OpenAI CEO Sam Altman took the witness stand Tuesday to defend his business record in a trial pitting him against Elon Musk, rebutting testimony that disparaged his leadership at a pivotal time for the ChatGPT maker.

Musk, the world’s richest man, is seeking Altman’s ouster from the company leadership as part of a civil lawsuit accusing him of betraying their shared vision for OpenAI. Since its start as a nonprofit funded primarily by Musk, OpenAI has evolved into a capitalistic venture now valued at $852 billion.

More than two weeks into the trial in a federal courthouse in Oakland, California, neither of the tech titans has emerged as an overly sympathetic character. But nobody has more to lose than Altman.

Even if Musk loses the case, the trial has invited further scrutiny of Altman’s leadership at a crucial time for the company and its competition with Musk’s own AI firm and another rival, Anthropic, formed by a group of seven ex-OpenAI leaders. All three firms are moving toward planned initial public offerings that are expected to be some of the largest ever.

Under a barrage of questions by a lawyer for Musk, Altman said he did not agree with trial testimony that depicted him as dishonest.

“I believe I am an honest and trustworthy businessperson,” Altman said.

A jury that’s already heard about Altman’s character from a parade of his former allies and adversaries will ultimately decide the verdict. But the repercussions could reverberate widely.

“This is not looking good for any of them, and I think that that’s a little bit unfortunate for the AI industry at a time when the public perception of AI is quite negative and seems to be getting worse,” said Sarah Kreps, director of Cornell University’s Tech Policy Institute.

Testimony about Altman has been a font of social media memes

The lawsuit accuses Altman and his top lieutenant, Greg Brockman, of double-crossing Musk by straying from the San Francisco company’s founding mission to be an altruistic steward of a revolutionary technology. The lawsuit alleges they shifted into a moneymaking mode behind his back. Musk is seeking an unspecified amount of money to be paid to fund the altruistic efforts of OpenAI’s charitable arm.

While Musk, the head of SpaceX, Tesla and a slew of other companies, was well known by the San Francisco Bay Area jury pool, fewer knew who Altman was before the start of the trial, even if they were familiar with ChatGPT.

Since the start of the trial, testimony about Altman’s turbulent tenure at OpenAI has become prime fodder for internet jokes. One piece of evidence that has inspired countless memes was a text exchange between Altman and a company officer, Mira Murati, in 2023 during his short-lived ouster as CEO, when Altman asked if things were moving “directionally good or bad” and she wrote back: “Sam this is very bad.”

Jurors have heard from witnesses including OpenAI ex-board members Helen Toner and Tasha McCauley, who spoke about the decision to fire Altman in 2023 before they were themselves ousted from the board of directors when Altman returned to his role.

In video testimony last week, Toner said a starting point for the decision to oust Altman was when OpenAI co-founder Ilya Sutskever, a respected AI scientist, reached out to confide some of his own concerns.

“A phrase we used was ‘a pattern of behavior,’ so no one single cause,” Toner said. “The pattern of behavior related to his honesty and candor, his resistance of board oversight.”

Sutskever was instrumental in the unsuccessful attempt to oust Altman but later said he regretted his role in the shakeup. In his own testimony Monday, Sutskever confirmed that he wrote a 2023 memo to OpenAI’s board that characterized Altman as pitting his executives against one another and exhibiting a “consistent pattern of lying” that was causing a loss of trust and productivity.

He said he later backtracked and signed a letter supporting Altman’s reinstatement to try to keep the company from being destroyed.

Altman has cast Musk as bent on control of OpenAI

The trial has carried risks also for Musk, who is pursuing an initial public offering this summer for his rocket ship maker, SpaceX, which could make him the world’s first trillionaire.

Sutskever testified to his early admiration for Musk as an entrepreneur but said that once they were working together as co-founders, Musk’s push for a controlling stake in the startup “just felt aggressive to me.”

OpenAI has brushed off Musk’s allegations as an unfounded case of sour grapes that’s aimed at undercutting its rapid growth and bolstering Musk’s own xAI, now part of SpaceX.

Altman and Musk both vied to be OpenAI’s CEO in its early years. In his testimony Tuesday, Altman said he had concerns about Musk’s attempts to gain more control over OpenAI, which was aiming to safely build a better-than-human form of AI called artificial general intelligence.

“Part of the reason we started OpenAI is we didn’t think AGI could be under the control of any one person, no matter how good their intents are,” Altman said.

He described what he called a “particularly hair-raising moment when my co-founders asked Mr. Musk about, well, ‘If you have control, what happens when you die?’”

Altman said Musk’s response was that maybe “control of OpenAI should pass to my children.” Altman said he did not feel comfortable with that.

Altman said Musk was known to be “fairly mercurial” and only trusted himself to make the right decisions that were not obvious to others but which Musk believed would “turn out to be correct.” Among the pressures on OpenAI were Musk’s repeated attempts to have his car company Tesla absorb OpenAI, a proposal Altman said would not have aligned with OpenAI’s mission.

Altman testified that OpenAI has ended up creating “through a ton of hard work, this extremely large charity” and sought to challenge Musk’s contention that Altman had violated the nonprofit’s original purpose.

“Mr. Musk did try to kill it, I guess twice,” Altman added, before Musk’s lawyer interrupted to object to Altman’s remark. The judge struck it from the record.

Near the end of his testimony, Altman said he had thought incredibly highly of Musk during his early involvement with OpenAI, but “felt he abandoned us” as he pulled away his commitment and financial contributions.

“It’s been an incredibly painful thing for me,” he said. He called Musk a “critical contributor” to OpenAI and attributed his leaving to jealousy as he was working on launching a competing AI startup.

O’Brien contributed from Providence, Rhode Island.