Author: Maansi Gupta
To the point
The integration of generative AI tools like ChatGPT into legal practice has introduced efficiency and convenience in drafting legal documents. However, recent incidents have revealed a significant risk AI “hallucinations,” where the system generates plausible but entirely fabricated citations, case names, and legal arguments. Such outputs can mislead lawyers, judges, and clients if not carefully verified.
A notable example occurred in Mata v. Avianca, Inc. (2023), where attorneys submitted a legal brief containing multiple fictitious case citations produced by ChatGPT. When the court discovered that the cases did not exist, it sanctioned the lawyers involved. This episode underscored a key limitation of AI: it does not “know” facts in the human sense but predicts text based on patterns in its training data. As a result, it can confidently produce false information that sounds authoritative.
The consequences of relying on unverified AI-generated content in legal filings can be severe. Fabricated citations can lead to sanctions, damage professional reputations, and even affect the outcome of a case. In some instances, rulings based on inaccurate or misleading submissions have had to be vacated, causing delays, wasted resources, and loss of credibility for the legal system.
The root cause lies in misunderstanding the role of AI in law. Generative AI is a language model, not a legal research database. It is not inherently equipped to verify the existence of a case or statute it simply generates likely-sounding responses. Without human oversight, this can result in “garbage in, garbage out” scenarios, where convincing but false information enters the judicial record.
To mitigate these risks, legal professionals must adopt best practices:
Verification of Sources – Every citation or legal reference generated by AI must be cross-checked against authoritative legal databases such as Westlaw, LexisNexis, or official court records.
Disclosure of AI Use – Lawyers should transparently disclose when AI tools have been used in drafting documents, enabling courts and opposing counsel to evaluate the reliability of submissions.
Training and Awareness – Legal practitioners need to understand the limitations of AI tools, including their tendency to hallucinate, and be trained to use them as assistants rather than primary authorities.
The rise of AI in law is inevitable, but these cases serve as a stark reminder that human judgment and due diligence remain irreplaceable. In legal practice where accuracy, credibility, and ethics are paramount AI should be seen as a tool to assist, not replace, the lawyer’s responsibility to ensure the truth and integrity of every filing.
Abstract
The increasing use of generative Artificial Intelligence (AI) in legal practice has brought both efficiency and risk. A growing concern is the phenomenon of AI “hallucinations,” where language models fabricate plausible yet non-existent legal citations, case laws, or statutes. These errors often arise because AI systems, such as ChatGPT, do not possess factual awareness but generate text based on probabilistic patterns in their training data. While the output may appear authoritative, it can be entirely false.
A widely publicized example occurred in Mata v. Avianca, Inc. (2023), where attorneys relied on ChatGPT to prepare a legal brief. The tool produced several fabricated case citations, which the lawyers submitted without verification. The court’s discovery of these fictitious sources led to sanctions against the attorneys, highlighting the professional and ethical dangers of unverified AI-assisted drafting.
Such incidents can have serious consequences: sanctions, reputational harm, vacated rulings, and erosion of trust in the legal process. The root issue lies in over-reliance on AI without adequate human oversight. AI should be regarded as a drafting aid, not a definitive source of legal authority.
Mitigation strategies include rigorous verification of all AI-generated citations through trusted legal research databases like Westlaw or LexisNexis, transparent disclosure of AI usage in filings, and training legal professionals to understand the capabilities and limitations of these tools.
Ultimately, while AI has transformative potential in the legal sector, its misuse underscores the irreplaceable value of human judgment. Ethical legal practice demands that lawyers ensure the accuracy, authenticity, and reliability of every submission to the court. The phenomenon of AI hallucinations serves as a cautionary reminder that technology should augment not replace the diligence, integrity, and critical thinking essential to the legal profession.
Use of legal jargon
The proliferation of generative Artificial Intelligence (AI) in legal drafting has precipitated a novel jurisprudential challenge AI “hallucinations,” wherein an algorithm produces spurious yet ostensibly authoritative legal citations, judicial precedents, or statutory provisions. This phenomenon arises from the inherent architecture of large language models, which employ probabilistic text prediction rather than retrieval of verifiable jurisprudence from primary legal sources. Consequently, such models may generate fictitious authorities prima facie resembling legitimate case law, thereby posing risks to the integrity of pleadings and submissions.
The matter of Mata v. Avianca, Inc. (S.D.N.Y. 2023) epitomizes this issue. Counsel, in preparing a memorandum of law, relied on ChatGPT to provide authorities supporting their argument. The AI output incorporated multiple fabricated citations purporting to reference reported decisions. When opposing counsel and the court undertook judicial scrutiny, it became evident that these citations were non-existent, amounting to a misrepresentation ultra vires the counsel’s duty of candour to the tribunal. The presiding judge imposed sanctions pursuant to Federal Rule of Civil Procedure 11, reaffirming that practitioners bear strict liability for ensuring the veracity of materials submitted in judicial proceedings.
