Implausible Enterprises Legal Research

LLM Law Library

Free, open legal research for humans and AI.

10.9M opinions 2.34M statutes 882K definitions 52 jurisdictions GET + POST + MCP

Are you an LLM with only a chat window and web access? No installation is needed. Open For Chat-Window LLMs, then follow its ordinary GET links and research recipes. The same plans are also available as readable skill files.
Search 10.9 million court opinions across all 50 states and federal courts. Use BM25 mode for exact citations and party names.
Search 1.9 million statutory sections across all 50 states, DC, and federal law. Filter by jurisdiction to search a single state.
Look up where any legal term is statutorily defined across US jurisdictions. About 882K definition pointers and 215K unique terms. Enable “red flags” to see where a term is used but NOT defined.
10.9M

Case Law

US court opinions across all 50 states and federal courts. Hybrid search (BM25 + semantic vector). Automated treatment data is a research lead, not a good-law verdict.

2.34M

Statutes

All 50 states + DC + federal (US Code). 52 jurisdictions. BM25 deterministic search. Filterable by state.

882K

Definitions

Where each legal term is statutorily defined. About 215K unique terms, ranked by how often courts cite each definition.

10.8K

Red Flags

Terms used in statutes but NOT defined in that jurisdiction. Each is a prompt to investigate, not proof that no definition exists.

Install the MCP (Claude Code)

One command. No dependencies beyond Python 3.

curl -O https://raw.githubusercontent.com/giblfiz/llm-law-lib/master/caselaw-mcp.py claude mcp add llm-law-library python3 $(pwd)/caselaw-mcp.py

Install the MCP (Claude Desktop)

Download caselaw-mcp.py, then add to config:

{ "mcpServers": { "llm-law-library": { "command": "python3", "args": ["/path/to/caselaw-mcp.py"] } } }

REST API

No authentication required. POST remains available; ordinary GET URLs work for chat-window models. GET query strings may be logged, so do not put confidential facts in them.

# Search case law https://implausible.enterprises/api/caselaw/search?query=qualified%20immunity&mode=hybrid&top_k=5 # Search statutes (California only) https://implausible.enterprises/api/caselaw/statute/search?query=negligence&jurisdiction=state%3ACA # Look up a term definition https://implausible.enterprises/api/caselaw/term/search?term=fiduciary&include_red_flags=true

Key Concepts

Search modes
Hybrid (default) fuses BM25 + vector via RRF. BM25 is deterministic. Vector finds conceptually similar passages.
Treatment signals
Automated citation-graph and opinion-text signals about later discussion. They can be noisy or misattributed; inspect the later opinions and use an authoritative citator where the stakes require it.
Red flags
Terms used heavily but with no statutory definition found. Four causes: cross-reference gap, missed cross-reference, common-law reliance, or extraction gap.
Definition pointers
We store WHERE terms are defined, not the definitions themselves. “Person” has 40+ definitions across jurisdictions.
Trust hierarchy
xml_structured > caselaw_cite > bm25_pattern > flash_classification
Data
Caselaw from CourtListener / Free Law Project (CC0). Federal statutes from OLRC USLM XML. State statutes from official legislative websites. Not legal advice.

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