What was hallucinated

Fabricated: Case Law | Non-existent case citation appeared in Defendants' summary judgment opposition; court found it to be an AI hallucination and counsel later conceded AI use. || Fabricated: Case Law | Defendants' opposition to the sanctions motion contained four citations that do not exist (identified by Plaintiff and cited by the Court as AI-generated). || False Quotes: Case Law | Seven quotations in Defendants' sanctions-opposition brief do not exist in the cited cases (Plaintiff identified them; Court treated them as AI-generated false quotations). || Misrepresented: Case Law | Three quotations in Defendants' briefs were from real cases but do not support the propositions for which they were offered (misstated precedent identified by Plaintiff).

Details

"This case adds yet another unfortunate chapter to the story of artificial intelligence misuse in the legal profession. Here, Defendants' counsel not only included an AI-hallucinated citation and quotations in the summary judgment brief that led to the filing of this motion for sanctions, but also included multiple new AIhallucinated citations and quotations in Defendants' brief opposing this motion. In other words, counsel relied upon unvetted AI—in his telling, via inadequately supervised colleagues—to defend his use of unvetted AI."

Sanction teardown · SC New York, USA · 2025-10-01

Ader v Ader

What happened

In SC New York, USA, a filing relied on an unnamed/unconfirmed AI tool to help draft legal argument. The court identified the following problems with the citations in that filing:

Fabricated (Case Law)

Non-existent case citation appeared in Defendants' summary judgment opposition; court found it to be an AI hallucination and counsel later conceded AI use.
Fabricated (Case Law)

Defendants' opposition to the sanctions motion contained four citations that do not exist (identified by Plaintiff and cited by the Court as AI-generated).
False Quotes (Case Law)

Seven quotations in Defendants' sanctions-opposition brief do not exist in the cited cases (Plaintiff identified them; Court treated them as AI-generated false quotations).
Misrepresented (Case Law)

Three quotations in Defendants' briefs were from real cases but do not support the propositions for which they were offered (misstated precedent identified by Plaintiff).

Which AI tool

an unnamed/unconfirmed AI tool. Note: Charlotin's public database records tool attribution only where a court order, brief, or reporting on the matter states it explicitly; "unidentified" or "implied" means the record indicates AI use but does not name a specific product — we do not guess.

Outcome

Costs Order; Referral to Bar Authorities (monetary penalty: 1 .)

Additional detail

"This case adds yet another unfortunate chapter to the story of artificial intelligence misuse in the legal profession. Here, Defendants' counsel not only included an AI-hallucinated citation and quotations in the summary judgment brief that led to the filing of this motion for sanctions, but also included multiple new AIhallucinated citations and quotations in Defendants' brief opposing this motion. In other words, counsel relied upon unvetted AI—in his telling, via inadequately supervised colleagues—to defend his use of unvetted AI."

How Citation Safe would have caught this

Citation Safe runs three deterministic layers before a brief is filed: (1) does the citation exist against CourtListener's database of published opinions, (2) if quoted, does that exact language appear in the source, (3) does the cited case actually support the proposition it is cited for. Fabricated case citations fail Layer 1. Fabricated or misattributed quotations fail Layer 2 even when the underlying case is real. Misrepresented holdings — a real case cited for a proposition it does not support — are the target of Layer 3. None of these checks involve asking another language model whether the citation looks right; they are lookups and text-matches against the actual source, which is why a hallucinated citation has to survive a direct lookup against the authoritative source — not another model's opinion — to earn a VERIFIED stamp; our measured false-verify rate is published live at /quality.

Check a brief before you file it → · See our live false-verify rate

Source: https://www.damiencharlotin.com/documents/849/Ader_v_Ader__2025_N.Y._Misc._LEXIS_7848.PDF, via Damien Charlotin's public AI Hallucination Cases Database (CC0).