AI Citation Sanctions Roundup, Week 6: EDNY Finds a Rule 11 Violation, Then Corrects Its Own Hallucination Finding
Short answer: between October 2 and October 15, 2026, EDNY held that defense counsel violated Rule 11 by citing cases he found with an AI tool and never checked, then corrected its own finding that one case was fabricated. W.D. Wis. admonished counsel; S.D. Cal. declined an order to show cause.
This roundup picks up where our week five roundup stopped, with orders dated October 1 or later. The AI Hallucination Cases database lists 27 United States entries dated October 1 through 15, 2026, 22 of them pro se. We report only lawyer orders we read in full and matched against a court or government copy.
What did EDNY decide in Mercante v. Tarzia?
On October 2, 2026, Chief Judge Margo K. Brodie issued a Memorandum and Order in Mercante v. Tarzia, No. 24-CV-8471 (MKB) (E.D.N.Y.), ECF No. 114. Plaintiff appealed Magistrate Judge Lara K. Eshkenazi’s refusal to issue an order to show cause over defense citations. Counsel first called the errors “clerical numbering errors,” then admitted using a Westlaw AI tool to identify cases without confirming them.
Of five citations in ECF No. 88, the court found that one, A.M. v. City of New York, was “a hallucination: this case does not exist and is fictitious.” Two others were real cases whose database identifiers pointed to unrelated decisions. It held: “The Court therefore finds that defense counsel violated Rule 11.”
It still affirmed: under Rule 72(a), the magistrate judge’s choice to admonish rather than sanction was not “clearly erroneous or is contrary to law.” The decision, it added, “is not an endorsement or approval of defense counsel’s actions.”
Why did the Mercante court correct its own hallucination finding?
On October 15, 2026 (Filing 118), the court changed course. It wrote that “A.M. v. City of New York, 21-CV-5191, 2022 WL 20472225 (E.D.N.Y. Aug. 8, 2022) is a genuine decision.” Counsel had “cited to the incorrect database identifier of 2022 WL 17543173.” The court corrected the October 2 decision where it called the case “an obvious hallucination.”
The Rule 11 finding survived. The court said it “did not rest solely on its finding that” the case was hallucinated, but also on counsel’s admission “to using AI to identify cases without checking those propositions and citations to confirm their accuracy.” Quoting Park v. Kim, 91 F.4th 610, 615 (2d Cir. 2024), it restated the duty to “read, and thereby confirm the existence and validity of, the legal authorities on which they rely.” Proving a case exists afterward does not cure the failure to read it first.
W.D. Wis.: Duckett v. Board of Regents of the University of Wisconsin System
On October 7, 2026, District Judge James D. Peterson dismissed Duckett v. Board of Regents, No. 25-cv-684-jdp (W.D. Wis.), Dkt. 23, with prejudice. In footnote 9, the court noted that “defendants pointed out in their reply brief that the cited case does not exist.” Plaintiffs’ counsel then acknowledged using “artificial intelligence to help conduct research,” withdrew that citation, and withdrew a quotation attributed to Payan v. L.A. Cmty. Coll. Dist., 11 F.4th 729 (9th Cir. 2021), “that they admit does not exist.”
No sanction issued. AI use is not prohibited, the court said, but counsel must “read their filings and take reasonable care to avoid misrepresentations, factual and legal,” and “Plaintiffs’ counsel failed to do that in the case.” Then: “The court expects plaintiffs’ counsel to do better the next time they litigate in this court.”
S.D. Cal.: a misquoted case in MeetingTV v. KOI Security
On October 2, 2026, Magistrate Judge Michelle M. Pettit denied expedited discovery in MeetingTV, Inc. v. KOI Security Inc., No. 26-cv-1705-AJB-MMP (S.D. Cal.), ECF No. 58. The motion quoted Pod-Ners, LLC v. Northern Feed & Bean of Lucerne Ltd., 204 F.R.D. 675 (D. Colo. 2002). “As Defendant correctly observes, the language Plaintiff quotes does not appear in Pod-Ners.” Plaintiff said it had “inadvertently misquoted what should have been stated without quotation marks.”
The court noted the filing attorney “has been terminated from the case,” stated that “the Court does not issue an Order to Show Cause at this time,” and added: “The Court reminds parties of their Rule 11 obligations and potential penalties for misrepresentations to the Court.”
The rule text behind this week’s orders
| Provision | Operative language | Source read |
|---|---|---|
| Fed. R. Civ. P. 11(b)(2) | “the claims, defenses, and other legal contentions are warranted by existing law or by a nonfrivolous argument for extending, modifying, or reversing existing law or for establishing new law” | law.cornell.edu |
| Fed. R. Civ. P. 11(c)(3) | “On its own, the court may order an attorney, law firm, or party to show cause why conduct specifically described in the order has not violated Rule 11(b).” | law.cornell.edu |
| Fed. R. Civ. P. 11(c)(4) | “A sanction imposed under this rule must be limited to what suffices to deter repetition of the conduct or comparable conduct by others similarly situated.” | law.cornell.edu |
| Fed. R. Civ. P. 72(a) | “A party may serve and file objections to the order within 14 days after being served with a copy.” | law.cornell.edu |
| Fed. R. Bankr. P. 9011(b)(2) | “the claims, defenses, and other legal contentions are warranted by existing law or by a nonfrivolous argument to extend, modify, or reverse existing law, or to establish new law” | law.cornell.edu |
| Cal. Code Civ. Proc. § 128.7(b)(2) | “The claims, defenses, and other legal contentions therein are warranted by existing law or by a nonfrivolous argument for the extension, modification, or reversal of existing law or the establishment of new law.” | california.public.law and codes.findlaw.com, agreeing |
| 22 NYCRR 130-1.1(c)(1) | Conduct is frivolous if “it is completely without merit in law and cannot be supported by a reasonable argument for an extension, modification or reversal of existing law” | law.cornell.edu |
Drafting-ready text: an AI research verification statement
If a court asks how your citations were checked, this declaration tracks what Mercante and Duckett found missing. Check the assigned judge’s own order first; see our AI disclosure tracker.
