The New Consensus on Class Certification: What it Means for the Use of Economic and Statistical Evidence in Meeting the Requirements of Rule 23

Abstract

Offering expert testimony that is a hair's breadth away from nutty is no longer sufficient to secure class certification according to an emerging consensus across the circuit courts. The court must also get into any merits issues that are relevant to the class issues. As a practical matter credible expert testimony will prove more important going forward in all types of class certification for both plaintiffs and defendants. This note summarizes the consensus that is emerging and describes the sorts of analyses that will prove critical in seeking or opposing the certification of a particular class.

Keywords: class certification, economic evidence, statistical evidence, Rule 23, expert testimony

JEL Classification: K00