A court found over 2,200 Westlaw headnotes were copied to train Ross's legal AI

In Thomson Reuters v. Ross Intelligence, decided February 11, 2025, US Circuit Judge Stephanos Bibas granted summary judgment of direct copyright infringement on more than 2,200 of Westlaw’s editorial headnotes, finding they were original enough to be protected and had been copied to help train Ross’s competing legal-research tool. He also rejected Ross’s fair-use defense. It was the first US court ruling to hold that using copyrighted material to train an AI system could be infringement, and the first to reject fair use in that setting - though Ross had built a search-and-retrieval tool rather than a generative model.