Officials at the National Labor Relations Board filed a complaint against Elon Musks SpaceX on Wednesday, accusing the company of making workers sign illegal confidentiality and non-disparagement clauses as a condition of getting severance pay.

The complaint also alleges the aerospace company ran afoul of the law by requiring workers to sign certain arbitration agreements and class-action waivers as a condition of getting their jobs, according to an agency spokesperson.

The NLRBs general counsel argues that overly broad employment contracts can be coercive and prevent workers from speaking out to improve their working conditions.

SpaceX did not immediately respond to a request for comment.

The new complaint escalates a battle between labor officials and Musk, who has mounted a legal challenge to the boards very existence. SpaceX has argued in federal court that the structure of the NLRB is unconstitutional and therefore the agency shouldnt be able to pursue a case against the company. (Trader Joes and Amazon have aired essentially the same argument in labor board proceedings.)