us-eli-mcp

us-eli-mcp

MCP server for US law with verifiable citations. Five sources behind ten read-only tools:

• Congress.gov API - the federal legislative process: bills as they move through committees and floor votes.
• GovInfo API - enacted law text as published packages: US Code, Statutes at Large, CFR annual editions, Federal Register issues.
• Federal Register API - full-text search over 1,003,504 FR documents (1994-2026, live-verified 2026-07-07), including 8,513 presidential documents (1,550 executive orders). Keyless.
• CourtListener search API - full-text search over 8,294,123 court opinions (live-verified 2026-07-07). The headline value is STATE case law (California, New York, Texas, ...), which no federal source covers. Keyless, ~5 requests/min anonymous.
• eCFR API - the CURRENT Code of Federal Regulations: section-level full-text search over 412,846 sections plus per-section amendment history. Keyless.

What this is not

• State legislation (all 50 states) - see LegiScan, a free-tier aggregator (30,000 queries/month) not wrapped here.
• A federal case-law workhorse - for heavy federal case-law research the mature MIT-licensed wrappers (blakeox/courtlistener-mcp, john-walkoe/courtlistener_citations_mcp) remain the recommendation; the case-law tools here exist primarily for state courts. See SOURCES.md.

Tools

Tool	Purpose
us_search_bills	List bills by congress (e.g. 118) and type (hr, s, hres, ...)
us_get_bill	Full detail + latest action for one bill
us_list_code_packages	List GovInfo packages in a collection (USCODE, CFR, FR, STATUTE)
us_get_code_package	Metadata + download links (PDF/XML/TXT) for one package
us_search_federal_register	Full-text search over FR documents; filter rules, notices, executive orders
us_get_federal_register_doc	One FR document with its official citation (e.g. 91 FR 41591)
us_search_case_law	Full-text search over 8M+ opinions; court filter (e.g. cal, ny, scotus)
us_get_case	One opinion cluster by cluster_id
us_search_cfr_sections	Full-text search over the current CFR (eCFR)
us_get_cfr_section_history	Amendment history of one CFR section (e.g. 15 CFR 744.3)
us_coverage	Declare what this connector covers, when each family was captured, and - explicitly - what it does NOT cover. Every gap carries a fallback.

Every response carries lex_uri (a resolvable API URL), human_readable_citation (the official convention: "H.R. 1, 118th Congress", "91 FR 41591", "People v. Miranda-Guerrero, 519 P.3d 1004 (California Supreme Court 2022)", "15 CFR § 744.3") and source_url (the public page). Reporter citations are taken verbatim from the source and never fabricated; when none exists the docket number is used instead.

Install

As a Claude plugin (Claude Code or the desktop app, needs uv); see plugin/README.md for what it sends and stores:

/plugin marketplace add matematicsolutions/us-eli-mcp
/plugin install us-eli-mcp@us-eli-mcp

As a standalone server:

pip install us-eli-mcp

Windows 11 with Smart App Control

Smart App Control blocks unsigned executables, which covers uvx.exe, pip.exe and the us-eli-mcp.exe launcher that pip writes at install time. The python.exe and py.exe from the python.org installer are signed by the Python Software Foundation, so running the module through the interpreter works:

python -m pip install us-eli-mcp
python -m us_eli_mcp

pip.exe is blocked for the same reason, so install with python -m pip, not pip install. If python is not on PATH, use the Windows launcher: py -3 -m us_eli_mcp.

{ "mcpServers": { "us-eli-mcp": { "command": "python", "args": ["-m", "us_eli_mcp"] } } }

Do not turn Smart App Control off to work around this - it cannot be re-enabled without reinstalling Windows.

Configuration

Env var	Default
US_ELI_API_KEY	DEMO_KEY (shared, low rate limit - get your own free key at api.congress.gov/sign-up)
US_ELI_GOVINFO_API_KEY	reuses US_ELI_API_KEY (same api.data.gov key family)
US_ELI_CACHE_DIR	~/.matematic/cache/us-eli
US_ELI_AUDIT_DIR	~/.matematic/audit
US_ELI_BASE_URL	https://api.congress.gov/v3
US_ELI_GOVINFO_BASE_URL	https://api.govinfo.gov
US_ELI_FR_BASE_URL	https://www.federalregister.gov/api/v1 (keyless)
US_ELI_COURTLISTENER_BASE_URL	https://www.courtlistener.com/api/rest/v4 (keyless)
US_ELI_ECFR_BASE_URL	https://www.ecfr.gov/api (keyless)

The Federal Register, CourtListener and eCFR tools need no key at all.

Network: the server talks to the five sources above and the local filesystem. Once, on first use, it also fetches a small configuration file (us-runtime.json.gz, updated source addresses) from this repository's GitHub Releases. That request carries no query content; GitHub's download counter for the file is the only usage signal we see. US_ELI_RUNTIME_URL="" turns it off; the Claude plugin ships with it off. No LLM provider, no other telemetry.

License

Apache-2.0 (code). Congress.gov, GovInfo, Federal Register and eCFR data are US government works (public domain). CourtListener data is provided by the Free Law Project.