CourtListener

A Model Context Protocol server that gives AI assistants access to the CourtListener legal database (US federal + state court opinions, dockets, RECAP filings, PACER data, oral arguments, judges) and the Electronic Code of Federal Regulations via the official CourtListener API v4.

Use it with Claude Desktop, Claude Code, Cursor, VS Code, Windsurf, ChatGPT Desktop, or any MCP-compatible client.

Forked from Travis-Prall/court-listener-mcp. This fork adds a hosted endpoint, bring-your-own-key (BYOK) auth, a /health route, Dockerfile hardening, a full eCFR (federal regulations) tool suite, cursor pagination, per-client rate limiting, and read-only tool annotations. See the changelog for details.

When to use this vs. the official server

Free Law Project (who run CourtListener) host an official MCP at https://mcp.courtlistener.com/ (OAuth, free with any CourtListener account) - see their announcement. Prefer it if you want OAuth and the broadest CourtListener coverage. Use this server if you want: eCFR federal-regulations tools (the official server has none), simple BYOK header auth (no OAuth dance), or a self-hosted/embeddable Python server. The two are complementary.

Use the hosted endpoint (no install)

The Vaquill team runs a public instance for the community:

https://courtlistener-mcp.vaquill.ai/mcp/

You bring your own free CourtListener token from courtlistener.com/help/api/rest/, the server forwards it. We never see or store your key.

Claude Desktop / Claude Code

~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "courtlistener": {
      "url": "https://courtlistener-mcp.vaquill.ai/mcp/",
      "headers": {
        "X-CourtListener-Token": "YOUR_COURTLISTENER_TOKEN"
      }
    }
  }
}

Cursor

.cursor/mcp.json:

{
  "mcpServers": {
    "courtlistener": {
      "url": "https://courtlistener-mcp.vaquill.ai/mcp/",
      "headers": { "X-CourtListener-Token": "YOUR_COURTLISTENER_TOKEN" }
    }
  }
}

VS Code (GitHub Copilot Chat)

.vscode/mcp.json:

{
  "servers": {
    "courtlistener": {
      "type": "http",
      "url": "https://courtlistener-mcp.vaquill.ai/mcp/",
      "headers": { "X-CourtListener-Token": "YOUR_COURTLISTENER_TOKEN" }
    }
  }
}

Claude Web (custom connector)

Settings → Connectors → Add custom connector → paste the URL and add X-CourtListener-Token as a header. Workspace owners only.

Windsurf, Continue, etc.

Any client that supports MCP streamable HTTP with custom headers works. For stdio-only clients, run the server locally (see below) or proxy with mcp-remote.

Tools

34 tools across 4 groups (each group is namespaced). All are read-only.

Group	Tools
Search (CourtListener)	search_opinions, search_dockets, search_dockets_with_documents, search_recap_documents, search_audio, search_people
Get (CourtListener)	get_opinion, get_docket, get_audio, get_court, get_person, get_cluster
Citation	citation_lookup_citation, citation_batch_lookup_citations, citation_verify_citation_format, citation_parse_citation_with_citeurl, citation_extract_citations_from_text, citation_enhanced_citation_lookup
eCFR (federal regulations)	ecfr_list_titles, ecfr_get_title_versions, ecfr_get_title_structure, ecfr_get_ancestry, ecfr_get_source_xml, ecfr_list_agencies, ecfr_list_all_corrections, ecfr_list_corrections_by_title, ecfr_search_regulations, ecfr_get_search_count, ecfr_get_search_summary, ecfr_get_title_search_counts, ecfr_get_daily_search_counts, ecfr_get_hierarchy_search_counts, ecfr_get_search_suggestions
System	status

Search tools accept a cursor param and return a next_cursor for pagination. See app/README.md for full parameter details.

Authentication

Two modes, in priority order:

1. Per-request header (BYOK) — preferred for hosted / shared deployments. Send the user's CourtListener key on every MCP request:
   • X-CourtListener-Token: <key> (preferred), or
   • Authorization: Token <key> (CourtListener's native scheme — only works if the MCP server itself isn't already gated by Authorization).
2. Server env fallback — set COURT_LISTENER_API_KEY on the server. Used when no per-request header is supplied. Leave unset on public instances to force BYOK and avoid burning the operator's quota.

If neither is provided, tools return a ValueError with a clear message.

Self-host

Docker

git clone https://github.com/Vaquill-AI/courtlistener-mcp.git
cd courtlistener-mcp
cp .env.example .env  # optionally set COURT_LISTENER_API_KEY for single-tenant
docker compose up -d
# server at http://localhost:8000/mcp/

Python (uv)

uv sync
uv run python -m app --transport http

Stdio (local CLI integration)

uv run python -m app --transport stdio

Add to Claude Desktop:

{
  "mcpServers": {
    "courtlistener-local": {
      "command": "uv",
      "args": ["run", "--directory", "/abs/path/to/courtlistener-mcp", "python", "-m", "app", "--transport", "stdio"],
      "env": { "COURT_LISTENER_API_KEY": "your_token" }
    }
  }
}

Configuration

Var	Required	Default	Notes
COURT_LISTENER_API_KEY	Optional*	—	Fallback when no per-request header. Leave unset on public servers.
COURTLISTENER_BASE_URL	No	https://www.courtlistener.com/api/rest/v4/
COURTLISTENER_TIMEOUT	No	30	seconds
MCP_TRANSPORT	No	stdio	stdio | http | sse
MCP_PORT	No	8000	http/sse only
HOST	No	0.0.0.0	http/sse only
ECFR_BASE_URL	No	https://www.ecfr.gov	eCFR API base (no key required)
RATE_LIMIT_ENABLED	No	true	Per-client MCP rate limiting
RATE_LIMIT_RPS	No	15	Max requests/sec per client
RATE_LIMIT_BURST	No	40	Burst capacity per client

* Required only if running in single-tenant mode without BYOK.

Health check

curl https://courtlistener-mcp.vaquill.ai/health
# {"status":"healthy","service":"courtlistener-mcp","version":"..."}

Development

uv sync --dev
uv run pytest
uv run ruff format . && uv run ruff check .
uv run mypy app/

Changelog

0.2.0

• Added a full eCFR (federal regulations) tool suite (15 tools): titles, structure, versions, ancestry, source XML, agencies, corrections, and full-text regulation search + analytics. This is the differentiator over CourtListener-only servers.
• Fixed a validation crash: optional search filters are now nullable (str | None), so clients that send explicit JSON null no longer get a ValidationError (previously broke search_dockets / search_recap_documents).
• Real pagination: removed the no-op hit param; search tools now honor limit and expose a next_cursor token plus an input cursor.
• Read-only tool annotations on all tools (better client UX, no write prompts).
• Per-client rate limiting middleware (configurable, on by default).
• Migrated import_server → mount (FastMCP 3), fixed the API-key env-var alias, refreshed project metadata, and got the test suite green (unit tests mocked; live-API tests gated behind RUN_INTEGRATION=1).

Credits & License

• Original implementation: Travis-Prall/court-listener-mcp
• Hosted by: Vaquill — courtlistener-mcp.vaquill.ai
• License: MIT (see LICENSE)

CourtListener data is provided by the Free Law Project under their respective terms. eCFR data is from ecfr.gov.