Current and former employees of an ambulance service company sued their employer for unpaid meal and rest periods. The complaint alleges claims on behalf of a putative class as well as non-class claims under the Private Attorneys General Act of 2004 (“PAGA”). The trial court denied plaintiffs’ class certification motion, but in this opinion the Court of Appeal determined the trial court had erred and issued a peremptory writ of mandate commanding the trial court to vacate that portion of its order denying class certification as to the on-duty rest period claims. The appellate court denied AMR’s motion to dismiss the appeal and exercised its discretion to treat the appeal as a writ petition. While the Court affirmed denial of class certification of the on-duty meal period claims (“an on-call meal period is [not] necessarily ‘on-duty’ for purposes of the wage and hour laws”), it found error in the trial court’s similar determination with respect to on-call rest periods based upon the recent California Supreme Court opinion in Augustus v. ABM Sec. Servs., Inc., 2 Cal. 5th 257 (2016), which post-dated the trial court’s order in the case. Cf. Microsoft Corp. v. Baker, 582 U.S. ___, 137 S. Ct. 1702 (2017) (federal courts of appeals lack jurisdiction to review an order denying class certification or striking class allegations after the named plaintiffs have voluntarily dismissed their claims with prejudice).