Federal Judge Rules Against AI Legal Tool in Copyright Dispute

A federal judge has ruled that Ross Intelligence Inc. violated copyright laws by using Thomson Reuters’ Westlaw headnotes to train its AI-powered legal research tool. According to Bloomberg, the decision, issued by U.S. District Court Judge Stephanos Bibas, found that Ross’s use of these headnotes did not qualify as “fair use” under copyright law.

Judge Bibas, who serves on the 3rd U.S. Circuit Court of Appeals and was sitting by designation in the U.S. District Court for the District of Delaware, determined that two of the four fair use factors weighed in favor of Thomson Reuters. Specifically, the court ruled that Ross’s purpose in using the headnotes and the potential market harm to Westlaw justified rejecting Ross’s fair use defense, per Bloomberg.

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The ruling granted partial summary judgment in favor of Thomson Reuters on its direct copyright infringement claims, covering more than 2,000 headnotes. The court specifically found that Ross’s actions infringed on Thomson Reuters’ copyrights in 2,243 Westlaw headnotes. Judge Bibas emphasized that Ross had utilized these headnotes as AI training data to build a competing legal research tool, strengthening the case against fair use.

The ruling marks a shift from a previous 2023 decision in which Judge Bibas had largely denied Thomson Reuters’ motions. However, while this latest decision is significant, it does not bring the case to a complete resolution. As Bloomberg reports, several issues remain to be determined at trial, including questions about the expiration of certain Thomson Reuters copyrights and whether Ross copied Westlaw’s Key Number System, as alleged.