Third Circuit: Westlaw Headnotes Not Fairly Usable to Train ROSS Legal AI
The Third Circuit held on September 29, 2026 that Westlaw headnotes are copyrightable and that ROSS Intelligence's copying of 2,243 of them to train a legal-research AI was not fair use, affirming partial summary judgment.
On September 29, 2026, the Third Circuit affirmed in part summary judgment for Westlaw's publisher, holding that 2,243 Westlaw headnotes carry sufficient originality to qualify for copyright protection and that ROSS Intelligence's reproduction of them to train a legal-research AI product was not fair use. The opinion is the first appellate treatment in the Third Circuit of headnote-based copying claims against a generative-AI developer, and it joins a growing line of decisions confronting publishers of legal research materials with the fair-use defense.
The holding matters beyond Westlaw. Legal headnotes, citators, annotations, and editorial headnotes sit at the center of the value proposition of every major research platform, and vendors increasingly license or scrape that material to train retrieval and drafting tools. A ruling that treats headnotes as protectable expression — and that rejects a market-substitution-based fair use argument at the summary judgment stage — raises licensing-cost and design questions for AI vendors, law-firm AI procurement teams, and research providers alike.
Practitioners should read the opinion closely for the authorship and originality analysis and the treatment of the fourth fair-use factor before relying on it. Watch for further proceedings below and for parallel litigation in other circuits that may produce conflicting appellate authority. This summary reflects a single secondary account; the slip opinion itself has not been reviewed here.