Deterministic rules-as-code evaluator

Statuta

A rules engine for law. Each rule points to the exact words of a statute, and the evaluator gives the same verdict for the same facts every time, with unknown facts never counting as permission. It starts with license plate reader laws in three states.

  • Python
  • JSON Schema
Code on GitHub (opens in a new tab)

How it works

  1. Statute textConnecticut, Oregon, Virginia
  2. Rulestied to exact spans
  3. Independent reada second encoding to compare
  4. Evaluatorno network, no model
  5. Verdictcites rules and gaps
  6. Transparency logwhat was decided, not asked
Statute text is encoded as rules that each point to an exact span of the law. A second, independent reading of the same statute is compared with the encoding. The evaluator, which has no network or model access, applies the rules to the facts and returns a verdict that cites its rules and any gaps. Each evaluation is recorded in an append-only log that holds metadata only.

Decisions that matter

  • A model may propose, never decide

    A language model can draft rules offline, but it never decides an access question at runtime. The evaluator only reads JSON rules and makes no network call, model call or clock read.

  • Unknown never becomes permission

    Every condition comes out true, false or unknown. Missing facts never resolve to permission, and a prohibition that fires beats every other effect.

  • Every rule carries its source

    A released rule has to point to an exact span of statute text, with hashed source provenance and human-review notes. Low-confidence extractions go to a person first.

  • A log that does not hold the question

    Evaluations are committed to an append-only Merkle log (RFC 6962) that keeps metadata only, so anyone can check that a decision was logged without the log containing a plate, a name or a location.

Limits

This is not a legal service or a released corpus: three statutes are encoded as drafts with independent reads. The log proves a check was logged, not that its input was true or that the verdict was obeyed.

Next projectVestQuest