AI Hallucination Cases

AI Use

Lawyer admitted at a hearing that he used a generative AI tool to draft Defendants’ opposition to a motion in limine, without performing a manual cite-check. This only came to light after repeated questioning by the court.

Hallucination Details

The Opposition included nearly thirty major defects:

• Nonexistent cases (e.g., fabricated citations like Perkins v. Fed. Fruit & Produce Co., 945 F.3d 1242)
• Real cases misattributed to incorrect jurisdictions (e.g., Eastern District of Kentucky decisions wrongly cited as District of Colorado cases)
• Paraphrased material falsely quoted as direct text
• Fabricated or materially inaccurate statements of law allegedly drawn from cited authorities

Ruling/Sanction

The court issued a show cause order requiring defendants’ counsel to explain why sanctions and disciplinary referrals should not be imposed. The court is considering monetary sanctions, personal discipline for the counsel involved, and mandated disclosure of misconduct to defendant Michael Lindell.

Key Judicial Reasoning

The judge stressed that generative AI is no substitute for professional competence. Rule 11 requires a reasonable inquiry, and lawyers remain personally responsible for the contents of their filings. The court treated Kachouroff’s admissions and excuses with marked skepticism, indicating that misconduct was not merely negligent but bordered on reckless or deliberate disregard for ethical duties.

AI Use

Counsel filed opposition briefs citing two nonexistent cases. The court suspected generative AI use based on "hallucination" patterns but Counsel neither admitted nor explained the citations satisfactorily. Failure to comply with a standing AI order aggravated sanctions.

Hallucination Details

Two fake cases cited. Citation numbers and Westlaw references pointed to irrelevant or unrelated cases. No affidavit or real case documents were produced when ordered.

Ruling/Sanction

Counsel's appearance was struck with prejudice. The Court ordered notification to the State Bar of Pennsylvania and the Eastern District Bar. Consel was required to inform his client, Bevins, of the sanctions and the need for new counsel if re-filing.

Key Judicial Reasoning

The judge emphasized that citing nonexistent cases—even inadvertently—is a violation of Rule 11(b)(2), constituting at least negligence. Compliance with the Court’s AI Standing Order was mandatory. Self-certification obligations under Federal and Local Rules remain fully in force despite technological assistance.

AI Use

The respondent retailer's defense cited Italian Supreme Court judgments that did not exist, claiming support for their arguments regarding lack of subjective bad faith. During subsequent hearings, it was admitted that these fake citations were generated by ChatGPT during internal research by an assistant, and the lead lawyer had failed to independently verify them.

Hallucination Details

Cited fabricated cassation rulings allegedly supporting subjective good faith defenses. No such rulings could be found in official databases; court confirmed their nonexistence. Hallucinated decisions related to counterfeit goods sales defenses

Ruling/Sanction

The court declined to impose a financial sanction under Article 96 Italian Code of Civil Procedure but issued a formal rebuke. It refused the defending party's requests for costs and treated the fabricated citations as weakening the credibility of the defense. Court emphasized that using unverifiable AI outputs to support legal arguments is a procedural violation undermining the adversarial system.

Key Judicial Reasoning

The Tribunal held that reliance on hallucinated case law undermines judicial process integrity and cannot be excused by ignorance or delegation to assistants. While no malice was found, gross negligence in verifying legal claims was established. Judicial reliance on trustworthy authorities is non-negotiable. The court noted that AI hallucinations are an increasingly recognized threat, drawing implicit parallel to international cases like Mata v. Avianca.

AI Use

Justice Nolan suspected that Reddan's submissions, especially references to "subornation to perjury" and Constitutional Article 40 rights, were AI-generated, exhibiting typical hallucination patterns (pseudo-legal concepts, inappropriate cut-and-paste fragments). Reddan did not admit using AI but relied on internet-sourced legal arguments that closely resembled LLM-style outputs.

Hallucination Details

Inappropriate invocation of "subornation to perjury," a term foreign to Irish law. Constitutional and criminal law citations (Article 40, Non-Fatal Offences Against the Person Act) irrelevant to judicial review context. Assertions framed in hyperbolic, sensationalist terms without factual or legal basis. General incoherence of pleadings, consistent with AI-generated pseudo-legal text

Ruling/Sanction

The High Court refused leave to apply for judicial review on all nine grounds. While no formal financial sanction was imposed, Justice Nolan issued a sharp rebuke, highlighting the improper use of AI and warning against making scurrilous, unverified allegations in legal pleadings. The Court stressed that misuse of AI-generated material could itself amount to an abuse of the judicial process.

Key Judicial Reasoning

The Court held that AI tools do not excuse litigants from ensuring precision, coherence, and factual basis in pleadings. It emphasized that judicial review demands rigorous pleading standards, and the insertion of AI-fabricated concepts or incoherent arguments amounts to a violation of procedural rules. The ruling underlined the broader systemic risks posed by AI misuse in legal filings.

AI Use

Counsel admitted using ChatGPT to draft two motions (Motion to Withdraw and Motion for Leave to Appeal), without verifying the cases or researching the AI tool’s reliability.

Hallucination Details

2 Fake cases:

• McNally v. Eyeglass World, LLC, 897 F. Supp. 2d 1067 (D. Nev. 2012) — nonexistent
• Behm v. Lockheed Martin Corp., 460 F.3d 860 (7th Cir. 2006) — nonexistent

Misused cases:

• Degen v. United States, cited for irrelevant proposition
• Dow Chemical Canada Inc. v. HRD Corp., cited despite later vacatur
• Eavenson, Auchmuty Greenwald v. Holtzman, cited despite being overruled by Third Circuit precedent

Ruling/Sanction

The Court sanctioned Counsel $2,500 payable to the court and ordered him to complete at least one hour of CLE on AI and legal ethics. The opinion emphasized that deterrence applied both specifically to Counsel and generally to the profession.

