Ross Intelligence Seeks Rehearing in Westlaw Case

The AI legal research startup asks the Third Circuit for a new appellate hearing after losing its fair use defense against Thomson Reuters.

Updated on Nov. 3, 2026 in Artificial Intelligence

Isometric editorial illustration of a tall stack of oxblood and cream bound volumes on a slate plinth, evoking legal precedent and written authority. — Ross Intelligence asked the Third Circuit on Wednesday for a new appellate hearing after losing its fair use defense in Thomson Reuters's Westlaw copyright suit. AI Illustration. Upload story photo >

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Ross Intelligence filed a request on Wednesday for a new appellate hearing in its copyright dispute with Thomson Reuters. The company was sued in 2020 over training its legal research platform on Westlaw headnotes, and a three-judge Third Circuit panel ruled against its fair use claim in September.

Why it matters

The case tests whether using copyrighted legal headnotes to train an AI model can qualify as fair use. A ruling against Ross could shape how AI developers across the United States source training material from published legal databases.

The case is tracked through federal appellate filings, with the Third Circuit panel's September ruling and the February 2025 district court decision forming the record. The source does not report how many similar AI training cases are pending, leaving the broader scope unresolved.

The players

Ross Intelligence

Ross Intelligence is an artificial intelligence legal research startup whose training of an AI model on Westlaw headnotes is at the center of the copyright litigation.

Thomson Reuters

Thomson Reuters is a global information services company that owns the Westlaw legal research platform and sued Ross in 2020 over its headnotes.

Third Circuit

The Third Circuit is the federal appellate court whose three-judge panel ruled against Ross's fair use claim in September.

Stephanos Bibas

Stephanos Bibas is a federal judge who ruled in February 2025 that Ross was not entitled to a fair-use defense.

The details

Thomson Reuters alleges Ross obtained Westlaw headnotes from a licensee and used them to rush out a competing product, seeking to avoid the time and resources needed to create the material itself. The Third Circuit held that Thomson Reuters's materials are copyrightable and that Ross's use was not fair. Entertainment and publishing groups filed friend-of-the-court briefs backing Westlaw, while NetChoice backed Ross.

2020: Thomson Reuters sues Ross over Westlaw headnotes.
February 2025: Judge Stephanos Bibas rules Ross is not entitled to a fair-use defense.
September: A three-judge Third Circuit panel rules against Ross.
Wednesday: Ross files its request for a new appellate hearing.

Big Picture

The case applies the U.S. fair use doctrine under the Copyright Act to AI training on copyrighted legal headnotes, extending a long-standing copyright test into machine learning. Its outcome could define how courts treat AI developers who draw on proprietary published databases.

The outcome could affect which legal research tools and AI products are available to lawyers and the pricing and access terms those tools carry. It may also determine whether AI developers can freely train on proprietary published material without licensing it.

The takeaway

Developers of AI tools should expect copyright claims over training data to be litigated seriously, and licensing terms for proprietary sources will matter. Readers tracking legal technology should watch whether the Third Circuit grants the rehearing request.