AI Hallucination Cases

This database tracks legal decisions1 I.e., all documents where the use of AI, whether established or merely alleged, is addressed in more than a passing reference by the court or tribunal.

Notably, this does not cover mere allegations of hallucinations, but only cases where the court or tribunal has explicitly found (or implied) that a party relied on hallucinated content or material.

As an exception, the database also covers some judicial decisions where AI use was alleged but not confirmed. This is a judgment call on my part.
in cases where generative AI produced hallucinated content – typically fake citations, but also other types of AI-generated arguments. It does not track the (necessarily wider) universe of all fake citations or use of AI in court filings.

While seeking to be exhaustive (913 cases identified so far), it is a work in progress and will expand as new examples emerge. This database has been featured in news media, and indeed in several decisions dealing with hallucinated material.2 Examples of media coverage include:
- M. Hiltzik, AI 'hallucinations' are a growing problem for the legal profession (LA Times, 22 May 2025)
- E. Volokh, "AI Hallucination Cases," from Courts All Over the World (Volokh Conspiracy, 18 May 2025)
- J-.M. Manach, "Il génère des plaidoiries par IA, et en recense 160 ayant « halluciné » depuis 2023" (Next, 1 July 2025) - J. Koebler & J. Roscoe, "18 Lawyers Caught Using AI Explain Why They Did It (404 Media, 30 September 2025)

If you know of a case that should be included, feel free to contact me.3 (Readers may also be interested in this project regarding AI use in academic papers.)

Based on this database, I have developped an automated reference checker that also detects hallucinations: PelAIkan. Check the Reports Report icon in the database for examples, and reach out to me for a demo !

For weekly takes on cases like these, and what they mean for legal practice, subscribe to Artificial Authority.

State
Party
Nature – Category
Nature – Subcategory

Case Court / Jurisdiction Date ▼ Party Using AI AI Tool Nature of Hallucination Outcome / Sanction Monetary Penalty Details Report(s)
Lothamer Tax Resolution, Inc. v. Paul Kimmel (1) W.D. Michigan (USA) 29 August 2025 Pro Se Litigant Implied
Fabricated Case Law (3)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Warning
Stewart v Good Shepherd Victoria CA (Australia) 29 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1)
Misrepresented Case Law (1)
Gribble v Essential Energy NSW D.C. (Australia) 29 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (2)
Plaintiff ordered to exclude all Gen AI material
Cunningham v healthAlliance NZ Limited Employment Court (New Zealand) 29 August 2025 Pro Se Litigant Implied
Fabricated Case Law (2)
Warning
Alana Kotler v Ontario Secondary School Teachers’ Federation Ontario Labour Relations Board (Canada) 29 August 2025 Pro Se Litigant Implied
Fabricated Case Law (14)
Misrepresented Case Law (1)
Arguments ignored

The applicant relied on numerous case citations that the Board and OSSTF could not locate as cited; one located decision did not support the proposition relied upon. Applicant acknowledged possible citation errors and was asked to provide copies but objected. The Board refused to rely on unlocatable authorities and dismissed the application.

Lonnie Allbaugh v. University of Scranton M.D. Pennsylvania (USA) 28 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (2)
Monetary sanction; complaint dismissed without prejudice; leave to amend granted. 1000 USD

The court later declined to reconsider its sanction (see here).

Source: Robert Freund
Multiphone Latin America v. Millicom International Cellular S.D. Florida (USA) 28 August 2025 Lawyer Implied
Fabricated Case Law (2)
False Quotes Case Law (2)
Misrepresented Case Law (1)
Referral to District Ad Hoc Committee and the Florida Bar for investigation
Source: Robert Freund
Thackston v. Driscoll W.D. Texas (USA) 28 August 2025 Lawyer Implied
Fabricated Case Law (1), Doctrinal Work (1)
False Quotes Case Law (4)
Misrepresented Case Law (3)
Outdated Advice Overturned Case Law (1)
Magistrate Judge recommended Rule 11 sanctions

Magistrate Judge found Plaintiff's Reply contained multiple citations that do not exist, quotes not found in the cited authorities, and material mischaracterizations of cases; court concluded counsel likely used generative AI and failed to verify outputs and recommended the District Court consider Rule 11 sanctions.