Key Judicial Reasoning

Rule 11(b)(2) mandates reasonable inquiry into all legal contentions. No AI tool displaces the attorney’s personal duty. Ignorance of AI’s unreliability is not a defense. The Court cited Mata v. Avianca and Gauthier v. Goodyear to emphasize that sanctions for AI hallucinations are now a well-established judicial response.

AI Use

Attorney Rudwin Ayala of Morgan & Morgan used the firm's internal AI platform (MX2.law, reportedly using ChatGPT) to add case law support to draft motions in limine in a product liability case concerning a hoverboard fire. This was reportedly his first time using AI for this purpose.

Hallucination Details

Eight out of nine case citations in the filed motions were non-existent or led to differently named cases. Another cited case number was real but belonged to a different case with a different judge. The legal standard description was also deemed "peculiar".

Ruling/Sanction

After defense counsel raised issues, Judge Kelly H. Rankin issued an order to show cause. The plaintiffs' attorneys (Ayala, T. Michael Morgan, Taly Goody) admitted the error, withdrew the motions, apologized, paid opposing counsel's fees related to the motions, and reported implementing new internal firm policies and training on AI use. Judge Rankin found Rule 11 violations. Sanctions imposed were: $3,000 fine on Ayala (the drafter) and revocation of his pro hac vice admission; $1,000 fine each on T. Michael Morgan and Taly Goody (the signing attorneys) for failing their duty of reasonable inquiry before signing.

Key Judicial Reasoning

The court acknowledged the attorneys' remedial steps and honesty but emphasized the non-delegable duty under Rule 11 to make a reasonable inquiry into the law before signing any filing. The court stressed that while AI can be a tool, attorneys remain responsible for verifying its output. The judge noted this was the "latest reminder to not blindly rely on AI platforms' citations".

AI Use

The petitioner’s counsel used an AI-based platform to draft the legal petition.

Hallucination Details

The petition cited 36 fabricated or misquoted Israeli Supreme Court rulings. Five references were entirely fictional, 14 had mismatched case details, and 24 included invented quotes. Upon judicial inquiry, counsel admitted reliance on an unnamed website recommended by colleagues, without verifying the information's authenticity. The Court concluded that the errors were likely the product of generative AI.

Ruling/Sanction

The High Court of Justice dismissed the petition on the merits, finding no grounds for intervention in the Sharia courts’ decisions. Despite the misconduct, no personal sanctions or fines were imposed on counsel, citing it as the first such incident to reach the High Court and adopting a lenient stance “far beyond the letter of the law.” However, the judgment was explicitly referred to the Court Administrator for system-wide attention.

Key Judicial Reasoning

The Court issued a stern warning about the ethical duties of lawyers using AI tools, underscoring that professional obligations of diligence, verification, and truthfulness remain intact regardless of technological convenience. The Court suggested that in future cases, personal sanctions on attorneys might be appropriate to protect judicial integrity.

AI Use

Counsel admitted at a show cause hearing that he used generative AI tools to draft multiple briefs and did not verify the citations provided by the AI, mistakenly trusting their apparent credibility without checking.

Hallucination Details

Three distinct fake cases across filings. Each was cited in a separate brief, with no attempt at Shepardizing or KeyCiting.

Ruling/Sanction

The Court recommended a $15,000 sanction ($5,000 per violation), with the matter referred to the Chief Judge for potential additional professional discipline. Counsel was also ordered to notify Hoosiervac LLC’s CEO of the misconduct and file a certification of compliance.

Key Judicial Reasoning

The judge stressed that reliance on AI outputs without verification is a violation of Rule 11. Good faith ignorance about AI hallucination capabilities is irrelevant. The decision emphasized that generative AI can assist research but cannot replace professional obligations. The judge invoked multiple authorities on sanctions for failure to verify case law and analogized using AI improperly to wielding dangerous tools without caution.

AI Use

Aleto submitted, shortly before hearing, a supplementary document claiming that environmental zoning category differences significantly impact real estate values in North Limburg. The document’s information was obtained via ChatGPT. The prompt/question to ChatGPT was not submitted, nor were sources or independent verifications provided.

Hallucination Details

ChatGPT-generated generalizations about the impact of environmental zoning (milieucategorieën) on property value. No formal references or empirical data supporting the AI output. ChatGPT itself warned that proper valuation requires consulting a human real estate expert.

Ruling/Sanction

The Court refused to consider the ChatGPT-based information as valid evidence. It emphasized that real estate valuation disputes involve complex expertise that cannot be substituted by AI outputs. Aleto’s appeal was dismissed, and the Council expressly reaffirmed that without a proper independent expert report, ChatGPT statements are legally worthless.

Key Judicial Reasoning

Judicial decision-making requires rigorously tested, verifiable inputs. AI outputs that do not disclose the input question or underlying data, and that disclaim reliability themselves, cannot satisfy this standard. Especially in technical fields like property tax and environmental valuation, human expert reports, not AI summaries, are mandatory.

AI Use

Defense counsel Andrew Francisco submitted filings quoting and relying on a fabricated case (United States v. Harris, 761 F. Supp. 409 (D.D.C. 1991)) and a nonexistent quotation. Although Francisco claimed he had not used AI, the court found the fabrication bore the hallmarks of an AI hallucination and rejected his explanations as implausible.

Hallucination Details

Francisco cited and quoted from a wholly fictitious United States v. Harris case, which neither existed at the cited location nor contained the quoted material. Upon confrontation, Francisco incorrectly tried to shift the source to United States v. Broussard, but that case also did not contain the quoted text. Searches in Westlaw and Lexis confirmed the quotation existed nowhere.

