Elon Musk’s SpaceX has been accused by a U.S. labor agency of requiring employees who were laid off or fired from the rocket and satellite maker to sign unlawful agreements barring them from disparaging the company and joining class-action lawsuits against it.

The complaint, filed late Wednesday by a National Labor Relations Board (NLRB) regional official in Seattle, comes as SpaceX is already facing a separate case before the NLRB and has in turn filed a lawsuit claiming the agency’s structure violates the U.S. Constitution.

SpaceX, based in Hawthorne, California, is accused in the new complaint of requiring separated employees to sign severance agreements with confidentiality and non-disparagement clauses that restrict them from exercising their rights under U.S. labor law, the labor board said in a release on Thursday.

Those provisions are common in severance pacts signed by workers, but the NLRB has said such agreements must make clear that workers cannot waive their rights to advocate for better working conditions or file complaints with the NLRB.