Myeesha Parker v. Costco Wholesale Corp. W.D. Washington (USA) 28 August 2025 Lawyer Implied
False Quotes Case Law (6)
Misrepresented Case Law (1), Exhibits or Submissions (2)
Show Cause Order
Source: Robert Freund
Myers v. Tarion Warranty Corporation Ontario (Canada) 28 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Arguments ignored
USA v. Sethi E.D. Texas (USA) 28 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1), Exhibits or Submissions (1)
False Quotes Case Law (2)
Court denied defendant's motions; sentencing ordered to proceed as scheduled; no professional sanctions imposed.
Butler and National Disability Insurance Agency Administrative Review Tribunal (Australia) 28 August 2025 Expert Unidentified
Fabricated Exhibits or Submissions (1)
Tribunal criticised the reliability of AI-assisted expert reports and gave them reduced weight

The Agency raised concerns that several expert reports were prepared with assistance of an artificial intelligence program and contained unverified citations and inserted text. The Tribunal noted admissions by at least one practitioner (Ms McPhee) that AI assisted drafting and found instances where citations had been corrected by another witness and where the author could not confirm whether AI added certain phrases. The Tribunal criticised the lack of independent verification and gave the reports reduced weight but did not impose sanctions.

Lee v. R&R Home Care, Inc. E.D. Louisiana (USA) 28 August 2025 Lawyer Google Gemini
Fabricated Case Law (1)
False Quotes Case Law (1)
Monetary sanction; referral 1000 USD
In re Richburg South Carolina (Bankruptcy) (USA) 27 August 2025 Lawyer Microsoft CoPilot
Fabricated Case Law (2)
3 hours of CLE to be proven

Counsel filed a motion containing case citations that did not exist; counsel admitted the citations were generated by Microsoft CoPilot and not independently verified. The court found a Rule 9011 violation, declined to impose monetary sanctions because of procedural limits and dismissal, and ordered CLE focused on AI ethics.

United States v. Michael Shane DeBaere (1) W.D. Virginia (USA) 27 August 2025 Pro Se Litigant Implied
Fabricated Case Law (3), Doctrinal Work (1)
Warning
Takefman v. The Pickleball Club, LLC Third District Court of Appeal, State of Florida (USA) 27 August 2025 Pro Se Litigant Implied
Fabricated Case Law (2)
Misrepresented Case Law (1)
Order to show cause

" Opposing counsel, and the court, should not have to parse case citations and parentheticals to discern whether cases exist, and if so, if they stand for the propositions asserted. "

The Boys of Rockanje v. Dwaard Rotterdam D. (Netherlands) 27 August 2025 Lawyer Implied
Fabricated Case Law (1)
Misrepresented Case Law (1)

" When asked, Dwaard (his lawyer) stated that all this was caused by a problem converting a Word file to PDF. This statement raises questions. The court leaves these questions and the question of whether this violated Article 21 of the Dutch Code of Civil Procedure unanswered, because, on balance, Dwaard did not benefit from the incorrect representation of the facts in the statement of defense. " (Google Translate)

Helgen Industries GAO (USA) 26 August 2025 Pro Se Litigant Implied
Fabricated Case Law (4)
Warning
Source: David Timm
Orano Mining v. Niger (2) ICSID Tribunal (International Arbitration) 26 August 2025 Lawyer Implied (by me)
Fabricated Case Law (5)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Arguments ignored

Although the tribunal did not address it as a case of hallucinations or misuse of artificial intelligence, the details make clear that this was very likely at issue.

While the decision is not public, further details have been reported by, uh, me:

🔗 Damien Charlotin, Niger’s proposal to disqualify Fernando Mantilla-Serrano from uranium mining arbitration is rejected; challenge procedure is marred by citations and authorities that couldn’t be borne out when scrutinized by co-arbitrators (Investment Arbitration Reporter, 28 August 2025).

3 ORbs 164/25 KG Berlin (Germany) 25 August 2025 Lawyer Implied
Fabricated Exhibits or Submissions (1)
Giacomino y Otros v. Montserrat y Otros Rosario CA (Argentina) 22 August 2025 Lawyer Unidentified
Fabricated Case Law (1)
Referral of the issue to the Bar
In re Mascio D. Colorado (Bankruptcy) (USA) 22 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1)
Warning
Source: Jesse Schaefer
Chenco v. Do-Fluoride D. Idaho (USA) 22 August 2025 Lawyer Implied
False Quotes Case Law (5)
Misrepresented Case Law (1)
Court denied defendant's motion for leave to file a surreply, admonished counsel for submitting non-existent quotations, and granted plaintiff's motion to remand.