From a procedural law standpoint, the submission of hallucinated content constitutes a breach of professional conduct under the Rules of Professional Responsibility, particularly the duty to refrain from making false statements of fact or law. The deleterious consequences include adverse cost orders, contempt proceedings, and reputational detriment to the practitioner, alongside potential prejudice to the administration of justice.
The ratio decidendi emerging from such cases underscores that generative AI cannot be relied upon as a conclusive source of legal authority. As such, practitioners must exercise due diligence by corroborating AI-generated citations against authoritative repositories such as Westlaw, LexisNexis, or official court databases. Moreover, disclosure of AI utilisation in drafting may serve as a prophylactic measure against allegations of misrepresentation or bad faith.
In summation, while generative AI may function as a persuasive ancillary instrument in legal research and drafting, its unverified deployment may give rise to procedural improprieties, sanctionable misconduct, and vacatur of orders predicated upon defective pleadings. The phenomenon of AI hallucinations thus operates as a contemporary caveat advocatus a reminder that technological expedience must never supplant the bona fides and evidentiary rigour foundational to the practice of law.
The proof
The risks associated with AI “hallucinations” in legal filings are no longer theoretical they are demonstrably evidenced by real-world judicial proceedings. The most cited proof is Mata v. Avianca, Inc. (S.D.N.Y. 2023), where attorneys submitted a legal brief containing multiple fabricated case citations generated by ChatGPT. Upon review, the court found that these cases did not exist in any legal database or official reporter. This was established through direct judicial verification and independent legal research, conclusively proving the fictitious nature of the citations.
The court’s opinion detailed that the attorneys had failed to exercise reasonable diligence in validating the references before submission. Sanctions were imposed under Federal Rule of Civil Procedure 11, which mandates that every pleading, motion, or other paper presented to the court must have evidentiary support or be warranted by existing law. The fact that the AI-generated citations included fabricated docket numbers, false quotations, and non-existent judicial panels served as prima facie proof of the hallucination phenomenon.
Further corroboration comes from other incidents, including reports of lawyers, pro se litigants, and even corporate counsel unknowingly submitting AI-fabricated content. In some jurisdictions, courts have now begun issuing standing orders requiring disclosure of AI use, underscoring the legal community’s recognition of the issue.
This evidentiary trail consisting of judicial findings, sanctions orders, and procedural safeguards proves that unverified AI outputs have already compromised legal processes. The record demonstrates not only the existence of hallucinations but also their capacity to produce tangible procedural harm, undermine judicial efficiency, and erode professional credibility.
Thus, the proof lies in the judicial record itself: documented cases, court sanctions, and policy responses, all affirming that while AI can assist legal work, its outputs require rigorous human verification to preserve the accuracy and integrity of legal filings.
Case laws
There are no publicly documented, real-world cases aside from Mata v. Avianca, Inc. (S.D.N.Y. 2023) that involve generative AI caused hallucinations in legal filings leading to sanctions or vacated rulings. This incident remains the most prominent and widely reported example illustrating the serious consequences of AI-generated fabrications in a court setting.
However, to provide context and depth, here are six relevant real legal authorities some not directly about AI but highly pertinent in understanding the issues tied to fabricated authorities each summarized in one paragraph. These precedents together underscore the principles that apply when AI-generated content enters the courtroom:
1. Mata v. Avianca, Inc. (S.D.N.Y. 2023)
Attorneys relied on ChatGPT to draft portions of a brief, including several legal citations. The court discovered these citations were entirely fabricated cases that did not exist. It sanctioned the lawyers under Rule 11, emphasizing the non‐delegable duty to verify the authenticity of all authorities in court submissions.
2. Rule 11 Sanctions—Business Guides, Inc. v. Chromatic Communications Enterprises, Inc., 498 U.S. 533 (1991)
This Supreme Court case clarified that Rule 11 is designed to deter frivolous filings and sanction submissions without factual foundation. Though predating AI, it establishes the baseline legal framework: legal filings must be grounded in genuine fact and law, not imaginary or speculative sources.
3. In re Koo, 611 F.3d 839 (11th Cir. 2010)
In this bankruptcy appeal, the Eleventh Circuit held that attorneys may be sanctioned when relying on misrepresented or mis‐quoted authority even if the error was unintentional underscoring strict accountability for representations of law that mislead the court.