Ruling/Sanction

The Court formally sanctioned Francisco for degrading the integrity of the court and violating professional responsibility rules. Although monetary sanctions were not immediately imposed, the misconduct was recorded and would be taken into account in future disciplinary proceedings if warranted.

Key Judicial Reasoning

The court emphasized that submitting fake legal authorities undermines judicial credibility, wastes opposing parties' resources, and abuses the adversarial system. Persistent refusal to candidly admit errors aggravated the misconduct. The Court explicitly cited Mata v. Avianca and other AI hallucination cases as precedent for sanctioning such behavior, finding Francisco’s case especially egregious due to repeated bad faith evasions after being given opportunities to correct the record.

AI Use

Professor Jeff Hancock, a Stanford University expert on AI and misinformation, used GPT-4o to assist in drafting an expert declaration submitted by the Minnesota Attorney General's office in defense of a state law regulating AI deepfakes in elections.

Hallucination Details

The declaration contained citations to three non-existent academic articles, apparently generated when the AI misinterpreted Hancock's notes to himself (e.g., "[cite]") as prompts to insert references. Opposing counsel identified the fake citations.

Ruling/Sanction

Professor Hancock admitted the errors resulted from unchecked AI use, explaining it deviated from his usual practice of verifying citations for academic papers, and affirmed the substance of his opinions remained valid. Judge Laura M. Provinzino found the explanation plausible but ruled the errors "shattered his credibility". The court excluded the expert declaration as unreliable, emphasizing that signing a declaration under penalty of perjury requires diligence and that false statements, innocent or not, are unacceptable.

Key Judicial Reasoning

The court found it "particularly troubling" that the expert exercised less care with a court filing than with academic work. While not faulting the use of AI itself, the court stressed the need for independent judgment and verification, stating the incident was a reminder that Rule 11's "inquiry reasonable under the circumstances" might now require attorneys to ask witnesses about their AI use and verification steps. The irony of an AI misinformation expert falling victim to AI hallucinations in a case about AI dangers was noted.

AI Use

Alim Al-Hamim, appearing pro se (self-represented), used a generative AI tool to prepare his opening brief appealing the dismissal of his claims against his landlords. He had also submitted a document with fabricated citations in the lower court.

Hallucination Details

The appellate brief contained eight fictitious case citations alongside legitimate ones. The court could not locate the cases and issued an order to show cause.

Ruling/Sanction

Al-Hamim admitted relying on AI, confirmed the citations were hallucinations, stated he failed to inspect the brief, apologized, and accepted responsibility. The court affirmed the dismissal of his claims on the merits. While finding his submission violated Colorado Appellate Rules (C.A.R. 28(a)(7)(B)), the court exercised its discretion and declined to impose sanctions.

Key Judicial Reasoning

Factors against sanctions included Al-Hamim's pro se status, his contrition, lack of prior appellate violations, the absence of published Colorado precedent on sanctions for this issue, and the fact that opposing counsel did not raise the issue or request sanctions. However, the court issued a clear and strong warning to "the bar, and self-represented litigants" that future filings containing AI-generated hallucinations "may result in sanctions". The court emphasized the need for diligence, regardless of representation status.

AI Use

Monk admitted using the Claude AI tool to draft a summary judgment opposition without adequately verifying the case citations or quotations. He later claimed to have attempted post-hoc verification through Lexis AI but did not correct the errors until after a judicial show cause order.

Hallucination Details

Cited two completely nonexistent cases. Also fabricated quotations attributed to real cases, including Morales v. SimuFlite, White v. FCI USA, Burton v. Freescale, among others. Several "quotes" did not appear anywhere in the cited opinions.

Ruling/Sanction

The court imposed a $2,000 fine, ordered Monk to complete at least one hour of CLE on generative AI in legal practice, and mandated formal disclosure of the sanctions order to his client. It also permitted amendment of the defective filing but warned of the severity of the misconduct.

Key Judicial Reasoning

The court emphasized that attorneys remain personally responsible for the verification of all filings under Rule 11, regardless of technology used. Use of AI does not dilute the duty of candor. Continued silence and failure to rectify errors after opposing counsel flagged them exacerbated the misconduct.

AI Use

During the hearing, the plaintiff’s representative cited an answer generated by ChatGPT to argue that the Moroccan authorities systematically monitor political dissidents abroad, implying a risk of persecution on return. However, the representative failed to provide the actual question, the ChatGPT output, or any independent corroboration.

Hallucination Details

ChatGPT’s unverified assertion was used to claim Moroccan authorities tracked Hirak activists abroad, without any independent evidence. The Court noted that ChatGPT provided no source references and that the question/answer pair was never filed into the case record

Ruling/Sanction

The Court held the ChatGPT output legally irrelevant and gave it no probative value. While it did not impose sanctions on the plaintiff’s counsel, it criticized the reliance on unverifiable AI content in judicial proceedings. The plaintiff's asylum appeal was ultimately dismissed.

Key Judicial Reasoning

The Court emphasized that judicial decisions must be based on verifiable evidence. AI-generated content without transparent sourcing or record authentication fails even minimal evidentiary standards. Citing such outputs does not meet the burden of proof for substantiating claims of future persecution.

AI Use

Plaintiff’s counsel admitted using generative AI to draft a motion to remand without independently verifying the legal citations or the factual accuracy of quoted complaint allegations.

Hallucination Details

Cited a fabricated case (details of the specific case name not listed in the ruling). Included fabricated quotations from the complaint, suggesting nonexistent factual allegations.

