California SB 942: the four duties, and the evidence each one leaves behind

01The clock

SB 942 passed in 2024 with a 1 January 2026 start. AB 853 moved it, and the new date was not arbitrary: California landed on the same day the EU AI Act's transparency article begins to apply. A provider serving both markets gets one deadline, not two.

1. 2024 · SB 942 enacted The California AI Transparency Act is signed

   Adds a new chapter to division 8 of the Business and Professions Code, with an original operative date of 1 January 2026.

2. 13 October 2025 · AB 853 Amended, delayed, and widened

   AB 853 pushes the operative date to 2 August 2026 and extends the regime beyond the original covered providers to further classes of duty holder on later dates.

3. 2 August 2026 · operative The four duties attach

   Latent disclosure, the manifest disclosure option, the public detection tool, and the 96-hour revocation duty are all live. Penalties accrue per day.

4. Same day · Brussels EU AI Act Article 50 begins to apply

   The marking and disclosure obligations of Regulation (EU) 2024/1689 start on the same date. The EU duties are different in shape — one evidence trail can answer both, but only if it was designed to.

02Are you covered?

This is the first question every reader has, and most summaries bury it. The test is narrow, and it lands on the builder of the system rather than the business that merely uses one.

Two things about that third question are widely misread, and both come from the drafting history rather than from any commentary.

There is no measurement window. As introduced, SB 942 counted users "on average over the preceding 12 months." An Assembly committee amendment in June 2024 struck the averaging clause, and no committee discussed the deletion. What survives is a bare threshold with no lookback at all — so a system that crosses one million in a single month has, on the face of the text, crossed it. AB 853 later wrote further thresholds with windows and did not restore one here.

The count is not California-only. The enacted text counts visitors and users; it does not limit them to the state. An Assembly analysis of AB 853 glosses the law as reaching developers with a million monthly California users, but a committee gloss that contradicts the enacted text is weak authority — and that phrasing appears to have been carried over from a different bill that never passed. Plan against the worldwide count.

03The four duties

Each duty below is stated as the statute frames it, then as an engineer has to build it, then as an enforcement inquiry will test it. The third framing is the one nobody writes down, and it is the only one that decides whether you can answer.

04Proving the negative

Here is the problem nobody's compliance page addresses. Suppose you produce four million images a month and you seal a record for every disclosure you embed. An investigator asks the question that actually matters: how do I know you didn't skip some?

A pile of receipts proves the acts you chose to record. It says nothing about the ones you didn't. Evidence that only ever confirms is not evidence — it is a testimonial with extra steps.

The fix is arithmetic. Before any duty records are written, a covered provider declares the system once: what it is in scope to produce, which marking techniques are in use, and — critically — where in its own code a per-system counter increments. From then on, each record carries that counter's value. Gaps in the sequence are visible to anyone reading the series. Omission stops being invisible and becomes a number.

This does not make the counter honest. Nothing can. What it does is make the audit question answerable in one sentence instead of an engagement: the sequence runs 1 to 4,102,887 with no gaps, and the declaration that bound the counter was sealed before the first record. Narrowing scope later is possible, but it is an affirmative, dated act that supersedes the prior declaration and leaves the old one standing in the record — not a quiet retroactive edit.

05The answer the legislature wrote down

There is a paragraph in this bill's committee history that nobody cites, and it describes the compliance architecture the statute was expected to produce.

That is a hash-record compliance path, endorsed in the legislative record, and it is not in any client alert we can find. It matters for a reason beyond flattery of our own design: an output-side corpus of hashes is not caught by the retention limits the statute puts on the detection tool itself. The tool is forbidden from emitting personal provenance data. A hash ledger of what you produced is a different object, held on your side, and answers a different question.

The rest of this page is what that record looks like when it is built to survive a hostile reading rather than merely to exist.

06Duty → receipt

This is where Planisphere enters, and not before. The California pack registers one event type per statutory act. The field names below are not illustrative — they are the fields the API accepts, and they were chosen to match the statute's own vocabulary.

Two properties matter more than the field list. Content never leaves your systems — source_payload takes hash commitments, never bytes, so a record can commit to an image without the image ever being transmitted. And each record is sealed on write: hash-chained into a per-tenant series, signed, and periodically anchored, so a later edit to any earlier record breaks the chain in a way a third party can detect without trusting either of us.

07The integration

One HTTPS call per act, from wherever the act happens. This is the whole surface — there is no agent to install, no proxy in your generation path, and nothing that can fail closed and take your pipeline down with it.

Declare the system once, before anything else:

Then one call per act. Here is the disclosure record — note that only hashes cross the wire:

At volume you do not want one HTTPS round trip per image in the render path. Batch transport exists for exactly this, and batching changes nothing about the evidence: each item is still its own record with its own key and its own place in the chain. The 96-hour revocation duty uses the same call with license_revoked, where starts_from_action_key ties the revocation to the moment of discovery, so the elapsed time is computed from sealed records rather than asserted.

