A second reason that AI companies could be liable for copyright infringement is that a model itself could be considered an illegal copy. Mark Lemley, a Stanford law professor who has represented Stability AI and Meta in such lawsuits, told me he isn’t sure whether it’s accurate to say that a model “contains” a copy of a book, or whether “we have a set of instructions that allows us to create a copy on the fly in response to a request.” Even the latter is potentially problematic, but if judges decide that the former is true, then plaintiffs could seek the destruction of infringing copies. Which means that, in addition to fines, AI companies could in some cases face the possibility of being legally compelled to retrain their models from scratch, with properly licensed material.