California judge relied on fictitious AI case law in H.C. v. Contreras
A California judge's ruling was reversed after the court relied on a fictitious case citation produced by generative AI. The trial court had ignored warnings from opposing counsel regarding the nonexistent authority.
Reliance on fake cases is fundamentally incompatible with an informed exercise of discretion controlled by genuine principles of law.
Key facts
- What
- A California judge's ruling was reversed after the court relied on a fictitious case citation produced by generative AI.
- Incident date
- May 28, 2026
- Who
- Contreras (Counsel)
- Failure mode
- Hallucination
- AI surface
- Search / RAG
- Severity
- High
What happened
In the case H.C. v. Contreras, counsel for Rudy Contreras submitted a closing brief containing a nonexistent case citation, Enrique M. v. Angelina V. (2005). Despite opposing counsel alerting the trial court that the citation was fictitious, Judge Irene A. Luna incorporated the fake case into her ruling. The California Court of Appeal subsequently reversed the judgment and ordered the case be reassigned to a new judge.
What broke inside the model
- 01 · TriggerA user asks for a fact, a citation, or a figure.
- 02 · Model stepThe model writes a fluent, confident answer.
- 03 · Control gapNothing ties the claim back to a real source.
- 04 · FailureA fabricated fact ships as if it were verified.
- 05 · ConsequenceThe false claim reaches a customer, a court, or the public.
Confidence holds, and even spikes, as the claim detaches from any source.
A lawyer used a generative AI tool for legal research but failed to verify the resulting citations, leading to the inclusion of a hallucinated case. This failure was compounded by the trial court's failure to verify the citation's validity despite explicit warnings from opposing counsel.
What it cost
Sources
- PressCalifornia Judge "Cited and Relied on a Fictitious Case" Submitted by Lawyer, Even Though ...reason.com
- Court FilingH.C. v. Contreraswww4.courts.ca.gov
- PrimaryAI Hallucination Cases Databasedamiencharlotin.com
Cite this entry
https://failureindex.ai/failures/california-judge-relied-fictitious-law-contrerasAI Failure Index. "California judge relied on fictitious AI case law in H.C. v. Contreras" (FI-0584). Realm Labs. https://failureindex.ai/failures/california-judge-relied-fictitious-law-contreras (indexed Jun 16, 2026).Data fields CC-BY 4.0, prose citation permitted. Incident ID FI-0584. Full dataset at /data.
Note from Realm Labs, the Index steward
How Realm would have caught this
- Prism
- OmniGuard
- AI Detection & Response (AIDR)
A runtime layer that watches the model's internal state can flag the moment a model commits to a claim it has no support for, and hold or reroute the response before it reaches a user. Realm reads those signals in real time rather than grading the transcript after the fact.