## Facts

- Public health authorities traced a multi-state hepatitis A outbreak to a frozen fruit product, “Townsend Farms Organic Anti-Oxidant Blend,” sold by Costco.
- Costco removed the product from shelves and notified purchasers after the outbreak was identified.
- Consumers who bought and consumed the product in nine western states sued Costco and the manufacturer, alleging exposure risk and seeking costs for vaccinations, testing, and related medical care.
- The case was filed in California state court in 2013 and removed to federal court.
- Plaintiffs moved to certify a class under Rule 23; to address differences in state product-liability law, they proposed alternative subclass structures (multi-state groupings or single-state subclasses).
- Defendants opposed certification, arguing that variations in the nine states’ substantive laws defeated predominance and manageability.

## Issues

1. Whether the proposed class satisfied Rule 23(a) numerosity, commonality, typicality, and adequacy.
2. Whether Rule 23(b)(3) predominance and superiority were met given differing product-liability standards across nine states.
3. Whether subclassing could manage state-law variations while preserving predominance, including through certification of a liability-only class.

## Decision

- The court granted the motion for class certification.
- The court found Rule 23(a) satisfied: thousands of affected purchasers supported numerosity; core liability questions were common; named plaintiffs’ claims were typical; and representation was adequate.
- The court held common issues predominated under Rule 23(b)(3) because liability turned on common proof about a single product, a single contamination event, and defendants’ uniform course of conduct.
- The court concluded a class action was superior because individual suits would be inefficient and economically impractical for relatively small, repetitive claims.
- To address individualized issues, the court certified a liability-only class and permitted multiple subclasses to manage material state-law differences.

## Legal Principles

- Rule 23(a) commonality is met when class members share central liability questions capable of common proof, even if exposure histories and damages vary.
- Rule 23(b)(3) predominance can be satisfied in a multi-state products case when common liability questions outweigh individualized issues and when only limited state-law variations materially affect outcomes.
- State-law differences do not necessarily bar certification if they can be handled through targeted subclassing or other case-management methods.
- A court may certify a liability-only class under Rule 23(b)(3) to resolve common liability questions collectively while reserving individualized damages for later proceedings.

## Conclusion

The court certified a Rule 23(b)(3) liability-only class arising from a single alleged contamination event, holding that common liability questions predominated and that state-law variations could be addressed through subclasses without defeating manageability or superiority.


Petersen v. Costco Wholesale Co., 312 F.R.D. 565 (C.D. Cal. 2016)