In order to obtain class certification under Federal Rule 23(b)(3), the plaintiffs must be able to show that their damages arose from actions attributable to the defendants who create legal liability. Plaintiffs must show at the class certification stage that they can prove, through common evidence, that all proposed class members were injured by the defendant’s alleged wrongful conduct (or if there are a few who were not, it will be possible to easily identify and exclude those individuals).
In the Comcast antitrust case, the federal court had initially granted certification in Comcast to decide whether the Daubert standard applied to class certification. The federal court ended up decertifying the antitrust class based on two flaws in the damages model offered by the plaintiffs’ expert. First, the court found the model failed to show that damages could be determined on a common basis across the class. Second, the court found that the damages model did not track the plaintiffs’ theory of liability because it included three theories of antitrust injuries the plaintiffs were no longer pursuing and did not categorize the alleged harm from each.
The Comcast case, which was handed down in 2013, is no longer an easy shield for defendants in class certification matters. Comcast does not stand for just antitrust cases. The case decision however, does require plaintiffs to produce a workable damages model that excludes plaintiffs who were not injured.