California Gov. Gavin Newsom (D) signed a bill Monday requiring artificial intelligence (AI) companies to disclose safety information about large-scale frontier models in a key win for the push to regulate AI in Silicon Valley’s home state. 

S.B. 53, the Transparency in Frontier AI Act, will require developers of these leading-edge AI models to publish frameworks detailing how they assess and mitigate catastrophic risks. 

“California has proven that we can establish regulations to protect our communities while also ensuring that the growing AI industry continues to thrive,” Newsom said in a statement Monday. “This legislation strikes that balance.”  

“AI is the new frontier in innovation, and California is not only here for it but stands strong as a national leader by enacting the first-in-the-nation frontier AI safety legislation that builds public trust as this emerging technology rapidly evolves,” he continued. 

Newsom hinted last week that he supported the legislation, a key vote of confidence after the governor vetoed an earlier iteration of the AI bill. 

S.B. 53 is considered the successor to last year’s S.B. 1047. The bill put forward a much stricter AI framework, which sought to require models to undergo safety testing before release and hold developers accountable for potential harm. Despite passing the state legislature, S.B. 1047 was ultimately rejected by Newsom. 

It also faced pushback from federal lawmakers, with several prominent California Democrats in Congress voicing concerns about the legislation. By contrast, S.B. 53 has been more well-received. 

Anthropic endorsed the legislation earlier this month. Jack Clark, co-founder and head of policy at the AI firm, said Monday that the bill “establishes meaningful transparency requirements for frontier AI companies without imposing prescriptive technical mandates.”  

“While federal standards remain essential to avoid a patchwork of state regulations, California has created a strong framework that balances public safety with continued innovation,” Clark added. 

Given California’s prominent role in the AI space, experts have suggested its AI legislation could serve to create a de facto national standard, especially amid a lack of progress at the federal level. 

However, this is likely to face resistance from the Trump administration and Republican lawmakers, who have voiced concerns about the Golden State setting the rules for AI across the nation and have increasingly pushed to preempt state AI laws that they worry could limit innovation.