The Bartz precedent already established the operative rule: training on copyrighted material is fair use, but pirating it to acquire the corpus is not—and it cost Anthropic $1.5B. This new music-publisher suit targets the same acquisition-method vulnerability (torrenting), meaning your legal exposure hinges on data provenance, not model use, so licensed or cleanly-sourced training and RAG corpora are now the defensible path regardless of how you deploy the outputs.