive, design the damages model to measure only those theories.
- Use Dr. McClave's error as an object lesson. The failure to isolate damages attributable to the surviving overbuilder-deterrence theory was the Comcast plaintiff's fatal error. In any case with multiple liability theories, instruct the damages expert to run sensitivity analyses — model that isolates damages from each theory independently.
- *Anticipate the Comcast motion.* Defendants in class actions routinely challenge predominance by arguing that individual damage calculations will overwhelm common questions. The responsive brief should explain, with specificity, how the damages model measures class-wide injury attributable to the specific accepted theory.
V. The Interplay with Rule 23(a) Commonality and Dukes
Comcast builds on Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338 (2011), which held that certification requires affirmative demonstration of compliance with Rule 23(a)'s requirements. Dukes introduced a "rigorous analysis" standard at the certification stage; Comcast extended that rigor specifically to damages models in (b)(3) actions.
Together, Dukes and Comcast imposed what many practitioners describe as a "merits creep" in class certification proceedings. Courts must now assess whether (1) there is a common question susceptible to classwide resolution (Dukes), (2) the damages methodology measures damages attributable to that common question (Comcast), and (3) the statistical proof is reliable and could have been used in individual actions (Tyson Foods). This tripartite framework is the doctrinal foundation of every substantial Rule 23(b)(3) certification motion today.
VI. Practice Notes for Plaintiffs' Counsel
- Design the damages model before discovery is complete. In consumer fraud and antitrust cases, the damages expert should be engaged at the pleading stage to assess whether a classwide model is viable. If no classwide damages model can be constructed, a class action may not be the appropriate vehicle.
- Align the complaint with the damages model. The Comcast trap arises when the plaintiff argues multiple liability theories before the court narrows them, and the damages model was designed for all theories. Drafting the complaint with a damages focus — and preserving the ability to adapt the model as theories are tested — is essential.
- *Explore Tyson Foods' record-reconstruction avenue. Where defendants have failed to maintain required records (wage records, pricing data, claim records), the plaintiff can argue that representative statistical proof is the only feasible means of establishing classwide harm, and that Tyson Foods* authorizes its use.
- Issue class certification separately from merits summary judgment. Rule 23 contemplates early certification rulings. In complex cases where the Comcast alignment question will be contested, consider bifurcating the certification briefing from the merits to permit focused judicial analysis.
VII. Open Questions
- *Whether Comcast requires complete alignment of every component of the damages model with the accepted liability theory, or only the "general" alignment of the model's approach:* Lower courts have divided on how much "slippage" between the theory and the model is tolerable.
- *The scope of the Tyson Foods individual-action test:* Whether a class member "could have relied" on representative evidence in an individual action remains contested — particularly in FLSA collective actions and state-law wage class actions.
VIII. Closing
Comcast imposed a structural discipline on class certification that has been genuinely consequential: plaintiffs cannot certify a class using an all-theories damages model when only some theories survive judicial scrutiny. Tyson Foods provided important relief for cases where individual proof is infeasible — but did not retreat from Comcast's alignment requirement. The Eleventh Circuit has applied both, and the doctrinal synthesis is now well-settled: at certification, plaintiffs must present a damages model that is both classwide and specifically calibrated to the surviving liability theory. Mastering this requirement is, for modern plaintiffs' class action lawyers, as fundamental as pleading itself.
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