Fake Case Citation Checker - Verify AI Legal Briefs

Paste a brief and get every case citation back marked verified, name mismatch, not found or invalid reporter, with a link to the real case. Built for law firms, court clerks and legal-AI teams after the string of sanctions for filings that cited cases an AI invented. It checks two things most tools skip: that the citation exists, and that the case name written next to it is the case that actually sits there.

Works with no token. Adding a free CourtListener token widens coverage.

Input examples

1. Paste a brief (no token needed)

{ "text": "See Roe v. Wade, 410 U.S. 113 (1973); Varghese v. China Southern Airlines Co., 925 F.3d 1339 (11th Cir. 2019)." }

2. With a free CourtListener token, and only the problems

{ "text": "...your brief...", "courtListenerToken": "YOUR_TOKEN", "onlyProblems": true }

3. A plain list of citations

{ "citations": ["Miranda v. Arizona, 384 U.S. 436 (1966)", "Smith v. Jones, 410 U.S. 113 (1973)"] }

Run with no input for a demo brief that mixes real, mismatched and invented citations.

How verification works

Mode	Used when	Source	Coverage
Token	You supply a CourtListener token	CourtListener citation-lookup API v4	Federal and state courts incl. recent decisions. Rate limit: about 60 citations a minute, handled for you.
No token	Default	Harvard Caselaw Access Project volume files, then CourtListener anonymous search	Every volume the Caselaw Access Project holds (federal and state reporters, mostly published through the 2010s and early 2020s). Newer volumes fall back to CourtListener search.

Every row says which source answered and how confident it is. In no-token mode:

• high confidence means the reporter volume is in the Caselaw Access Project and the answer is definitive: a case begins on that page or none does.
• medium confidence means only CourtListener search was available; a "not found" is a prompt to check, not proof.
• UNVERIFIED means no free source covers that citation (Westlaw or Lexis numbers, some neutral citations, very recent volumes). These rows are never charged.

To get a CourtListener token: create a free account at courtlistener.com, open Profile, then Developer Tools. Your token is used only during your run and is marked secret in the form.

Output

One row per distinct citation plus one brief-report row per document.

Field	Meaning
status	VERIFIED, NAME_MISMATCH, NOT_FOUND, AMBIGUOUS, INVALID_REPORTER or UNVERIFIED
confidence, source	How sure, and which source answered
caseNameAsCited	Parties as written in your text
matchedCaseName, matchedDate, matchedCourt, matchedCitations, matchedUrl	The real case found at that citation
explanation	Plain-English reason
flags	For example YEAR_DIFFERS (cited 2019, decided 2018)
riskLevel (report row)	HIGH, REVIEW, LOW or NONE, plus counts and problemCitations

Sample rows:

{ "type": "citation", "citation": "925 F.3d 1339", "caseNameAsCited": "Varghese v. China Southern Airlines Co.", "status": "NOT_FOUND", "confidence": "high", "source": "case.law-static",
  "explanation": "No case exists at 925 F.3d 1339. Volume 925 of F.3d is in the Caselaw Access Project (...) and no case begins on page 1339." }
{ "type": "citation", "citation": "410 U.S. 113", "caseNameAsCited": "Smith v. Jones", "status": "NAME_MISMATCH", "matchedCaseName": "Roe v. Wade", "matchedDate": "1973-01-22",
  "explanation": "410 U.S. 113 is a real citation, but it is Roe v. Wade (1973), not \"Smith v. Jones\". Neither party name matches." }

Use it with

• A legal-AI drafting pipeline: run this Actor on the draft before it leaves your system and block on riskLevel: HIGH.
• Court or clerk intake: feed filed briefs (as text) through it and queue the flagged citations for a person.

FAQ

Does VERIFIED mean the case supports the proposition? No. It means the citation points at a real case and the party names match. Whether the case says what the brief claims is for a lawyer to read.

Which citations are extracted? Full case citations in the usual reporter format (U.S., F.3d, F. Supp., S. Ct., state reporters and so on), using an eyecite-style extractor. Short forms (Id., supra), statutes and regulations are skipped.

Why was a real case marked NAME_MISMATCH? Party names are compared with abbreviation-tolerant matching, but unusual styling of a case name can still miss. Read the explanation and the matched case before you rely on it.

PDFs? Paste the text; PDF files are not read.

Honest limits

• This is a research aid, not legal advice. Confirm every flagged citation in an official reporter.
• No free source holds every state and recent decision. In no-token mode newer volumes can only be checked through CourtListener search at medium confidence.
• Westlaw and Lexis citation numbers cannot be looked up for free and come back UNVERIFIED.

Price

Pay per event: $0.003 per citation checked (citation-checked, charged when you get a definite answer, not for UNVERIFIED) and $0.01 per brief report (brief-report). A brief with 40 citations costs about $0.13.