Ruling/Sanction

The Court imposed a $2,500 sanction payable by December 30, 2024. Counsel was also required to notify the California State Bar of the sanction and file proof of notification and payment. The Court recognized mitigating factors (health issues, post-hoc corrective measures) but stressed the seriousness of the violations.

Key Judicial Reasoning

Rule 11 requires attorneys to conduct a reasonable inquiry into both facts and law. Use of AI does not diminish this duty. Subjective good faith is irrelevant: violations occur even without intent to deceive. AI-generated filings must be reviewed with the same rigor as traditional submissions.

AI Use

In a trust accounting proceeding, the objectant's damages expert testified that he used Microsoft Copilot (described as an AI chatbot) to cross-check his damages calculations presented in a supplemental report.

Hallucination Details

The issue wasn't fabricated citations, but the reliability and verifiability of the AI's calculation process. The expert could not recall the specific prompts used, nor could he explain Copilot's underlying sources or methodology. He claimed using AI tools was generally accepted in his field but offered no proof.

Ruling/Sanction

The court had already found the expert's analysis unreliable on other grounds, but specifically addressed the AI use. The court attempted to replicate the expert's results using Copilot itself, obtaining different outputs and eliciting warnings from Copilot about the need for expert verification before court use. The court held, potentially as an issue of first impression in that court, that counsel has an affirmative duty to disclose the use of AI in generating evidence prior to its introduction, due to AI's rapid evolution and reliability issues. AI-generated evidence would be subject to a Frye hearing (standard for admissibility of scientific evidence in NY). The expert's AI-assisted calculations were deemed inadmissible.

Key Judicial Reasoning

The court emphasized the "garbage in, garbage out" principle, stressing the need for users to understand AI inputs and processes. It stated that the mere fact AI is used does not make its output admissible; reliability must be established. The lack of transparency regarding the AI's process was a key factor in finding the evidence unreliable.

AI Use

The Court noted that the false citations could stem from AI, disorganized database use, or invention. Counsel claimed a database error but provided no evidence. The Court found the origin irrelevant: verification duty lies with the submitting lawyer.

Hallucination Details

Nineteen separate fabricated citations to fictional Constitutional Court judgments. Fake quotations falsely attributed to those nonexistent decisions. Cited to falsely bolster claims of constitutional relevance in an amparo.

Ruling/Sanction

The Constitutional Court unanimously found that the inclusion of nineteen fabricated citations constituted a breach of the respect owed to the Court and its judges under Article 553.1 of the Spanish Organic Law of the Judiciary. Issued a formal warning (apercibimiento) rather than a fine due to absence of prior offenses. Referred the matter to the Barcelona Bar for possible disciplinary proceedings

Key Judicial Reasoning

The Court stressed that even absent express insults, fabricating authority gravely disrespects the judiciary’s function. Irrespective of whether AI was used or a database error occurred, the professional duty of diligent verification was breached. The Court noted that fake citations disrupt the court’s work both procedurally and institutionally.

AI Use

Plaintiff, opposing motions to dismiss, filed a brief containing three fake federal case citations. Defendants raised the issue in their reply, suggesting use of ChatGPT or a similar tool. Plaintiff did not deny the accusation.

Hallucination Details

Three nonexistent cases were cited. Each cited case name and number was fictitious; none of the real cases matching those citations involved remotely related issues.

Ruling/Sanction

The court issued a formal warning to Plaintiff: any future filings containing fabricated citations or quotations will result in sanctions, including striking of filings, monetary penalties, or dismissal. No sanction imposed for this first occurrence, acknowledging pro se status and likely ignorance of AI risks.

Key Judicial Reasoning

Reliance on nonexistent precedent, even by pro se litigants, is an abuse of the adversarial system. The court cited Mata v. Avianca and Park v. Kim as establishing the principle that hallucinated case citations undermine judicial integrity and waste opposing parties’ and courts' resources. Plaintiff was formally warned, not excused.

AI Use

The court inferred the use of AI from the pattern of errors (fake cases and fabricated quotes) and opposing counsel’s explicit accusation ("ChatGPT run amok"). Plaintiff's counsel did not deny it or clarify origins, leaving the inference unchallenged.

Hallucination Details

Two nonexistent cases cited, and fabricated quotations attributed to real cases:

• Graves v. Lioi (4th Cir.) – quotation absent from opinion
• Bostock v. Clayton County (U.S. Supreme Court) – quotation absent from opinion

Misreporting of Menocal case citation to imply relevance

Ruling/Sanction

The court issued a show cause order demanding explanation why sanctions and/or bar disciplinary referrals should not be imposed. Silent failure to contest fabrication allegations worsened the finding.

Following show cause proceedings, the court declined to sanction counsel.

Key Judicial Reasoning

The judge emphasized that AI use does not lessen the lawyer’s duty to ensure accurate filings. Fabricated cases and misquotes are serious Rule 11 violations. Attorneys are responsible for vetting everything submitted to the court, regardless of source. Silence when fabrication is exposed constitutes further misconduct.

AI Use

The plaintiff, proceeding pro se, submitted filings citing multiple nonexistent cases. The court noted patterns typical of ChatGPT hallucinations, referencing studies and prior cases involving AI errors, though the plaintiff did not admit using AI.

Hallucination Details

Several fake citations identified, including invented federal cases and misquoted Supreme Court opinions. Defendants flagged these to the court, and the court independently confirmed they were fictitious.

Ruling/Sanction

No sanctions imposed at this stage, citing special solicitude for pro se litigants. However, the court issued a formal warning: further false citations would lead to sanctions without additional leniency.

