This continues our series of blog posts on effective partnering between inside and outside counsel to defend against class action lawsuits. Here, we focus on the uses of expert testimony.
The Role of the Expert at the Class Certification Stage
At the class certification stage, the role of the expert will be to refute specific propositions that the plaintiffs need to establish to obtain class certification, including, for example, that injury to class members can be proved with common evidence or that all class members relied on allegedly fraudulent misconduct. In a securities class action, for example, an expert may be able to show that the conditions that permit an assumption of common reliance due to “fraud on the market” simply do not exist in the circumstances of a particular case (e.g., due to an inefficient market for the securities at issue). Likewise, in an antitrust case, an expert may be able to show why actual or “but-for” prices cannot be demonstrated with common proof given marketplace realities and the way transactions actually occur.
Sometimes experts can be helpful to refute the viability of the plaintiffs’ proposed methodology for demonstrating classwide effect. Carlton Fields has found that in environmental contamination cases, for example, expert analysis may help demonstrate the lack of any kind of formulaic or common method for showing impact and damages to property owners across the putative class. Even when the plaintiffs have proffered an expert model in an attempt to show a common proof approach to impact and damages, contrary expert evidence may be available to demonstrate the “infeasibility” of the plaintiffs’ expert’s approach, either because it or its applications is not recognized and does not comply with Daubert; because it cannot be applied in practice to the case at hand given the unavailability of data or other necessary information; or because the methodology ignores certain important facts uncovered in discovery or investigation that cannot be squared or reconciled with its application (e.g., in a medical monitoring case, showing that exposure and degree of ingestion vary widely based on changing plant operations over time and that employee turnover was so high as to make common assumptions infeasible).
If the company plans to retain a defense expert at the class certification stage, we recommend that this task be accomplished early so that the expert can help outside counsel prepare for the depositions of the class representatives. Experts can help outside counsel understand the importance of admissions the company may be able to obtain. It is important, however, to take the depositions of the class representatives before the plaintiffs; expert coaches them on what to say—or not to say—in the course of providing expert disclosures or deposition testimony.
In an effort to certify a class, plaintiffs sometimes retain law professors as experts on a legal question such as whether the rule-based class certification requirements have been satisfied or whether variations in the state laws applicable to different class members’ claims cause individual questions of law to swamp common questions. Plaintiffs also sometimes retain a legislator as an expert witness to testify that lawmakers did not intend for reliance to be required under a consumer protection statute (because, if it were, it would cause individual issues to predominate). This is a questionable practice, and we do not recommend following suit as a defense strategy unless the court makes clear that it is going to accept such testimony from plaintiffs’ expert. The better course is to file a motion to strike the plaintiff’s expert’s testimony, even when it is offered ostensibly to help the court make a determination whether certifying the class would be consistent or inconsistent with the way other courts have handled such issues.
Our next post will discuss case management considerations.
 See, e.g., Unger v. Amedisys Inc., 401 F. 3d 316, 324-25 (5th Cir. 2005) (noting that, at the class certification stage, a decision on whether the market for a particular security was efficient may benefit from or be aided by expert analysis).
 See, e.g., In re New Motor Vehicles Canadian Export Antitrust Litigation, 522 F.3d 6, 20-21 (1st Cir. 2008) (auto manufacturers introduced expert testimony from an economist to refute the representative plaintiffs’ claims that import restrictions on Canadian vehicles had an appreciable classwide effect on American auto prices).