A federal judge in San Francisco ruled late on Monday that Anthropic’s use of books without permission to train its artificial intelligence system was legal under US copyright law. Siding with tech companies on a pivotal question for the AI industry,

U.S. 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 U.S. copyright law because it was “quintessentially transformative.”