Anthropic today publicly endorsed California’s SB 53, a bill by state Senator Scott Wiener that would impose the nation’s first transparency requirements on frontier AI developers. In a blog post, the company said it still prefers federal rules but argued that “powerful AI advancements won’t wait for consensus in Washington.” The endorsement is a rare and significant win for the bill, which requires large AI developers to publish safety frameworks, release transparency reports before deploying new models, report critical safety incidents within 15 days, and protect whistleblowers. Companies that fail to comply could face financial penalties.

The bill targets the largest AI model developers, particularly those with gross revenue of more than $500 million, and uses a compute threshold of 10^26 FLOPS to determine which systems are covered. It was shaped by an expert panel convened by Governor Gavin Newsom after his veto of last year’s broader SB 1047. Anthropic says SB 53 largely codifies practices it already follows—like its Responsible Scaling Policy and system cards—and would create a level playing field where disclosure is mandatory, not optional. The company acknowledged the bill has room for improvement, particularly in updating compute thresholds and requiring more detailed evaluations.

Much of the tech industry opposes SB 53. The Consumer Technology Association and Chamber of Progress are lobbying against it, and Andreessen Horowitz has argued it may violate the Commerce Clause. OpenAI’s chief global affairs officer, Chris Lehane, sent the governor a letter in August warning against regulations that could push startups out of California. But policy experts say the bill’s more modest approach—dropping earlier third-party audit requirements—gives it a realistic chance of passage. Dean Ball, a former White House AI policy adviser who criticized SB 1047, said the drafters have “shown respect for technical reality” and “legislative restraint.” The bill still needs a final Senate vote before reaching Newsom’s desk.