Cassata v. Michael Macrina Architect, P.C.
Supreme Court of New York, Suffolk County · Sup. Ct., Suffolk County, N.Y. · New York bar guidance
Conduct
Counsel filed opposition brief citing nonexistent cases, fabricated quotations, and propositions of law not supported by cited authority.
Consequence
$1,000 + $1,000 fines (associate + supervising); $8,000 attorneys' fees to opposing counsel; opposition brief stricken.
Lesson
N.Y. Sup. Ct. Kevins announces three-factor verification framework adapted from Mattox: inquiry, candor, accountability. Supervising attorney sanctioned alongside drafter.
Verified May 8, 2026
- Citation
- Cassata v. Michael Macrina Architect, P.C., No. 617183/2025, 2026 N.Y. Slip Op. 26014, 2026 WL 263521 (Sup. Ct. Suffolk County Jan. 27, 2026)
- Decided
- January 27, 2026
Summary
Defense counsel Maria-Eleni Kiousenterlis of Milber Makris Plousadis & Seiden, LLP (MMPS) filed an opposition brief that contained two nonexistent cases (Harris v Seward Park Housing Corp. and DiLorenzo v D.C. & D. Transp. Corp.), a fabricated quotation, and two real cases (New York Univ. v Cont'l Ins. Co. and Becker v Elm Air Conditioning Corp.) cited for propositions they do not support, with substantial portions plagiarized from an unrelated brief that itself had been condemned for nonexistent citations. Justice Linda Kevins, after a sua sponte show cause order and December 22, 2025 hearing, found Kiousenterlis denied using AI but conceded she copied from a Westlaw brief without verification, while supervising attorney Thomas M. Fleming II admitted the firm had recently acquired AI-enhanced Westlaw and that he did not "really know how to use any AI stuff." The court found violations of NY Rules of Professional Conduct 1.1, 1.3, 3.1, 3.3, and 5.1, and 22 NYCRR 130-1.1.
- AI tool:
- Unspecified generative AI
- Sanction amount:
- $10,000
What sanction did the court impose?
$1,000 fine against Kiousenterlis and $1,000 fine against Fleming, both payable to the Lawyer's Fund for Client Protection; $8,000 in attorneys' fees, costs, and expenses against MMPS payable to plaintiff's counsel; defendant's opposition brief stricken. The court declined to refer counsel to the Grievance Committee but strongly recommended CLE training on generative AI.
Why does Cassata v. Michael Macrina Architect, P.C. matter for law firms using AI?
Cassata is notable as a state trial court decision that catalogues, in a 12-page chart appended to the order, the emerging body of state and federal sanctions case law on AI hallucinations and plagiarized briefs. Justice Kevins (a co-founder of the Suffolk County Bar Association AI Committee) treats the offense as sanctionable whether or not the attorney personally invoked AI: copy-pasting from another brief without verifying citations is itself a Rule 1.1 competence failure, and a supervising attorney who concedes he cannot operate his firm’s AI-enhanced research tool cannot adequately supervise an associate using it. For managing partners, the case is a clean example of joint exposure across the associate, the supervising partner, and the firm entity.
The opinion adopts a three-factor framework (drawn from Mattox v. Product Innovations Research, the federal counterpart) for evaluating AI-citation conduct: (1) verification and inquiry, (2) candor and correction, and (3) accountability and supervision. The supervisory-liability prong is doctrinally distinctive: Justice Kevins fined both the associate who drafted the brief and the supervising attorney who signed it, grounding the supervisor’s sanction in N.Y. RPC 5.1 (responsibilities of partners, managers, and supervisory lawyers). The decision treats AI-citation conduct as a supervisory failure, not just a drafter failure, expanding the supervisory-liability exposure for senior attorneys in firms whose junior staff may use AI-assisted research without independent verification.
The opinion’s published status (NY Slip Op 26014, rather than unpublished trial-court order) and its grounding in widely-applicable rules (RPC 1.1, 1.3, 3.1, 3.3, 5.1, plus 22 NYCRR § 130-1.1) make it citable in any New York trial court considering similar conduct.
Quotable lines
“Whether Kiousenterlis used AI to conduct her research or not, citing non-existent cases, quotations, and specific propositions of law for which they do not stand and/or do not support, is unethical and sanctionable conduct.”
“Citing nonexistent case law or misrepresenting the holdings of a case is making a false statement to a court. It does not matter if [generative AI] told you so.” (quoting United States v. Hayes, 763 F. Supp. 3d 1054, 1067)
“A reasonable inquiry requires more than reliance on an automated tool; it demands independent confirmation through recognized primary legal sources.”
Implications for your firm
Operational steps a firm reading this case may wish to consider documenting. Strategic and rule-application calls belong to your firm's attorneys.
- Supervising attorneys are co-sanctionable for AI-fabricated citations filed by associates under the Kevins framework. Firms with N.Y. Sup. Ct. matters in Suffolk County should ensure supervisory review processes for any associate-drafted brief that may include AI-assisted research.
- Cassata is the first New York trial-court decision to formally adopt the Mattox three-factor framework (inquiry, candor, accountability). Cite Cassata for the proposition that supervising-attorney liability under N.Y. RPC 5.1 attaches to AI-citation conduct, not just substantive supervision failures.
- The decision was published in NY Slip Op (rather than unpublished trial-court order), giving it persuasive weight beyond Suffolk County. New York firms should expect other trial courts to cite Cassata when sanctioning AI-citation conduct.
Sources
Primary sources
Further reading
Source PDF is a Westlaw printout mirrored from the Damien Charlotin hallucination database. We are working to add the underlying court docket (PACER, CourtListener, or court website) as a second source.