Class discovery is inherently more limited than normal fact discovery for trial, and litigators understandably approach it in a more narrow fashion than they would trial discovery. The Fifth Circuit recently reminded class action litigators, however, that such tailoring should not be extended to expert discovery. In Prantil v. Arkema Inc., the court joined the Second, Seventh, and Eleventh Circuits in ruling that the Daubert analysis governing the admission of expert testimony at trial applies with full force at the class certification stage.

The case involved a putative class of southeastern Texas property owners who claimed both physical injury and property damage to their homes when the defendant’s plastic production facility combusted due to the heavy winds and floods of Hurricane Harvey and released toxic ash and smoke into the surrounding communities. During class discovery, the named plaintiffs enlisted four experts in support of their certification arguments, and when the defendant challenged the admission of the expert testimony, the district court excluded one expert and credited the three others. In reaching its decision, the district court expressed uncertainty as to whether the Daubert analysis applied at the certification stage and “impl[ied] that Daubert is less applicable to evidence used for certification.”

On review, the Fifth Circuit affirmatively adopted Daubert’s application at the class certification stage explaining that “if an expert’s opinion would not be admissible at trial, it should not pave the way for certifying a proposed class.” The circuit court insisted that where “the cementing of relationships among proffered class members of liability or damages … turns on scientific evidence,” “the metric of admissibility be the same for certification and trial.” It ruled that the district court erred in that it “was not as searching in its assessment of the expert reports’ reliability as it would have been outside the certification.” Because the district court’s decision “reflect[ed] hesitation to apply Daubert’s reliability standard with full force,” the Fifth Circuit remanded the matter for further proceedings.