"Counsel should take seriously its obligation to provide the Court with an accurate description of the law. See, e.g., United States v. Hayes, 763 F. Supp. 3d 1054 (E.D. Cal. 2025) (levying $1,500 in monetary sanctions against counsel personally for fictitious cases and quotations that the court suspected were produced using artificial intelligence),reconsideration denied, No. 2:24-CR-0280-DJC, 2025 WL 1067323 (E.D. Cal. Apr. 9, 2025); Grant v. City of Long Beach, 96 F.4th 1255 (9th Cir. 2024) (striking an appellant's brief and dismissing an appeal for materially misrepresenting or fabricating case citations). After New Materials freely accused opposing counsel of misstating the law, New Materials’ submission of non-existent quotes is troubling (Dkt. 30 at 5 (“Chenco's argument for remand collapses under the weight of its own misreading of the law”); id.at 7 (“Chenco fundamentally misrepresents the applicable removal standard”); Dkt. 34 at 1 (“The proposed sur-reply ... is necessary to address new legal misstatements ....”); id. at 2-3 (“Chenco's failure to address this standard ... misstates controlling law and warrants correction.”)). Accordingly, the Court reminds counsel of their duties to act according to the Idaho Rules of Professional Conduct."

Fernando Betancourt Gómez v. Colegio de Profesionales Puerto Rico (USA) 22 August 2025 Lawyer Implied
Fabricated Case Law (5)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Trial court imposed a monetary sanction of $1,000 on the lawyers for causing unjustified delay; referred the lawyers to the Puerto Rico Supreme Court for disciplinary evaluation; judge inhibited from cases involving those lawyers and case to be reassigned. 1000 USD
The Meniscus Trust v Chief Commissioner of State Revenue NSW (Australia) 21 August 2025 Pro Se Litigant Google Gemini; ChatGPT Use of generative AI in submissions resulting in unverified legal citations Arguments produced by AI given lesser weight

The self-represented Applicant admitted using generative AI (Google Gemini and ChatGPT) to prepare submissions. NCAT Procedural Direction 7 requires verification of citations when Gen AI is used; the Applicant did not verify citations. The Tribunal accepted the submissions into the record but placed greater weight on primary records and noted non-compliance with the verification requirement.

In re R.L. CA Illinois (USA) 20 August 2025 Lawyer Implied
Fabricated Case Law (2)
No additional sanctions (given sanctions for Counsel in other cases)
JML Rose Pty Ltd v Jorgensen (No 3) Federal Court of Australia (Australia) 19 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (1), Legal Norm (1)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Outdated Advice Repealed Law (1)
N/A

""101    The use of AI technology in the Courts has been the subject of judicial observations, particularly regarding legal practitioners who are subject to professional and ethical obligations and responsibilities. However, as Bell CJ observed in May v Costaras [2025] NSWCA 178 at [15], with whom Payne JA and McHugh JA agreed, in the context of considering the use of AI in the preparation of submissions, that “(a)ll litigants are under a duty not to misled the court or their opponent.” The reliance on unverified materials produced by generative AI does have the potential to misled the Court.

102    Although the termed used in relation to erroneously generated references by AI is “hallucinations”, this is a term which seeks to legitimise the use of AI. More properly, such erroneously generated references are simply fabricated, fictional, false, fake and as such could be misleading.

103    All persons appearing before the Court have a duty to verify that the case law and legislation referred to and relied on, is accurate and that such materials actually exist. The references in Ayinde at [85] and [86] and in Costaras at [14]-[15], to matters involving litigants who are acting in person who rely on AI generated material clearly supports the position that all are required to verify the submissions made to the Court. There are many publicly available legal research websites, some which are accessible without a fee. Further, and without attempting to be exhaustive, the Queensland Supreme Court library is open and available to the public.

104    The use of generative AI to prepare submissions that may include fake authorities will nearly always introduce added costs, complexity and add to the burden of other parties and to the Court: Costaras at [16] and [49]. I gratefully adopt the observation from Ayinde at [9] that “(t)here are serious implications for the administration of justice and public confidence in the justice system if artificial intelligence is misused.” The Court in Ayinde observed from [10] to [31] the existing guidance, regulatory duties of the profession, referrals and the Court’s powers. Matters which are within the Court’s own domain include in the most serious of cases contempt of Court. The observations in Ayinde at [26]-[28] regarding contempt of court are not limited to legal practitioners.

