Stephen v. Enterprise Rent-a-Car, 235 Cal. App. 3d 806 (1991) held that a party has no right to bring a second motion to certify a class after the court has denied the first motion and the time for appeal has passed.  Stephen arose when a plaintiff failed to timely appeal an order denying certification.  But Stephen did not consider all of the unusual permutations that could occur.  In Safaie v. Jacuzzi Whirlpool Bath, Inc. (February 22, 2011), the Court of Appeal (Fourth Appellate District, Division One) examined whether, after an unsuccessful appeal of an order decertifying a class, the plaintiff could move for recertification on the basis of new law (Tobacco II).  The Court concluded that, because the plaintiff did not petition for review while Tobacco II was pending, the order affirming decertication was final and no further attempts at certification were permissible absent equitable considerations necessary to prevent unfairness.

The Court offered interesting comments about the course that it expects class actions to follow:

We agree with Stephen's holding and find its rationale persuasive. To ensure fairness to the class action plaintiff, trial courts are required to liberally grant continuances and ensure a plaintiff has the opportunity to make a complete record before the court rules on class certification. (See Stephen, supra, 235 Cal.App.3d at pp. 814- 815.) Once the record is complete, if the trial court issues a final order denying a class certification motion in its entirety, the plaintiff has the right to seek immediate appellate review and to obtain a written ruling from a Court of Appeal on the disputed issues, and then, if dissatisfied, to petition for review in the California Supreme Court. Thus, unlike the situation with most interlocutory orders, the plaintiff is provided the right to an immediate appeal even though the case is still pending. However, this special status has a necessary ramification: once the appellate period has passed or once the appellate court has affirmed the order and a remittitur has issued, the order is final and plaintiff is bound by the final decertification decision.

Slip op., at 12.  The Court later discussed the possibility of equitable exceptions to the rule in Stephen:

In reaching this conclusion, we recognize trial courts have broad discretion to determine the propriety of class actions, including to be procedurally innovative in certifying an appropriate class and in formulating procedures to ensure fairness and avoid manifest injustice in class action litigation. (See Sav-On Drug Stores, Inc. v. Superior Court (2004) 34 Cal.4th 319, 339.) Moreover, a court has the discretion to move sua sponte to certify a class. (See City of San Jose v. Superior Court (1974) 12 Cal.3d 447, 453-454.) However, to the extent there may be equitable exceptions to the rule precluding successive class certification motions after a final order denying certification, the circumstances here do not come within this exception.

Slip op., at 17.

From all of this I take away two possible lessons.  First, you must file a petition for review with the California Supreme Court if there is any chance that a change in law could help your certification arguments.  Second, the farther away you get from the wellspring of all consumer and employee protection, the more likely it is that your class action will receive the firing squad, not a certification order.  This theory would explain why Los Angeles is dicey, Orange County is perilous, and San Diego is the kiss of death.  But it's just a theory.