> "The training use was a fair use," [the judge] wrote. "The use of the books at issue to train Claude and its precursors was exceedingly transformative."

> However, the judge ruled that Anthropic's use of millions of pirated books to build its models – books that websites such as Library Genesis (LibGen) and Pirate Library Mirror (PiLiMi) copied without getting the authors' consent or giving them compensation – was not.

It seems clear from the article that while the use of pirated works was illegal, the use of copyrighted works (a the work a book is based on is still copyrighted if you buy the book) was fine and transformative.