A California law requiring AI-generated photos, videos, and audio to carry permanent digital fingerprints identifying them as machine-made took effect Saturday, Aug. 1.

The measure was authored by state Sen. Josh Becker, D-Menlo Park, who represents San Mateo in District 13.

Under the California AI Transparency Act (Senate Bill 942), any company that builds or operates a generative AI system accessible to California users must now embed provenance metadata into the content its tools produce. That metadata records how and when the content was created and stays attached permanently, giving anyone downstream a way to verify whether an image, clip, or audio file was made by a human or a machine.

"This is one of the biggest things I've ever done," Becker told the San Mateo Daily Journal on Thursday, July 30. "This is a global issue, which I sought to answer three years ago — how do we help people tell if something is created by AI or not?"

Becker said deepfake scams and election misinformation prompted him to begin work on the bill roughly three years ago. He argued that embedding origin data in metadata is harder to fake than a visible watermark, which can be stripped from AI content or added to real content to sow confusion.

The law applies to all generative AI systems with California users, meaning companies nationwide and globally will need to update their tools. Violations carry a $5,000 civil penalty per instance, enforceable by the California Attorney General, a city attorney, or county counsel.

For San Mateo residents, the immediate change is invisible: the metadata lives behind the scenes. The consumer-facing phase arrives Jan. 1, 2027, when large social media platforms must read that embedded data and give users a way to check whether content they're viewing was generated by AI.

A third phase in 2028 will require camera manufacturers to embed similar provenance data in real photographs, further separating authentic images from synthetic ones.

Becker co-authored the bill with Assemblymember Buffy Wicks, D-Oakland, and Assemblymember Rick Chavez Zbur, D-Los Angeles. A companion bill, Senate Bill 1000, is moving through the legislature and would extend the requirements to AI systems with fewer than one million monthly users.

The Almanac reported that the European Union delayed implementation of its own AI law to Sunday, Aug. 2, one day after California's start date. Becker has said the two jurisdictions are working together to set a global standard.

The Attorney General's office has not detailed how it will detect violations or process complaints. Becker told Palo Alto Online on Wednesday, July 29, that "the work will be ongoing as technology develops and changes."