At A Glance
Summary: New York AI hallucination sanctions now extend to appellate practice, as the Third Department imposed sanctions for AI-generated fake case citations submitted in appellate briefs.
The New York Appellate Division, Third Department imposed sanctions after counsel submitted appellate briefs containing fabricated, AI-generated case citations, holding that such conduct is frivolous and sanctionable. Because this appears to be the first New York Appellate Division decision addressing AI-generated fake case citations, the Third Department’s holding constitutes binding authority for trial courts statewide unless and until another department or the Court of Appeals rules otherwise.
Court: New York Appellate Division, Third Department
Decision Date: January 8, 2026
Case: Deutsche Bank Natl. Trust Co. v LeTennier, 2026 NY Slip Op 00040 (3rd Dept 2026)
Topic: Sanctions for frivolous conduct based on artificial intelligence hallucinations.
Related Post: AI Hallucinated Case Citation Sanctions in New York Litigation
The Court’s Position
Submitting fabricated legal authorities, including AI-generated “hallucinated” cases, constitutes frivolous conduct under 22 NYCRR 130-1.1 because it presents false legal authority to the court. Attorneys remain fully responsible for verifying all citations, and reliance on generative AI does not excuse failures in cite-checking, quote verification, or factual accuracy.
From A Claims Perspective
AI-generated errors in legal briefing now carry direct litigation risk.
Claims adjusters should evaluate defense counsel’s briefing accuracy and consider early challenges where opposing submissions rely on unsupported or fabricated authority.
Questions This Case Answers
- Can AI-generated fake case citations in a court document lead to sanctions in New York?
- What are the sanctions for AI-generated fake case citations in New York courts?
- Does using artificial intelligence excuse inaccurate legal citations?
- What qualifies as frivolous conduct under 22 NYCRR 130-1.1?
- How do courts treat repeated litigation misconduct combined with artificial intelligence misuse?
- Are courts enforcing AI-related professional responsibility rules?
What Happened
The defendant repeatedly challenged standing despite prior appellate rejection. The defendant’s attorney filed multiple motions deemed frivolous by the trial court.
On appeal, the defendant’s attorney cited numerous nonexistent cases. Opposing counsel flagged the citations as fictitious. The defendant’s attorney admitted using generative AI but failed to verify the cited information. Across filings, the Court identified at least 23 fabricated cases and multiple misstatements of real law.
The Decision
The Court affirmed all trial orders, including prior sanctions. It held that fabricated case citations are frivolous as defined in 22 NYCRR 130-1.1 .
The Court found misconduct aggravated because (1) the fake citations continued after notice, (2) counsel failed to correct the errors, and (3) additional filings repeated the issue.
The Third Department imposed a $7,500 sanction against the defendant’s attorney and a $2,500 sanction againt the defendant. It treated AI hallucinations as a credibility and ethics violation issue, not a technology issue, emphasizing that false citations are equivalent to misrepresentations to the tribunal.
Why This Matters
The Third Department’s holding shows that courts are now actively policing AI misuse. A counsel’s reliance on AI-hallucinated cases and quotations can undermine an otherwise defensible claims.
Sanctions based on such frivolous conduct increase litigation costs and exposure
The Third Department’s sanctions, and sanctions in unrelated AI-misuse cases in other jurisdictions show that repeated procedural abuse and AI misuse escalate penalties quickly.
What to Know
Artificial intelligence use is permitted to research and write motions and briefs to the court, but unverified output is not. Fake citations are sanctionable, even if the legal argument is correct.
Attorneys are responsible for every citation submitted in a filing to a court. Continued AI misuse after court notice can significantly increase penalties.
Most importantly, LeTennier provides the first New York Appellate Division guidance addressing sanctions for AI-generated hallucinated case citations and will likely be cited by trial courts confronting similar misconduct.
Practice Pointers
- Treat artificial intelligence output as unverified draft material only
- Implement mandatory cite-check protocols before filing court documents
- Independently confirm every case, quote, and proposition
- Immediately correct errors once identified by opposing counsel or the court
- Do not rely on “substantial accuracy” arguments; courts require accuracy
- Train partners, associates, clerks, paralegals, and administrative assistants on AI hallucination risks and attorneys’ ethical obligations
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Authority
The Court relied on 22 NYCRR 130-1.1, holding that fabricated legal citations constitute frivolous conduct because they assert false legal authority and cannot form a reasonable legal argument.
Sources
- 22 NYCRR 130-1.1
- Rules of Professional Conduct (22 NYCRR 1200.0), Rule 3.3 [a] [1]
- Ader v Ader, 87 Misc 3d 1213 (A) (Sup Ct, NY County 2025)
Related Topics
Artificial Intelligence Risk, Sanctions, Appellate Practice, Attorneys’ Ethical Obligations in New York
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