AI companies are purchasing millions of physical books from secondhand markets, destroying them after scanning for training data. Pre-2022 printed books are sought because they contain no AI-generated text, avoiding “model collapse” during training. The judge declared that Anthropic’s practice of purchasing physical books, slicing off their spines for industrial scanning, and destroying the originals constitutes “fair use” under Section 107 of the Copyright Act. ISBNdb, a company that sources printed books for AI training data, advertises on its website that “the world’s best AI training data is sitting on a shelf.” The company describes printed books as “curated, peer-reviewed, domain-specific human knowledge, structured in a way no web crawl can replicate.”