AI Hallucination Cases

Sullivan & Cromwell acknowledged that its April 9, 2026 Motion contained AI-generated inaccuracies including fabricated and misquoted case citations. The firm apologized, identified and corrected the errors in Schedule A, undertook remedial measures, and filed corrected papers. The issue was brought to the firm's attention by opposing counsel (Boies Schiller Flexner).

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Order to show cause is here. Final judgment on costs is here. Final Opinion and Order is here. (Defendants prevailed partly because brief full of hallucinated material had been struck.)

"{¶133} This case illustrates the peril. An attorney who, by his own counsel’s admission, was sophisticated in his understanding of AI tools permitted a non-attorney staff member to use a public generative AI platform to prepare an appellate filing. The AI tool fabricated transcript quotations—attributing specific, inflammatory statements to a real prosecutor that were never spoken. The attorney filed the document without verifying its contents. When the fabrications were identified, he did not correct the record. He appealed this court’s denial of the tainted application to the Supreme Court of Ohio without disclosing the fabrications. He proffered an AI policy that itself appeared to have been generated by AI, complete with unfilled placeholder brackets. Two months after a sanctions hearing, a filing in another court bore the unmistakable hallmarks of unchecked AI output, including a ChatGPT prompt embedded in the text of a legal brief.

{¶134} This court does not write to condemn the use of artificial intelligence in the practice of law. To the contrary, this court recognizes that AI is an inevitable and potentially beneficial feature of modern legal practice. But the use of AI does not relieve an attorney of any of the obligations imposed by the Rules of Professional Conduct, by the rules of court, or by the oath of admission to the bar. An attorney who files a document containing AI-generated content is responsible for that content, fully and without qualification. The duty to verify, the duty of candor, the duty of competence, and the duty of supervision cannot be delegated to a machine.

{¶135} The sanctions imposed herein are proportionate, individually justified, and collectively designed to serve the purposes for which the court’s sanctioning authority exists: to compensate for harm, to deter future misconduct, to protect the integrity of the judicial process, to preserve public confidence in the administration of justice, and to ensure that the practice of law remains a profession grounded in truth, accuracy, and candor. "

Petitioner’s opening brief contained at least 15 fabricated case citations and at least nine purported quotations that do not exist in Oregon case law; counsel acknowledged reliance on unverified search-engine results and some use of AI for an outline. Court capped sanctions at $10,000, required a replacement brief limited to accurately described authorities, and required certification that no generative AI was used to draft the brief and that cited authorities were verified.