Third Circuit affirms: ROSS's AI training on Westlaw headnotes was not fair use
In Thomson Reuters v. ROSS Intelligence (No. 25-2153), a Third Circuit panel (Restrepo, Montgomery-Reeves, Bove JJ; opinion by Montgomery-Reeves) affirmed that ROSS's use of Westlaw headnotes to build a competing legal-research AI was not fair use. It weighed purpose and character, amount copied and market effect against ROSS, finding harm to both Westlaw's market and the emerging market for licensing headnotes as AI training data; the nature-of-the-work factor leaned slightly towards ROSS. This is an appellate ruling on fair use in AI training, but it turns on a non-generative tool competing directly with its source, so it does not settle the LLM cases. For a deployer, the practical point is that training on a competitor's content to build a substitute product carries real exposure, and vendor warranties and indemnities on training-data provenance now matter more.
Source: U.S. Court of Appeals for the Third Circuit (opinion)
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Begin in writing →This briefing is general information, not legal advice, and does not create an advisor–client relationship. Summaries are original; follow source links for the full record. Adesanya AI Advisory — Abdulwahab B. Adesanya, Barrister-at-Law (Nigeria).