Italy's Supreme Court fines an appellant €5,000 for AI-hallucinated case citations

The problem

A defence lawyer’s appeal to Italy’s Supreme Court of Cassation — a criminal-execution matter seeking revocation of a demolition order — supported its argument with three Court of Cassation precedents (source). On verification none of the three said what the appeal attributed to them: the Court found the cited rulings and their principles “inesistenti e non riferibili alle richiamate sentenze” and concluded they “appaiono il frutto di un evidente fenomeno di allucinazione informatica”, “probabilmente dovuta all’impiego di sistemi di intelligenza artificiale” (source). No specific AI product was named or adjudicated (source).

What was built

Not a build. This is a court-origin precedent on AI accountability in litigation. The Terza Sezione Penale decided the case on 11 June 2026 and filed judgment no. 23006/2026 on 22 June 2026 (source).

The outcome

The Court declared the appeal inadmissible and, under art. 616 cod. proc. pen., ordered the appellant to pay a sum “determinata in via equitativa, di euro 5.000,00 in favore della Cassa delle Ammende” — an amount set above the ordinary measure (source). Its reasoning: citing non-existent case law generated by artificial intelligence “non attenua, ma anzi accentua il giudizio di colpevolezza processuale” (source).

Using an AI tool does not create a liability-free zone: the professional who signs the brief keeps full responsibility to verify the truth, relevance and specificity of the sources, and failure to do so is qualified negligence exceeding the threshold of excusable error (source). The €5,000 falls on the appellant/party under art. 616, not as a Bar disciplinary sanction (source).

How this was verified

Method: primary signed judgment PDF (byte-tied to Wayback capture 20260725103717) read against five independent Italian outlets published after deposit, each independently stating the €5,000 art. 616 order and the “allucinazione informatica” finding. No source is the subject of the story and no figure is rounded or inferred; the €5,000 and the count of three non-existent precedents are quoted from the judgment text. Where reporting differs on framing (party sanction vs. professional discipline), the judgment controls: art. 616 falls on the appellant. Method date: 2026-08-14.

Related case files

• Mazaheri v Law Society of Ontario — Canadian tribunal, costs award for AI-fabricated citations.
• Murray (Wamba Wemba) v Victoria — Federal Court of Australia, indemnity costs on the same fact pattern.
• Kruse v Karlen — US appellate sanction where 22 of 24 citations were fictitious.

Sources

1. Il Fatto Quotidiano — “Intelligenza artificiale nelle sentenze: Cassazione e Csm contro le allucinazioni”, 26 June 2026 — https://www.ilfattoquotidiano.it/2026/06/26/intelligenza-artificiale-sentenze-cassazione-csm-notizie/8430206/ — Tier 1 (national newspaper of record, independent)
2. Agenda Digitale — “Cosa rischia l’avvocato che fa abuso di AI: la Cassazione chiarisce” — https://www.agendadigitale.eu/documenti/cosa-rischia-lavvocato-che-fa-abuso-di-ai-la-cassazione-chiarisce/ — Tier 2 (specialist legal-tech analysis, independent)
3. lentepubblica — “IA sotto accusa: Cassazione punisce avvocati che citano sentenze inventate” — https://lentepubblica.it/cittadini-e-imprese/ia-sotto-accusa-cassazione-punisce-avvocati-che-citano-sentenze-inventate/ — Tier 2 (independent trade press)
4. La Discussione — “Cassazione, stop alle ‘allucinazioni’ dell’IA” — https://ladiscussione.com/448678/societa/cassazione-stop-alle-allucinazioni-dellia-lavvocato-resta-responsabile-degli-atti-e-delle-sentenze-inventate/ — Tier 2 (independent national outlet)
5. misterlex — “Ricorso con sentenze inventate dall’AI: avvocato responsabile”, 26 June 2026 — https://www.misterlex.it/doc/ricorso-sentenze-inventate-ai-avvocato-responsabile/ — Tier 3 (legal database summary, quotes judgment text)
6. Avvera — “Usare l’AI senza verificarne le citazioni è colpa qualificata” — https://www.avvera.it/usare-ai-senza-verificarne-le-citazioni-e-colpa-qualificata/ — Tier 3 (practitioner analysis, corroborating)