Many commentators correctly [predicted] that the decision in Wal-Mart Stores, Inc. v. Dukes would be favorable to business interests.  However, unlike the Court’s earlier decision in AT&T Mobility v. Concepcion, the decision does not necessarily threaten to sound a death knell for class actions or even a particular category of class actions.  Instead, the decision merely clarifies the standards on which future class actions are to be evaluated in the federal courts, but it does so in a way that is likely to impact class actions in many areas of the law outside of the employment law context.  Here are some of the key issues on which the opinion will undoubtedly be cited in the future, and some thoughts on the potential impact of the decision on each issue.

1. Standard of review – The majority’s decision clarifies a long-standing misconception about the ability of a federal court to consider questions relating to the merits of a case in the class certification phase.  For more than 30 years, plaintiffs’ counsel and many courts have cited the Court’s opinion in Eisen v. Carlisle & Jacquelin, 417 U.S. 156 (1974), as prohibiting any examination of the plaintiffs’ claims on the merits at the class certification phase.  Consistent with the majority trend in the lower federal courts, the Supreme Court’s decision in Wal-Mart Stores, Inc. confirms that a court should consider and resolve any issues of fact that are necessary to determine whether one or more elements of Rule 23 are satisfied, regardless of whether those issues may overlap or be identical to one or more issues to be decided in ruling on the merits of the plaintiff’s claims.
2. Evaluation of Expert Testimony – The majority decision makes clear that it is appropriate for a federal court to conduct a Daubert analysis to consider the reliability and helpfulness of expert witness opinions at the class certification phase.  It is no longer sufficient for a plaintiff to present expert testimony and then argue that the Court may find that testimony reliable at some later point in the proceedings.  Again, in keeping with the trend among the federal circuit courts, the Court’s analysis in Wal-Mart Stores, Inc. makes clear that the reliability and relevance of expert testimony proposed as “common proof” should be evaluated before granting class certification.
3. Use of Statistical Evidence in Support of Class Certification – The majority’s decision leaves open the possibility that statistical evidence might be used in establishing the existence of common proof in certain cases, but it sets a high standard for when proffered statistical evidence can be considered as adequate proof of the existence of “common issue.”  Significantly, Part III of Justice Scalia’s opinion, which was joined by all 9 justices, disapproves of the “Trial by Formula” approach to class actions, in which a sample of claims is tried on the merits, and the results of that sample are then applied proportionally to the claims of the entire class.
4. Certification of Claims Seeking Monetary Relief Under FRCP 23(b)(2) – This is perhaps the most uncontroversial aspect of the opinion in that part of the unanimous holding of the Court.  The Court’s holding is also straightforward, at least conceptually: claims for monetary relief may not be certified under FRCP 23(b)(2) unless they are merely incidental to injunctive or declaratory relief being requested on behalf of the class as a whole.  However, the devil may be in the details, as future courts (especially outside the employment law context) will be left with the task of defining what monetary relief is “incidental” to injunctive or declaratory relief and what is not.

Ed. Note: The Supreme Court’s slip opinion for Wal-Mart Stores, Inc. v. Dukes can be read here.