Unsealed opinion shows why Thomson Reuters won landmark AI fair-use ruling
TRI•A U.S. appeals court ruled that Ross Intelligence did not make fair use of Thomson Reuters’ Westlaw headnotes when building a competing legal search engine, affirming a lower court decision. The ruling is the first time a U.S. appeals court has weighed in on fair use in the AI context.
1. Appeals court rejects defense
The 3rd U.S. Circuit Court of Appeals said Ross’ use of headnotes from Thomson Reuters’ Westlaw legal research platform was not transformative and rejected Ross’ fair-use defense. The court also rejected Ross’ argument that the headnotes were not copyrightable, affirming a Delaware district court ruling.
2. Case involved non-generative AI
The court distinguished the case from other AI training lawsuits, saying Ross’ search engine did not use generative AI. Judge Tamika Montgomery-Reeves wrote for a unanimous three-judge panel that the case concerned whether Thomson Reuters’ materials were sufficiently original for copyright protection and whether Ross’ use was fair.
3. Ross shut down in 2021
Thomson Reuters sued Ross in 2020, alleging that it copied thousands of headnotes to train its competing legal search engine. Ross shut down its platform in 2021, citing the costs of the litigation.




