The National Labor Relations Board said it was an illegal threat. After Tesla appealed, 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.

But Tesla sought a rehearing, and the full 5th Circuit later threw out the earlier decision and voted to hear the matter again. In an opinion dated Friday, the judges split 9-8 in favor of Tesla and Musk.

“We hold that Musk’s tweets are constitutionally protected speech and do not fall into the categories of unprotected communication like obscenity and perjury,” the unsigned opinion said.