What did the Third Circuit decide in Thomson Reuters v. ROSS?

On 29 September 2026 the court held that 2,243 Westlaw headnotes are original enough for copyright protection and that ROSS's copying of them to train its AI legal search engine was not fair use. It affirmed the District Court's partial summary judgment.

Does the ruling cover generative AI?

No. The opinion notes that ROSS's AI was not generative and only returned passages from existing opinions, and it says concerns raised about large language models in other cases do not apply here.

Thomson Reuters v. ROSS Intelligence: Policy Overview, Specs and News

Thomson Reuters v. ROSS Intelligence

Thomson Reuters v. ROSS Intelligence is a US copyright case over the use of Westlaw headnotes to train ROSS's AI legal search engine. The District of Delaware rejected ROSS's fair use defence, and on 29 September 2026 the Third Circuit affirmed, the first federal appeals ruling on fair use and AI training data.

Last reviewed 28 Oct 2026

Facts at a glance

Court	US Court of Appeals for the Third Circuit, on appeal from the District of Delaware
Appeal number	No. 25-2153 (District Court No. 1:20-cv-00613) source
Panel	Circuit Judges Restrepo, Montgomery-Reeves (author) and Bove source
Argued	11 June 2026 source
Decided	29 September 2026, affirmed source
Works at issue	2,243 Westlaw headnotes source
Holding	Headnotes are copyrightable; ROSS's use to train its AI was not fair use

Questions people ask

What did the Third Circuit decide in Thomson Reuters v. ROSS?: On 29 September 2026 the court held that 2,243 Westlaw headnotes are original enough for copyright protection and that ROSS's copying of them to train its AI legal search engine was not fair use. It affirmed the District Court's partial summary judgment.
Does the ruling cover generative AI?: No. The opinion notes that ROSS's AI was not generative and only returned passages from existing opinions, and it says concerns raised about large language models in other cases do not apply here.