Openlaw

by LegalAI Space

A free, open-source Model Context Protocol (MCP) server that exposes UK and EU open law — judgments, statutes, regulations, regulator notices — to host LLMs such as Claude, ChatGPT, and Cursor.

Where general-purpose chatbots invent citations, openlaw-mcp fetches the real text from official open-data sources (The National Archives' Find Case Law, legislation.gov.uk, EUR-Lex, HUDOC, ICO, HMRC) and returns it with full provenance and licence attribution. Every tool result is cite-back ready.

Install

Three ways to use openlaw-mcp:

1. Free hosted endpoint — fastest path, zero install, point your client at our URL.
2. Local stdio — runs inside Claude Desktop / Cursor / Claude Code via npx.
3. Self-hosted HTTP — node dist/http.js after npm run build.

1. Free hosted Streamable HTTP endpoint

A community endpoint is available at https://openlawmcp.legalaispace.com/v1/mcp. No API key, no signup, no rate-limit gate beyond the per-IP throttle. Best-effort uptime — no SLA, may be rate-limited, throttled, or migrated as load grows.

Codex CLI

codex mcp add openlaw --url https://openlawmcp.legalaispace.com/v1/mcp

Claude Code CLI

claude mcp add --transport http openlaw https://openlawmcp.legalaispace.com/v1/mcp

Claude Desktop / Cursor (config file)

{
  "mcpServers": {
    "openlaw": {
      "url": "https://openlawmcp.legalaispace.com/v1/mcp"
    }
  }
}

Health check: curl https://openlawmcp.legalaispace.com/healthz should return {"status":"ok","service":"openlaw-mcp"}.

2. Claude Desktop / Cursor / Claude Code (stdio)

Runs locally — no dependency on the hosted endpoint.

{
  "mcpServers": {
    "openlaw": {
      "command": "npx",
      "args": ["-y", "@legalaispace/openlaw-mcp"]
    }
  }
}

3. Self-host the HTTP transport

npm install
npm run build
node dist/http.js   # listens on PORT (default 3000), mount /v1/mcp

Behind a reverse proxy (nginx, Cloudflare, etc.), set TRUST_PROXY to the number of proxy hops so express-rate-limit keys by the real client IP — see Configuration.

Sample prompts

Once the server is configured, paste any of these into your host LLM. They are UK-focused and chosen to exercise the tools where MCP grounding makes the biggest difference — exact statute text, point-in-time status, judgment paragraph quotes, regulator deep links, and ICO / HMRC material that a plain web search cannot reliably return verbatim.

Statute lookups (lookup_statute, legislation_toc)

• "Quote subsection (1) of section 1 of the UK Bribery Act 2010 verbatim, with a link to the legislation.gov.uk source."
• "What is the current in-force text of section 1 of the Online Safety Act 2023 (c.50) on legislation.gov.uk? If the section has not been commenced, say so and cite the source you used."
• "What did section 2 of the Data Protection Act 2018 say as in force on 25 May 2018? Use legislation.gov.uk's point-in-time view."
• "Give me the table of contents for the Procurement Act 2023 — parts, chapters, and section numbers."
• "Compare the wording of section 1 of the Computer Misuse Act 1990 as enacted vs as currently in force, and cite both versions on legislation.gov.uk."

Case law (search_caselaw, fetch_judgment, grep_judgment, citator_lite)

• "Quote paragraph 1 of R (on the application of Miller) v The Prime Minister [2019] UKSC 41 verbatim, with the Find Case Law URL."
• "Find UK Supreme Court judgments from 2024 onwards that consider Article 8 of the ECHR. Return neutral citations with Find Case Law links and a one-line summary of each."
• "In Uber BV v Aslam [2021] UKSC 5, find every paragraph that mentions the word 'control' and quote each one in full."
• "List judgments published on Find Case Law that cite Pepper v Hart [1992] UKHL 3. Return neutral citations and links — no treatment classification needed."
• "Search Find Case Law for First-tier Tribunal (Tax Chamber) decisions on IR35 / off-payroll working handed down in 2023, and return the first 10 hits."

