The Supreme Court issued its decision today in Tyson Foods, Inc. v. Bouaphakeo, No. 14-1146, a case that many commentators predicted would provide an opportunity for the Court to limit or bar the use of statistical evidence as a substitute for common proof in class actions. The majority opinion, authored by Justice Kennedy, rejected the invitation to create a “broad rule” limiting the use of statistical evidence, however. Instead, the Court offered practical guidance on the situations in which statistical evidence may or may not be appropriate. The relevant portion of the opinion is short and succinct, so I have quoted it in its entirety below:
[P]etitioner and various of its amici maintain that the Court should announce a broad rule against the use in class actions of what the parties call representative evidence. A categorical exclusion of that sort, however, would make little sense. A representative or statistical sample, like all evidence, is a means to establish or defend against liability. Its permissibility turns not on the form a proceeding takes—be it a class or individual action—but on the degree to which the evidence is reliable in proving or disproving the elements of the relevant cause of action. See Fed. Rules Evid. 401, 403, and 702.
It follows that the Court would reach too far were it to establish general rules governing the use of statistical evidence, or so-called representative evidence, in all class-action cases. Evidence of this type is used in various substantive realms of the law. Brief for Complex Litigation Law Professors as Amici Curiae 5–9; Brief for Economists et al. as Amici Curiae 8–10. Whether and when statistical evidence can be used to establish classwide liability will depend on the purpose for which the evidence is being introduced and on “the elements of the underlying cause of action,” Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. 804, 809 (2011).
In many cases, a representative sample is “the only practicable means to collect and present relevant data” establishing a defendant’s liability. Manual of Complex Litigation §11.493, p. 102 (4th ed. 2004). In a case where representative evidence is relevant in proving a plaintiff’s individual claim, that evidence cannot be deemed improper merely because the claim is brought on behalf of a class. To so hold would ignore the Rules Enabling Act’s pellucid instruction that use of the class device cannot “abridge . . . any substantive right.” 28 U.S.C. § 2072(b).
Those who were hoping for a rule barring statistical evidence as a proxy for common evidence in class actions will no doubt be disappointed, but Justice Kennedy’s opinion does go much further than it had to in beginning to develop standards that will govern resolution of the issue in future cases. To summarize:
- There is no general rule barring the use of statistics to prove class-wide liability in a class action.
- The extent to which statistical evidence is allowable in a class action depends on whether the evidence is reliable in proving or disproving the elements of a relevant cause of action.
- Statistical evidence is admissible in a class action if it would be admissible in an individual action to prove or disprove elements of a plaintiffs’ claim.
- Whether statistical evidence can be used to establish class-wide liability depends on the purpose for which the evidence is being introduced and on “the elements of the underlying cause of action.”
As a final side-note, the decision in Tyson Foods does not appear to have been impacted at all by the recent death of Justice Scalia. Only two of the eight remaining Justices, Justices Thomas and Alito, dissented.