There was a time when Elon Musk and Sam Altman were friends. But the two tech billionaires are now embroiled in a bitter legal battle in the United States that could reshape not just OpenAI, the artificial intelligence (AI) firm behind ChatGPT they cofounded in 2015, but also the future of the technology more broadly.

Launched by Musk in 2024, the lawsuit is the culmination of a years-long feud that centres on the evolution of OpenAI from a non-profit to a for-profit enterprise.

The trial, which kicked off this week in California, is expected to last roughly three weeks. But its ripple effects could be felt for many years to come.

The case and the cast

The lawsuit pits Musk against Altman, OpenAI president Greg Brockman, OpenAI itself, and Microsoft, the AI firm’s largest backer.

Musk cofounded and helped fund OpenAI to the tune of about US$44 million. By his own account from the witness stand this week, he “came up with the idea, the name, recruited the key people, taught them everything I know, provided all of the initial funding”.

Brockman served as technical cofounder; Altman became chief executive in 2019. Their alliance with Musk fractured as the organisation grew. Musk departed the board in 2018. He says he was pushed out.

However, OpenAI says he walked when denied majority control. Musk subsequently launched his own rival AI venture, xAI, which is now part of........

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