On February 11, 2025, the U.S. district court for the District of Delaware revised its own 2023 opinion and found on summary judgment that ROSS Intelligence’s (“Ross”) use of certain Westlaw “headnotes” to develop Ross’s AI-powered legal research tool constituted copyright infringement and not fair use. The court granted most of copyright owner Thomson Reuters’ motion for partial summary judgment on direct copyright infringement, granted Thomson Reuters’ motion for partial summary judgment on fair use, and denied Ross’s motion for summary judgment on fair use. In evaluating the fair use factors, the court emphasized that “Ross’s AI is not generative AI (AI that writes new content itself).”

Thomson Reuters owns the legal research service Westlaw. Westlaw’s publications include public domain material, such as judicial opinions, statutes, and regulations, but also Westlaw-authored summaries of case holdings and key points of law called “headnotes.” Westlaw organizes its content using the Key Number System, a numerical taxonomy of legal issues.

Thomson Reuters sued Ross, alleging that Ross had infringed its copyrights in the Westlaw headnotes by using them to develop a data set with which to train Ross’s AI-powered legal research tool. Initially, Ross had sought a license to Westlaw’s content, but when Thomson Reuters refused, Ross hired a third party (LegalEase) to develop “Bulk Memos” to train Ross’s legal research tool. Bulk Memos are lawyers’ compilations of legal questions and answers. To create the Bulk Memos, LegalEase hired freelance lawyers and provided them with a guide on creating legal questions using Westlaw headnotes, while clarifying that the lawyers should not just copy and paste headnotes directly into the questions. LegalEase sold Ross roughly 25,000 Bulk Memos, which Ross used to train its AI search tool. When Thomson Reuters found out, it sued Ross for copyright infringement.

In September 2023, the court issued an opinion denying Thomson Reuters’ motion for summary judgment on the claim of copyright infringement and the parties’ cross-motions on Ross’s fair use defense. The court concluded that genuine disputes of material fact precluded summary judgment and that, in particular, factual determinations concerning the scope of copyright protection in the headnotes and the evaluation of Ross’s fair use defense instead “must go to a jury.”

Reversing course, the court subsequently invited the parties to renew their summary judgment briefing. Thomson Reuters again moved for partial summary judgment on its claim of direct copyright infringement and Ross’s related defenses. Ross moved for summary judgment on Thomson Reuters’ copyright claims. And both parties moved for summary judgment on fair use.

In the court’s latest ruling, the court granted most of Thomson Reuters’ motion for partial summary judgment on direct copyright infringement, granted Thomson Reuters’ motion for partial summary judgment on fair use, and denied Ross’s motion for summary judgment on fair use.

Direct Copyright Infringement Claim

On the claim of direct copyright infringement, the court found that Ross directly infringed Thomson Reuters’s copyright in 2,243 headnotes (Thomson Reuters had moved for summary judgment on only two subsets of headnotes, and the court deemed it inappropriate to grant summary judgment on certain headnotes).

In reaching that conclusion, the court determined that:

• Thomson Reuters’ headnotes were protectable as factual compilations and as individual, copyrightable works. Although the text of judicial opinions is not copyrightable, key points of law summarizing those opinions introduce a level of creativity that renders each headnote protectable.
• The Bulk Memo questions corresponding to the 2,243 headnotes were so substantially similar to the headnotes that “no reasonable jury could find otherwise.”
• Ross’s defenses of innocent infringement, copyright misuse, merger, and scenes à faire each failed.

Fair Use Defense

Balancing the four fair use factors, the court rejected Ross’s fair use defense and granted summary judgment in favor of Thomson Reuters. Specifically, the court held that:

• On the first factor (purpose and character of the use), Ross’s use of the headnotes was for a commercial purpose, i.e., to compete with Thomson Reuters’ service. While commerciality is not dispositive, the court held that Ross’s use was not transformative because it did not have a “further purpose or different character” from Thomson Reuters’ use. The court emphasized that Ross’s AI-powered research tool is not generative AI, which generates new content, but rather “spits back relevant judicial opinions that have already been written.” Accordingly, the process “resembles how Westlaw uses headnotes and key numbers to return a list of cases with fitting headnotes.”
• Regarding the second factor (nature of the copyrighted work), Westlaw’s material is “not that creative,” despite having the “minimal spark of originality required for copyright validity.” While this factor weighed in favor of fair use, the court noted that this factor rarely carries much weight in the overall analysis.
• On the third factor (amount and substantiality of the use), this factor must be construed as assessing the amount of the copyrighted work that is made accessible to the public. Because Ross’s outputs to an end user do not include Westlaw headnotes, this factor weighed in Ross’s favor.
• Regarding the fourth factor (effect of the use on the market for or value of the work), Ross meant for its research tool to be a market substitute for Westlaw’s, and thus this factor weighed against a finding of fair use.

As this decision is expected to be appealed, these legal and factual questions will continue to be evaluated.

The case is Thomson Reuters Enter. Centre GmbH et al v. ROSS Intelligence Inc., Case No. 1:20-cv-00613-SB (D. Del. Feb. 11, 2025).

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