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AI Citation Checker
Paste a motion, brief, or any filing. Every case citation is checked against CourtListener's ~9M-opinion database, so you can confirm an opposing brief's authorities — or your own — resolve to real opinions before you file.
In 2023, a federal court in the Southern District of New York sanctioned attorneys $5,000 after they filed a brief citing multiple non-existent opinions generated by ChatGPT — Mata v. Avianca, Inc., No. 1:22-cv-01461 (S.D.N.Y. 2023). The model had produced plausible-looking citations, complete with invented case names and internal quotes, that did not correspond to any real opinion. This tool checks every citation in a brief against CourtListener's database of roughly 9 million federal and state opinions, so unresolvable cites are surfaced before they reach a court.
Common questions
- How do I check if a brief's citations are real?
- Paste the full text of the brief into this tool. It automatically detects every case citation and queries CourtListener's database of roughly 9 million federal and state opinions. Citations that resolve to a real opinion are marked found with a link to the opinion. Citations that do not resolve are flagged — that means CourtListener has no record of an opinion matching that reporter, volume, and page, which warrants independent follow-up before you rely on it or file it.
- Can AI make up fake case citations?
- Yes. Large language models, including ChatGPT and similar tools, can generate plausible-looking but entirely fabricated case citations — complete with invented case names, reporters, volume numbers, and page numbers. In Mata v. Avianca, Inc. (S.D.N.Y. 2023), attorneys submitted ChatGPT-generated briefs that cited multiple non-existent opinions. Judge P. Kevin Castel sanctioned counsel $5,000 and noted the fabricated cases showed up with invented quotations and internal citations. The problem is structural: these models predict plausible text, not accurate legal records.
- How do I verify opposing counsel's citations?
- Paste the full text of the opposing brief here. The tool will flag any citation that does not resolve in CourtListener. A not-found result is a starting point for your own verification — confirm the citation in Westlaw, Lexis, or the court's own docket before raising it. An unverifiable citation may be a transcription error, a very obscure opinion not yet in CourtListener's corpus, or a citation that does not correspond to a real case. How you proceed is your professional call.
- Does this check if a case is still good law?
- No. This tool confirms whether a citation resolves to a real opinion in CourtListener's database. It does not check whether that case has been overruled, limited, distinguished, or whether it stands for the proposition cited. It does not perform good-law analysis — for that you need Shepard's Citations (Lexis) or KeyCite (Westlaw). Always verify authority independently before relying on it.