LibreJustice MCP Server

LibreJustice

librejustice.fr: a free search engine for French-language and European law, plus current public notices. It links case law from France's administrative and judicial courts to consolidated legal texts and makes them searchable in plain language on the web and through MCP.

Free and open source. ~3.8 million decisions and ~3.9 million legal articles in one database, linked article by article, resynchronised daily. That is the whole point: texts and case law live together, so there is no second server to plug in for the codes and no third one for the citation graph.

What you search

• Case law: Conseil d'État, Cour de cassation, cours d'appel, administrative and judicial first-instance courts, Conseil constitutionnel, CNIL, CNDA (publicly released decisions only), Tribunal des conflits, ECHR, CJEU. Filters by court, date, outcome and cited articles.
• Legal texts: codes and statutes as they stood on any date (consolidated versions with per-article history), the full Journal officiel, EU law, treaties and bilateral accords, collective agreements, BOFiP, circulaires, and the codes of 59 foreign countries.
• Public notices: open public procurement opportunities from BOAMP and buyer platforms, deduplicated with submission links and deadlines.
• Directory: lawyers, companies and courts, linked to their litigation.

Corpus refreshed daily from open sources (Judilibre, DILA/Légifrance, EUR-Lex...).

What the official sources do not offer

Public databases are silos, each with a search engine bounded by its own fonds (Judilibre covers the judicial courts only; the administrative open data searches CE/CAA/TA by keyword, court and date; Légifrance holds the texts). LibreJustice consolidates them and adds the missing layer:

• plain-language search (hybrid lexical + semantic) with AI reranking, dynamic facets and similar decisions;
• the graph: citations extracted and resolved, from a decision to the exact articles it cites at the right version, and from an article back to the decisions that cite it;
• cross-source deduplication (one decision, one page) and recovery of decisions missing from the official channels;
• AI summaries per decision, always kept distinct from verbatim excerpts;
• a remote MCP endpoint for AI assistants.

Using LibreJustice from an AI assistant

The public MCP server is https://librejustice.fr/mcp (OAuth 2.1 with dynamic client registration: no API key to configure). Four tools: search_decisions, get_decision, search_norms, get_norm.

With Claude Code, the plugin installs the connector and the usage skills:

/plugin marketplace add librejustice/librejustice
/plugin install librejustice@librejustice

The skills alone (without the MCP connector) install into any compatible agent through skills:

npx skills add librejustice/librejustice

On claude.ai, LibreJustice is listed in the connector directory. One click, then the OAuth authorisation. With ChatGPT, Le Chat or Perplexity, add a custom connector pointing at https://librejustice.fr/mcp.

Using LibreJustice from your own code

The same corpus in REST, described by openapi.json (OpenAPI 3.1). The key is free: create an account, then a key from your profile. Guide at librejustice.fr/api-guide.

curl -H 'Authorization: Bearer ljk_your_key' \
  'https://librejustice.fr/api/search?q=trouble+anormal+de+voisinage&limit=3'

Five routes: /api/search, /api/search-textes, /api/decision/{id}, /api/texte/{code}/{article} and the same with a trailing /{date} for the version in force that day.

Stack

A single-server node, Postgres + ParadeDB + VectorChord (hybrid BM25 + vector search), API and front end in Rust.

A pure Rust Cargo workspace, split in two roots:

• packages/ libraries:
  • lj-core pure core: the decision model and its normalisation.
  • lj-parse source parsers into the decision model.
  • lj-norm referential of the legal texts: article keys, aliases, applicability.
  • lj-extract field and citation extraction from decisions.
  • lj-sources source I/O (Judilibre JSON, opendata ZIP/XML).
  • lj-store Postgres access (tokio-postgres + deadpool) and migrations.
  • lj-llm embedding backends, cache, quantisation, Mistral client (chat/OCR).
  • lj-dtos api to web contracts (serde).
  • lj-telemetry tracing and OTLP export.
  • lj-api API layer (Axum + MCP rmcp + OAuth).
  • lj-web Leptos front end (SSR + WASM hydration), Tailwind.
• apps/ shippable binaries:
  • lj-server single deployment: API + MCP/OAuth + SSR.
  • lj-ingest ingest CLI and cron runner.

Build and dev

The Rust toolchain is pinned by rust-toolchain.toml. Tasks run through mise:

mise run test      # rustfmt --check + clippy -D warnings + cargo test --workspace
mise run dev       # merged lj-server (cargo leptos watch, :3000)

For a local database: mise run dbs. The task prepares the Postgres state under LIBREJUSTICE_STATE_DIR, owning the data directory and copying the configuration mounted by the container, before starting it.

Deployment

Single server through podman compose (infra/docker-compose.yml): Postgres (ParadeDB + VectorChord), the merged lj-server binary, a caddy front end and the ingest cron. Fill in .env (see .env.example), then:

mise run ensure-pg                                                          # Postgres state and conf
podman compose -f infra/docker-compose.yml --profile prod up -d --build
podman compose -f infra/docker-compose.yml exec -T cron lj-ingest migrate   # migrations

lj-server serves the API, MCP/OAuth, SSR and the assets. It listens in clear; caddy holds :443 and terminates TLS, so the socket stays bound when the application container is recreated.

The shipped Postgres configuration (infra/pg-conf/) carries what the application requires (extensions, ParadeDB settings, compression) sized for a development machine. A production instance raises shared_buffers and effective_cache_size to match its hardware.

Licence

Apache-2.0.