In Mazza v. Am. Honda Motor Co., 666 F.3d 581 (9th Cir. 2012), the Ninth Circuit Rule 23 predominance was defeated where many (or even most) class members “were never exposed to the allegedly misleading advertisements” (666 F.3d at 597) because the defendant subjected only a small segment of an expansive class of car buyers to misleading material as part of a “very limited” advertising campaign (id. at 595).  This decision raised questions about how federal courts in the Ninth Circuit would actually evaluate UCL claims when faced with reconciling In re Tobacco II and Mazza.  In Ruiz Torres v. Mercer Canyons Inc. (9th Cir. Aug. 31, 2016), a wage & hour suit in which the District Court certified a class, the Ninth Circuit analyzed Mazza in a manner demonstrating that it may be constrained in its application moving forward.

The defendant focused a substantial part of its challenge to the District Court's certification order on the notion that the class was drawn too broadly, arguing that certain class members were not injured due to the omission of information that, under plaintiff's theory, was improperly withheld from them, because they were not looking for work, would not have been hired, or for other individual reasons. The Court was not persuaded, saying that "such fortuitous non-injury to a subset of class members does not necessarily defeat certification of the entire class, particularly as the district court is well situated to winnow out those non-injured members at the damages phase of the litigation, or to refine the class definition." Slip op., at 18.  The Court then contrasted the possibility that some class members suffered no injury from the omission with Mazza:

This stands in contrast to the situation in Mazza, where many class members were not injured by virtue of the fact that they “were never exposed to the allegedly misleading advertisements.” 666 F.3d at 597. In Mazza, the defendant subjected only a small segment of an expansive class of car buyers to misleading material as part of a “very limited” advertising campaign. Id. at 595. Under those circumstances, we found that Rule 23 predominance was defeated, since “it was unreasonable to assume that all class members purchasing cars had seen the potentially misleading ads.” Id. at 596. That is not the situation here, where the existence of a common policy or practice, if proven, is evidence that the class as a whole was exposed to purportedly misleading omissions about H-2A jobs.

Slip op., at 18-19. The Court then discussed the related argument that the class was too broadly drawn.  The Ninth Circuit held that this potential flaw was not fatal:

Mercer’s dispute merely reflects the existence of contrasting litigation positions on the proper scope of liability, and a merits issue that the district court will later resolve concerning the breadth of Mercer’s disclosure duty over time.

Slip op., at 20.  The Ninth Circuit concluded that there was "a reasonably close fit with Plaintiffs’ theory of liability, such that Rule 23(b)(3) predominance is maintained."  Slip op., at 22.  The Court also affirmed the certification of an equal pay subclass.