What was hallucinated

False Quotes: Case Law | Plaintiff attributed quotations to cited cases that, per Take-Two and the Court, do not contain those quotes; plaintiff later withdrew or clarified he was not quoting directly, and replacement citations did not support his argument. || Fabricated: Case Law | Plaintiff cited cases that, per Take-Two, could not be located; the Court noted the withdrawal and cautioned that use of fictitious cases may warrant Rule 11 sanctions.

Details

Court held that: "The use of fictitious quotes or cases in filings may subject a party, including a pro se party, to sanctions pursuant to Federal Rule of Civil Procedure 11 as “pro se litigants are subject to Rule 11 just as attorneys are.”

Sanction teardown · D. Colorado, USA · 2025-05-06

Harris v. Take-Two Interactive Software

What happened

In D. Colorado, 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:

False Quotes (Case Law)

Plaintiff attributed quotations to cited cases that, per Take-Two and the Court, do not contain those quotes; plaintiff later withdrew or clarified he was not quoting directly, and replacement citations did not support his argument.
Fabricated (Case Law)

Plaintiff cited cases that, per Take-Two, could not be located; the Court noted the withdrawal and cautioned that use of fictitious cases may warrant Rule 11 sanctions.

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

Warning

Additional detail

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/344/Harris_v._Take-Two_Interactive_Software_Inc._Colorado_USA_May_6_2025.pdf, via Damien Charlotin's public AI Hallucination Cases Database (CC0).

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