The NLRB has come under fire from companies including Amazon and Elon Musk's SpaceX, who have argued that the labor board's structure is unconstitutional.

Gwynne Wilcox, who was appointed to the board by former President Joe Biden, said in a lawsuit filed in the U.S. District Court for the District of Columbia that her firing last week violated U.S. law.

WASHINGTON—A member of the National Labor Relations Board fired by President Trump sued him Wednesday, setting up a high-stakes battle over whether federal law limiting the president’s power to remove top executive-branch officials is constitutional.