The trial pitting Elon Musk against Sam Altman and OpenAI began in earnest on Tuesday with opening arguments, as lawyers for the two tech moguls seek to convince a California jury of their client’s version of the AI company’s history. The trial is set to feature testimony from both billionaires, as well as some of the most powerful executives in the tech industry.

Musk argues that Altman, OpenAI and its president Greg Brockman broke a foundational agreement to better humanity when the non-profit pivoted towards a for-profit structure. Musk, who left OpenAI in 2018 after co-founding it with Altman and Brockman three years earlier, also alleges that his co-founders unjustly enriched themselves as the company raised billions of dollars and grew into the AI behemoth it is today.

OpenAI rejects all of Musk’s claims, stating his case is “motivated by jealousy” and characterizing him as an embittered co-founder seeking revenge after failing to take total control. OpenAI has also pointed out Musk started his own rival AI company, xAI, alleging that “this lawsuit has always been a baseless and jealous bid to derail a competitor”.

In the early hours of Tuesday morning, long lines snaked outside the Oakland federal courthouse as reporters, legal teams and court watchers waited to get inside. Altman and Brockman were present at the courthouse on Monday, while Musk was nowhere to be seen. The two tech leaders passed through security around 15 minutes apart on Tuesday morning.

The trial is a culmination of a years-long feud between Musk and Altman that has become increasingly vicious. As the trial started jury selection on Monday, Musk posted a stream of insults against Altman on X, the social media platform Musk owns, including repeatedly calling him “Scam Altman”. Musk also used his power over the platform to boost a post to followers that featured the New Yorker’s unflattering investigation of Altman from earlier this month.

The outcome of the case carries potentially enormous stakes for OpenAI, which is seeking to go public later this year at about a $1tn valuation. Musk is seeking to undo its corporate restructuring and force the removal of Altman as CEO and Brockman as president. He is also seeking around $134bn in damages, which he wants redistributed to OpenAI’s non-profit that still oversees the company.

On Monday, nine jurors were seated after a day-long selection process that included a questionnaire about their feelings towards AI and Musk. Many prospective jurors stated they had negative feelings about the Tesla CEO and thoughts about AI, while Judge Yvonne Gonzalez Rogers assured the court that the case would not focus on technical details.

“This is just a case about promises and breaches of promises, it won’t get technical at all,” Gonzalez Rogers said.

The trial is expected to last around three weeks. Other tech industry bigwigs who may testify include Microsoft CEO Satya Nadella and Neuralink executive Shivon Zilis, who is also the mother of four of Musk’s children.