Rule 23 of the Federal Rules of Civil Procedure governs certification of class actions, including discrimination and other employment claims. Last week, the U.S. Supreme Court tightened standards for such certification by requiring that plaintiffs demonstrate that damages can be calculated for the proposed class as a whole rather than on an individual basis.

Comcast Corp. v. Behrend was an antitrust case involving two million subscribers in the Philadelphia cable television market. The plaintiffs attempted to use expert testimony to show a common methodology for calculation of class damages. In a 5-4 decision, the Supreme Court concluded that the experts' damages model did not match the specific antitrust theory used by the plaintiffs. As a result, individual damages issues would overwhelm the questions common to the proposed class.

While this decision may assist employers in resisting class action certification, its impact may be limited. Rule 23(b)(3) requires a specific demonstration of damages that can be calculated on a class-wide basis. In the employment context, however, plaintiffs' attorneys may be able to adapt their certification efforts to allege an aggregate damages model.

The Court avoided the larger question under Rule 23 of the use of expert witness testimony at the class certification stage. Earlier precedent suggests that such testimony is not admissible at this point in the litigation absent special circumstances. The Supreme Court failed to address the applicability of this requirement to the type of damages proof required under the Comcast decision.