Regulator material (search_fca_handbook, fetch_fca_notice, search_ico_guidance, fetch_hmrc_manual)

• "Give me the official handbook.fca.org.uk deep link for SYSC 4.1.1R."
• "Resolve these FCA rule references into deep links: SYSC 6.1.1R, COBS 9.2.1R, CASS 7.13.3R."
• "Find recent ICO enforcement actions (monetary penalty notices and enforcement notices) issued in 2025 — return the title, date, and source URL for each."
• "From the HMRC Business Income Manual, give me the section on the badges of trade (BIM20205). Return the bodyText and the gov.uk URL."
• "From the HMRC Employment Status Manual (ESM), summarise the contents page (just the navigation tree, not the bodies)."

EU material (fetch_eurlex)

• "Fetch CELEX 32016R0679 (the GDPR) and return Article 5 in full, with the EUR-Lex source URL."
• "Fetch CELEX 32024R1689 (the EU AI Act) and tell me which articles deal with prohibited AI practices."

ECHR / Strasbourg (fetch_hudoc)

• "Pull the full English text of the ECHR judgment in Bărbulescu v Romania (Application 61496/08) and quote the operative paragraphs."
• "Search HUDOC for Grand Chamber judgments where the United Kingdom was the respondent state between 2020 and 2024."

Citation hygiene (format_oscola)

• "Format the following bundle of UK cases in OSCOLA, one per line: Donoghue v Stevenson [1932] AC 562; Pepper v Hart [1992] UKHL 3; R (Miller) v The Prime Minister [2019] UKSC 41."
• "Convert this sloppy reference into OSCOLA and produce a working Find Case Law URL: 'Uber BV v Aslam, 2021 Supreme Court, UKSC 5'."

When MCP shines (and when it doesn't)

• Strongest payoff: "verbatim text of section X" prompts, point-in-time statute lookups, FCA Handbook deep-link resolution, and any request that needs current in-force wording or a recent ICO/HMRC publication. Generic web search either guesses or gets blocked by upstream JS challenges (notably legislation.gov.uk's AWS WAF); the MCP server is allow-listed and returns parsed, cite-ready XML.
• Marginal payoff: quoting a famous paragraph from a landmark judgment, or formatting a textbook citation. The host LLM often gets these from training data alone — MCP still adds provenance and reduces hallucination risk, but the wording would have been correct anyway.
• No payoff: purely conceptual questions ("explain the difference between the FCA and the PRA"). These should be answered without calling any tool; if your host LLM fires MCP tools here, treat it as an over-eager router rather than a useful grounding.

Tools

Tool	What it does	Source / URL
search_caselaw	Search The National Archives' Find Case Law (E&W courts + tribunals from 2001).	https://caselaw.nationalarchives.gov.uk/atom.xml?query=...
fetch_judgment	Pull a full judgment as structured Akoma Ntoso.	https://caselaw.nationalarchives.gov.uk/{court}/{year}/{number}/data.xml
grep_judgment	Run a regex inside a single judgment's paragraphs.	https://caselaw.nationalarchives.gov.uk/{court}/{year}/{number}/data.xml
lookup_statute	Point-in-time lookup of any UK statute section on legislation.gov.uk.	https://www.legislation.gov.uk/{type}/{year}/{number}/section/{section}/data.xml (or .../{YYYY-MM-DD}/data.xml)
legislation_toc	Walk the table of contents for an Act or SI.	https://www.legislation.gov.uk/{type}/{year}/{number}/contents/data.xml
fetch_eurlex	Fetch an EU document by CELEX number.	https://publications.europa.eu/resource/celex/{CELEX}
fetch_hudoc	Fetch an ECHR judgment (English / French Court-authored text only).	Search/metadata: https://hudoc.echr.coe.int/app/query/results; body: https://hudoc.echr.coe.int/app/conversion/docx/html/body?...
search_fca_handbook	Resolve an FCA Handbook reference (SYSC 4.1.1R) to a deterministic deep link.[^1]	Local computation only (no fetch); emits deep link under https://www.handbook.fca.org.uk/handbook/...
fetch_fca_notice	Build metadata + deep link for a known FCA Final or Decision Notice slug.[^1]	Local computation only (no fetch); emits deep link https://www.fca.org.uk/publication/{category}/{slug}
search_ico_guidance	Search ICO guidance and enforcement notices.	POST https://ico.org.uk/api/search (mirrors listing at https://ico.org.uk/action-weve-taken/enforcement/)
fetch_hmrc_manual	Fetch a section of an HMRC internal manual.	https://www.gov.uk/api/content/hmrc-internal-manuals/{manual}[/{section}]
format_oscola	Format a parsed citation in OSCOLA (UK / Ireland) or Bluebook.	Local computation only (no network call)
citator_lite	Forward citation lookup for a judgment. Treatment classification is not included.	https://caselaw.nationalarchives.gov.uk/atom.xml?query=%22[citation]%22

