Sixth Circuit Shuts The Door On “Trial By Formula” And “Mini Trials” In Reversing Class Certification

Clippinger solidifies two complementary class certification principles: predominance fails where individualized proceedings are necessary to resolve liability or damages, and plaintiffs cannot engineer predominance through a trial plan that strips defendants of their right to litigate individual claims. It may be argued that those principles extend beyond the insurance context to any class action where some aspects of liability may be subject to common proof but the path to individual recovery requires claim-by-claim proceedings.

In Clippinger v. State Farm Automobile Insurance Co., 173 F.4th 817 (6th Cir. 2026), the Sixth Circuit held that individual vehicle-valuation questions defeated Rule 23(b)(3) predominance in an auto insurance total-loss class action, joining the Third, Fourth, Fifth, Seventh, and Ninth Circuits in rejecting certification where liability and damages turn on member-specific inquiries.

State Farm calculated “actual cash value” using advertised comparable-vehicle prices and then applied a “typical negotiation” reduction. Plaintiff Clippinger alleged that reduction breached the policy under Tennessee law, and the district court certified a class of roughly 90,000 members. As the Sixth Circuit recognized, Tennessee law equates “actual cash value” with fair market value, meaning that proving breach required comparing State Farm’s payment to each vehicle’s fair market value—a determination driven by individualized factors, such as year, model, mileage, and condition.

Reversing, the Sixth Circuit first held that the predominance inquiry requires courts to “separate issues that a jury can decide for the class (common issues) from those that will require member-by-member decisions (individual issues),” and that “[i]f, on balance, the latter outweigh the former, common issues do not predominate.” Id. at 832. Where resolving each class member’s claim requires “an independent and individualized assessment” based on member-specific facts, individualized issues predominate—even if the defendant employed a uniform method subject to common proof. Id. at 832 (quoting Tarrify Props., LLC v. Cuyahoga Cnty., Ohio, 37 F.4th 1101, 1106 (6th Cir. 2022)).

The court emphasized that Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338 (2011), requires a “rigorous,” forward-looking analysis that forecasts how a trial will unfold before certifying the class. Clippinger, 173 F.4th at 826. Here, that meant confronting the reality that liability—whether the defendant “undercompensated” any class member—could not be established without “‘individual proof’ on a ‘plaintiff-by-plaintiff’ basis.” Id. at 833 (quoting Drummond v. Progressive Specialty Ins. Co., 142 F.4th 149, 159-60 (3d Cir. 2025)).

The court further held, again citing Dukes, that courts “may not meet the predominance element by barring a defendant from raising unique statutory or contractual ‘defenses to individual claims,’” and that “a district court flouts the Rules Enabling Act if it seeks to make a class action more manageable by ‘replac[ing]’ the claim-by-claim proceedings required by ‘individualized’ defenses with a ‘Trial by Formula’ approach.” Id. at 834 (quoting Dukes, 564 U.S. at 367). This foreclosed the district court’s trial plan that precluded the defendant from introducing vehicle-specific evidence other than a database-generated report. 

The court distinguished the plaintiff’s principal authority, Jama v. State Farm Mutual Automobile Insurance Co., 113 F.4th 924 (9th Cir. 2024). In Jama, state law categorically prohibited the challenged adjustment, so a formulaic damages calculation survived because each class member’s injury “equaled ‘the exact amount of the impermissible negotiation deduction.’” Clippinger, 173 F.4th at 836 (quoting Jama, 113 F.4th at 933). Because Tennessee law did not apply a categorical prohibition, the defendant in Clippinger retained the right to contest each class member’s valuation. Id.