FromHydrogen PeroxidetoComcast: The new rigor in antitrust class actions☆James Keyte, Paul Eckles and Karen Lent are partners in the antitrust group of Skadden, Arps, Slate, Meagher & Flom LLP

In 2009, the Third Circuit decidedHydrogen Peroxide, which announced a more rigorous standard under Federal Rule of Civil Procedure 23(b)(3) for assessing whether a putative class could establish antitrust injury. Earlier this year, the Supreme Court decidedComcast v. Behrend, a case that carries potentially broad implications for both antitrust cases and Rule 23(b)(3) class actions generally. A review of the case law starting withHydrogen Peroxideand continuing throughComcastand its progeny reveals the new rigor in antitrust class action decisions and suggests what the future may hold, including the type of arguments that may provide defendants the most likely chance of defeating class certification. AfterComcast, rigor under 23(b)(3) can no longer be avoided in assessing all class actions questions, and courts should now applyDaubertfully in the class setting concerning both impact and damages. Courts should also closely evaluate plaintiffs’ proposed methodologies for proving impact to determine if they apply to each class member. Finally, courts will inevitably have to determine how rigorously to scrutinize experts’ damages methodologies and whetherComcastrequires or suggests more scrutiny in assessing common evidence for measuring damages.