Appeals Court Upholds Thomson Reuters' AI Training Copyright Win Over Ross Intelligence

The 3rd U.S. Circuit Court of Appeals on Tuesday, Sept 29, upheld Thomson Reuters' (TRI) landmark win in its copyright case against Ross Intelligence, a former legal research competitor. The court affirmed a 2025 district court ruling by Judge Bibas that Ross infringed copyrighted headnotes from Westlaw, Thomson Reuters' legal research service, and that its use was not fair use. Reuters described it as the first U.S. appeals court ruling on whether training AI on copyrighted material can be fair use.

The appeals court's reasoning is not yet public: the opinion was temporarily filed under seal, and the parties have 10 days to propose redactions. The underlying district ruling found Ross copied the headnotes to make it easier to develop a competing legal research tool, which weighed against fair use. Ross ceased operations in 2021, citing the cost of the litigation. Thomson Reuters said respecting copyright is essential for fostering innovation. One caveat limits how far the precedent reaches: Ross's system retrieved existing legal documents rather than generating new content, unlike the generative AI cases pending against model developers.

For Thomson Reuters, the ruling strengthens the legal protection around Westlaw's editorial content as it builds its own AI legal assistant, CoCounsel. The shares were down about 22% this year as of late September, and no coverage we read tied a share move to the ruling. What to watch: the unsealed opinion, whether Ross seeks further review, and how courts handling generative AI suits cite the decision.