A recent decision from the District Court for the Northern District of Illinois highlights the critical role Rule 23(b)(3)’s predominance requirement can play in defeating class certification in putative consumer fraud class actions. In that case, Mednick v. Precor Inc., no. 1:14-cv-03624, the putative class representatives alleged that a manufacturer of exercise equipment had misrepresented the efficacy of the heart-rate monitors on its products. The plaintiffs claimed that the heart-rate monitors were inherently defective because the equipment users’ movement could prevent the monitors from accurately measuring their heart rates. They brought the consumer fraud class action on behalf of all individuals who purchased any of Precor’s 20 exercise machines, which could have any of Precor’s three heart-rate monitoring systems.

In support of their claim, plaintiffs introduced the expert opinion of a biomedical engineer. The expert measured the Precor heart-rate monitors’ performance by evaluating the results from one person who used three different Precor treadmills. However, he conceded that the heart-rate monitors could produce different results based on different users’ body shape and chemistry. The defendant challenged the sufficiency of the plaintiff’s expert’s opinion under Daubert, arguing his methodology was fatally flawed because one person’s heart rate results could not represent the entire class.

The court agreed with the defendant, ruling that the expert’s opinions were fatally flawed in part because the expert had not used a representative sampling of class members to evaluate the performance of the machines. Absent a representative sample, the expert’s conclusions were “mere speculation.” Additionally, the court emphasized that the expert did not have evidence to make the logical leap from “the user’s movement can change the results of heart-rate monitors” to “the heart-rate monitors cannot compensate for user’s movements, rendering the machines defective.”

The court also denied the plaintiffs’ motion for class certification. Just as the differences in user body types rendered the expert’s opinions unrepresentative of all class members, the user differences created individual questions of fact that outweighed the common issues. The court noted that the determination of whether the heart-rate monitors failed to compensate for user’s movements “would require individualized inquiry into each user, each type of machine and each heart rate system at issue.” As such, the class did not meet Rule 23(b)(3)’s requirement that class-wide issues “predominate” over individual issues.

This outcome underscores the importance of evaluating whether class-wide issues predominate when opposing class certification. This issue may mirror the argument regarding whether the experts’ samples are representative of the class as a whole.