How it works
Short version: Lex keeps every dated version of a law exactly as the official publisher issued it, proves it has not altered a byte, and refuses to answer when it does not know. Here is the longer version.
Why "what does the law say" is the wrong question
Laws are amended constantly. Ask what the Luxembourg Covid measures act said and the honest answer is: which of its 32 texts? Almost every legal question that matters, was this contract valid, was that fine lawful, did we comply, is really a question about a date. Most legal websites show you only today's text.
Where the text comes from
Only from the official sources: Legilux for Luxembourg, EUR-Lex for the EU. Lex downloads the publisher's own file for each version and stores it byte for byte, untouched, with a SHA-256 fingerprint. Nothing is rewritten, summarised or "cleaned".
A second layer then splits that file into one record per article, still deterministic, no AI involved, so you can ask for Article 92 rather than a whole 600-page regulation. Each article's fingerprint chains back to the publisher's original file, so any tampering anywhere in the chain is detectable.
How you can check all of this yourself
Every index Lex serves is cryptographically signed (ECDSA P-256). You can download the public key, verify the signature, recompute any article's hash, and compare it against the publisher's own file, all without trusting this site. The step-by-step recipe, with code →
What it will not do
It will not guess. If you ask for a date Lex has no version for, it says so with a reason code (no_version_for_date) instead of producing a plausible text. The assistant on the front page is a small model whose only job is to pick the right lookup and quote what comes back, every answer shows the evidence underneath it, so you can check the answer against the source without leaving the page. Watch it refuse →
What it holds today
1,409 laws 4,705 dated versions 3,167 with full text refreshed nightly
Lex holds every Luxembourg law the state maintains a consolidated edition for, plus a set of EU financial and data regulations. Roughly 24,000 Luxembourg acts never receive a consolidated edition and are not here, and the gaps are published rather than hidden. Exactly what is and is not held →
Under the hood
The two-layer data model, the extraction profiles, the index schema and the refusal taxonomy are documented for engineers. The architecture page → · How it was built, and what was hard → · Use it from your own code →