After some disappointing responses to the defense bars efforts to make obtaining class certification in the securities litiation arena more challenging, the defense bar received some welcome news from the Supreme Court in Comcast Corp. v. Behrend (http://www.supremecourt.gov/opinions/12pdf/11-864_k537.pdf). In Comcast, plaintiffs brought an antitrust suit relating to cable subscriptions in the Philadelphia market. They asserted four distinct theories of antitrust injury and claimed an economic model that identified cumulative injuries relating to those theories. The trial court, however, accepted only one of the four theories as viable and allowed plaintiffs to proceed solely on that theory. Comcast then argued that the dmages model could not support class certification because it did not isolate damages from the one viable theory. The class was certified and the Third Circuit declined to consider Comcast's arguments about the damages model because such an argument went too much to the merits. The Supreme Court reversed, reiterating that lower courts must engage in a searching analysis, including on issues that cross over with the merits, to ensure Rule 23's requirements for class certification are met. Comcast thus may presage deeper scrutiny into class certification arguments both in antitrust particularly but also more generally.