## Facts

- Comcast, a cable provider, pursued a “clustering” strategy in the Philadelphia region by acquiring and consolidating cable systems.
- Philadelphia-area subscribers sued under federal antitrust law, alleging the clustering reduced competition and resulted in supracompetitive prices.
- Plaintiffs sought to certify a damages class exceeding two million current and former subscribers under Federal Rule of Civil Procedure 23(b)(3).
- Plaintiffs proposed four theories of antitrust impact; the district court found only one suitable for classwide treatment: deterrence of “overbuilders” (new entrants that would build competing cable networks).
- Plaintiffs offered an economist’s regression model to measure damages on a classwide basis, but the model produced an aggregate damages estimate constructed to reflect all four impact theories, not solely overbuilder deterrence.
- The district court certified the class, and the Third Circuit affirmed, declining to assess whether the damages model matched the surviving theory because it viewed that inquiry as improperly reaching the merits.

## Issues

1. Whether Rule 23(b)(3) predominance is satisfied when the plaintiffs’ damages model does not measure damages attributable to the only antitrust impact theory accepted for classwide adjudication.
2. Whether a court deciding class certification may examine the adequacy of the plaintiffs’ damages methodology even if that examination overlaps with the merits.

## Decision

- The Supreme Court reversed the Third Circuit and held the class was improperly certified under Rule 23(b)(3).
- The Court held that certification requires a rigorous analysis, including resolving disputes relevant to Rule 23 requirements even when they overlap with merits questions.
- Because the district court accepted only the overbuilder-deterrence theory, plaintiffs had to show damages could be measured classwide in a manner consistent with that theory.
- Plaintiffs’ regression model did not isolate damages attributable to overbuilder deterrence and therefore did not establish that damages were measurable on a classwide basis for the certified theory.
- Without a classwide damages method tied to the theory of liability, common questions did not predominate as Rule 23(b)(3) requires.

## Legal Principles

- A party seeking class certification must prove compliance with Rule 23 through evidentiary proof; certification depends on a “rigorous analysis.”
- Courts may “probe behind the pleadings” and must address Rule 23 disputes even if the analysis overlaps with the merits.
- Under Rule 23(b)(3) predominance, a proposed class must show that common questions predominate, including that damages can be measured on a classwide basis using a common methodology when damages proof is part of the predominance showing.
- A damages model supporting certification must measure only those damages attributable to the theory of antitrust impact (and resulting injury) that will be tried on a classwide basis.

## Conclusion

The Court required that Rule 23(b)(3) certification be supported by a classwide damages methodology that fits the certified theory of liability, and it confirmed that courts must scrutinize such proof at certification even when the inquiry overlaps with merits issues.


Comcast Corp. v. Behrend, 569 U.S. 27 (2013)