us-eli-mcp 0.3.0

MCP server for US law: bills (Congress.gov), US Code (GovInfo), Federal Register, case law (CourtListener), eCFR - with verifiable citations.

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)

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

pip install us-eli-mcp

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.

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.