December 19, 2018 Practice Points

Expert Witness Challenges under Daubert in Class-Action-Certification Proceedings

Lawyers navigating putative class-action litigation should consider early on the extent to which expert testimony will inform class certification.

By Julie E. Cohen

The battle over certifying a class action usually comes relatively early in putative class-action litigation. However, demonstrating that a class action meets the requirements of Federal Rule of Civil Procedure 23 often involves the introduction of expert testimony to demonstrate, for example, commonality or predominance of injury among the putative class. This raises the question of how to evaluate the admissibility of expert testimony offered at this stage of the litigation and whether full-blown scrutiny under Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), should be conducted even before reaching discovery and the merits of underlying claims. Understanding in advance what to expect with respect to Daubert challenges in the class-certification process can be critical to navigating expert issues at this earlier-than-usual stage of the proceedings.

The U.S. Supreme Court has emphasized that determining whether to certify a class action involves a “rigorous” analysis, and that the party seeking class certification must “affirmatively demonstrate” compliance with Rule 23’s requirements. Comcast Corp. v. Behrend, 569 U.S. 27, 33 (2013) (citing Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 350 (2011)). Although the Court has not spoken directly to how this standard applies when evaluating expert testimony at the certification stage, it has come close. In Comcast, the Court had certified, and the parties briefed, the question of whether expert admissibility standards apply in class-certification proceedings, but the Court ultimately addressed a different question. See Comcast, 569 U.S. at 39 (Ginsburg, J., dissenting). And, in Dukes, the Court noted that “the District Court concluded that Daubert did not apply to expert testimony at the certification stage of class-action proceedings. We doubt that is so . . . .” Dukes, 564 U.S. at 354.

The federal courts of appeals have addressed in varying ways the extent to which a Daubert analysis is required at the class-certification stage. While these courts seem to agree that some Daubert analysis may be required, there is divergence as to extent.

For example, several circuits have found that when an expert’s report or testimony is crucial to class certification, the district court must perform a full-scale Daubert analysis before certifying the class. See, e.g., Messner v. Northshore Univ. HealthSystem, 669 F.3d 802, 812–14 (7th Cir. 2012) (“When an expert’s report or testimony is ‘critical to class certification,’ we have held that a district court must make a conclusive ruling on any challenge to that expert’s qualifications or submissions before it may rule on a motion for class certification.” (citation omitted)); Sher v. Raytheon Co., 419 F. App’x. 887, 890 (11th Cir. 2011) (following the Seventh Circuit’s approach); see also Sali v. Corona Reg’l Med. Ctr.,No. 15-56460, 2018 WL 6175617, at *7 (9th Cir. Nov. 27, 2018) (“[I]n evaluating challenged expert testimony in support of class certification, a district court should evaluate admissibility under the standard set forth in Daubert.”); In re Carpenter Co., No. 14-0302, 2014 WL 12809636, at *3 (6th Cir. Sept. 29, 2014) (noting that the issue is an open one in the circuit, but that the district court did not abuse its discretion in applying Daubert to critical expert witnesses supporting class certification).

On the other hand, the Eighth Circuit upheld a district court’s decision not to conduct a “full and conclusive Daubert inquiry” in the context of a class-certification motion. In re Zurn Pex Plumbing Prods. Liab. Litig., 644 F.3d 604, 610, 614 (8th Cir. 2011). Instead, the court approved of a more “tailored” Daubert analysis examining only “the reliability of the expert opinions in light of the available evidence and the purpose for which they were offered.” The Eighth Circuit reasoned that, at least when there is no disagreement about qualifications or methodology, courts need not decide “at the class certification stage, and before merits discovery has even commenced, whether or not the expert opinions will ultimately be admitted at trial.” In 2015, the Eighth Circuit reaffirmed Zurn’s holding that only a “focused” Daubert analysis—not a full Daubert inquiry—is required at the class-certification stage. Smith v. ConocoPhillips Pipe Line Co., 801 F.3d 921, 925 n.2 (8th Cir. 2015) (“Zurn is a binding and well decided precedent which we need not revisit here.”).

The Third Circuit threaded the needle on the issue. The court found support in Comcast and Dukes to hold that “a plaintiff cannot rely on challenged expert testimony, when critical to class certification, to demonstrate conformity with Rule 23 unless the plaintiff also demonstrates, and the trial court finds, that the expert testimony satisfies the standard set out in Daubert.” In re Blood Reagents Antitrust Litig., 783 F.3d 183, 187 (2015). However, the court declined to examine any deeper disagreement among its sister circuits and noted that, consistent with its ruling, both the Seventh and Eighth Circuits “limit the Daubert inquiry to expert testimony offered to prove satisfaction of Rule 23’s requirements.”

Lawyers navigating putative class-action litigation should accordingly consider early on the extent to which expert testimony will inform class certification. This analysis should also take into account the circuit in which the case is pending as courts continue to address the boundaries of how Daubert applies at the certification stage. Moreover, counsel should consider the implications an early Daubert challenge may have should the same expert be expected to opine on both class certification and merits-based issues.

Julie E. Cohen is counsel at Skadden, Arps, Slate, Meagher & Flom LLP in New York, New York. Skadden associate Hannah Sowell contributed to this post.


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