[^1]: FCA materials are link-only / metadata-only. The server does not fetch FCA Handbook or notice body text, and notice listing is disabled unless FCA grants written permission for automated access. Users are pointed to the FCA's own site for authoritative content. See ATTRIBUTIONS.md for the legal posture.

Resources

Clients that support MCP resources can also read:

Resource template	What it returns	Source / URL
judgment://{slug}/{year}/{number}/header	TNA judgment header text. URL-encode slugs with /, e.g. ewca%2Fciv.	https://caselaw.nationalarchives.gov.uk/{slug}/{year}/{number}/data.xml
judgment://{slug}/{year}/{number}/index	JSON paragraph index for a judgment.	https://caselaw.nationalarchives.gov.uk/{slug}/{year}/{number}/data.xml
judgment://{slug}/{year}/{number}/para/{eId}	A single judgment paragraph by Akoma Ntoso eId.	https://caselaw.nationalarchives.gov.uk/{slug}/{year}/{number}/data.xml
statute://{type}/{year}/{number}/section/{section}	Current legislation.gov.uk section document as JSON.	https://www.legislation.gov.uk/{type}/{year}/{number}/section/{section}/data.xml

How tools and resources work technically

Common runtime flow (all tools)

1. MCP client sends tool name + JSON arguments (inputSchema validated by zod).
2. Server handler calls either:
   • a source client (src/sources/*.ts) that performs HTTP fetches via shared Fetcher, or
   • a local computation path (FCA link resolvers, citation formatter) with no network call.
3. Handler normalizes/parses upstream data into stable data fields.
4. Server returns an envelope: data, provenance (source, source_url, fetched_at, content_hash, cache_hit, licence metadata), and learn_more; some tools also include note.
5. On upstream errors, tools return isError: true plus a canonical authoritative URL.

Per-tool technical behavior

• search_caselaw: receives search filters (query, optional court/date/page), fetches TNA Atom feed, parses entries into normalized judgment refs, returns paged hits + provenance.
• fetch_judgment: receives neutral citation or TNA URI, resolves to /data.xml, parses Akoma Ntoso into meta, header, paragraphs, returns full structured judgment + provenance.
• grep_judgment: same fetch/parsing as fetch_judgment, then runs JS regex across parsed paragraph text, returns match list/snippets + provenance.
• lookup_statute: receives legislation type/year/number/section (+ optional as_of), fetches CLML section XML, extracts title/text/version metadata/extent/prospective flags, returns normalized section document + provenance.
• legislation_toc: receives legislation type/year/number, fetches CLML contents XML, flattens parts/chapters/sections into entries, returns TOC + provenance.
• fetch_eurlex: receives CELEX, validates/normalizes it, blocks out-of-scope national sectors (7/8), fetches from Cellar with content negotiation (XHTML then HTML fallback), returns raw body + detected media type + provenance.
• fetch_hudoc: receives either itemid or search query. Search path fetches JSON results and suppresses out-of-policy records. Item path fetches metadata then body only when language/doctype/translation guard passes. Returns records/body + provenance + suppression note when applicable.
• search_fca_handbook: receives parsed handbook reference inputs, computes deterministic deep link locally, returns metadata + local provenance (urn:openlaw-mcp:local) without FCA content fetch.
• fetch_fca_notice: receives known notice slug (+ category), computes deterministic FCA deep link locally, returns metadata + local provenance; listing path intentionally errors (scraping disabled).
• search_ico_guidance: receives optional type/sector/date/page filters, posts to ICO /api/search, shapes response into enforcement list items, returns paged results + provenance.
• fetch_hmrc_manual: receives manual slug (+ optional section slug), fetches GOV.UK Content API JSON, returns either manual navigation tree or section body (bodyHtml + bodyText) + provenance.
• format_oscola: receives citation text + formatting options, parses and formats locally (OSCOLA/Bluebook), optionally emits derived Find Case Law URL for neutral citations, returns formatted output + local provenance.
• citator_lite: receives neutral citation, searches TNA Atom with quoted query to find citing judgments, trims to limit, returns citing list + disclaimer + provenance.