DECLARATION OF [NAME] RE: VERIFICATION OF AUTHORITIES I, [NAME], declare: 1. I am counsel of record for [PARTY] and signed [DOCUMENT]. 2. [No generative AI tool was used to locate authority.] OR [I used [TOOL] to identify potential authorities.] 3. Before filing, I or [NAME], under my supervision, retrieved and read each cited authority, confirmed that the case name, reporter or database identifier, and pin cite match the decision retrieved, and confirmed that it supports the proposition for which it is cited. 4. Each quotation was compared word for word against the source. I declare under penalty of perjury under the laws of the United States of America that the foregoing is true and correct. Executed on [DATE] at [CITY, STATE]. _______________________ [NAME]
Worked example: the 14-day Rule 72(a) objection clock
Mercante reached the district judge as an objection to a magistrate judge’s non-dispositive ruling. Assume such an order is served through CM/ECF on Friday, October 2, 2026. Rule 6(a)(1) says to “exclude the day of the event that triggers the period” and “count every day, including intermediate Saturdays, Sundays, and legal holidays.”
- Day 0: Friday, October 2 (excluded).
- Days 1 to 14: October 3 through October 16. Columbus Day, Monday, October 12, falls inside and counts.
- Last day: Friday, October 16, 2026. Not a weekend or legal holiday, so nothing rolls forward.
- Then the standard: “clearly erroneous or is contrary to law.” The Mercante movant lost on it despite a Rule 11 finding.
Cross-jurisdiction contrast, limited to what we verified today
Federal district court. All three courts chose words over money, though Rule 11(c)(3) lets a court act on its own. See Rule 11 and the AI-Generated Brief.
Bankruptcy court. Rule 9011(b)(2) carries the same certification. No bankruptcy decision was verified this window.
California state court. Section 128.7(b)(2) mirrors the federal text, and a motion is filed only if the paper is not corrected “within 21 days after service of the motion, or any other period as the court may prescribe.” The MeetingTV misquote in a superior court filing would fall under section 128.7.
New York state court. Part 130 is a separate costs regime: conduct is frivolous if “completely without merit in law.” Mercante is federal and says nothing about Part 130. Sanctions, discipline, and malpractice are separate tracks; none of these three orders makes a referral.
Pre-filing checklist
- Read every case an AI tool surfaces before you cite it. Mercante held that is the duty, whether or not the case turns out to exist.
- Copy the database identifier from the decision you actually opened. A wrong WL number made a real case look fake to the court.
- Assume opposing counsel will check, as in Duckett and MeetingTV.
- Never put a paraphrase inside quotation marks. That is how the MeetingTV misquote happened.
- Run our pre-filing citation verification protocol and keep the log; see the longer sanctions record.
Have someone read every cite before you sign
Our citation verification service does the step Mercante found missing: a person reads every authority in your brief, checks each identifier and pin cite, and compares each quotation word for word. You get a log you can rely on if a court asks. See citation and rule compliance review.
Authorities cited
Mercante v. Tarzia, No. 24-CV-8471 (MKB) (E.D.N.Y. Oct. 2, 2026), ECF No. 114, read in the AI Hallucination Cases database PDF and in the Justia copy of Filing 114; the October 15, 2026 order (Filing 118) read at Justia. Duckett v. Board of Regents of the University of Wisconsin System, No. 25-cv-684-jdp (W.D. Wis. Oct. 7, 2026), Dkt. 23, read in the database PDF and at govinfo.gov. MeetingTV, Inc. v. KOI Security Inc., No. 26-cv-1705-AJB-MMP (S.D. Cal. Oct. 2, 2026), ECF No. 58, read in the database PDF and at govinfo.gov. Park v. Kim is quoted only as the Mercante court quoted it. Rule text read today at law.cornell.edu: Fed. R. Civ. P. 6, 11 and 72, Fed. R. Bankr. P. 9011, 22 NYCRR 130-1.1. Section 128.7 read on california.public.law and codes.findlaw.com, agreeing.
Left out for lack of verification. Glenn v. Absolute Resolutions Investments, LLC (M.D. Fla. Oct. 9, 2026) had no court or government copy we could find. Deen v. VMK, Inc. (Cal. Ct. App. Oct. 13, 2026, H053576, nonpub.): the courts.ca.gov PDF could not be retrieved. Kid International, LLC v. City National Bank of Florida (Fla. 4th DCA) was not located in a second source. A September 18, 2026 Mercante sanctions ruling on other issues was not read. Pro se entries were not reviewed.
This article is for informational purposes only and is NOT legal advice. LegalBriefsUSA.com provides drafting and research support to licensed attorneys and law firms. This article is written for attorneys and does not create an attorney-client relationship.