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Courts on AI / Fabricated or misquoted citations

United States v. Jose Marquez

United States Court of Appeals for the Fifth Circuit · Federal courts of appeals · · No. 25-50866 Summary Calendar · opinion

Fabricated or misquoted citations

The Fifth Circuit on 2026-04-24 warned the self-represented plaintiff to verify legal authorities and cautioned that future hallucinated or nonexistent citations may bring sanctions in United States v. Jose Marquez. The self-represented plaintiff filed a brief with one fabricated case citation, one false case quotation, and one mischaracterized case citation.

Disposition
The court warned the self-represented plaintiff to verify legal authorities and cautioned that future hallucinated or nonexistent citations may bring sanctions.
Recorded conduct
The self-represented plaintiff filed a brief with one fabricated case citation, one false case quotation, and one mischaracterized case citation. — outcome: warning; actor: litigant in person
Canonical record
Incident tracker entry — verified outcome, regulator disposition and related rules

What the court wrote

Verbatim from the court's document (public domain). Ellipses mark omitted text; nothing is paraphrased.

2023). Before concluding, we note that Marquez’s deceptive briefing practices deserve special mention and admonition. After an exhaustive reviewofMarquez’sbrief,weconcludethatsomeofthecasesMarquezcites do not exist and nearly every quotation from the caselaw that he cites from existing caselaw is either misquoted or fabricated. Further, most of the legal propositions that Marquez posits are supported by our caselaw are either inappositetothecaseshecitesor,worse,contradictedbyourcaselaw. While we afford pro se plaintiffs some leeway, we will not ignore Marquez’s use of non-existentcaselawandfabricatedquotations,whichfloutstherequirement in Federal Rule of Appellate Procedure 28(a)(8)(A) that all briefs contain arguments supported by cited authority. SeeFed.

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