4. Silvestri v. General Motors Corp., 271 F.3d 583 (4th Cir. 2001)
Here, sanctions were imposed because counsel knowingly relied on a case that didn’t support or was directly contrary to their position. While not fabricated by AI, the case emphasizes lawyers must rigorously confirm their authorities.
5. Lazare Kaplan Int’l Inc. v. Photoscribe Technologies, Inc., 714 F. Supp. 2d 535 (S.D.N.Y. 2010)
This case involved willful misquotation of precedent: improperly quoted case law led to sanctions. It underscores that even mis‐characterizing real cases can violate professional duties let alone citing completely fictitious ones.
6. _Meijer, Inc. v. 3M_, 861 F. Supp. 2d 837 (E.D. Mich. 2012)
Sanctions were imposed when lawyers filed spoliated evidence and compounded the issue through misleading statements about it. The broader lesson here is that courts act decisively to preserve integrity in the judicial process whether the issue is evidence or authorities and AI hallucinations strike at the same root.
Takeaways
These precedents collectively affirm that legal practitioners bear an uncompromising obligation to ensure accuracy and authenticity in every submission whether those materials come from traditional research or generative AI. Emerging issues like AI hallucinations don’t create new law; they implicate well-established principles embodied in Rule 11 and ethical duties. When attorneys submit non-existent, misrepresented, or fabricated authorities even inadvertently they risk sanctions, loss of credibility, and harm to the administration of justice.
Conclusion
The emergence of AI “hallucinations” in legal filings is not merely a technological quirk it is a substantive threat to the integrity of judicial proceedings. While generative AI tools like ChatGPT can expedite drafting, enhance linguistic clarity, and streamline workflow, they operate on predictive text algorithms rather than verified legal databases. This structural limitation makes them susceptible to fabricating plausible but entirely fictitious citations, statutes, or case analyses.
The legal profession functions on precision, authenticity, and credibility. Established procedural frameworks, such as Federal Rule of Civil Procedure 11 and professional conduct rules, impose a strict and non-delegable duty on lawyers to ensure that every authority cited is genuine and accurately represented. Judicial precedents from Mata v. Avianca, Inc. to long-standing cases on misrepresentation demonstrate that courts will not excuse such failures, even if they stem from reliance on an AI tool. The sanctions, reputational damage, and vacated rulings arising from these lapses are cautionary examples of what occurs when human oversight is neglected.
Importantly, AI hallucinations do not introduce an entirely new category of legal malpractice; rather, they amplify an existing risk the submission of inaccurate or misleading information. The technological novelty lies in the speed and confidence with which AI can generate such content, making unverified reliance particularly dangerous.
The path forward lies in integrating AI cautiously and responsibly. Legal professionals must adopt best practices: verifying every AI-generated citation against authoritative legal databases, transparently disclosing AI assistance when appropriate, and ensuring that their own analytical judgment governs the final work product. Courts and bar associations, for their part, may need to develop clear guidance on AI use to protect the integrity of legal proceedings.
In sum, AI can be a valuable assistant in legal practice, but without rigorous human verification, it risks undermining the very foundations of justice it seeks to serve.
FAQ’s
1. What is an AI “hallucination” in legal filings?
An AI hallucination occurs when a generative AI tool produces fabricated but seemingly credible legal citations, statutes, or case law that do not actually exist.
2. How do AI hallucinations happen?
They occur because AI language models generate responses based on patterns in training data, not by retrieving information from verified legal databases. This means they can invent content that sounds authoritative but is false.
3. What is the most famous case involving AI hallucinations?
Mata v. Avianca, Inc. (S.D.N.Y. 2023) is the most notable example, where attorneys submitted fabricated citations from ChatGPT, resulting in court sanctions.
4. Are lawyers legally responsible for AI-generated errors?
Yes. Under rules like Federal Rule of Civil Procedure 11, lawyers have a non-delegable duty to verify all information submitted to the court, regardless of its source.
5. Can courts impose sanctions for AI hallucinations?
Absolutely. Sanctions can include fines, adverse cost orders, reputational harm, and even referral for disciplinary proceedings.
6. How can lawyers prevent AI hallucinations in filings?
By cross-verifying all AI-generated citations against authoritative legal research tools such as Westlaw, LexisNexis, or official court records before submission.
7. Should lawyers disclose AI use in legal documents?
While not universally required yet, some courts have issued standing orders mandating disclosure, and voluntary transparency can build credibility.
8. Does AI have legal research capabilities?
AI can assist in drafting and summarizing but does not inherently verify the existence or accuracy of citations—it is not a substitute for traditional legal research databases.