105    As the reasons above demonstrate, the circumstances of this case involved many fake authorities, fabricated quotes and false propositions. It is unhelpful for the Court to be referred to, and for parties to rely on, such matters."

Lahti v. Consensys Software Inc. S.D. Ohio (USA) 19 August 2025 Pro Se Litigant Implied
Fabricated Case Law (3)
Misrepresented Case Law (1)
Submission Stricken

"The case at bar epitomizes the concern. Inordinate judicial resources were expended on reviewing cases cited by Plaintiff that did not exist. No doubt Plaintiff’s opponent in this litigation was forced to expend similar energies. Here, too, as noted, certain cases Plaintiff cited in support of her arguments stood for the opposite result from that which Plaintiff stated in her briefs. This kind of activity not only wastes precious and limited judicial resources, but it also drives up the cost of litigation unnecessarily for those who must defend against or seek to prosecute claims on behalf of paying clients, given the underpinnings of the American Rule that attaches to most civil litigation in this country."

Clark v. JPMorgan Chase Bank, N.A. E.D. Michigan (USA) 19 August 2025 Pro Se Litigant Implied
Fabricated Case Law (3)
Misrepresented Case Law (1)
Plaintiff's motion denied as frivolous; reply and sur-reply struck; plaintiff ordered to show cause
Source: Jesse Schaefer
Garces v. Hernandez Fifth Circuit CA (USA) 19 August 2025 Pro Se Litigant Implied
Fabricated Case Law (5)
Admonishment and Warning
Williams v. Kirch CA Indiana (USA) 18 August 2025 Pro Se Litigant Implied
Fabricated Case Law (3)
Admonishment
In re Sonja Helvig DeRosa-Grund S.D. Texas (Bankruptcy) (USA) 18 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (1)
False Quotes Case Law (2)
Case dismissed with prejudice for one year

The debtor, Sonja Helvig DeRosa-Grund, engaged in substantial abuse of the Chapter 13 process by filing numerous frivolous motions and making false allegations against opposing counsel. The debtor repeatedly cited non-existent case law and fabricated quotes from existing cases, despite being warned about this behavior. The court dismissed the case with prejudice for one year, terminated the debtor's ECF filing privileges, and imposed additional protective measures to prevent future abuse. The court found that the debtor violated Bankruptcy Rule 9011(b) by making arguments based on non-existent case law and misquoting cases.

Wang v Moutidis County Court of Victoria (Australia) 18 August 2025 Pro Se Litigant Gen AI
Fabricated Case Law (2)
False Quotes Exhibits or Submissions (1)
Misrepresented Case Law (1), Exhibits or Submissions (1)
Arguments disregarded
WCAT Decision A2501051 (Hilary Thomson) BC Workers' Compensation Appeal Tribunal (Canada) 18 August 2025 Pro Se Litigant Implied
Fabricated Case Law (2)
Misrepresented Case Law (1)
Outdated Advice Repealed Law (1)
Clonan v. Centrastate Healthcare system D. New Jersey (USA) 15 August 2025 Pro Se Litigant Westlaw (and others unidentified)
False Quotes Case Law (3)
Warning
Maxwell v. WestJet Airlines Ltd. Civil Resolution Tribunal (Canada) 15 August 2025 Pro Se Litigant ChatGPT
Fabricated Case Law (1)
Misrepresented Exhibits or Submissions (1)
Outdated Advice Repealed Law (1)
Argument given no weight
Source: Steve Finlay
in re: Nasser E.D. Michigan (Bankruptcy) (USA) 15 August 2025 Lawyer Implied
False Quotes Exhibits or Submissions (1), Legal Norm (1)
Misrepresented Legal Norm (1)
Warning
Source: Jesse Schaefer
JNE24 v Minister for Immigration and Citizenship Federal Circuit and Family Court (Australia) 15 August 2025 Lawyer Claude AI, Microsoft Copilot
Fabricated Case Law (1)
Misrepresented Case Law (1)
Referral to the Bar; Personal costs order against lawyer (who reimbursed his client) 8371 AUD
Kuzniar v General Dental Council Employment Tribunal (UK) 15 August 2025 Pro Se Litigant ChatGPT
Fabricated Case Law (1)
False Quotes Case Law (1)
Misrepresented Case Law (1)
Tribunal declined to award costs
Director of Public Prosecutions v GR Supreme Court of Victoria (Australia) 14 August 2025 Lawyer Unidentified
Fabricated Case Law (2), Legal Norm (2)
False Quotes Doctrinal Work (2)
Misrepresented Case Law (1)
N/A

