GM won a major legal victory Friday when a federal appeals court voted to decertify a class action lawsuit accusing the automaker of knowingly selling about 800,000 vehicles with defective transmissions.

In a 9–7 ruling, the 6th U.S. Circuit Court of Appeals in Cincinnati found that the differences among affected vehicle owners were too substantial to justify a single class action. The court cited the complexity of 26 statewide subclasses and 59 separate state-law claims, concluding that the case could not be fairly managed as a single unified suit.

The decision reverses an August 2024 ruling by Circuit Judge Karen Nelson Moore, who had approved the class certification. According to the appeal, Moore dissented from Friday’s opinion, accusing the majority of creating “insurmountable barriers to certification for plaintiffs who file class-action complaints against national manufacturers.”

Moreover, the case involves Chevrolet, GMC, and Cadillac models from the 2015 to 2019 model years equipped with GM’s 8L45 or 8L90 eight-speed automatic transmissions. Plaintiffs alleged that the vehicles shook and shuddered at higher speeds and hesitated or lurched at lower speeds, even after attempted repairs.

Affected models include the Cadillac CTS, CT6, and Escalade; Chevrolet Camaro, Colorado, Corvette, and Silverado; and GMC Canyon, Sierra, and Yukon.
The appeals court’s decision sends the case back to U.S. District Judge David Lawson in Detroit, who may now consider whether smaller, more narrowly defined subclasses can still be certified.

Class actions typically allow plaintiffs to pursue larger claims more efficiently.
However, GM argued that the wide variability in how the defects manifested across states and vehicles made the case unsuitable for group litigation.