Two pharmaceutical drug manufacturers told a federal en banc appeals panel on Thursday that plaintiffs were trying to circumvent the U.S. Class Action Fairness Act, which requires that “mass actions” be tried in federal court, by coordinating dozens of cases in California state court.

The U.S. Court of Appeals for the Ninth Circuit panel, hearing arguments in Seattle on an issue of first impression, appeared reluctant to accept the drugmakers’ view, since doing so could force California’s judicial branch or legislators to change the language of a common court procedure used in mass torts.