Elon Musk, founder of SpaceX and chief executive officer of Tesla, waves as he arrives for a discussion at the Satellite 2020 conference in Washington, DC on Monday, March 9, 2020.

Andrew Harrer | Bloomberg | Getty Images

The National Labor Relations Board ruled that Tesla was breaking labor laws by firing a union activist, and when CEO Elon Musk wrote on Twitter in 2018, “Nothing is stopping the Tesla team at our auto plant from voting for the union. Could do this if they wanted to. But why pay union dues and give up stock options for nothing? “

Among other things, the federal agency has ordered Tesla to ask Musk to remove his offensive tweet and offer a job to the resigned employee Richard Ortiz. Tesla must also compensate Ortiz for lost earnings, benefits, and adverse tax consequences resulting from his layoff.

The employee was part of an organization campaign “Fair Future at Tesla”. At the time of the campaign, Tesla said its business should remain union free. But Musk’s public comments on his Twitter account, on which he has tens of millions of followers, have been viewed as threatening. Tesla considers tweets from Elon Musk to be official corporate communications, as stated in the financial filings.

Tesla also has to revise a confidentiality agreement that employees naturally have. The company previously informed employees that they would not be allowed to speak to the media without express written permission. However, national labor law generally protects “workers when they are talking to the media about working conditions, labor disputes or other terms of employment,” according to the NLRB.

The board also directed Tesla to publish notices nationwide and hold a meeting (or series of meetings) at their main U.S. facility in Fremont to educate workers about their intellectual property rights. During the meeting, Musk himself or a “board agent” in the presence of Musk must read this notice to workers, security, managers and supervisors.

News of the decision was previously reported by Bloomberg and confirmed by the United Auto Workers who brought the suit. Tesla wasn’t immediately available for comment.

UAW Vice President and Director of UAW Organizations, Cindy Estrada, said in a statement, “While we celebrate the justice in today’s decision, it nonetheless highlights the significant flaws in US labor law. Here is a company that is clearly against has broken the law and yet it takes three years for these workers to achieve a minimum of justice. “

Thursday’s decision was largely in line with the September 2019 decision of an administrative judge who had previously examined the complaint. Tesla contested this until full board.

Read the full decision and order of the NLRB here.

CNBC’s Michael Wayland contributed to this report.