The court identified issues with the use of artificial intelligence in preparing written submissions. The submissions contained fabricated citations and fictitious quotes, which were initially filed as joint submissions by the defense and prosecution. Upon discovery, the defense counsel took responsibility, citing the use of AI without proper verification. The court allowed revised submissions to be filed, emphasizing the importance of accuracy in legal documents and the responsible use of AI. No professional sanctions or monetary penalties were imposed, but the court reiterated the need for adherence to guidelines on AI use in litigation.

Monster Energy Company v. John H. Owoc S.D. Florida (USA) 14 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (1)
Community service and certification requirement for future filings

The court imposed sanctions under Rule 11, requiring Mr. Owoc to complete 10 hours of community service and to certify the accuracy of legal citations in future filings if AI is used. No monetary penalty was imposed.

Johnny McMurry, Jr. v. Neiders Company LLC, et al. W.D. Washington (USA) 14 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1)
Court admonished plaintiff for citing a non-existent case and warned of potential Rule 11 sanctions; no sanction imposed.
Woody Nora v. M & A Transport, Inc., et al. E.D. Louisiana (USA) 13 August 2025 Lawyer Implied
Fabricated Case Law (2)
Misrepresented Case Law (2)
Monetary Sanction; 1 hour of CLE on Generative AI; referral to the Disciplinary Committee. 1000 USD
Source: Volokh
Oready, LLC (1) GAO (USA) 13 August 2025 Pro Se Litigant Implied
Fabricated Case Law (4)
Misrepresented Case Law (1)
Warning

"Second, the protester's explanation--that it was “manual mismatches in secondary summaries” that caused the citation errors (Protester's Resp., Aug. 8, 2025, at 1)--does not meaningfully explain the number of citation errors in the protester's filings. Indeed, Oready's patently erroneous citations are far removed from mere typographical or scrivener's errors, and instead, bear the hallmarks of the use of a large-language model or other artificial intelligence (AI) without adequate verification that the generated results were accurate. "

Goya v. Hayashida CA Florida (4th D) (USA) 13 August 2025 Pro Se Litigant Implied
Fabricated Case Law (2)
Warning

" We have the authority to sanction Wife under Florida Rule of Appellate Procedure 9.410(a) for failure to comply with Florida Rule of Appellate Procedure 9.210(c). See Gutierrez v. Gutierrez, 399 So. 3d 1185, 1188 (Fla. 3d DCA 2024). However, we decline to do so. Our decision is tempered by the fact that Wife is defending a judgment on appeal in an unrepresented capacity, Husband has not sought the imposition of sanctions, and Wife has not brought any other meritless or frivolous filings in this Court. See id. at 1187–88; Al-Hamim, 564 P.3d at 1125–26. Instead, we admonish Wife for her counterfeit brief and warn her that the Court will not regard similar infractions as mildly in the future. "

Meital Kasantini v. Hagiva'a Proyectim Handasiim Ltd Ashdod Magistrate Court (Israel) 12 August 2025 Lawyer Unidentified
Fabricated Case Law (1)
The court imposed a monetary penalty and dismissed the fabricated evidence. 1000 ILS
MS (Bangladesh) Immigration and Asylum Chamber (UK) 12 August 2025 Lawyer ChatGPT
Fabricated Case Law (1), Exhibits or Submissions (1)
Referred to the Bar Standards Board for investigation

Underlying judgment (in which the hallucination had been observed) is here.

Holloway v Beckles First-tier Tribunal (UK) 12 August 2025 Pro Se Litigant Unidentified
Fabricated Case Law (1)
Costs Order 750 GBP
Herr v. Elos Environmental, LLC E.D. Louisiana (USA) 11 August 2025 Pro Se Litigant Implied
Fabricated Case Law (2)
False Quotes Case Law (1)
Warning
Source: Jesse Schaefer
Lori Chavez-DeRemer v. NAB, LLC, Asia Trinh, and Nicole Brown D. Nevada (USA) 11 August 2025 Pro Se Litigant Implied
Fabricated Case Law (1)
Misrepresented Case Law (1)
Warning
Source: Jesse Schaefer