In a 5-4 decision, the U.S. Supreme Court has determined that courts may have to “probe behind the pleadings” when deciding whether Rule 23’s prerequisites have been satisfied, because the class-certification analysis will frequently “overlap with the merits of the plaintiff’s underlying claim.” Comcast Corp. v. Behrend, No. 11-864 (U.S., decided March 27, 2013). Writing for the majority, Justice Antonin Scalia found that the Third Circuit Court of Appeals erred in failing to consider arguments challenging the class proponent’s damages model on the ground that they were relevant to both the propriety of class certification and a merits determination. Finding that the model fell far short of establishing that damages could be measured class wide, the majority reversed the Third Circuit certification ruling.

Dissenting Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor, and Elena Kagan criticized the Court’s rephrasing of the issue on appeal and would have dismissed the writ of certiorari as improvidently granted. According to the dissent, the rephrasing “shifted the focus of the dispute from the District Court’s Rule 23(b)(3) analysis to its attention (or lack thereof) to the admissibility of expert testimony. The parties, responsively, devoted much of their briefing to the question whether the standards for admissibility of expert evidence set out in Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), apply in class certification proceedings. … As it turns out, our reformulated question was inapt,” the dissenters contended, because the class challenger never objected to the admissibility of the damages model expert’s testimony.