Yesterday, the Supreme Court issued its opinion in Comcast Corp. v. Behrend, the antitrust case which commentators (including me) had expected would finally resolve the question of whether a trial court must apply the Daubert evidentiary standard to expert testimony in a certification debate.  It turns out we were wrong. Due to a procedural defect below (Comcast had not objected to the admissibility of the expert’s testimony in the trial court), the Court ultimately did not decide the Daubert issue. But it did issue an opinion that, while limited, provides some help to defendants at certification.

Behrend in a nutshell: The plaintiffs filed a class action accusing Comcast of monopolizing the market for cable services in Philadelphia, driving up prices. (This was a violation of Section 2 of the Sherman Act.) During the certification debate, they offered expert testimony that showed the effects of four different practices on cable prices, although the report did not disaggregate those effects. The trial court certified a class based on only one of the four challenged practices, referred to as "overbuilding," in which the company provided more infrastructure than demand supported, driving prices down and keeping out competitors. When Comcast objected that plaintiffs had not provided classwide evidence that overbuilding had led to the price increases they challenged, the lower court held that the expert report was sufficient to serve as classwide proof, and delving any further would be an impermissible merits inquiry. The Third Circuit affirmed.

The majority, in a brief 5-4 opinion, began from the premise it articulated most recently in Dukes, that class actions require a rigorous inquiry that may overlap with the merits. While Dukes discussed the commonality standard of Rule 23(a),

[t]he same analytical principles govern Rule 23(b). If anything, Rule 23(b)(3)’s predominance criterion is even more demanding than Rule 23(a).

(Emphasis added.)  It then held that a plaintiff’s theory must remain consistent enough that the class certified will reflect the actual case tried, including the theory of damages:

at the class-certification stage (as at trial), any model supporting a plaintiff’s damages case must be consistent with its liability case, particularly with respect to the alleged anticompetitive effect of the violation.

(Internal quotation omitted.) This, held the Court, was where the lower courts had gone wrong. They had certified a class based on an expert opinion that did not actually match the theory of the case the class would be allowed to pursue. Moreover, the lower court had punted on the question of whether the expert’s method made sense at all:

The Court of Appeals simply concluded that respondents “provided a method to measure and quantify damages on a classwide basis,” finding it unnecessary to decide “whether the methodology [was] a just and reasonable inference or speculative.” Under that logic, at the class-certification stage any method of measurement is acceptable so long as it can be applied classwide, no matter how arbitrary the measurements may be. Such a proposition would reduce Rule 23(b)(3)’s predominance requirement to a nullity. 

(Emphasis added, internal citation omitted.)

This is not the last we’ve heard of the Daubert debate. As the dissent points out, before it learned that the admissibility question had been waived, the Court had reformulated the question on appeal specifically to address the admissibility of expert testimony. I would guess that the Court will remain vigilant for an opportunity to further clarify what expert testimony can support certification. Meanwhile, defendants can use the Court’s discussion here to good advantage when challenging classes where individualized issues predominate.