Two law firms sanctioned $31,100 over AI-hallucinated citations in federal brief

A federal special master sanctioned two law firms, Ellis George and K&L Gates, a combined $31,100 in a California insurance case after discovering that a supplemental brief filed on their clients’ behalf cited legal authorities that did not exist. Of 27 citations in the ten-page brief, roughly nine were fabricated, including at least two purported court decisions with no basis in the case record.

The brief originated when an attorney at Ellis George used AI tools — including CoCounsel, Westlaw Precision and Google’s Gemini — to draft an outline, which he passed to colleagues at K&L Gates. Those lawyers incorporated the material into the filing without independently verifying the citations or being told AI tools had been involved in producing it. Special Master Michael Wilner, reviewing the brief, wrote that he had looked up the cited decisions “only to find that they didn’t exist. That’s scary,” and called the episode a “collective debacle,” though he declined to sanction any individual attorney by name.

The case was one of a growing number of court sanctions for AI-fabricated citations that had accumulated since the 2023 case of Mata v. Avianca first drew national attention to the problem. By mid-2025 such incidents were frequent enough that law-firm risk-management guidance tracked them as a recurring category of professional-conduct exposure rather than an isolated novelty, with courts increasingly treating “we used an AI tool” as no defence against a lawyer’s duty to verify what they file.