A U.S. federal appeals court has ruled that using copyrighted editorial summaries to train artificial intelligence models can constitute copyright infringement, marking the first time a federal appellate court has addressed the issue in a major legal clash between legal publisher Thomson Reuters and defunct AI startup ROSS Intelligence.
Thomson Reuters and ROSS Intelligence Legal Battle Reaches Appeals Court
The U.S. Court of Appeals for the Third Circuit upheld a lower court decision in favor of Thomson Reuters, resolving a high-stakes copyright dispute centered on how artificial intelligence systems learn from protected texts. The legal challenge began in 2020 when the publishing giant sued ROSS Intelligence over the development of a competing legal search tool.
ROSS developed an AI-driven platform that allowed users to ask legal questions in plain English and receive relevant excerpts from court opinions. To train the underlying algorithm, third-party contractors used thousands of specialized summaries produced by editors for the company’s proprietary database, Westlaw. The dispute zeroed in on 2,243 short legal summaries known as headnotes, which distill key legal principles from judicial opinions.
Originality of Westlaw Headnotes and Fair Use Defense Rejected
During the litigation, ROSS argued that the contested headnotes lacked sufficient originality to warrant copyright protection and maintained that using them to train an algorithm qualified as fair use. The appellate court squarely rejected both arguments.
Writing for the court, U.S. Circuit Judge Tamika Montgomery-Rees noted that while the case touched on the future of AI-driven legal technology, the core matter remained a standard copyright violation. The court found that Westlaw editors exercised independent judgment in determining which legal issues to highlight, what facts and reasoning to include, and how to formulate concise descriptions.
Because those editorial products contained the requisite minimum creative spark, the court concluded they qualified as original works protected by copyright, even though the underlying judicial opinions themselves reside in the public domain.
Commercial Competition and Market Harm Shape the Verdict
When evaluating the fair use defense, the appellate panel focused heavily on the commercial nature of the competing product. Although the text snippets were used only during an intermediary training phase, the end goal of both systems was functionally identical: helping users locate necessary extracts from court decisions.
The court ruled that the AI developer’s utilization of the material was in the best case minimally transformative. The judges also determined that ROSS's actions could inflict financial harm on both the core Westlaw business and the prospective licensing market for training data.
The legal pressure ultimately reshaped the tech startup’s trajectory. ROSS Intelligence shut down operations in 2021, pointing directly to the mounting financial burden of the ongoing litigation. Following a partial ruling from a federal court in Delaware in February 2025, the latest appellate decision solidifies the outcome for Thomson Reuters.