John Rewch

The case hinges on whether OpenAI's founding mission of creating AI as a non-profit for the benefit of humanity has been lost.

Musk helped found the company a decade ago, but he left in 2018 amid disagreements with Altman and others about who would run a for-profit arm of the company that would be set up to raise money.

Musk testified about his role early on.

He says he recruited a key AI researcher and used his contacts at Microsoft and Nvidia to get access to computing power.

And he says he wasn't opposed to setting up a for-profit entity, but he wanted control of it.

In an opening statement, OpenAI's lead lawyer said the other founders were not okay with one person having control.

Musk left, launched a competitor, XAI, and then sued.

The trial is set to run for several more weeks.

John Rewich, NPR News, Oakland, California.