From an L.A. Superior Court order earlier this month in Yasiel Puig Valdes v. All3 Media, LLC:
In reply, Moving Defendants contend that Plaintiff's opposition should be stricken for citing fabricated cases. Upon review of Plaintiff's opposition, the court confirms that Plaintiff improperly cited to "Edwards v. Hearst Corp. (1991) 53 Cal.3d 30, 43" and "Heath v. San Joaquin Comm. Hosp. Dist. (1993) 15 Cal.App.4th 708, 713-14". (Opp., at p. 5.) These cases apparently do not exist. At the hearing, the Plaintiff's counsel confirmed that those citations do not exist and appeared when Plaintiff's counsel sought the assistance of ChatGPT to assist him in filing the Opposition.
Moreover, Plaintiff filed an ex parte application "to correct" errors in his Opposition. The court denied the motion as

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