Thomson Reuters CoCounsel

CoCounsel is Thomson Reuters’ AI assistant for legal and other professionals. It began as a product of Casetext, a legal technology company founded in 2013, whose CoCounsel assistant was powered by GPT-4 and delivered document review, legal research memos, deposition preparation and contract analysis; Thomson Reuters closed its $650 million cash acquisition of Casetext on August 17, 2023.¹ Thomson Reuters describes its current CoCounsel Legal as an agentic AI solution, with Deep Research on Westlaw Advantage and Practical Law, that brings together legal research, workflow automation, document search and AI assistance, and it launched in the UK on January 26, 2026 after its US introduction.²

One feature it describes in detail is Tabular Analysis, launched in beta in November 2025, for high-volume document review: users upload collections of up to 10,000 documents and 100 questions and get a filterable table of results. Those limits and the “human oversight” language are Thomson Reuters’ own, as is its quoted customer testimony.² The firm-level evidence is Borden Ladner Gervais (BLG), a Canadian firm with over 800 lawyers, intellectual property agents and other professionals, which said on December 3, 2025 that it had adopted CoCounsel firmwide after piloting several versions, and that lawyers, law clerks, paralegals and business services staff can all use it for research, drafting and document analysis.³

MetaRoles grades the BLG rollout as in production, since a named firm states it runs the tool, and treats Thomson Reuters’ product descriptions as vendor claims. Neither release states a price or a measured result. An independent Stanford evaluation of 2024 versions of Thomson Reuters’ and LexisNexis’ legal research tools found each hallucinated between 17% and 33% of the time, which is why the firms say a lawyer reviews the output; see AI legal research and lawyers: what the court records show and the comparison of seven legal AI platforms.⁴