# Recycled-bill detection methodology

How the "This bill is back" tracker decides two bills are the same idea, and where the method is weak. Data: `data/recycled-bills.json` (15 pairs as of 2026-10-01).

## What counts as a "recycled" bill

A pair = a **prior bill** (2023–24 session, or year 1 of the 2025–26 session) and a **current bill** (2025–26 session) where the current bill re-introduces the same policy idea after the prior one was vetoed or died. Detection uses three signals, strongest first:

1. **Committee "prior legislation" citations.** Assembly and Senate committee analyses routinely list related bills ("Governor veto: last year Governor Newsom vetoed AB 2286…"). These are the gold standard — a bill's own official analysis naming its predecessor. Example: the AB 33 analysis cites the AB 2286 veto.
2. **Same-author reintroduction.** An author carrying back their own dead or vetoed bill under a new number in the new session, usually with adjustments aimed at the veto message. Example: Soria's community-college BSN pilot (AB 2104 → AB 2301), Bauer-Kahan's AI anti-bias bill (AB 2930 → AB 1018).
3. **Press-reported lineage.** Credible outlets describing the current bill as a revival, "copy," or "virtually identical" version of a named prior bill, even with a different author. Example: Agri-Pulse on SB 1299 → AB 1336 ("virtually identical"), CalMatters on Papan's AB 93 → AB 2469.

When signals conflict (press says "revival," but the policy machinery changed), the pair is kept and the `what_changed` field explains exactly what was redesigned.

## Lineage chains, not just pairs

Several ideas took three or more runs, with intermediate bills that also failed. The dataset records the 2023–24 → 2025–26 arc and notes intermediates in `prior_status_detail` rather than multiplying entries:

- Driverless trucks: AB 316 (2023, vetoed) → AB 2286 (2024, vetoed) → AB 33 (2025, vetoed)
- Recovery housing: AB 2479 (2024, died) → AB 255 (2025, vetoed) → AB 1556 (2026, signed)
- AI anti-bias: AB 331 (2023, died) → AB 2930 (2024, died) → AB 1018 (2025–26, two-year)
- Community-college BSN: AB 2104 (2024, vetoed) → AB 1400 (2025) → AB 2301 (2026, vetoed)

Two pairs are year-1 → year-2 revivals within the same 2025–26 session (AB 1309 → AB 2129 on Cal Fire pay; AB 93 → AB 2469 on data-center water). They are marked `pair_type: "year1_to_year2"` rather than excluded, because they illustrate the same reintroduction dynamics.

## How gut-and-amend is handled

Gut-and-amend — where a bill's number survives but its contents are replaced — is **not** in this dataset. A gut-and-amended bill keeps the same number, so there is no prior→current bill-number pair to detect, and press coverage of amendments is inconsistent. That means this tracker undercounts ideas that returned via gut-and-amend vehicles late in session. This is a known blind spot, not a claim of completeness.

## Known limits

1. **Editorial, not exhaustive.** This is a curated list skewed toward vetoed bills with publicly documented lineage. It is not a census of all reintroductions.
2. **Press-dependent.** New-author pickups are only caught when coverage names the prior bill. Quiet reintroductions without press or committee citations slip through.
3. **Statuses are point-in-time** (2026-10-01). Pending two-year bills can still move in 2026; vetoed bills could return again.
4. **"Same subject" is a judgment call.** Two bills can share a goal while the machinery differs (e.g., SB 351 replaced AB 3129's transaction pre-approval with AG enforcement). The `what_changed` field is the audit trail for that judgment.
5. **Authors are lead authors as introduced.** Joint authors and coauthors (e.g., Wicks as joint author of AB 2222) are noted in `current_author` but `same_author` compares the principal authors.
6. **Not legal advice.** This is a research tool; statuses come from leginfo and press records, not from a lawyer's bill history.