Courts on AI / Fabricated or misquoted citations

United States v. Marquez

United States Court of Appeals for the Fifth Circuit · Federal courts of appeals · 2026-04-24 · No. No. 25-50866 · opinion

Fabricated or misquoted citationscourt does not name AI

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 denial of compassionate release was affirmed, and Marquez was warned that similar deceptive briefing practices may result in sanctions.
Recorded conduct: Marquez’s pro se appellate brief cited cases that do not exist and nearly every quotation from existing caselaw was misquoted or fabricated; the court also found most cited propositions inapposite or contrary to the cited cases. — 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.

Court document: govinfo.gov
Public copy first read: damiencharlotin.com
Read: 2026-09-08 · court's own copy read
Found via: charlotin-hallucinations-db
Notes: Official copy located 2026-09-08 via govinfo; quoted passage confirmed in the official document. Re-coded from the document 2026-09-08 (independent second read).

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