AI Platforms · Platform Profile
CoCounsel is Thomson Reuters' AI legal assistant — born at Casetext — that performs research, document review, and drafting with citations grounded in Westlaw and Practical Law.
CoCounsel began at Casetext, a legal research company founded in 2013, which launched the original CoCounsel assistant in March 2023 as one of the first generative AI products built for lawyers. Thomson Reuters acquired Casetext for $650 million in cash in August 2023, and the product now ships as CoCounsel Legal, the primary AI offering in the Thomson Reuters legal portfolio.
The platform works as an agentic assistant: a user describes a task in plain language, and the system plans and executes multi-step work — legal research memos, document review, deposition preparation, contract analysis — returning cited work product. Its defining advantage is grounding: research answers draw on Westlaw case law and Practical Law guidance, and a Deep Research capability runs extended research workflows across that corpus alongside the user's own uploaded or DMS-stored documents.
A next-generation version of CoCounsel Legal, rebuilt on Anthropic's Claude Agent SDK, opened early access in June 2026, with US general availability planned for August 2026 and rollouts to Canada, the UK, and Australia to follow. The UK launch of the current product came in January 2026, and Thomson Reuters has put the product in front of more than 120,000 law students at over 200 US law schools.
Broad market — solo and small firms through large firms, corporate legal departments, and government offices. Because it rides on Westlaw's install base, CoCounsel has wider small-firm and plaintiff-firm reach than most enterprise-first legal AI platforms; for many firms it arrives as an extension of a research subscription they already hold.
| Current product name | CoCounsel Legal |
|---|---|
| Vendor | Thomson Reuters (NYSE/TSX: TRI) |
| Lineage | Built by Casetext (founded 2013); acquired by Thomson Reuters for $650M, August 2023 |
| Category | AI legal assistant — research, review, drafting |
| Content grounding | Westlaw, Practical Law, plus the firm's own documents |
| Key integrations | Westlaw, Practical Law, Microsoft 365 (Word/Outlook), document management systems |
| Pricing model | Tiered per-user subscriptions via Thomson Reuters sales; prices not published |
| Availability | US, UK (Jan 2026); Canada and Australia rollouts announced |
| Website | legal.thomsonreuters.com |
CoCounsel sits in the research-and-drafting layer of a firm's stack, alongside — not in place of — case management. For plaintiff firms it typically complements PI-specific platforms (demand generation, medical chronology tools) rather than competing with them: its strength is authority-grounded research and general legal drafting, bundled with the Westlaw ecosystem many firms already pay for.
Packaging is tied to Thomson Reuters research subscriptions, so the practical evaluation question is usually not whether to add CoCounsel in isolation but what the firm's overall Westlaw relationship includes — which tier, which content, and at what negotiated rate.
CoCounsel is sold in tiers, and its research capabilities draw on Westlaw and Practical Law content. Packaging is bundled with Thomson Reuters research subscriptions, so firms should confirm which tier includes which content.
Yes — output links citations to the underlying Westlaw sources so a lawyer can check each authority, a design carried over from Casetext's original grounding approach.
Yes. It analyzes uploaded documents and connects to document management systems and Microsoft 365 content in addition to the research corpus.
The UK launch came in January 2026, and Canada and Australia rollouts of the next-generation product were announced to follow the August 2026 US general availability.
Systems firms typically evaluate alongside CoCounsel — competitors, complements, and the adjacent layers of the same stack.
Evaluating CoCounsel — or trying to get more out of it? Send the question. A real person answers.
This page is an independent editorial overview published by Maestro Strategic Partners, an operations and AI consultancy for plaintiff law firms. Maestro is not affiliated with, sponsored by, or endorsed by Thomson Reuters Corporation. CoCounsel and related marks are the property of their respective owners; they are used here for identification only. Product details verified as of July 2026 and may have changed — confirm specifics with the vendor.
