What to do if a hallucinated citation already reached a filing

In Mata v. Avianca, Inc., No. 22-cv-1461 (PKC) (S.D.N.Y.), Judge P. Kevin Castel issued an Opinion and Order on Sanctions on June 22, 2023. The CourtListener docket records sanctions under Rule 11, or alternatively the court's inherent authority: a $5,000 penalty jointly and severally, and letters to the plaintiff and to each judge falsely identified as the author of nonexistent opinions named in the order. The opinion text is also on Justia.

The useful lesson is not that a tool is banned. A filing left the office without a documented verification step. The court treated the lawyers as responsible for what was submitted. That fact pattern is why firms need an incident path in the written AI policy—not only a pre-filing preference to "double-check."

What ABA Formal Opinion 512 and California Practical Guidance add

ABA Formal Opinion 512 (July 29, 2024) maps generative-AI use onto existing Model Rules. Under Rule 3.3 themes, a lawyer may not knowingly make a false statement of law or fact to a tribunal, and must correct a material false statement the lawyer previously made. Uncritical reliance on generated output can also implicate Rule 1.1 competence. Rules 5.1 and 5.3 put the supervisory duty on the lawyers who manage the firm.

California attorneys should also read the California State Bar Practical Guidance on the Use of Generative Artificial Intelligence in the Practice of Law (November 2023) alongside Opinion 512. The Practical Guidance reinforces confidentiality, competence, and supervision themes for generative tools in California practice. It is California State Bar ethics guidance—not a Bar endorsement of any course or vendor. Neither Opinion 512 nor the Practical Guidance replaces that court's rules on how to correct a filed paper. Neither document invents a single nationwide correction statute.

Crisis playbook: already filed / verify / correct / disclose as appropriate

Stay high-level. Local procedure controls how a particular tribunal wants a correction. The checklist below is a practitioner sequence grounded in candor and competence themes from Opinion 512 and the Practical Guidance—not a substitute for counsel admitted in the matter.

1. Already filed — stop relying. Stop treating the citation as authority. Do not quote it again in a letter, a reply brief, a meet-and-confer email, or an oral argument outline.
2. Verify the scope. List every citation, quote, and legal proposition that came from a generative tool, or that nobody can point to in a reporter or on the docket. One fake cite often means the same draft contains more unverified material.
3. Notify supervising counsel the same day. Do not wait for opposing counsel or the court to discover it first. Supervisors need the inventory, the filing date, and how the text entered the draft.
4. Correct as that court requires. How you correct it depends on that court's rules and the posture of the case. Many courts respond better to a voluntary notice of errata, a corrective letter, or another formal withdrawal of fabricated authority than to silence. A lawyer admitted in the matter has to make that call. This page does not invent a procedural statute or a universal form.
5. Disclose to the client if material. Tell the client if the error is material to the representation. What counts as material is a judgment for counsel on that matter under communication duties (Rule 1.4 themes).
6. Keep the record. Do not delete the prompts, the draft, the chat export, or the review notes. Preserve what you will need to explain what happened and what you changed.
7. Harden the firm policy after the filing is corrected. Write the miss into the firm AI policy: who may use which tool, what may never be pasted into a consumer chatbot, and which citations require a signed check before the next filing leaves the office. See what a firm AI policy should include.

Voluntary correction framing (high-level)

Voluntary correction is about candor: once you know a citation is false or unverifiable, continuing to leave it in place for the tribunal creates a separate problem from the original miss. Opinion 512's Rule 3.3 themes and the Practical Guidance's competence themes both push toward prompt, documented remediation rather than hope that nobody notices.

Voluntary correction is not a compliance guarantee. It does not promise that a court will decline sanctions, that an opposing party will stay silent, or that an insurer or client will treat the matter as closed. It is a practitioner posture: identify, inventory, notify, correct under local rules, document, and prevent recurrence. Compare syllabi and firm policies against Opinion 512 and the Practical Guidance; do not treat marketing copy as a court order.

What not to do

• Do not cover up a citation you now know is false.
• Do not leave the false authority in place hoping nobody finds it.
• Do not destroy the tool output, prompts, or drafts after the miss is discovered.
• Do not quote the same citation again while "looking into it."
• Do not treat a one-line email as the firm's only remedial step. Put verification and supervision in the written policy.
• Do not assume a dashboard "regenerate" fixed the legal proposition. Verification is against primary sources, not against another generative pass.

After the correction

Once the tribunal record is addressed under that court's rules, shift to prevention. Name approved tools. Ban paste destinations that cannot meet confidentiality expectations. Require a human citation check before filing. Train associates and staff—Rules 5.1 and 5.3 are not satisfied by a prohibition alone. Ask vendor questions in writing before the next pilot has client files in it: vendor questions before you sign.

Related: what a firm AI policy should include. For a longer California-framed incident companion, see California attorney: AI hallucinated citation already filed. For CLE that maps Opinion 512 and the Practical Guidance, see California MCLE that covers ABA Formal Opinion 512.

FAQ

What to do if a hallucinated citation already reached a filing?

Stop treating the citation as authority. Inventory every citation and proposition that came from a generative tool or that nobody can verify. Tell supervising counsel the same day. Correct the tribunal under that court's rules. Tell the client if the error is material. Keep the prompts and drafts. Then write the miss into the firm AI policy.

What do I do if ChatGPT invented a case citation I already filed?

Act the same day. Do not cover it up. File a corrective notice or otherwise correct the record as that court's rules require, explain what happened, and put verification gates in place so the next filing does not leave without a check.

What should I not do after discovering a fake citation in a filing?

Do not quote the citation again. Do not delete the prompts or drafts. Do not hope opposing counsel misses it. Hiding a known false citation is a separate candor problem from the original miss.

Does voluntary correction eliminate sanctions risk after a hallucinated citation is filed?

No. Correction is about candor and competence under themes in ABA Formal Opinion 512 and California Practical Guidance; it does not guarantee a court, opposing party, insurer, or client will treat the matter as closed. Follow that court's rules and counsel admitted in the matter.

The on-demand California MCLE course is $249. It includes the five modules, the 111-page reading, and the 35-question assessment. California MCLE accreditation is pending. The certificate is issued when the provider number is assigned. The course does not guarantee compliance, prevent sanctions, or satisfy a court, insurer, or client.

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