Unsealed opinion shows why Thomson Reuters won landmark AI fair-use ruling

Thomson Reuters

30/09/2026 20:42

By Blake Brittain
Sept 30 (Reuters) - The Philadelphia-based 3rd US Circuit Court of Appeals said in a ruling unsealed on Wednesday that defunct legal-research company Ross Intelligence did not make fair use of Thomson Reuters' TRI.TO copyrighted material to build an AI-based legal search engine.
The appeals court said that Ross' use of "headnotes" from Thomson Reuters' Westlaw legal research platform to build a similar, competing product was not transformative, sinking its fair use defense to Thomson Reuters' infringement claims.
The ruling, filed under seal on Tuesday, is the first time that a US appeals court has weighed in on fair use in the AI context. Fair use is a key copyright infringement defense that tech companies are relying on in a wave of high-stakes lawsuits over AI training.
The 3rd Circuit distinguished Thomson Reuters' case from other AI training cases. Unlike the technology in those cases, Ross' search engine did not feature generative AI — AI that creates new content — and the appeals court said in a footnote that concerns raised by the US Department of Justice in a copyright lawsuit against OpenAI "do not apply here."
"Under ROSS’s framing, this case appears to concern the future of AI legal technology," US Circuit Judge Tamika Montgomery-Reeves wrote for a unanimous three-judge panel. "But appearances can be deceiving. In truth, this is no more than an ordinary copyright case; we must determine whether Thomson Reuters’ materials are sufficiently original for copyright protection and whether ROSS’s use of those materials was fair."
Thomson Reuters is the parent company of Reuters News.
Spokespeople for Ross and Thomson Reuters did not immediately respond to requests for comment on the unsealed opinion on Wednesday. A Thomson Reuters spokesperson said on Tuesday, before the opinion was unsealed, that the company "firmly believes that respecting copyright is essential for fostering innovation while protecting the intellectual property that fuels fiduciary-grade AI solutions." 
Thomson Reuters' 2020 lawsuit accused Ross of copying thousands of headnotes, which summarize points of law in court opinions, to train its competing AI-based legal search engine. Ross shut down its platform in 2021, citing the costs of Thomson Reuters' litigation. 
Affirming a Delaware district court ruling, the 3rd Circuit rejected Ross' fair use defense, as well as its separate argument that the headnotes were not copyrightable. 
"Thomson Reuters’ materials possess a creative spark, and ROSS aspired to be a direct competitor by using them for a highly similar purpose," the appeals court said.
The case is Thomson Reuters Enterprise Centre GmbH v. Ross Intelligence Inc, 3rd US Circuit Court of Appeals, No. 25-2153.
For Thomson Reuters: Dale Cendali of Kirkland & Ellis
For Ross: Mark Davies of White & Case
     
Read more:
Thomson Reuters wins AI copyright 'fair use' ruling against one-time competitor
US appeals court upholds Thomson Reuters' landmark win in AI training lawsuit
     

(Reporting by Blake Brittain in Washington)
((blake.brittain@tr.com; +1 (202) 938-5713))