STORY: It has drawn protests outside the court.
And will likely see drama inside.
Elon Musk and Sam Altman are set for a legal showdown in California.
The Tesla billionaire is seeking $150 billion in damages from OpenAI and its backer Microsoft.
That's according to a person involved in the case.
Musk is set to argue that Altman and OpenAI co-founder Greg Brockman conned him into investing in the startup.
He says they strayed from the nonprofit mission to focus on profit, rather than helping society, and he wants them both ousted.
Reuters tech correspondent Deepa Seetharaman says the ChatGPT maker's likely response is clear.
"OpenAI is fighting like hell to make sure that nothing happens to the company that even remotely approaches what Elon is asking for. You know, Open AI is, their argument has been all along Elon Musk is jealous. He's mad that he left the organization before it hit it big."
Court documents show Musk gave OpenAI seed money of about $38 million from 2016, before growing disenchanted and ultimately leaving the board.
The startup subsequently restructured to become a for-profit entity.
Its nonprofit wing retains a stake, however, and would get any damages that Musk wins.
Seetharaman says OpenAI will argue that he is really acting to benefit his own startup xAI, amid a fierce battle for leadership in the sector.
And she says no one dares call the outcome:
"Genuinely, every lawyer, every source I've talked to that's in and around this particular case, none of them feel comfortable making a prediction as to what could happen."
Jury selection for the Oakland court was completed Monday, with opening statements expected the following day.
Silicon Valley heavy hitters including Musk, Altman and Microsoft boss Satya Nadella are all expected to testify.
Any defeat could have unpredictable consequences for OpenAI, which has plans for a blockbuster IPO that could value it at $1 trillion.
As for the protesters, they'd like to see both sides lose:
"They have stated and run ad campaigns that they want to replace workers with machines. What is there left for us to do? What human economy will there be left after that? And then they've built, they will have built the tools to oppress us for complaining about it. So there's nothing good that I see about this technology."
