SpaceX on Thursday went to court to try to derail a US National Labor Relations Board hearing over complaints by workers who say they were fired for criticizing chief executive Elon Musk.

SpaceX argued that the structure of the regulatory board is unconstitutional and the hearing process violates the company's right to a jury trial, according to a copy of the complaint filed in a federal court in Texas.

The filing did not refute the notion that former workers whose complaints are at issue in the case were fired for asking colleagues to sign a letter critical of Musk's social media behavior.

"The Open Letter demanded that SpaceX take certain actions addressing perceived shortcomings" and linked to a survey, the filing contended.

A small group of SpaceX employees used the company's internal communication platform to send the open letter to thousands of colleagues in June of 2022, according to the complaint.

In the letter, SpaceX employees called on leadership at the company to address what they considered disparaging and inappropriate comments by Musk on what was then Twitter, since renamed X, according to US media.

Employees who were subsequently fired complained to the NLRB, accusing SpaceX of violating labor law.

Eight complaints deemed to have merit were consolidated by the NLRB this week. An administrative hearing is set for 5 March.

SpaceX called on a federal court in Texas to stop the hearing from taking place and declare that the NLRB structure violates the Constitution.