A federal appeals court on Monday upheld the dismissal of a class action lawsuit from former employees of The Chemours Co. who said they were duped into taking a less generous buyout deal as the chemical firm downsized after its spinoff from DuPont.

A three-judge panel of the U.S. Court of Appeals for the Third Circuit ruled that Chemours’ voluntary severance did not violate a 1974 law meant to protect workers’ voluntary pension and health plans, ending a federal challenge launched by three former workers at the Wilmington chemical giant.