Per-resource technical behavior

• judgment://.../header: MCP resource vars (slug, year, number) are validated/parsed, server fetches TNA judgment XML once, extracts plain-text header, returns text/plain.
• judgment://.../index: same fetch path, maps parsed paragraphs to { eId, num, preview }, returns application/json.
• judgment://.../para/{eId}: same fetch path, selects one paragraph by exact Akoma Ntoso eId, returns text/plain ([num] text when num exists).
• statute://.../section/{section}: validates resource vars, fetches legislation.gov.uk section XML via legislation client, returns parsed section document JSON.

Provenance

Every tool response carries a provenance block:

{
  "data": { },
  "provenance": {
    "source": "Find Case Law",
    "source_url": "https://caselaw.nationalarchives.gov.uk/uksc/2024/12/data.xml",
    "fetched_at": "2026-05-12T12:00:00Z",
    "content_hash": "sha256-...",
    "cache_hit": false,
    "licence": "Open Justice Licence v2.0",
    "licence_url": "https://caselaw.nationalarchives.gov.uk/open-justice-licence",
    "attribution": "Contains information licensed under the Open Justice — Licence v2.0"
  },
  "learn_more": "https://legalaispace.com"
}

If you redistribute the content downstream, preserve the attribution.

Limitations

• No BAILII. BAILII's terms prohibit programmatic re-use; the client blocks all outbound requests to it.
• No FCA scraping or full text. FCA Handbook and Notices are link-only / metadata-only by design. Known slugs and references are converted into deep links; the server does not enumerate FCA notices or fetch FCA page/PDF bodies without written permission.
• HUDOC scope. Only English/French Court-authored judgments. Third-party translations are excluded.
• Find Case Law coverage is E&W courts and tribunals from 2001 onwards. Older judgments are out of scope.
• EUR-Lex Member State legislation reached via N-Lex is excluded; only EU-authored content is fetched.
• legislation.gov.uk WAF. www.legislation.gov.uk is fronted by an AWS WAF that issues a JavaScript challenge (HTTP 202 Accepted with x-amzn-waf-action: challenge and an empty body) to clients whose IPs it considers suspicious — typically datacenter egress. From a residential network or an allow-listed deployment the API serves XML normally. Affected calls (lookup_statute, legislation_toc) surface a clear error and retry with backoff; we do not bypass the challenge by fingerprint-spoofing.
• Caselaw is not training data. openlaw-mcp fetches on demand for individual user queries; it does not maintain a persistent cross-user index of fetched content.

Troubleshooting

lookup_statute / legislation_toc fail with an AWS WAF challenge

The error you see in your host LLM will read something like:

upstream responded with an AWS WAF JavaScript challenge (HTTP 202) on every attempt

www.legislation.gov.uk is fronted by an AWS WAF that issues a JavaScript challenge to clients whose IPs it considers suspicious — typically datacenter egress, some VPNs, and an evolving list of residential prefixes. The server detects the challenge (HTTP 202, x-amzn-waf-action: challenge, empty body) and surfaces a structured error rather than spoof fingerprints to bypass it. See Limitations for the design rationale.