Key Judicial Reasoning

The court emphasized that even pro se parties must comply with procedural and substantive law, including truthfulness in court filings. Cited Mata v. Avianca and Park v. Kim as established examples where AI-generated hallucinations resulted in sanctions for attorneys, underscoring the seriousness of the misconduct.

AI Use

The appellant relied on ChatGPT to generate a list of ten "economically comparable" vehicles for purposes of arguing a lower trade-in value to reduce bpm (car registration tax). The Court noted this explicitly and criticized the mechanical reliance on AI outputs without human verification or contextual adjustment.

Hallucination Details

ChatGPT produced a list of luxury and exotic cars supposedly comparable to a Ferrari 812 Superfast. The Court found that mere AI-generated association of vehicles based on "economic context and competition position" is insufficient under EU law principles requiring real-world comparability from the perspective of an average consumer.

Ruling/Sanction

The Court rejected the appellant’s valuation arguments wholesale. It stressed that serious, human-verified reference vehicle comparisons were mandatory and that ChatGPT lists could not establish the legally required comparability standard under Dutch and EU law (Art. 110 TFEU). No monetary sanction imposed, but appellant’s entire case collapsed on evidentiary grounds.

Key Judicial Reasoning

The Court reasoned that a list generated by an AI program like ChatGPT, without rigorous control or verification, is inadmissible for evidentiary purposes. AI outputs lack the nuanced judgment necessary to assess "similar vehicles" under Art. 110 TFEU and Dutch bpm tax rules. It underscored that the test is based on the perceptions of a human average consumer, not algorithmic proximity.

AI Use

The appellants’ lawyer submitted an opening brief riddled with hallucinated cases and mischaracterizations. The court did not directly investigate the technological origin but cited the systematic errors as consistent with known AI-generated hallucination patterns.

Hallucination Details

Two cited cases were completely nonexistent. Additionally, a dozen cited decisions were badly misrepresented, e.g., Hydrick v. Hunter and Wall v. County of Orange were cited for parent–child removal claims when they had nothing to do with such issues.

Ruling/Sanction

The Ninth Circuit struck the appellants' opening brief under Circuit Rule 28–1 and dismissed the appeal. The panel emphasized that fabricated citations and grotesque misrepresentations violate Rule 28(a)(8)(A) requirements for arguments with coherent citation support.

Key Judicial Reasoning

Fabricated and misrepresented authorities defeat the appellate function. Counsel failed to provide even minimally reliable legal arguments. Attempts to explain at oral argument were evasive and inadequate, reinforcing the sanction. Dismissal was portrayed as necessary to preserve the integrity of appellate review and judicial economy.

AI Use

Michael Cohen, former lawyer to Donald Trump but then disbarred, used Google Bard to find case law supporting his motion for early termination of supervised release. He stated he believed Bard was a "super-charged search engine" and was unaware it could generate fictitious cases.

Hallucination Details

Cohen provided three non-existent case citations generated by Bard to his attorney, David M. Schwartz (not the same Schwartz as in Mata), who included them in a court filing. There was a misunderstanding between Cohen and his attorneys regarding who was responsible for verifying the citations. The fake citations were discovered by Cohen's other counsel, Danya Perry, who disclosed the issue to the court. One fake citation involved a chronological impossibility.

Ruling/Sanction

Judge Jesse Furman identified the citations as fake and issued an order to show cause regarding sanctions against the attorney. However, Judge Furman ultimately declined to impose sanctions on Cohen himself, noting his non-lawyer status, his stated (though surprising) ignorance of generative AI risks, and the expectation that his licensed attorney should have verified the citations. The judge nonetheless described the incident as "embarrassing" for Cohen and denied his underlying motion on the merits.

Key Judicial Reasoning

The court highlighted the importance of verifying AI-generated content and the responsibility of licensed attorneys to ensure the accuracy of filings, even when research suggestions come from clients. The incident further underscored the unreliability of generative AI for legal research if used without verification.

AI Use

The appellant's authorized representative submitted arguments based on ChatGPT outputs attempting to challenge the tax valuation of real property. The representative failed to specify what exact queries were made to ChatGPT, rendering the outputs unverifiable and untrustworthy.

Hallucination Details

No explicit fabricated case law was cited. Instead, the appellant relied on generalized, unverifiable statements produced by ChatGPT to contest the capitalization factor and COVID-19 valuation discounts applied by the tax authorities.

Ruling/Sanction

The Court refused to attribute any evidentiary value to the ChatGPT-based arguments. It found that without disclosure of the input prompts and verification of AI outputs, the content was legally inadmissible as probative material. However, no sanctions were imposed, likely due to the novelty of the misuse and the lack of bad faith.

Key Judicial Reasoning

The Court emphasized that judicial proceedings demand verifiable, fact-based arguments. AI outputs that lack transparency (particularly about the underlying prompt and methodology) cannot serve as a substitute for evidence. The judgment explicitly notes that reliance on ChatGPT statements without verifiability "does not affect" the Court’s reasoning or the tax authority's burden of proof.

AI Use

Vancouver lawyer Chong Ke used ChatGPT to assist in preparing a Notice of Application in a family law case concerning parental travel with children.  

Hallucination Details

The application included references to two fictitious cases generated by ChatGPT. Opposing counsel identified the non-existent cases.  

Ruling/Sanction

Ms. Ke informed the court she was unaware ChatGPT could be unreliable, had not verified the cases, and apologized. Justice D.M. Masuhara reprimanded the lawyer but rejected the opposing side's request for a special costs order against her. The Law Society of British Columbia confirmed it was investigating Ms. Ke's conduct.  

