Hill v. Workday, Inc.
U.S. District Court, Northern District of California · N.D. Cal. · California bar guidance
Verified April 26, 2026
- Citation
- Hill v. Workday, Inc., No. 23-cv-06558-PHK (N.D. Cal. Sept. 5, 2025)
- Decided
- September 5, 2025
Summary
Attorneys Lenden F. Webb and Katherine E. Cervantes of Webb Law Group APC, representing plaintiff Anthony C. Hill in an employment action against Workday, filed a brief containing a fabricated case citation labeled "Mashup" that did not correspond to any real opinion. The citation was generated using Thomson Reuters' CoCounsel and was filed without verification against primary sources. Magistrate Judge Peter H. Kang issued an order to show cause, and after counsel's response, sanctioned the attorneys for the unverified AI-generated citation.
- AI tool:
- CoCounsel
What sanction did the court impose?
Judge Kang ordered counsel to circulate the sanctions decision within their law firm and to complete continuing legal education on the use of generative AI in legal practice. No monetary sanction was imposed in this order. Webb Law Group was subsequently terminated as counsel of record following a substitution of attorneys.
Why does Hill v. Workday, Inc. matter for law firms using AI?
Hill v. Workday is one of the first published sanctions orders identifying a name-brand legal-research AI assistant, Thomson Reuters’ CoCounsel, as the source of a fabricated citation. For managing partners evaluating vendor selection, the case is a reminder that purpose-built legal AI products do not eliminate the verification duty: counsel remained responsible for confirming each citation against the primary source before filing, and the court’s remedial order targeted firm-wide education rather than the individual attorney alone.
Sources
Primary sources
Further reading
Source PDF is a Westlaw printout mirrored from the Damien Charlotin hallucination database. We are working to add the underlying court docket (PACER, CourtListener, or court website) as a second source.
- Specific CLE hour requirement and exact wording of the firm-circulation order could not be read from the available PDF text layer; descriptive summary based on Charlotin's hosted court order and contemporaneous Law360 reporting.