But the company is still on the hook and must now go to trial over how it acquired those books by downloading them from online “shadow libraries” of pirated copies.
US District Judge William Alsup of San Francisco said in a ruling filed late Monday that the AI system’s distilling from thousands of written works to be able to produce its own passages of text qualified as “fair use” under US copyright law because it was “quintessentially transformative”.
“Like any reader aspiring to be a writer, Anthropic’s [AI large language models] trained upon works not to race ahead and replicate or supplant them – but to turn a hard corner and create something different,” Alsup wrote.

But while dismissing a key claim made by the group of authors who sued the company for copyright infringement last year, Alsup also said Anthropic must still go to trial in December over its alleged theft of their works.
“Anthropic had no entitlement to use pirated copies for its central library,” Alsup wrote.