After a dramatic first day of opening statements and testimony from Elon Musk in his case against Sam Altman and OpenAI, the trial continues on Wednesday with a cross examination of the Tesla CEO. OpenAI’s defense attorneys will get a chance to press the world’s richest man on his allegations, which yesterday included suggesting Altman “stole a charity” and would endanger humanity with AI.

Musk is accusing his OpenAI co-founders Altman and Greg Brockman of breaking the founding agreement of the company to build AI to benefit humanity, instead shifting the non-profit to a for-profit structure and unjustly enriching themselves along the way. He is seeking the removal of Altman and Brockman, the undoing of the for-profit structure and $134bn in damages, which he wants redistributed to OpenAI’s non-profit arm.

OpenAI has rejected Musk’s claims as “motivated by jealousy”, stating that he was always aware of plans for the business and that he left OpenAI in 2018 only after a failed bid to take over. The company holds that what Musk describes as his $38m investment into the non-profit was actually a tax deductible donation, and does not entitle him to any say over the firm. OpenAI also emphasizes that it is still overseen by the original non-profit.

Musk’s lawyer, Steven Molo, called him to testify on Tuesday following opening statements from both sides. The billionaire began with a rehash of his career and rise to power, before getting into his version of how OpenAI was founded in 2015. Musk claimed that the company only existed because of an alarming conversation about artificial intelligence he had with Google co-founder Larry Page, which made him believe that he needed to build a counterpoint or Page would doom humanity.

With Musk on the stand, his lawyers have tried to paint him as a tech pioneer who is deeply invested in helping humanity. As Molo started his line of questioning on Wednesday, he showed Musk emails from OpenAI engineers praising him for his tech knowledge. He also showed him a document where Musk called OpenAI’s safety team “jackasses” and asked him what he meant.

Musk said the “jackass” statement was a joke. “I don’t yell at people basically,” Musk said. “You occasionally have to use strong language to get people to change their course.”

The trial is being extremely closely watched in Silicon Valley as it pits two of the tech industry’s most powerful men against each other and promises to intensify their ongoing feud. Altman and Musk have openly sniped at each other on social media in the leadup to the trial, causing Judge Yvonne Gonzalez Rogers to request that both parties keep their posts to a minimum.

Investors and other AI companies are also keeping an eye on the trial because it threatens severe consequences for OpenAI. The company is seeking to go public on the US stock market later this year at around a $1tn valuation, and any changes to its leadership or corporate structure would threaten that IPO.

The trial is taking place in an Oakland, California, federal court where a nine person jury will decide on Musk’s claims. If OpenAI is found liable, however, Judge Gonzalez Rogers will be the one to decide on any remedies. The trial is expected to last around three weeks.