@pipeworx/court-listener

Connect: https://gateway.pipeworx.io/court-listener/mcp · Install: one-click buttons

Tools: 10

US court opinions from Free Law Project’s CourtListener: 8.3 million opinions across 3,361 courts, going back to 1761. The largest free, structured database of American case law.

Most of it is state law. That surprises people, and it is the point:

Federal appellate law is easy to find elsewhere. Six million state opinions, assembled and addressable, are not.

Auth

None for case lookup and opinion text — no key, no signup, no rate limit.

search_opinions and search_dockets search upstream by topic and are subject to CourtListener’s throttling. A free token from Free Law Project lifts it.

Tools

For litigation documents the path is search_dockets → list_docket_filings → get_docket_filing. Every filing tool is keyed by docket_id, and only search_dockets produces one — a PACER case number will not resolve.

Opinions and filings answer different questions: an opinion is what a court decided, a filing is what the parties filed.

search_opinions returns one cases shape whichever path served it (mirror or live), and the most-cited case inlines an excerpt of its lead opinion — the opening, its holding language, and the query match — so “what did the court hold” is answerable from the search result alone; get_opinion reads the full text.

The usual path is find_case → list_case_opinions → get_opinion. Results from find_case and lookup_citation are ranked by citation count, because among cases sharing a name the one later courts actually cite is nearly always the one being asked about — “roe wade” returns the 1973 Supreme Court decision (5,581 citations) ahead of the 1970 district case (53).

Abbreviated and copy-pasted case names

Name matching is AND over every token, so one token the corpus does not carry sinks the whole lookup. That used to mean find_case returned nothing for Bell Atl. Corp. v. Twombly — the corpus stores “Bell Atlantic Corp.”, and atl does not stem to atlant — and nothing for a name pasted out of a brief with its scaffold attached (TABLE OF AUTHORITIES Bowers v. Hardwick).

When the name as given matches nothing, find_case now retries once with Bluebook abbreviations, citation scaffold and corporate suffixes dropped (never expanded or guessed — under AND semantics dropping a token can only widen). A result found that way is labelled:

{ "matched": "relaxed", "matched_query": "Bell v Twombly", "note": "…" }

Treat a matched: "relaxed" hit as a best-effort resolution of a messy citation and check the returned case_name is the case you meant. An exact match never carries the field, and a name that matches on the first pass still costs exactly one query.

Coverage

Keyless: opinion full text, case names, filing dates, judges, precedential status, citation counts, reporter citations.

Upstream, throttled: full-text topic search, and all three filing tools. Finding a case by topic can fail in a way that finding it by name or citation cannot.

RECAP filings (PACER documents) — keyless, via search only. ~9.7 million documents. The REST endpoints you would reach for, /recap-documents/ and /docket-entries/, both answer “Authentication credentials were not provided”; /search/?type=rd needs no token and is the path the filing tools use. Scoping goes through the q field query (q=docket_id:71886217) — passing ?docket_id= as a parameter is silently ignored and returns the whole 61.7M-document corpus rather than an error.

Caveats worth passing to a user

• A filing without a PDF is still a real filing. RECAP holds docket text for far more entries than it holds documents, because a PDF only exists once somebody has paid PACER for it. Each filing reports pdf_available; on a typical docket most entries are metadata-only. Read a missing PDF as “nobody has bought this one”, never as “this was not filed”.
• Filing tools spend a scarce budget. They go upstream to CourtListener’s /search/, throttled to roughly 125 requests a day without a token — the same throttle the opinion mirror exists to avoid. There is no mirror for RECAP. When it is exhausted the tools say so explicitly rather than returning an empty docket; opinion tools are unaffected.
• Recency. Responses carry a snapshot_date; opinions filed after it fall through to upstream search.
• 14.2% of the corpus is OCR of scanned volumes and reads accordingly. Responses set extracted_by_ocr so garbled text is attributable to the scan rather than to us.
• date_created is not a filing date. It is when the record entered CourtListener — a 1946 opinion can read 2020. date_filed, joined from the cluster, is when the court actually ruled.
• Citation counts are within CourtListener’s corpus, not a universal measure of importance.

Attribution

Data is CourtListener / Free Law Project, published under the Public Domain Mark. Free Law Project funds and maintains the corpus. If this pack is useful to you, https://free.law/donate/ is where that goes.

Tools

• search_opinions — Search US court opinions from CourtListener — 8.3 million of them, with no API key and no rate limit. Covers the UNITED STATES SUPREME COURT (SCOTUS), the federal circuit courts of appeals, the federa
• search_dockets — Search US court dockets by keyword. Covers PACER and RECAP archives. Each result carries docket_id, case name, court, filing and termination dates, docket number, nature of suit, the cause of action,
• search_case_law — Search the FULL TEXT of US court opinions by subject matter — “qualified immunity for police dogs”, “securities fraud scienter pleading standard”. Searches the full text of CourtListener opinions with
• find_case — Find a US court case BY NAME and get its citations, filing date, judges and how often it has been cited. Searches 8.3 million opinions across 3,361 courts — no API key, no rate limit. Ranked by citati
• lookup_citation — Resolve a US reporter citation such as “410 U.S. 113” or “347 U.S. 483” to the case it refers to, with name, filing date, judges and citation count. No API key, no rate limit. Use when a brief, opinio
• list_case_opinions — List every opinion filed in one case (cluster) — majority, concurrences and dissents — with the opinion_id needed to read each one via get_opinion. No API key, no rate limit. Use after find_case or lo
• get_opinion — Get the FULL TEXT of a US court opinion by its CourtListener opinion ID (the opinion_id returned by search_opinions). Covers 8.3 million opinions, 71% state case law — no API key needed. Returns the o
• list_docket_filings — List the filings on a US FEDERAL district or bankruptcy court docket — every complaint, motion, order and exhibit RECAP has recorded for that case, in filing order, with the document id, entry number,
• get_docket_filing — Get one filing from a US federal court docket by its document id — the entry description as the clerk wrote it, the filing date, page count, the docket_id it belongs to, a text excerpt where the docum
• search_court_filings — Search the TEXT of US federal court filings — complaints, motions, briefs, orders and exhibits from PACER as archived in RECAP, roughly 9.7 million documents. Use this to find what was actually argued