By Jonathan Stempel

(Reuters) – A federal appeals court has ordered General Motors Co. (NYSE:) to file a class action lawsuit alleging that it violated the laws of 26 U.S. states by knowingly selling hundreds of thousands of cars, trucks and SUVs with defective transmissions.

The U.S. Sixth Circuit Court of Appeals has ruled that a lower court judge has the authority to allow drivers to file class action lawsuits involving Cadillac, Chevrolet and GMC vehicles equipped with the 8L45 or 8L90 eight-speed automatic transmission sold between the 2015 and 2019 model years.

Drivers said the vehicles shuddered and shook in higher gears and hesitated and jolted in lower gears, even after repairs were attempted. They also accused GM of ordering dealers to ensure that the harsh shifts were “normal.”

GM did not immediately respond to requests for comment Thursday. The decision was issued Wednesday by a three-judge panel of the Cincinnati-based appellate court.

Class action lawsuits can result in larger awards at lower costs than if plaintiffs were forced to sue individually.

The GM litigation covers about 800,000 vehicles, including 514,000 certified vehicles.

Vehicles include the Cadillac CTS (NYSE:), CT6 and Escalade; the Chevrolet Camaro, Colorado, Corvette and Silverado; and the GMC Canyon, Sierra and Yukon.

In opposing class certification, GM argued that most class members had never had problems and therefore had no legal basis to sue.

It also found that there were too many differences among class members to justify a class action lawsuit.

But U.S. District Judge Karen Nelson Moore found that simply overpaying for allegedly defective vehicles was enough to prove the plaintiff had a legal basis.

It also said that “how and to what extent each individual plaintiff experienced judder or shift quality issues is irrelevant” to whether GM concealed known defects and whether drivers would consider that information material.

The court also rejected GM’s argument that many of the potential claims should be resolved in arbitration.

The case was reviewed by U.S. District Judge David Lawson in Detroit, who approved the seizure in March 2023.

“We look forward to holding GM accountable before a jury in Michigan,” Ted Leopold, a partner at Cohen Milstein Sellers & Toll representing the drivers, said in a statement.

The case is Speerly et al. v. General Motors LLC, U.S. Court of Appeals for the 6th Circuit, No. 23-1940.