In Brinker Restaurant Corp. v. Superior Court (2012) 53 Cal.4th 1004, the trial court certified three subclasses: (1) a "'"Rest Period Subclass,"'" defined as employees who worked more than three and a half hours without receiving a ten-minute rest break; (2) a "'"Meal Period Subclass,"'" defined as employees who worked more than five consecutive hours without receiving a 30-minute meal break; and (3) an "'"Off-the-Clock Subclass,"'" defined as employees who were required to work off-the-clock. (Id. at pp. 1019-1020.) The Court of Appeal reversed class certification of the three disputed subclasses, and the Supreme Court granted review "to resolve uncertainties in the handling of wage and hour class certification motions." (Id. at p. 1021.) Preliminarily, the Supreme Court noted that the class certification question "'is "essentially a procedural one that does not ask whether an action is legally or factually meritorious."'" (Brinker, supra, 53 Cal.4th at p. 1023.) Thus, "resolution of disputes over the merits of a case generally must be postponed until after class certification has been decided , with the court assuming for purposes of the certification motion that any claims have merit ." (Ibid.) The court recognized, however, that issues affecting the merits of a case are sometimes intertwined with class action requirements. (Ibid.) It therefore summarized the "governing principles" as follows: "Presented with a class certification motion, a trial court must examine the plaintiff's theory of recovery, assess the nature of the legal and factual disputes likely to be presented, and decide whether individual or common issues predominate. To the extent the propriety of certification depends upon disputed threshold legal or factual questions, a court may, and indeed must, resolve them. Out of respect for the problems arising from one-way intervention, however, a court generally should eschew resolution of such issues unless necessary." (Id. at p. 1025.) The court next clarified the deferential nature of review of class certification orders, noting that the decision to certify a class "'rests squarely within the discretion of the trial court, and we afford that decision great deference on appeal, reversing only for a manifest abuse of discretion.'" (Brinker, supra, 53 Cal.4th at p. 1022.) Further, it noted that predominance "is a factual question; accordingly, the trial court's finding that common issues predominate generally is reviewed for substantial evidence. We must 'presume in favor of the certification order . . . the existence of every fact the trial court could reasonably deduce from the record . . . .' " (Ibid.) Applying these principles, Brinker concluded that the trial court properly certified a rest period class. As to this proposed class, the court noted it was undisputed that the employer had a uniform rest break policy; the sole issue before the court was the legality of the policy. (Brinker, supra, 53 Cal.4th at p. 1033.) Thus, the trial court's certification of a rest break subclass should not have been disturbed: "Contrary to the Court of Appeal's conclusion, the certifiability of a rest break subclass in this case is not dependent upon resolution of threshold legal disputes over the scope of the employer's rest break duties. The theory of liability--that Brinker has a uniform policy, and that that policy, measured against wage order requirements, allegedly violates the law--is by its nature a common question eminently suited for class treatment." ( Id. at pp. 1033-1034.) The court reached a different result with regard to the plaintiff's off-the-clock claims. The court noted that these claims were "an offshoot of plaintiff's meal period claims" (Brinker, supra, 53 Cal.4th at p. 1051) because the plaintiff contended that defendant "required employees to perform work while clocked out during their meal periods; they were neither relieved of all duty nor afforded an uninterrupted 30 minutes, and were not compensated." (Ibid.) The court found that this claim was not susceptible to class treatment because the plaintiff had not provided substantial evidence of a uniform policy. The court explained: "Unlike for the rest period claim and subclass, for this claim neither a common policy nor a common method of proof is apparent. . . . The only formal Brinker off-the-clock policy submitted disavows such work, consistent with state law. Nor has plaintiff presented substantial evidence of a systematic company policy to pressure or require employees to work off-the-clock, a distinction that differentiates this case from those he relies upon in which off-the-clock classes have been certified. . . . . . . . . . As all parties agree, liability is contingent on proof Brinker knew or should have known off-the-clock work was occurring. Nothing before the trial court demonstrated how this could be shown through common proof, in the absence of evidence of a uniform policy or practice. Instead, the trial court was presented with anecdotal evidence of a handful of individual instances in which employees worked off-the-clock, with or without knowledge or awareness by Brinker supervisors. On a record such as this, where no substantial evidence points to a uniform, companywide policy, proof of off-the-clock liability would have had to continue in an employee-by-employee fashion, demonstrating who worked off-the-clock, how long they worked, and whether Brinker knew or should have known of their work. Accordingly, the Court of Appeal properly vacated certification of this subclass." (Id. at pp. 1051-1052.)