Key Judicial Reasoning

Justice Masuhara stated clearly that "generative AI is still no substitute for the professional expertise that the justice system requires of lawyers" and emphasized that competence in selecting and using technology tools, including AI, is critical for maintaining the integrity of the justice system. The case served as Canada's first high-profile example of the issue, prompting warnings about the need for diligence.

AI Use

The Cuddy Law Firm used ChatGPT-4 to purportedly validate and support its request for elevated attorney billing rates in its motion for attorneys’ fees under the IDEA. They invoked ChatGPT as a “cross-check” for the reasonableness of their requested rates ($550–$600 per hour for senior lawyers, $375–$425 for associates).

Hallucination Details

No fake cases or authorities cited. However, the Court found the reliance on ChatGPT-4 wholly inappropriate, calling it “utterly and unusually unpersuasive” and emphasizing that ChatGPT’s conclusions lacked transparency, reliability, and any grounding in actual legal practice or precedent. The court compared this misuse to the notorious ChatGPT hallucination cases (Mata v. Avianca and Park v. Kim).

Ruling/Sanction

The Court reduced the Cuddy Law Firm’s requested fee rates significantly (e.g., from $550 down to $400/hour for senior lawyers, and proportionately for others) and explicitly warned against using ChatGPT or similar tools as evidence in fee petitions. No financial sanction was imposed, but the Court expressed clear disdain and advised against repeating this practice.

Key Judicial Reasoning

The Court reaffirmed that billing rates must be based on prevailing legal market conditions and judicial precedent, not unverifiable or speculative AI outputs. The opinion underscores that AI tools, absent verifiable support, cannot serve as evidence in legal argumentation for judicial decision-making.

AI Use

Appellant Karlen admitted in his Reply Brief that he hired an online consultant (purportedly an attorney) to prepare his appellate filings cheaply. This consultant used generative AI, leading to the inclusion of numerous fictitious citations. Karlen denied intent to mislead but acknowledged ultimate responsibility for the submission.

Hallucination Details

Out of twenty-four total case citations in Karlen’s appellate brief:

• Only two were genuine (and misused).
• Twenty-two were completely fictitious.
• Multiple Missouri statutes and procedural rules were cited incorrectly or completely misrepresented

Ruling/Sanction

The Court dismissed the appeal for pervasive violations of appellate rules and awarded $10,000 in damages to the Respondent for the costs of defending against the frivolous appeal. The Court stressed that submission of fabricated legal authority is an abuse of the judicial system, regardless of pro se status.

Key Judicial Reasoning

The Court invoked Mata v. Avianca to reinforce that citing fake opinions is an abuse of the adversarial system. The opinion emphasized that self-represented parties are fully bound by Rule 55.03 (certification of factual and legal contentions) and the Missouri Rules of Appellate Procedure. The decision warned that the Court will not tolerate fraudulent or AI-hallucinated filings, even from non-lawyers.

AI Use

In a wrongful death case, plaintiff's counsel filed four memoranda opposing motions to dismiss. The drafting was done by junior staff (an associate and two recent law school graduates not yet admitted to the bar) who used an unidentified AI system to locate supporting authorities. The supervising attorney signed the filings after reviewing them for style and grammar, but admittedly did not check the accuracy of the citations and was unaware AI had been used.

Hallucination Details

Judge Brian A. Davis noticed citations "seemed amiss" and, after investigation, could not locate three cases cited in the memoranda. These were fictitious federal and state case citations.

Ruling/Sanction

After being questioned, the supervising attorney promptly investigated, admitted the citations were fake and AI-generated, expressed sincere contrition, and explained his lack of familiarity with AI risks. Despite accepting the attorney's candor and lack of intent to mislead, Judge Davis imposed a $2,000 monetary sanction on the supervising counsel, payable to the court.

Key Judicial Reasoning

The court found that sanctions were warranted because counsel failed to take "basic, necessary precautions" (i.e., verifying citations) before filing. While the sanction was deemed "mild" due to the attorney's candor and unfamiliarity with AI (distinguishing it from Mata's bad faith finding), the court issued a strong warning that a defense based on ignorance "will be less credible, and likely less successful, as the dangers associated with the use of Generative AI systems become more widely known". The case underscores the supervisory responsibilities of senior attorneys.

AI Use

Counsel admitted using ChatGPT to find supporting case law after failing to locate precedent manually. She cited a fictitious case (Matter of Bourguignon v. Coordinated Behavioral Health Servs., Inc., 114 A.D.3d 947 (3d Dep’t 2014)) in the reply brief, never verifying its existence.

Hallucination Details

Only one hallucinated case was cited in the reply brief: Matter of Bourguignon v. Coordinated Behavioral Health Servs., Inc., 114 A.D.3d 947 (3d Dep’t 2014). When asked to produce the case, Counsel admitted it did not exist, blaming reliance on ChatGPT.

Ruling/Sanction

The Court referred Counsel to the Second Circuit’s Grievance Panel for further investigation and possible discipline. Lee was ordered to furnish a copy of the decision (translated if necessary) to her client and to file certification of compliance.

Key Judicial Reasoning

The Court emphasized that attorneys must personally verify the existence and accuracy of all authorities cited. Rule 11 requires a reasonable inquiry, and no technological novelty excuses failing to meet that standard. The Second Circuit cited Mata v. Avianca approvingly, confirming that citing fake cases amounts to abusing the adversarial system.

AI Use

Osborne’s attorney, under time pressure, submitted reply papers heavily relying on a website or tool that used generative AI. The submission included fabricated judicial authorities presented without independent verification. No admission by the lawyer was recorded, but the court independently verified the error.

Hallucination Details

Of the six cases cited in the October 11, 2023 reply, five were found to be either fictional or materially erroneous. A basic Lexis search would have revealed the fabrications instantly. The court drew explicit comparisons to the Mata v. Avianca fiasco.

