On January 14, 2022, WLF urged the Fifth Circuit not to permit plaintiffs to obtain class certification on the basis of unreliable expert evidence. The case arises from a putative class action against The Boeing Company and Southwest Airlines following two tragic overseas accidents involving Boeing’s 737 MAX 8 airplane. In a case unrelated to those tragedies, the district court certified four classes comprising 200,000,000 claims after determining that the plaintiffs’ lone damages expert could ultimately “fix” demonstrable flaws in his conjoint survey as evidence of classwide damages. But, as WLF’s brief argues, a district court may not certify any class without first resolving whether the plaintiffs have introduced reliable evidence, including expert testimony, of classwide injury and damages. The district court violated that rule here by allowing the plaintiffs’ deeply flawed damages model to serve as the basis for class certification.