Incident Tracker / United States (state)
Cassata v. Michael Macrina Architect, P.C., 2026 NY Slip Op 26014
·New York Supreme Court, Suffolk County·US-STATESanctions
A New York trial court fined an associate and her supervising partner $1,000 each (to the Lawyers' Fund for Client Protection) and ordered the firm to pay $8,000 in fees after an opposition brief plagiarized from an AI-generated filing containing nonexistent cases and quotations. The court struck the opposition but declined to refer counsel to bar discipline.
- Court
- New York Supreme Court, Suffolk County
- Date
- 2026-01-27
- Who used the AI
- Not recorded
- AI tool
- generative AI (AI-enhanced Westlaw)
- Conduct
- Defense counsel filed an opposition containing nonexistent cases, fake quotations, and unsupported propositions largely plagiarized from another firm's AI-generated brief; the supervising partner and firm failed to supervise. Counsel denied using AI and the court disbelieved her.
- Outcome
- Sanctions
- Penalty
- US$10,000
- Regulatory outcome
- No separate regulatory disposition recorded
- Status
- Verified against listed sources
- Last checked
- 2026-09-04
What was fabricated or misused
- Harris v Seward Park Housing Corp., 147 AD3d 589 (1st Dep't 2017) — non-existent case cited in the opposition
- DiLorenzo v D.C. & D. Transp. Corp., 39 AD2d 950 (2nd Dept, 1972) — non-existent case cited in the opposition
- Quotation attributed to Harris v Seward Park Housing Corp., 147 AD3d 589 (1st Dep't 2017) — did not exist except in the opposition and the copied brief
- New York Univ. v Cont'l Ins. Co., 87 NY2d 308, 323 (1995) — cited for a proposition the case did not support
- Becker v Elm Air Conditioning Corp., 143 AD2d 965, 966 (2nd Dep't 1988) — cited for a proposition the case did not support
- Portions of a third-party brief in For a Financial Asset Securitization 2021, LLC v Teona, 2025 WL 334218 (2025) — copied without citation or verification
What the court said
“Six specific allegations regarding Kiousenterlis' alleged frivolous conduct are detailed in plaintiff's Reply Memorandum of Law (NYSCEF 30), Affirmation in Further Support (NYSCEF 25) and by plaintiff at the hearing.”
“During the hearing, both Kiousenterlis and Fleming appeared sincerely sorry and conceded to the truth of the above six allegations.”
“In any case, 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.”
“Accordingly, this Court rejects the defendant's request for a "redo."”
Timeline
- Plaintiffs moved to strike the defendant's affirmative defenses.
- Defendant filed the opposition later found to contain non-existent authorities and copied material.
- Plaintiffs' reply accused defense counsel of copying an AI-generated brief with non-existent cases.
- The court issued a show-cause order on sanctions.
- The court held the sanctions hearing.
- The court struck the opposition and imposed $10,000 in fines and fees.
Why this case matters
Cassata adds a New York trial-court example in which the sanctioned filing was not just a direct chatbot product. The associate said she copied a Westlaw brief from another case, while the court found AI use more likely and sanctioned the copied brief's false cases and unsupported propositions. Unlike Mata v Avianca, the order treated recycled, unverified work product as its own source of harm. It also reached the supervising partner and the firm, while stopping short of a bar referral.
Practice note
Reusing a brief is not a substitute for legal research. Before filing, counsel must read every cited case, confirm each quotation, and test each proposition against the cited authority. A supervising lawyer who signs or reviews an AI-enabled research product also needs to know how the tool works. When an opponent identifies fake cases, the response should identify the source, correct the record, and withdraw the tainted material rather than seek a simple redo.
Primary sources for this incident
Related regulation records for this incident
No related regulation record has been linked to this incident yet.
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Cite this record
SafeLegalAI Global Legal AI Incident Tracker, “Cassata v. Michael Macrina Architect, P.C., 2026 NY Slip Op 26014”, safelegalai.com/tracker/cassata-v-macrina (accessed 2026-09-16). Data: CC BY 4.0.