What Happened
In Anthropic's copyright battle with Universal Music Group and other publishers, an expert declaration by an Anthropic data scientist included a citation with a fabricated title and authors after lawyers at Latham & Watkins used Claude to format the reference. The underlying article was real, but Claude invented its bibliographic details and the firm's manual review failed to catch it. The attorneys apologized and called it an embarrassing, unintentional mistake.
Impact
A federal magistrate judge called the hallucination a serious and grave issue, and the irony of Anthropic's own model erring in its defense drew wide coverage and fueled skepticism of AI in legal workflows.
How to Prevent This
- Never use LLMs for citation formatting without verifying output against the source document
- Require two-person verification of all citations in court filings
- Log and disclose AI assistance used in preparing legal documents
- Use reference-manager software that pulls metadata directly from publisher databases
- Treat AI-touched text in filings as high-risk content requiring dedicated review