In recent years, numerous plaintiffs—including publishers of books, newspapers, computer code, and photographs—have sued AI companies for training models using copyrighted material. A key question in all of these lawsuits has been how easily AI models produce verbatim excerpts from the plaintiffs’ copyrighted content.For example, in its December 2023 lawsuit against OpenAI, the New York Times Company produced dozens of examples where GPT-4 exactly reproduced significant passages from Times stori...