California AB 853 (2025).
California Assembly Bill 853, known as the California AI Transparency Act, was signed into law by Governor Gavin Newsom on October 13, 2025, and chaptered as Chapter 674 of the Statutes of 2025.
The law amends the Business and Professions Code to establish comprehensive transparency requirements for generative artificial intelligence (GenAI) systems, large online platforms, and capture device manufacturers.
It mandates that developers of GenAI systems with over 1 million monthly users embed both visible (manifest) and invisible (latent) provenance disclosures into AI-generated content, and provide free AI detection tools to verify such content.
Starting January 1, 2027, large online platforms—defined as platforms with over 2 million unique monthly users—must detect and preserve compliant provenance data in user-uploaded content, and make this information accessible to users through a conspicuous interface that includes details such as the GenAI system or capture device used.
Capture device manufacturers, beginning January 1, 2028, must enable users to include latent provenance disclosures in content captured by devices such as smartphones and cameras, including information like the manufacturer's name.
The law also establishes a civil penalty of $5,000 per violation, enforceable by the Attorney General, city attorneys, or county counsel.
The bill was developed to address gaps in AI transparency, particularly the vulnerability of user-generated content to manipulation due to the lack of provenance data in capture devices and the stripping of such data during content distribution on online platforms.
Stanford Law School’s CodeX evaluated the bill favorably, scoring it highly across all eight AI life cycle core principles, including transparency, accountability, privacy, and security, though it identified potential gaps in accuracy, explainability, fairness, bias, and safety that could be addressed in future legislation.
The law is set to take full effect in phases, with the initial provisions operational on January 1, 2026, and the expanded requirements for platforms and manufacturers phased in through 2027 and 2028.
https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202520260AB853