The full API reference covers authentication, idempotency and rate limits; pricing is per record with a monthly free allowance.

08Anyone can check it, without an account

Evidence that only you can read is not evidence. Every sealed record has a public standing endpoint — no key, no login, no relationship with us. A regulator, an opposing counsel, or a customer can confirm that a record exists, that it has not been withdrawn, and which anchored epoch pins it:

The endpoint answers existence, standing and the anchor pin — deliberately not the contents. Your metadata stays yours; what a third party gets is the ability to confirm that the record you are showing them is the record that was sealed, unchanged, at the time you say it was.

09Who enforces it — and what has actually happened

Almost nothing, so far. That is worth stating plainly rather than implying a wave of enforcement that has not arrived.

There is no agency guidance, and there cannot be regulations. Chapter 25 delegates rulemaking authority to no one. Enforcement runs through the Attorney General, city attorneys and county counsel by civil action only — there is no agency with the power to write implementing rules, publish an FAQ with legal weight, or run a registry. An earlier draft of SB 942 did create a registry at a state department; committee amendments struck it in May 2024. The California Privacy Protection Agency has no role here either: its automated-decision rules govern decisions made about people, while this chapter governs content provenance. The two do not overlap.

There is no litigation on this statute. A docket search for the code sections returns nothing. Expect to see one case cited as though there were: a suit filed against the Attorney General in late 2025 by an AI developer is about California's training-data transparency law, not this one — its complaint does not mention these sections at all. The distinction matters for how much comfort you take from it, because compelled disclosure of proprietary training data is a much stronger First Amendment target than a requirement to label content with factual provenance.

Enforcement capacity was an open question during passage. The Department of Justice told an appropriations committee it could not absorb the work without additional staff, and noted that implementation would depend on funding. A committee analysis observed that if the department chose not to pursue enforcement, it would likely incur no costs. Draw your own conclusion about near-term risk — but note that the per-day penalty structure means exposure accrues quietly during exactly the period when nobody is knocking.

One live item: a further bill amending the large-online-platform section on system provenance data passed the Assembly unanimously in May 2026 and was moving through the Senate at the time of writing. It does not touch the operative date.

11Questions

We use a third-party model. Are we the covered provider?

Generally not — the duties fall on whoever creates, codes or produces the system, which is the model developer rather than a business calling its API. But check your licence terms: if you have licensed a covered system and modified it in a way that strips the disclosures, duty four makes you the subject of a 96-hour revocation by your licensor.

Does the penalty really run per day?

Yes, and it changes what "being compliant" means operationally. The defensible question is not are you compliant — it is on which days can you show you performed the duty. A continuous per-day record answers a per-day penalty. A screenshot does not.

We are already doing C2PA. Isn't that enough?

C2PA addresses the latent disclosure duty well, and it is the obvious way to meet the "consistent with industry standards" language. It does not address the detection tool, the manifest disclosure option, or the 96-hour revocation — and a manifest travelling with a file proves what the file claims today, not what you did on a date two years ago when the file is no longer in your hands.

What happens to our content and our metadata?

Content is never transmitted — only hash commitments. Declared metadata values are retained only when the pack marks the key as retainable and your organisation has enabled retention; otherwise only the key names and a canonical hash are kept. Person-identifying keys are never retainable.

What if we start recording after 2 August?

Then your evidence begins on the day you start, and it says so. A record cannot be back-dated — occurred_at is your own claim, but it is committed into the sealed payload and pinned by the anchor, so a record written in October cannot be made to look like one written in August. Starting late is recoverable. Starting late and pretending otherwise is not.

Does this cover the EU obligations too?

The same evidence discipline, different duties. Article 50 binds providers and deployers differently and turns on marking and disclosure rather than detection tools and licensing, so it has its own pack and its own event types. The EU page walks through it.

12Sources

Every date, threshold and figure on this page traces to one of these. Where the statute is summarised rather than quoted, the summary is ours and the citation points at the text so you can check it.

• Primary SB 942 — California AI Transparency Act, full text and history The four duties, the covered-provider definition, the one-million threshold, the $5,000 per-violation penalty, and the enforcement provisions.
• Primary AB 853 — the 2025 amendments Moves the operative date to 2 August 2026 and extends the regime to further classes of duty holder on later dates.
• Primary Regulation (EU) 2024/1689 — the EU AI Act Article 50, whose transparency obligations begin to apply on the same date California's do.
• Primary Assembly Privacy & Consumer Protection committee analysis, SB 942 The hash-record compliance path, the own-outputs-only reading of the detection tool, the unresolved question of whether text is covered, and the amendment that struck the 12-month averaging window.
• C2PA technical specification The provenance standard most covered providers are adopting to satisfy the latent disclosure duty.