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Buchanan v. Vuori, Inc.

Court
N.D. California
Jurisdiction
USA
Decided
2025-11-20
AI tool
ChatGPT-4, OpenAI, Claude, Clear Brief, Lexis Nexis & Westlaw
Outcome
Monetary Sanction; Referral to the Bar; Motions stricken without leave to refile
Monetary penalty
None reported

What was hallucinated

Fabricated: Case Law | The motion relies on a cited case that does not exist; Court's research found 2021 WL 4453429 is not a judicial opinion and no Reed v. ZipRecruiter opinion was located. || False Quotes: Case Law | Eight instances where the motion quotes language attributed to real cases but the quoted language does not appear in those cases (court identified specific ECF locations).

Details

Order to Show Cause is here.

Sanction teardown · N.D. California, USA · 2025-11-20

Buchanan v. Vuori, Inc.

What happened

In N.D. California, USA, a filing relied on ChatGPT-4, OpenAI, Claude, Clear Brief, Lexis Nexis & Westlaw to help draft legal argument. The court identified the following problems with the citations in that filing:

  • Fabricated (Case Law)
    The motion relies on a cited case that does not exist; Court's research found 2021 WL 4453429 is not a judicial opinion and no Reed v. ZipRecruiter opinion was located.
  • False Quotes (Case Law)
    Eight instances where the motion quotes language attributed to real cases but the quoted language does not appear in those cases (court identified specific ECF locations).

Which AI tool

ChatGPT-4, OpenAI, Claude, Clear Brief, Lexis Nexis & Westlaw. 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

Monetary Sanction; Referral to the Bar; Motions stricken without leave to refile

Additional detail

Order to Show Cause is here.

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/1075/Buchanan_v._Vuori_USA_20_November_2025.pdf, via Damien Charlotin's public AI Hallucination Cases Database (CC0).

Source: https://www.damiencharlotin.com/documents/1075/Buchanan_v._Vuori_USA_20_November_2025.pdf

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