Ruling/Sanction

The court struck the offending reply papers from the record and ordered the attorney to appear for a sanctions hearing under New York’s Rule 130-1.1. Potential sanctions include financial penalties or other disciplinary measures.

Key Judicial Reasoning

The court emphasized that while the use of AI tools is not forbidden per se, attorneys must personally verify all outputs. The violation was deemed "frivolous conduct" because the lawyer falsely certified the validity of the filing. The judge stressed the dangers to the judicial system from fictional citations: wasting time, misleading parties, degrading trust in courts, and harming the profession’s reputation.

AI Use

Catherine Harber, a self-represented taxpayer appealing an HMRC penalty, submitted a document citing nine purported First-Tier Tribunal decisions supporting her position regarding "reasonable excuse". She stated the cases were provided by "a friend in a solicitor's office" and acknowledged they might have been generated by AI. ChatGPT was mentioned as a likely source.  

Hallucination Details

The nine cited FTT decisions (names, dates, summaries provided) were found to be non-existent after checks by the Tribunal and HMRC. While plausible, the fake summaries contained anomalies like American spellings and repeated phrases. Some cited cases resembled real ones, but those real cases actually went against the appellant.  

Ruling/Sanction

The Tribunal factually determined the cited cases were AI-generated hallucinations. It accepted Mrs. Harber was unaware they were fake and did not know how to verify them. Her appeal failed on its merits, unrelated to the AI issue. No sanctions were imposed on the litigant.  

Key Judicial Reasoning

The Tribunal emphasized that submitting invented judgments was not harmless, citing the waste of public resources (time and money for the Tribunal and HMRC). It explicitly endorsed the concerns raised in the US Mata decision regarding the various harms flowing from fake opinions. While lenient towards the self-represented litigant, the ruling implicitly warned that lawyers would likely face stricter consequences. This was the first reported UK decision finding AI-generated fake cases cited by a litigant

AI Use

Attorney Zachariah C. Crabill, relatively new to civil practice, used ChatGPT to research case law for a motion to set aside judgment, a task he was unfamiliar with and felt pressured to complete quickly.

Hallucination Details

Crabill included incorrect or fictitious case citations provided by ChatGPT in the motion without reading or verifying them. He realized the errors ("garbage" cases, per his texts) before the hearing but did not alert the court or withdraw the motion.

Ruling/Sanction

When questioned by the judge about inaccuracies at the hearing, Crabill falsely blamed a legal intern. He later filed an affidavit admitting his use of ChatGPT and his dishonesty, stating he "panicked" and sought to avoid embarrassment. He stipulated to violating professional duties of competence, diligence, and candor/truthfulness to the court. He received a 366-day suspension, with all but 90 days stayed upon successful completion of a two-year probationary period. This was noted as the first Colorado disciplinary action involving AI misuse.

Key Judicial Reasoning

The disciplinary ruling focused on the combination of negligence (failure to verify, violating competence and diligence) and intentional misconduct (lying to the court, violating candor). While mitigating factors (personal challenges, lack of prior discipline) were noted in the stipulated agreement, the dishonesty significantly aggravated the offense.

AI Use

Defendants alleged that portions of Plaintiff’s response to a motion to dismiss were AI-generated.

Hallucination Details

No specific fabricated cases or fake quotations were identified. The concern was broader: incoherent and procedurally improper pleadings, compounded by apparent AI usage, which raised ethical red flags.

Ruling/Sanction

Rather than imposing sanctions, the court granted the pro se plaintiff leave to amend the complaint. Plaintiff was warned to comply with procedural rules and to submit a coherent, consolidated amended complaint, or face dismissal.

Key Judicial Reasoning

The judge stressed that AI use does not absolve pro se litigants of procedural compliance. Litigants must ensure pleadings are coherent, concise, and legally grounded, regardless of technological tools used. Courts cannot act as de facto advocates or reconstruct fragmented pleadings.

AI Use

Plaintiff, acting without counsel, submitted briefing that included multiple fabricated or erroneous judicial citations, likely generated by an AI tool used for research or drafting. While the tool itself is not named, the nature and clustering of errors mirror known AI output patterns.

Hallucination Details

Cited cases included wholly nonexistent opinions (e.g., "Las Cruces Sun-News v. City of Las Cruces") and real case names with incorrect volume/reporting details (e.g., misattributed circuits or invented page numbers). The citations lacked verifiable authority and were flagged by the court as spurious upon review.

Ruling/Sanction

The court dismissed several claims on substantive grounds but issued a sharp warning about the misuse of AI-generated legal citations. While no immediate sanctions were imposed, the judge explicitly referenced Mata v. Avianca and held this instance to be only the second federal case addressing AI hallucinations in pleadings. The plaintiff was cautioned that any recurrence would result in Rule 11 sanctions, including dismissal with prejudice.

Key Judicial Reasoning

The opinion stressed that access to courts is not a license to submit fictitious legal materials. Rule 11(b) requires factual and legal support for all filings, and even pro se litigants must adhere to this baseline. The court emphasized judicial efficiency, fairness to the opposing party, and the reputational harm caused by false citations. The misuse of AI was implicitly treated as a form of recklessness or bad faith, not excused by technological ignorance

AI Use

Jerry Thomas filed pro se pleadings citing at least ten fabricated cases. The citations appeared plausible but did not correspond to any real authorities. Despite opportunities to explain, Thomas gave vague excuses about "self-research" and "assumed reliability," without clarifying the sources - suggesting reliance on AI-generated content.

