New York's first appellate AI-sanction: a lawyer who conceded using AI, 23 fabricated cases, and $10,000 in penalties (Deutsche Bank Natl. Trust Co. v LeTennier)

The problem

Deutsche Bank commenced a mortgage-foreclosure action in Delaware County in 2018 after Jean LeTennier defaulted on a 2006 note (source). After summary judgment, judgment of foreclosure and sale, and a string of denied motions, LeTennier, represented by counsel Joshua A. Douglass but also filing pro se, appealed to the Appellate Division, Third Department (source). As the court put it, “the merits of this appeal are unremarkable in nature.” Where the appeal “becomes unconventional, however, is that defendant’s opening brief cites six cases which do not exist” (source). The plaintiff “identified these fabricated cases as possibly being the product of artificial intelligence (hereinafter AI), and moved for […] sanctions” (source).

What was built

Rather than correct the record, the briefs got worse: the appellant “opposed the motion for sanctions with more fake cases,” and “In total, defendant’s five filings during this appeal include no less than 23 fabricated cases, as well as many other blatant misrepresentations of fact or law from actual cases” (source). At argument, the AI use was conceded outright: “Defense counsel reluctantly conceded during oral argument that he used AI in the preparation of his papers and, although he told the Court that he checked his papers, the filings themselves demonstrate otherwise” (source). The court noted counsel “estimated that 90% of the citations he used were accurate, which, even if it were true, is simply unacceptable by any measure of candor to any court.” The order names no specific AI product. The panel took the occasion to state the governing rule: “the use of GenAI in no way abrogates an attorney’s or litigant’s obligation to fact check and cite check every document filed with a court” (source).

The outcome

“[R]ecognizing this as the first appellate-level case in New York addressing sanctions for the misuse of GenAI,” the court imposed “a monetary sanction on defense counsel Joshua A. Douglass in the amount of $5,000” for the fabricated authorities, and, finding the appeal itself frivolous, “an additional sanction of $2,500 […] on defense counsel Joshua A. Douglass and $2,500 […] on defendant Jean LeTennier for pursing this appeal” (source). The decretal order consolidates this as “sanctions in the amount of $7,500 […] against defendant’s counsel Joshua A. Douglass and $2,500 […] against defendant Jean LeTennier pursuant to 22 NYCRR 130-1.1, in each case to be paid within 60 days”, $10,000 in total, with counsel’s share deposited “with the Lawyers’ Fund for Client Protection” (source). Contemporaneous independent write-ups reported the same breakdown and the same first-in-New-York framing (source), (source).

How this was verified

Method: independent audit of the public record only. No party to this matter was contacted, and nothing here rests on a subject’s self-report. Every figure was read off the Third Department’s own decision (2026 NY Slip Op 00040, CV-23-0713) as published by the New York State Law Reporting Bureau and mirrored on Justia, then re-checked against the decision PDF and against four independent secondary reports that carry the figures firsthand. The sanction split ($7,500 counsel / $2,500 litigant), the count of 23 fabricated cases across five filings, and the court’s own “first appellate-level case in New York” characterisation each appear in at least two independent sources. Verification date: 2026-08-14.

Related case files

• Noland v. Land of the Free, California’s first published appellate opinion sanctioning AI-fabricated citations, $10,000
• Barber v. Morawa, Michigan’s first published AI-fabricated-citation sanction, with a grievance referral
• Landberg v. City of New York, a $10,500 sanction in the Second Department
• Prososki v. Regan, Nebraska Supreme Court strikes the brief, dismisses the appeal, refers for discipline

Sources

1. Tier 1 (primary, court decision). New York Appellate Division, Third Department, Deutsche Bank Natl. Trust Co. v LeTennier, 2026 NY Slip Op 00040 (CV-23-0713), decided 2026-01-08. https://law.justia.com/cases/new-york/appellate-division-third-department/2026/cv-23-0713.html
2. Tier 1 (primary, decision PDF). Full text of the Third Department decision as filed. https://www.hinshawlaw.com/a/web/ahfgLP8L332QWQ2S5bPaWW/bfy5KF/deutsche-bank-national-trust-company-v-letennier-decision-pdf.pdf
3. Tier 2 (independent legal analysis). CaseMine, “New York Appellate Sanctions for AI-Hallucinated Citations: A Nondelegable Duty to Verify Legal Authorities,” 2026. https://www.casemine.com/commentary/us/new-york-appellate-sanctions-for-ai-hallucinated-citations:-a-nondelegable-duty-to-verify-legal-authorities/view
4. Tier 2 (independent firm report). Farber Hopkins NY Law, “Appellate Division, Third Department, Issues Monetary Sanctions against Attorney for Misuse of GenAI in the ‘First Appellate Level Case In New York’ To Do So,” 2026. https://www.fhnylaw.com/appellate-division-third-department-issues-monetary-sanctions-against-attorney-for-misuse-of-genai
5. Tier 2 (independent firm report). Law Offices of John C. Lane, “New York Appellate Court Fines Attorney for Use of AI-Generated ‘Fake’ Cases,” 2026-02-19. https://thelanelawfirm.com/2026/02/19/new-york-appellate-court-fines-attorney-for-use-of-ai-generated-fake-cases/
6. Tier 2 (independent legal press). New York Civil Law, “AI Hallucinations in New York Courts: Sanctions Trend,” 2026-06-13. https://nycivillaw.blog/2026/06/13/ai-hallucinations-in-new-york-courts-sanctions-trend/