What is the fastest free way to check if a case citation exists?

Search the exact case name and reporter citation on CourtListener (courtlistener.com), a free, public case-law search engine covering federal courts and most state appellate courts. If it does not appear there, search PACER directly by docket number if you have one.

Can I ask the AI that generated the citation whether it's real?

No. In the Mata v. Avianca record, the attorney asked ChatGPT to confirm the citations were real, and the model insisted they were and produced fabricated excerpts to back up the claim. Verifying an AI's output by asking the same AI checks nothing.

Does Westlaw or Lexis automatically flag a fabricated citation?

Not directly — their citator tools (KeyCite, Shepard's) tell you whether a real case has been overruled or questioned, but if you search for a citation that doesn't exist, you typically just get a no-results page, which you still have to notice and act on.

How do I check if a case citation exists?

https://citationsafe.com/faq/how-to-check-if-a-case-citation-exists

Checking whether a case citation exists is a search problem, not a judgment call — the case is either findable in a primary-source database or it isn’t. The method that fails, reliably, is asking the AI tool that produced the citation to confirm it; the method that works is searching a primary source directly.

Step 1 — search a free primary-source database

CourtListener is a free, public search engine run by the nonprofit Free Law Project, covering federal district and appellate opinions plus most state appellate courts. Search the exact case name first, then the reporter citation (e.g. “925 F.3d 1339”) independently — a hallucinated citation sometimes uses a real reporter volume number attached to the wrong case, so checking the case name alone can miss it.

Step 2 — check PACER if you have a docket number

If the citation includes a docket number, PACER (pacer.uscourts.gov) is the authoritative federal court record system — it costs $0.10 per page (capped per document) but will conclusively confirm whether a docket, and the specific filing on it, actually exists.

Step 3 — check Westlaw or Lexis if you have access

If your firm subscribes to Westlaw or Lexis, searching the citation there gives you existence plus citator treatment (KeyCite or Shepard’s) in one step — useful because it also tells you if a real case has since been overruled, which is a different but related failure mode. Neither tool automatically warns you “this citation was AI-generated”; a no-results search result is the signal, and you still have to run the search and notice it.

Step 4 — verify the quote and the proposition, not just existence

A case existing is necessary but not sufficient. Once you’ve confirmed the case is real, open the actual opinion and confirm that any quoted language appears verbatim, and that the holding actually supports the proposition it’s cited for. See how to verify a legal citation manually for that full process.

The one method that reliably fails

Do not ask an AI tool — the same one or a different one — to confirm its own citation is real. The Mata v. Avianca record documents the attorney doing exactly this: asking ChatGPT whether the cases were real, and the model reassuring him they were, producing fabricated case excerpts when pressed. A confident-sounding confirmation from an AI model is not evidence a citation exists; it is the same pattern-generation process that produced the fabrication in the first place, run a second time.

Faster: run an automated check

Manually checking every citation in a 30-page brief against CourtListener is reliable but slow. Citation Safe’s free tool runs the same existence check across every citation in a document in seconds — see tools that catch AI-hallucinated citations for the full category of options.

Reverse citation check

Paste a brief. We'll flag anything fabricated.

Free: we'll show you which citations couldn't be verified. $19 unlocks the full annotated report -- no signup.

Layer 1–2 check (existence + quote match) against primary sources. Not legal advice.

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Written by the Citation Safe Research Desk · Reviewed by Andy Gaber, Founder