Thomson Reuters has won a legal battle against Ross Intelligence, after a judge ruled that the law firm's use of Thomson Reuters' legal content to train an AI model violated US copyright laws. The case stems from a 2020 lawsuit where Thomson Reuters accused the now-defunct legal research firm of using its Westlaw platform to build a competing AI system without permission.

Judge Stephanos Bibas confirmed that Ross Intelligence's use of the content did not qualify as "fair use" under US copyright law, which permits limited use of copyrighted material for purposes such as teaching or research. Thomson Reuters expressed satisfaction with the ruling, stating that copying its content for AI training was not a fair use.

This case is part of a broader trend of legal challenges involving AI and copyright issues, with authors, artists, and music labels filing similar lawsuits against AI developers for using their works without compensation. These cases all involve the claim that tech companies have used vast amounts of human-created content to train AI models, raising concerns about intellectual property rights and the ethics of AI development.