A group of federal appeals court judges in New Orleans is deciding whether a 2018 Twitter post by Tesla CEO Elon Musk unlawfully threatened Tesla employees with the loss of stock options if they decided to be represented by a union.

The National Labor Relations Board said it was an illegal threat. Three judges on the 5th U.S. Circuit Court of Appeals in New Orleans upheld that decision, as well as a related NLRB order that Tesla rehire a fired employee, with back pay.