A California federal judge ruled Thursday that three authors suing Anthropic over copyright infringement can bring a class action lawsuit representing all U.S. writers whose work was allegedly downloaded from libraries of pirated works. 

The filing alleges that Anthropic, the Amazon-backed OpenAI competitor behind the chatbot Claude, “violated the Copyright Act by doing Napster-style downloading of millions of works.” It alleges that the company downloaded as many as seven million copies of books from libraries of pirated works. 

The new ruling impacts a lawsuit filed last August by authors Andrea Bartz, Charles Graeber, and Kirk Wallace Johnson, who alleged that Anthropic had “built a multibillion-dollar business by stealing hundreds of thousands of copyrighted books.” Late last month, a federal judge sided with Anthropic to rule that training its AI models on legally-purchased books was fair use but noted the company would need to face a separate trial for using allegedly pirated books.

It also follows the lawsuit Reddit filed against Anthropic last month, claiming that the AI company’s bots had accessed Reddit more than 100,000 times since last July, after Anthropic had said it blocked them from doing so. 

The authors’ lawsuit is part of a growing trend of media outlets, platforms, companies, and creatives either suing AI companies over copyright infringement — for instance, Universal Music’s 2023 lawsuit against Anthropic over “systematic and widespread infringement of their copyrighted song lyrics” — or partnering up with them to willingly provide AI training data in order to get a slice of the profits.