What was hallucinated

Fabricated: Case Law | Approximately 24 unattributable or outright fabricated quotations in the opening brief that could not be traced to the cited opinions. || Misrepresented: Case Law | At least seven cases in the brief were mislabeled as Seventh Circuit precedent when they were opinions from other circuits or otherwise unrelated. || Misrepresented: Exhibits & Submissions | False factual assertions about the record — e.g., claiming 'credited testimony' that petitioner’s U.S. citizen children were 'deeply integrated into local schools' though all children are over 25 and out of school.

Sanction teardown · 7th Cir. CA, USA · 2026-06-01

Heriberto Perez-Castillo v. Todd W. Blanche

What happened

In 7th Cir. CA, USA, a filing relied on ChatGPT to help draft legal argument. The court identified the following problems with the citations in that filing:

Fabricated (Case Law)

Approximately 24 unattributable or outright fabricated quotations in the opening brief that could not be traced to the cited opinions.
Misrepresented (Case Law)

At least seven cases in the brief were mislabeled as Seventh Circuit precedent when they were opinions from other circuits or otherwise unrelated.
Misrepresented (Exhibits & Submissions)

False factual assertions about the record — e.g., claiming 'credited testimony' that petitioner’s U.S. citizen children were 'deeply integrated into local schools' though all children are over 25 and out of school.

Which AI tool

ChatGPT. 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; Admonishment; Bar Referral (monetary penalty: 4997 USD.)

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/2246/Perez-Castillo_v._Blanche_USA_1_June_2026.pdf, via Damien Charlotin's public AI Hallucination Cases Database (CC0).

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