Hallucination Details

Ten fake case citations systematically inserted across filings

Fabricated authorities mimicked proper citation format but were unverifiable in any recognized database

The pattern mirrored known AI hallucination behaviors: fabricated authorities presented with apparent legitimacy

Ruling/Sanction

The Court dismissed the action with prejudice as a Rule 11 sanction. It emphasized that fake citations delay litigation, waste judicial resources, and erode public confidence. The Court explicitly invoked Mata v. Avianca for the broader dangers of AI hallucinations in litigation and found Thomas acted in bad faith by failing to properly explain the origin of the fabrications.

Key Judicial Reasoning

Citing fabricated cases (even if resulting from AI use or negligence) is sanctionable because it constitutes an improper purpose under Rule 11. Sanctions were deemed necessary to deter further abuses, with dismissal considered more appropriate than monetary penalties given the circumstances.

AI Use

Lancaster, filing objections to a magistrate judge’s Report and Recommendation, cited several fabricated case authorities. The Court noted the possibility of reliance on a generative AI tool and explicitly warned Lancaster about future misconduct.

Hallucination Details

Fabricated or mutant citations, including:

• Bazzi v. Sentinel Ins. Co., 961 F.3d 734 (6th Cir. 2020) — mutant citation blending two unrelated real cases
• Maldonado v. Ford Motor Co., 720 F.3d 760 (5th Cir. 2013) — nonexistent
• Malliaras & Poulos, P.C. v. City of Center Line, 788 F.3d 876 (6th Cir. 2015) — nonexistent

Court highlighted that the majority of the cited cases in Lancaster’s objections were fake.

Ruling/Sanction

No immediate sanction imposed due to pro se status and lack of prior warnings. However, the Court issued a pointed warning that citing "made-up law" could lead to significant sanctions, either in that Court or any other court to which the case might be remanded.

Key Judicial Reasoning

The Court emphasized that unverified, fabricated legal citations undermine the judicial process and waste both judicial and litigant resources. Even without clear evidence of malicious intent, negligence in checking citations is sanctionable. Rule 11 duties apply fully to pro se litigants.

AI Use

The Court noted that the appellant's argument section appeared to have been drafted by AI based on telltale errors (nonexistent cases, jump-cites into wrong jurisdictions, illogical structure). A recent Texas CLE on AI usage was cited by the Court to explain the pattern.

Hallucination Details

Three fake cases cited. Brief also contained no citations to the record and was devoid of clear argumentation on the presented issues.

Ruling/Sanction

The Court declined to issue a show cause order or to refer counsel to the State Bar of Texas, despite noting similarities to Mata v. Avianca. However, it affirmed the trial court’s denial of habeas relief due to inadequate briefing, and explicitly warned about the dangers of using AI-generated content in legal submissions without human verification.

Key Judicial Reasoning

The Court held that even if AI contributed to the preparation of filings, attorneys must ensure accuracy, logical structure, and compliance with citation rules. Failure to meet these standards precludes appellate review under Tex. R. App. P. 38.1(i). Courts are not obligated to "make an appellant’s arguments for him," especially where brief defects are gross.

AI Use

Attorneys Steven A. Schwartz and Peter LoDuca of Levidow, Levidow & Oberman used ChatGPT for legal research to oppose a motion to dismiss a personal injury claim against Avianca airlines, citing difficulty accessing relevant federal precedent through their limited research subscription.

Hallucination Details

The attorneys' submission included at least six completely non-existent judicial decisions, complete with fabricated quotes and internal citations. Examples cited by the court include Varghese v. China Southern Airlines Co., Ltd., Shaboon v. Egyptair, Petersen v. Iran Air, Martinez v. Delta Airlines, Inc., Estate of Durden v. KLM Royal Dutch Airlines, and Miller v. United Airlines, Inc.. When challenged by opposing counsel and the court, the attorneys initially stood by the fake cases and even submitted purported copies of the opinions, which were also generated by ChatGPT and contained further bogus citations.

Ruling/Sanction

Judge P. Kevin Castel imposed a $5,000 monetary sanction jointly and severally on the two attorneys and their law firm. He also required them to send letters informing their client and each judge whose name was falsely used on the fabricated opinions about the situation.

Key Judicial Reasoning

Judge Castel found the attorneys acted in bad faith, emphasizing their "acts of conscious avoidance and false and misleading statements to the Court" after the issue was raised. The sanctions were imposed not merely for the initial error but for the failure in their gatekeeping roles and their decision to "double down" rather than promptly correcting the record. The opinion detailed the extensive harms caused by submitting fake opinions. This case is widely considered a landmark decision and is frequently cited in subsequent discussions and guidance.

AI Use

Mr. Scott, opposing a motion to dismiss, filed a brief containing multiple fabricated case citations with plausible formatting but nonexistent underlying cases. Court recognized the pattern as typical of AI hallucinations. Scott did not admit AI use, but the inference was clear.

Hallucination Details

Several case names, reporter citations, and quotations provided were fake; no match could be found in legal databases. Quotations attached to these cases were invented. Citations appeared superficially valid (correct format) but were unverifiable

Ruling/Sanction

Complaint dismissed in full

Sanctions imposed: Scott ordered to pay defendant’s reasonable attorney’s fees, costs, and expenses associated with the motion to dismiss and motion for sanctions

Court required affidavit from Fannie Mae detailing fees, after which Scott could contest reasonableness but not the sanction itself

Key Judicial Reasoning

The Court emphasized that using AI tools does not relieve any litigant of their duty to verify legal authorities. Citing or quoting nonexistent cases is a violation of Maine Rule of Civil Procedure 11. Even pro se litigants cannot "blindly rely" on AI outputs and are expected to exercise reasonable diligence. The judgment was framed explicitly to deter future abuse of AI-generated filings.