Filed in a California federal court, the suit seeks statutory damages of up to $150,000 per work, a figure that could lead to a massive financial penalty given the scale of the alleged theft.
This litigation matters because it marks the point where all three major music publishers are now actively suing the AI developer, following previous legal actions by Universal Music Publishing Group.
The music companies argue that Anthropic used pirated materials to train its large language models—complex systems designed to process and generate human-like text—to gain a competitive advantage without paying for licenses.
The publishers claim this behavior undermines the creative industry's infrastructure by treating intellectual property as a free resource to fuel the growth of a company now valued in the trillions.
As part of the legal proceedings, the publishers are demanding that Anthropic provide a detailed account of its training data and destroy all infringing copies of their songs.
The complaint relies on evidence suggesting that Anthropic employees used torrenting services to download millions of pirated works to build their technology more cheaply.
While the music firms state they support the development of ethical AI, they maintain that technology companies must operate within the bounds of the law and reach authorized agreements with rightsholders.