Sam Altman took the witness stand in Oakland federal court on Tuesday for the first time in Elon Musk's civil trial against OpenAI, and the nine jurors heard two very different versions of the same man.

In Altman's telling, he was the one who stopped Musk from seizing personal control of the most important AI company on the planet. In Musk's telling, Altman is a serial liar who stole a nonprofit and enriched himself. Both sides brought receipts.

'Maybe Control Should Pass to My Children'

The most explosive moment came early. Altman recounted a 2017 board discussion about restructuring OpenAI into a for-profit entity. Musk, Altman testified, demanded "total control" of any new commercial arm. When a co-founder asked what would happen to that control if Musk died, Altman said Musk replied: "I haven't thought about it a ton, but, you know, maybe it should just, the control should pass to my children."

Altman told the jury that moment crystallized his opposition. "Part of the reason that we started OpenAI was that we did not think AGI should be under the control of any one person, no matter how good their intentions are," he said. He added that his experience running Y Combinator had taught him that "founders who had control usually did not give it up."

Altman said Musk had also required co-founders Greg Brockman and Ilya Sutskever to "stack rank" researchers and "take a chainsaw through a bunch," a management tactic Altman testified "did huge damage for a long time to the culture of the organization." When asked about Musk's desire to absorb OpenAI into Tesla, Altman was blunt: "Tesla is a car company. And it does not have the mission of OpenAI."

Then Came the Cross-Examination

Musk's lawyers did not let Altman leave without a fight. During cross-examination, they confronted him with testimony from seven former OpenAI officials who said, under oath, that Altman was not trustworthy. They cited former board member Helen Toner's testimony that Altman fostered a "toxic culture of lying" at the company.

The Guardian reported that the trial has now "exposed even more details about OpenAI's fractious corporate past than previously documented," and that Altman's leadership and trustworthiness have been a subject of scrutiny going back years, including in a recent New Yorker profile in which multiple tech figures suggested Altman showed "deceptive tendencies."

Altman seemed "slightly nervous" at the start of cross-examination, CNBC reported, "speaking quietly, taking long pauses and stumbling occasionally." By the time the proceedings paused for the day, he had reportedly settled in. Judge Yvonne Gonzalez Rogers gave him firm instructions not to discuss his testimony with anyone overnight.

The Foundation Question

When directly asked "Did you steal a charity?" Altman pushed back hard. "It feels difficult to even wrap my head around that framing," he said. "We created one of the largest charities in the world. This foundation is doing incredible work and will do much more."

OpenAI board chair Bret Taylor testified the same day that the foundation now has assets on the order of $200 billion, and explained that the delay in hiring full-time foundation employees was simply because of "the challenge of converting OpenAI equity to cash" during the 2025 restructuring.

Altman also testified that after Musk left OpenAI in 2018, he continued updating him and seeking his funding and advice. He said no other donor besides Musk has ever complained that OpenAI deviated from its mission. But Facebook co-founder Dustin Moskovitz, a former OpenAI donor, wrote on Bluesky last month in response to the New Yorker profile: "Nobody who truly knows Sam trusts him."

What Happens Next

Altman's testimony continues Wednesday. Closing arguments are expected Thursday, May 14. The jury could begin deliberations the same day. The trial outcome could reshape the AI industry: Musk is seeking $134 billion in damages, and an unfavorable verdict could jeopardize OpenAI's planned IPO at a $1 trillion valuation.

Sources: TechCrunch, Business Insider, NBC News, The Guardian