Elon Musk arrives at the U.S. District Court in Oakland, Calif., Tuesday, April 28, 2026. Godofredo A. Vásquez/AP hide caption

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Godofredo A. Vásquez/AP

A courtroom brawl between two of the tech industry's most powerful leaders, Tesla CEO Elon Musk and OpenAI CEO Sam Altman, is underway in Oakland, California in a case that could transform one of the world's most important artificial intelligence companies.

"Ladies and gentlemen, we are here today because the defendants in this case stole a charity," Steve Molo, an attorney for Musk, said in his opening statement.

In his lawsuit, Musk has argued that Altman steered the company they cofounded a decade ago, ChatGPT creator OpenAI, away from its original mission as a nonprofit meant to develop advanced AI for the benefit of humanity and free of profit motives.

The case hinges on a decision early on by OpenAI's founders that they needed to create a for-profit entity to tap capital markets for funding on a scale necessary to build advanced AI.…