A group of major music publishers led by Concord Music Group and Universal Music Group has filed a lawsuit against Anthropic, alleging that the AI company illegally downloaded more than 20,000 copyrighted musical works.
According to a statement released by the publishers on Wednesday, the allegedly infringed materials include sheet music, song lyrics, and musical compositions. The publishers estimate that potential damages could exceed $3 billion, placing the case among the largest non–class action copyright lawsuits ever filed in the United States.
The lawsuit was brought by the same legal team that handled Bartz v. Anthropic, a separate case in which fiction and nonfiction authors accused Anthropic of using copyrighted books to train AI models such as Claude.
In the Bartz case, U.S. District Judge William Alsup ruled that training AI models on copyrighted works can be lawful under U.S. copyright law. However, he also made clear that acquiring those works through piracy is not legal. As a result, Anthropic faced penalties related to how the data was obtained rather than how it was used for training.
That earlier ruling resulted in a $1.5 billion penalty for Anthropic, with affected authors receiving roughly $3,000 per work across about 500,000 copyrighted titles. While $1.5 billion is a significant figure, it was widely viewed as manageable for Anthropic, which has been valued at approximately $183 billion.
Initially, music publishers sued Anthropic for allegedly using around 500 copyrighted works. However, during the discovery phase of the Bartz case, the publishers say they uncovered evidence that Anthropic had illegally downloaded thousands more copyrighted music files.
The publishers attempted to amend their original lawsuit to include newly discovered allegations of piracy. The court denied the request in October, ruling that the publishers had failed to investigate the piracy claims earlier in the process.
Following that decision, the publishers opted to file a separate lawsuit explicitly focused on the alleged large-scale piracy. The new complaint also names Anthropic CEO Dario Amodei and co-founder Benjamin Mann as defendants.
The case adds to growing legal pressure on AI companies over how copyrighted material is sourced and used, particularly as generative AI systems continue to scale rapidly across creative industries.
