While facing multiple federal lawsuits over copyright infringement, AI company Anthropic has allegedly engaged in a secret deal involving pirated books, according to court documents filed this week. The revelation comes amid ongoing litigation with major music publishers including Universal Music Group (UMG), who claim Anthropic unlawfully used copyrighted lyrics from approximately 500 songs to train its AI chatbot Claude.
The documents suggest Anthropic downloaded millions of pirated books to create a training library, a discovery that could greatly strengthen UMG’s position in their separate lawsuit filed in late 2023. This development follows Anthropic’s January 2, 2025 agreement with music publishers that implemented “guardrails” to limit Claude’s ability to reproduce copyrighted lyrics, effectively creating a temporary truce to avoid a federal injunction. The settlement specifically addressed songs like Katy Perry’s “California Gurls” and other copyrighted works mentioned in the original complaint.
Legal experts note that evidence of systematic copyright infringement in one domain could influence judicial opinions about Anthropic’s practices more broadly. “The book piracy allegations demonstrate a pattern of behavior that undermines Anthropic’s fair use defense in the music case,” explained copyright attorney Sarah Westbrook, who is not involved in the litigation.
On March 18, 2025, California US District Judge Eumi Lee denied music publishers’ motion for preliminary injunction against Anthropic, finding the requested remedies “poorly defined” and too vague to enforce effectively. Rapid AI growth has outpaced legislative responses to copyright concerns, creating a challenging legal environment for all parties involved.
However, in a parallel ruling, Judge Alsup refused to stay the book-related copyright trial despite ongoing appeals, signaling the courts’ willingness to proceed despite Anthropic’s procedural objections. UMG’s involvement with performance rights organizations could further complicate the case by bringing additional copyright management entities into the legal battle. Artists concerned about their work’s protection have increasingly turned to streaming distribution tools that offer better rights management options and transparency.
The alleged book piracy operation potentially exposes Anthropic to statutory damages that could reach billions of dollars if the company is found to have willfully infringed on millions of copyrighted works. Industry observers suggest this latest revelation may pressure Anthropic toward a more thorough settlement with all copyright holders.
Neither Anthropic nor UMG representatives responded to requests for comment on the new allegations, though court filings indicate both parties will appear for a status conference on April 8 to address discovery issues related to the training data sources.
