Amazon and SpaceX on Monday urged the U.S. Court of Appeals for the Fifth Circuit to halt National Labor Relations Board proceedings accusing the companies of unfair labor practices, arguing that the agency’s structure is unconstitutional.

The oral arguments represented the latest legal attack from corporations against the 89-year-old NLRB, buoyed by the U.S. Supreme Court's ruling this year in SEC v. Jarkesy that the Seventh Amendment right to a jury trial bars the U.S. Securities and Exchange Commission’s use of in-house judges to oversee enforcement actions for financial penalties. The ruling called into question the constitutionality of other agencies’ use of administrative law judges.