The 3rd US Circuit Court of Appeals upheld a ruling favoring Thomson Reuters in its copyright dispute with former legal-research rival Ross Intelligence. The court rejected Ross’ argument that using material from Thomson Reuters’ Westlaw platform to train an AI-powered legal search engine qualified as fair use, a legal doctrine allowing limited use of copyrighted material. The decision is the first by a U.S. appeals court in the growing wave of copyright litigation over AI training, although the case concerns a search engine rather than generative AI, which creates new content. The court’s reasoning remains sealed. Thomson Reuters sued Ross in 2020, alleging that Ross copied thousands of Westlaw headnotes, which summarize legal points in court opinions, to train a competing system that identified relevant cases in response to user queries. Ross shut down its platform in 2021, citing the cost of the litigation. A Delaware federal judge rejected Ross’ fair-use defense last year, leading to the appeal. Thomson Reuters is the parent company of Reuters News. The case comes amid dozens of lawsuits brought by authors, news organizations, music labels and others against technology companies over the alleged unauthorized use of copyrighted works to train AI systems.