California Moves To Regulate Frontier AI With A Focus On Catastrophic Risk

On September 29, 2025, California Governor Gavin Newsom signed into law the first frontier artificial intelligence (AI) safety legislation in the nation, Senate Bill (SB) 53, the Transparency in Frontier Artificial Intelligence Act (TFAIA). SB 53 will take effect January 1, 2026. Coming on the heels of 2024's SB 1047, a stricter version of the new law that passed the California legislature but was vetoed by the governor, SB 53 establishes state-level oversight of the use, assessment, and governance of advanced AI systems by requiring the most advanced AI developers to publish AI safety frameworks and transparency reports; share their catastrophic risk assessments as well as create new mechanisms to report critical safety incidents; and extend whistleblower protections. By establishing this state-level oversight, SB 53 seeks to create greater transparency and accountability for the most advanced AI developers and ensure they are rigorously assessing, mitigating, and