All too often, courts and class-action litigants take the question of commonality for granted.  But, when framed properly, the question of commonality can provide a court with the tools necessary to engage in a truly rigorous analysis of a proposed class.

In his recent essay "Common Answers for Class Certification," noted professor Richard Nagareda takes the Ninth Circuit’s recent Dukes decision and uses it as a platform to discuss what commonality really means in the context of a class action. In doing so, he provides an excellent analysis of how defense counsel can frame the question of commonality for courts deciding certification. As he puts it:

This Essay spotlights the crucial conceptual error in Dukes: its premise that the raising of common “questions” suffices for class certification. Properly understood, class certification does not turn upon the mere raising of common questions by way of expert submissions or any other form of evidence. Class certification instead turns on the capacity of a unitary proceeding to yield common answers.

Nagareda also points out that courts taking the alternative approach–looking only at whether the question is common, not whether they advance the litigation with common answers–are not wilfully misreading Rule 23.

The Dukes court acts on an understandable impulse—one whereby the format for adjudication inevitably would synchronize with the aggregate character of the allegations on the merits, at least when those allegations rise to the level of presenting a triable case.

Ultimately, Nagareda locates the issue in the fact that most courts are more used to determining issues on the merits than deciding class certification.

The fundamental problem with Dukes consists of the court’s confusion between the class certification determination and the most familiar type of pre-trial ruling that regulates the respective roles of the court and the fact finder at trial: summary judgment. On the Ninth Circuit’s account, the two are intertwined, such that the court regards itself as duty-bound not to withhold class certification when the plaintiffs have put forward a triable case as to the existence of a company-wide policy of discrimination on Wal-Mart’s part. Yet it is only if such a policy of nationwide scope exists that Wal-Mart has acted “on grounds that apply generally to the class,” so as to make appropriate relief “respecting the class as a whole” within the meaning of Rule 23(b)(2)—the basis for the Dukes certification.

In other words, a common question is not common unless the answer applies to the entire class no matter how it is decided.

What can defense lawyers take from Nagareda’s analysis? It‘s always worth reminding the court of how a class trial would actually proceed. Walking the court through how it would have to decide questions on the merits can highlight where supposedly common questions aren’t actually common at all.