It's always commonality that gets you in the end (Hendelman v. Los Altos)

When it comes to certification, you can fix almost any problem other than commonality (community of interest).  Inadequate representative?  Get a new one.  Problem with inexperienced class counsel?  Co-counsel.  Numerosity is not really amenable to correction, but most of the time firms just pass on the tiny classes.  But commonality, there's where the rubber meets the road.  In Hendelman v. Los Altos Apartments, L.P. (Jul. 22, 2013; pub. ord. Aug. 20, 2013), the Court of Appeal (Second Appellate District, Division Three) affirmed a trial court order denying plaintiffs' motion for class certificaiton for lack of ascertainability, community of interest, and superiority.  The bulk of the Court of Appeal opinion addresses the commonality-related failings.

The Court first held that the warranty of habitability claim was not suitable for resolution through common proof:

[T]he mere “existence of a prohibited (uninhabitable) condition or other noncompliance with applicable code standards does not necessarily constitute a breach of the warranty of habitability.” (Friedman et al., Cal. Practice Guide: Landlord-Tenant (The Rutter Group 2012) § 3:39, p. 3-13, citing Green v. Superior Court, supra, 10 Cal.3d at pp. 637-638.) “Whether the defect or code noncompliance is ‘substantial’ (and thus a cognizable breach) or ‘de minimis’ (no actionable breach) is determined on a case-by-case basis.” (Friedman et al., supra, § 3:40, p. 3-13.) “In considering the materiality of an alleged breach, both the seriousness of the claimed defect and the length of time for which it persists are relevant factors. Minor housing code violations standing alone which do not affect habitability must be considered de minimis and will not entitle the tenant to reduction in rent; and likewise, the violation must be relevant and affect the . . . common areas which [the tenant] uses.” (Hinson v. Delis (1972) 26 Cal.App.3d 62, 70, disapproved on other grounds by Knight v. Hallsthammar (1981) 29 Cal.3d 46, 55, fn. 7.) Stated otherwise, whether a particular defect or violation of a housing code constitutes a breach of the implied warranty of habitability depends on the severity and duration of the defect or violation. Breach is a rebuttable presumption affecting the burden of producing evidence. (Friedman et al., supra, §§ 3:46 to 3:47, pp. 3-14 to 3-15.)

Slip op., at 11.  The trial court concluded that even the code violations impacting all tenants did so differently and to different degrees, and the Court of Appeal, giving deference to the trial court, agreed.  One question raised by this decision is whether variation in entitlement to damage tainted the analysis as to whether liability could be shown through common proof, especially where strict liability is imposed on the landlord.  At times the Court seems to conflate proof of liability with nominal damages.

The Court then found that the claim for increased rent injected the same individualized questions about whether services to each tenant were reduced in any substantial manner that amounted to an implied increase in rent.

As to the retaliation claim, the Court found that no representative could state that claim, either due to statute of limitations problems or a failure to have been a tenant during the relevant time period.  And as with the habitability claim, the Court agreed that a nuisance action depended heavily on facts unique to each tenant, defeating commonality.

The Court declined to consider the many proposed adjustments or amendments to claims or the class definition on Appeal, finding that such arguments are, in the first instance, matters for the trial court.