Musk accused OpenAI, its CEO Sam Altman, president Greg Brockman and stakeholder Microsoft of violating terms of Musk's "foundational contributions to the charity," according to his motion for a preliminary injunction filed on Nov. 30.

Musk co-founded OpenAI in 2015 and was an early board member until he left the company in 2018. 

He has since launched xAI — the firm behind AI chatbot Grok — which he said is falling victim to OpenAI's anti-competitive practices.

"OpenAI's path from a non-profit to for-profit behemoth is replete with per se anticompetitive practices, flagrant breaches of its charitable mission, and rampant self-dealing," Musk's lawyers wrote.

Through a "series of exclusive arrangements" with Microsoft, the two companies have engaged in "predatory practices," enabling them to seize control of almost 70% of the generative AI market, lawyers for Musk said, adding:

"Microsoft and OpenAI now seek to cement this dominance by cutting off competitors' access to investment capital, while continuing to benefit from years' worth of shared competitively sensitive information during generative AI's formative years."

Allowing this to continue will hurt xAI and the public, which has become increasingly concerned about "rushed" and "unsafe" AI products, they added.

California law allows a nonprofit to convert to a for-profit stock corporation, but not to a limited liability company.

OpenAI said it remains nonprofit at its core but has established a for-profit subsidiary capable of issuing equity to raise capital and hire world-class talent. Still, those tasks would be administered at the direction of the nonprofit. 

An injunction to preserve what is left of OpenAI's nonprofit character is the only "appropriate remedy," Musk's lawyers said.

"No objective observer can look at OpenAI today and say it bears any resemblance whatsoever to what it promised to be. Enough is enough."