Cartagena v. Dixon

What sanction did the court impose?

Four orders address the citation conduct. On March 10, 2026 (ECF No. 161), Judge Rochon declined to strike Defendants' submissions or award attorneys' fees, issued a "lengthy historic recitation" of Blackburn's prior misconduct as a "public admonition aimed to deter future misconduct," warned that further misconduct may lead to sanctions or a referral for discipline, and denied Blackburn's own Rule 11 sanctions motion against Cartagena. On July 10, 2026 (Dkt. No. 220, entered in this case and in Dixon v. Cartagena, No. 25-cv-5144), Magistrate Judge Jennifer E. Willis granted Roc Nation's motion to strike Blackburn's opposition to its sanctions motion, which on seventeen occasions put language in quotation marks that is not identical to language in the cited cases, ruled that the sanctions motion "will be considered unopposed," and folded the fabricated quotations into Blackburn's existing referral to the Southern District of New York's Grievance Committee. On September 18, 2026 (Dkt. No. 242), Judge Rochon denied Blackburn's motion for reconsideration of the March 10 order. Through Dkt. No. 248 (Sept. 29, 2026) the court had not ruled on Roc Nation's sanctions motion ("A separate Order on the sanctions will follow"), and no monetary sanction for the citation conduct is recorded.

Why does Cartagena v. Dixon matter for law firms using AI?

Cartagena v. Dixon is the third documented AI-hallucination episode for attorney Tyrone A. Blackburn within roughly five months, following Jakes v. Youngblood (W.D. Pa. Oct. 6, 2025) and Gardner v. Combs (D.N.J. Dec. 15, 2025), and it continued after the first order. In the March 10, 2026 order, Judge Rochon imposed no monetary sanction and no discipline referral, electing instead a public admonition that catalogues five prior judicial findings of misconduct (Cote, Oetken, Stickman, the New Jersey court, and a New York state court). The March order also flagged a separate factual concern: Blackburn told the court the fabricated citations came from LexisNexis’s Protégé tool, but LexisNexis filed a letter stating he had no subscription to that product, raising a misrepresentation question independent of the AI hallucinations themselves. For managing partners, the case underscores that “I used an AI tool” is not a self-executing mitigation: the court will verify the claim with the vendor, and an unverified or false attribution to a specific platform compounds the underlying citation failure.

The warning did not hold. In July 2026, defending a sanctions motion brought by Roc Nation, Blackburn filed an opposition that on seventeen occasions put language in quotation marks that is not identical to language in the cases cited. When Roc Nation moved to strike, he defended the practice as “paraphrase or compression” and accused opposing counsel of the same failing. Magistrate Judge Willis struck the opposition on July 10, 2026, ruled that the sanctions motion would be treated as unopposed, and added the fabricated quotations to his existing referral to the Southern District of New York’s Grievance Committee, citing “a continued pattern of behavior by Blackburn of making misrepresentations to the Court in memoranda of law after being sanctioned by multiple courts, including this one, for doing so already.” Judge Rochon denied reconsideration of the March order on September 18, 2026. The July order turns on quotation practice rather than on AI as such: the court treated quotation marks followed by a citation as “a representation that the cited case contains the language which is in quotation marks” (quoting Goodman v. Bouzy, S.D.N.Y. Dec. 15, 2025), and weighed Blackburn’s earlier sanction for the same conduct in Jakes v. Youngblood.