What to do:

• Run from a residential or allow-listed network, or point your host LLM at the free hosted endpoint, which runs from an allow-listed IP.
• The legislation tools (lookup_statute, legislation_toc) are the only tools affected by the legislation.gov.uk WAF. Caselaw (search_caselaw, fetch_judgment, grep_judgment), ICO, HMRC, EUR-Lex, HUDOC, FCA Handbook, and OSCOLA formatting all use independent upstreams and continue to work.
• Quick sanity check from your shell:

  curl -s -o /dev/null -w "%{http_code}\n" https://www.legislation.gov.uk/ukpga/2010/23/section/1/data.xml
  

  200 → the API is reachable from your network. 202 → WAF is challenging your IP.

npx -y @legalaispace/openlaw-mcp fails to start in Claude Desktop / Cursor / Claude Code

• Confirm node --version is >= 22 (engines.node in package.json). On Windows, install Node via nvm-windows or fnm; on Linux, prefer your distribution's Node 22+ package or Volta.
• First-run npx downloads the package; subsequent runs are cached. If your host LLM kills the spawn before the download completes, run npm install -g @legalaispace/openlaw-mcp once and switch the config to { "command": "openlaw-mcp" }.

Cache acting up

Cached responses live in ~/.cache/openlaw-mcp/http-cache.sqlite (override with OPENLAW_CACHE_DIR; disable with OPENLAW_DISABLE_CACHE=1). Delete the file to force a fresh fetch from upstreams. See Cache for the multi-tenant guidance.

Circuit breaker tripped

The shared fetcher trips a per-host circuit breaker on repeated 5xx / network errors and cools down for 30 seconds before retrying. If you see "circuit open" errors, wait, then retry — and check the upstream's own status page.

Configuration

All configuration is via environment variables.

Variable	Default	What it does
OPENLAW_CACHE_DIR	~/.cache/openlaw-mcp	Path for the SQLite HTTP cache. Set to off to disable caching.
OPENLAW_DISABLE_CACHE	unset	Alternative way to disable caching; set to 1.
OPENLAW_MCP_PATH	/v1/mcp	Mount path for the Streamable HTTP transport.
OPENLAW_RPM_PER_IP	600	Per-IP request budget per minute for the HTTP transport.
OPENLAW_CORS_ORIGIN	*	Access-Control-Allow-Origin value for the HTTP transport.
PORT	3000	Listen port for the HTTP transport.
TRUST_PROXY	1	How many reverse-proxy hops to trust when reading X-Forwarded-For. Set to 0 or false when binding directly to the public network, or to the hop count when chained behind multiple proxies (2, etc.). Express trust proxy string values (loopback, uniquelocal, IP/CIDR) are passed through.

Cache

By default, GET responses are cached in ~/.cache/openlaw-mcp/http-cache.sqlite with source-specific TTLs. Delete the cache directory to clear stored responses.

Multi-tenant deployments: The cache is shared across all callers of a given process. The TNA Find Case Law content is licensed under the Open Justice Licence v2.0, whose "computational analysis" carve-out does not permit a persistent cross-user retrieval index. If you are running the HTTP transport for more than one end-user, either set OPENLAW_CACHE_DIR=off or give each tenant its own ephemeral cache directory. Single-user stdio usage (npx @legalaispace/openlaw-mcp) is unaffected.

Takedown

If you are a rights-holder and believe content fetched by this server has been redistributed in error, please email [email protected]. We will investigate within five working days.

Development

npm install
npm run dev:stdio          # run the stdio server locally
npm run dev:http           # run the Streamable HTTP server with watch
npm test                   # unit tests, MCP protocol tests, and the ICO fixture test
npm run lint && npm run typecheck
npm run build
npm pack --dry-run         # verify npm package contents; runs release gates

License and attribution

Source code is Apache-2.0; see LICENSE. Upstream-data attributions and prior-art credit (notably paulieb89/uk-legal-mcp) are in ATTRIBUTIONS.md.

Development assisted by AI and Daman Kaur.

The information returned by this server is for information and research only and does not constitute legal advice.