If expert testimony is offered in support of or opposition to a class certification motion, the trial court may consider it only if the testimony passes muster under the standard for admissibility of expert testimony adopted in Sargon Enterprises, Inc. v. University of Southern California (2012) 55 Cal.4th 747. There is only one standard for admissibility of expert testimony. It is the one adopted in Sargon. A court need not rule on the admissibility of certain expert opinion evidence offered in connection with class certification if it is irrelevant or unnecessary for its decision. But if expert opinion evidence provides the basis for a plaintiff’s arguments regarding numerosity, ascertainability, commonality, or superiority (or a defendant’s opposition thereto), a trial court must assess that evidence under Sargon. The trial court cannot postpone the Sargon test to the trial stage under those circumstances.
California Court of Appeal, Fourth District, Division One (O’Rourke, J.); January 29, 2018; 2018 WL 579858.