Four U.S. nonprofit organizations have jointly filed a lawsuit in San Francisco Superior Court against defendants including OpenAI, Google, Meta, Anthropic, and SpaceX's AI division. The plaintiffs allege that these companies have violated California's Unfair Competition Law, arguing that they cannot effectively prevent catastrophic harm from AI systems and that continued development of advanced AI will pose a serious threat to public safety. They are seeking a court order to block the companies from further developing or deploying new AI models. Unlike previous lawsuits that focused on AI copyright, privacy, or harm caused by specific products, this case directly seeks to restrict the development of frontier AI technology through judicial means. The complaint cites instances of AI systems participating in harmful activities and public warnings from some AI company executives about technological risks, pointing out that continued research and development may cause humanity to permanently lose control over the technology and pose existential risks. The four organizations also claim they have had to divert resources originally intended for other work to the field of AI safety. The lawsuit comes at a juncture when U.S. AI regulatory policy may shift. Currently, none of the five defendant companies have responded to requests for comment, the plaintiffs' claims have not yet been approved by the court, and the outcome of the litigation remains uncertain.