On October 1, 2025, Justice Cohen of the New York County Commercial Division issued a decision in Ader v. Ader, 2025 NY Slip Op. 51563(U), sanctioning a lawyer for poorly-checked use of AI in generating papers, explaining:
This case adds yet another unfortunate chapter to the story of artificial intelligence misuse in the legal profession. Here, Defendants’ counsel not only included an AI-hallucinated citation and quotations in the summary judgment brief that led to the filing of this motion for sanctions, but also included multiple new AI-hallucinated citations and quotations in Defendants’ brief opposing this motion. In other words, counsel relied upon unvetted AI—in his telling, via inadequately supervised colleagues—to defend his use of unvetted AI.
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Plaintiff . . . identified inaccurate citations and quotations in Defendants’ opposition brief that appeared to be hallucinated by an AI tool. After Plaintiff brought this issue to the Court’s attention, Defendants submitted a surreply affirmation in which their counsel, without admitting or denying the use of AI, acknowledged that several passages were inadvertently enclosed in quotation and clarified that these passages were intended as paraphrases or summarized statements of the legal principles established in the cited authorities. Plaintiff then submitted a letter in rebuttal to the Surreply Affirmation, to which the Court invited Defendants to respond. Defendants did not respond.
As set forth in detail in the Rebuttal Letter and the papers in support of the instant motion, defense counsel’s explanation of the citation and quotation errors as innocuous paraphrases of accurate legal principles does not hold water. Among other things, the purported paraphrases included bracketed terms to indicate departure from a quotation (not something one would expect to see in an intended paraphrase) and comments such as citation omitted. Moreover, the cited cases often did not stand for the propositions quoted, were completely unrelated in subject matter, and in one instance did not exist at all.
Even as to the subset of fake quotations that happened to be arguably correct statements of law, the court rejects the invitation to consider that actual authorities stand for the proposition that bogus authorities were offered to support. Use of fake citations and quotations that may generally support real statements of law is no less frivolous. Indeed, when a fake case is used to support an uncontroversial statement of law, opposing counsel and courts—which rely on the candor and veracity of counsel—in many instances would have no reason to doubt that the case exists. The proliferation of unvetted AI use thus creates the risk that a fake citation may make its way into a judicial decision, forcing courts to expend their limited time and resources to avoid such a result.
Unfortunately, the summary judgment briefing is not the end of the troubling conduct. Despite previously assuring the Court in defense counsel’s Surreply Affirmation during the summary judgment briefing that every effort will be made to avoid the recurrence of such issues and to maintain the clarity and integrity of the submissions before this Court, Defendants’ opposition to this sanctions motion contains another wave of fake citations and quotations. This time, Plaintiff has identified more than double the number of mis-cites, including four citations that do not exist, seven quotations that do not exist in the cited cases, and three that do not support the propositions for which they are offered. Separately, although not the subject of this motion, Plaintiff has also alerted the Court of still more fake citations in Defendants’ opposition to Plaintiff’s application seeking attorneys’ fees in connection with the award of summary judgment.
In response to the overwhelming evidence skillfully marshalled by Plaintiff’s counsel in the instant motion, Defendants vehemently denied the use of unvetted AI and complained that Plaintiff provides no affidavit, forensic analysis, or admission from Defendants confirming the use of generative AI thus implicitly suggesting that AI was not used in preparing Defendants’ summary judgment brief. At oral argument, the Court gave defense counsel the opportunity to set the record straight as to how exactly the many citation and quotation errors found their way into Defendants’ briefs in this action. Defendants’ counsel began with a prepared statement in which he acknowledged some citation errors, but continued initially to maintain that the cases are not fabricated at all.
Ultimately, however, upon questioning by the Court as to how a non-existent citation could possibly end up in the summary judgment briefing without the use of AI, counsel conceded that he did use AI, contending that he did verify and check the AI but must have missed the false citation, which he conceded (for the first time) was an AI hallucination. With respect to incorrect quotations from actual cases, counsel acknowledged (also for the first time), under Court questioning, that they were not his own drafted paraphrases from the decisions but were instead AI-generated fake quotations that were not properly verified.
Turning to the inclusion of AI-generated false citations and quotations in Defendants’ brief opposing the instant motion for sanctions, counsel began by indicating that he viewed the sanctions motion as a minimal matter relative to the other time-sensitive tasks on which he and his recently hired staff were working at the time. Ultimately, counsel conceded that a number of incorrect citations were AI-generated and not properly checked by lawyers he brought in to assist him. Indeed, he indicated that he identified at least one of the hallucinated citations during the drafting process and instructed his team to remove it from the brief, which they failed to do. In the end, it is undisputed that counsel signed a brief that contained the identified hallucination among several others.
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The Court may award sanctions for frivolous conduct against a party and/or an attorney in its discretion where appropriate. Moreover, Rule 3.3 of the New York Rules of Professional Conduct (“Conduct Before a Tribunal”) provides that a lawyer shall not knowingly make a false statement of fact or law to a tribunal.. Finally, 22 NYCRR § 100.3(D)(2) provides that a judge who receives information indicating a substantial likelihood that a lawyer has committed a substantial violation of the Rules of Professional Conduct (22 NYCRR Part 1200) shall take appropriate action.Use of AI is not the problem per se. The problem arises when attorneys abdicate their responsibility to ensure their factual and legal representations to the Court—even if originally sourced from AI—are accurate. The court relies on attorneys to do their jobs: advocate for their clients using law and facts—real law and real facts. When attorneys fail to check their work—whether AI-generated or not—they prejudice their clients and do a disservice to the Court and the profession. In sum, counsel’s duty of candor to the Court cannot be delegated to a software program.
By now the risks and consequences of AI-hallucinated citations should be familiar. Moreover, courts have made clear that reliance on the research of others is not a valid excuse for presenting false citations.
Here, Plaintiff seeks her attorney’s fees and costs and out-of-pocket expenses incurred by the delay in adjudicating her summary judgment motion as a sanction against Defendants for frivolous conduct. The Court finds that awarding Plaintiff her reasonable costs and attorney’s fees incurred in connection with the sanctions motion, together with such fees attributable to addressing Defendants’ unvetted AI citations and quotations in the summary judgment motion, is an appropriate monetary sanction against both Defendants and their counsel, jointly and severally.
In addition, in view of the reporting mandate of 22 NYCRR § 100.3(D)(2) and to deter such conduct going forward, the Court directs Plaintiff’s counsel to submit a copy of this decision and order to the Grievance Committee for the Appellate Division, First Department and the New Jersey Office of Attorney Ethics, copying Defendants’ counsel and this Court on its transmittal letters. The Court will provide a copy of this decision and order to Judge Katz, who is presiding over a matrimonial matter in this Court in which Defendants’ counsel is representing Jason Ader.
(Internal quotations and citations omitted).
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