Lawyers for Elon Musk and OpenAI began closing arguments Thursday in the landmark trial whose outcome could shape the future of artificial intelligence.

Musk, the world’s richest man, was a co-founder of OpenAI, which started as a nonprofit in 2015 and went on to create ChatGPT. After Musk invested $38 million in its first years, his lawsuit filed in 2024 accused OpenAI CEO Sam Altman and his top deputy of shifting into a moneymaking mode behind his back.

The trial’s outcome could sway the balance of power in AI — breakthrough technology that is increasingly feared as a threat to humanity’s survival. Scrutiny of Altman’s leadership comes at a crucial time for the company and its competitors, Musk’s own AI firm and 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 among the largest ever. In addition to damages, Musk is seeking Altman’s ouster from OpenAI’s board. If Musk wins, it could derail OpenAI’s IPO plans.

Timing of lawsuit is key question

One of the jury’s tasks is to decide if Musk filed his lawsuit in time. Much of the testimony has centered on OpenAI’s early years after its 2015 founding, but there’s a relatively short timeline to allege the claims Musk is making of breach of charitable trust and unjust enrichment.

OpenAI has argued that Musk waited too long and cannot claim harms that occurred before August 2021.

The judge wrote in a court filing last month that “if the jury finds that Musk failed to file his action within the statute of limitations, it is highly likely” that she will “accept that finding and direct verdict to the defendants.”

If the jury decides that the lawsuit was filed in time, they then have to decide if OpenAI had a “charitable trust” and that OpenAI and its executives broke that trust. Musk’s other claim means jurors must determine whether Altman, Greg Brockman — co-founder and president — and OpenAI unjustly enriched themselves at Musk’s expense.

For Microsoft, a co-defendant in the trial, the jury has to decide whether the company aided and abetted that breach.

Musk’s attorney, Steven Molo, told jurors Thursday morning that the Tesla CEO is “sorry he could not be here.”

Musk is in China with President Donald Trump and other prominent tech executives.

Musk lawyer focuses on Altman’s credibility

Molo began making his case doubling down on claims of Altman’s untrustworthiness, pointing to testimony from five witnesses who called the OpenAI CEO a “liar.”

“I confronted Sam Altman with the fact that five witnesses in this trial, all people that he’s known for years and worked with, called him a liar under oath. Liar’s a very powerful word in a courtroom.”

Those five people were Musk and another co-founder Ilya Sutskever, who was OpenAI’s chief scientist, as well as OpenAI’s former chief technology officer Mira Murati and two ex-board members, Helen Toner and Tasha McCauley.

“Sam Altman’s credibility is directly at issue in this case. He’s the defendants’ main witness. The defendants absolutely need you to believe Sam Altman. If you cannot trust him, if you don’t believe him, they cannot win. It’s that simple,” he said.

Because Musk, Altman and Brockman never signed an actual contract that could show they had a charitable trust that OpenAI then broke, Musk’s side has made the case that jurors should consider emails and other communication between them — along with everything from OpenAI’s website to press interviews — that constituted such a trust.

“The evidence proves Elon donated those funds for a specific charitable purpose,” he said, adding that this purpose was to create a nonprofit for the development of safe AI that would be open-source when applicable.

A question of money

In a terse exchange while jurors were out of the room, U.S. District Judge Yvonne Gonzalez Rogers sharply criticized Musk’s attorney for suggesting to jurors in his closing arguments that Musk wasn’t seeking any money in the lawsuit.

While Musk, before the trial, abandoned a bid for damages for himself, he is still seeking an unspecified amount of money to be paid to fund the altruistic efforts of OpenAI’s charitable arm.

Musk is seeking “billions of dollars of disgorgement,” the judge said, ordering Molo to either retract his statement or “drop your claim for billions of dollars.” They later agreed that the judge would correct the statement to jurors.

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O’Brien reported from Providence, Rhode Island.