Whether the requirements for class certification under Federal Rule of Civil Procedure 23 can be satisfied with inadmissible evidence

QUESTION PRESENTED This Court has held that a class cannot be certified unless the requirements of Rule 23 have been “satisflied] through evidentiary proof” while reserving the question whether that “evidentiary proof’ must be “admissible.” Comcast Corp. v. Behrend, 569 U.S. 27, 32 n.4 (2018); see Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 350 (2011). In this case, the Ninth Circuit reversed a denial of class certification and, while acknowledging a circuit split on the issue, held that “lilnadmissibility alone is not a proper basis to reject evidence submitted in support of class certification.” Pet. App. 13a. That ruling—which the court declined to rehear en banc over a dissent from Judge Bea and four other judges—puts the Ninth Circuit (along with the Eighth Circuit) squarely on the minority side of a lopsided circuit split; the majority (including the Second, Third, Fifth, and Seventh Circuits) recognizes that evidence supporting class certification must be admissible. The question presented is: Whether the requirements for class certification under Federal Rule of Civil Procedure 23 can be satisfied with inadmissible evidence.