CoCounsel Legal
Thomson Reuters' legal agent, which researches, drafts and checks citations against Westlaw and Practical Law.
By Thomson Reuters · launched 2025-08-05 · last checked 2026-11-01
Why 3: Deep Research writes and carries out a multi-step research plan and drafts documents, but lawyers remain responsible for checking its work before it is used.
What it does. CoCounsel Legal launched in August 2025 with Deep Research, which writes a multi-step research plan, carries it out and returns a cited report grounded in Westlaw and Practical Law. The next generation, released in the US on 20 August 2026 and built on Anthropic's Claude Agent SDK, adds a brief-drafting tool, a drafting agent in Word, review of up to 10,000 documents at once and a check of whether cited authority supports each assertion.
Where it falls short. Its answers are grounded in Thomson Reuters' own databases, which helps with citations but limits it to what those sources cover. We found no independent evaluation of its accuracy, and lawyers remain responsible for checking its work.
What it can do
Incidents
- None logged.
Closest fiction
Black Mirror: "The Entire History of You" — A perfect record is only as good as the person who checks it.
Related legal agents
- Harvey Harvey · autonomy 3/5
History
- 2026-11-01 Added to the index.
Sources
- Thomson Reuters Launches CoCounsel Legal, Transforming Legal Work with Agentic AI and Deep Research Thomson Reuters, 2025-08-05
- Thomson Reuters Expands CoCounsel Legal to UK, Continuing Its Transformation of Legal Work with Agentic AI Innovation Thomson Reuters, 2026-01-26
- Thomson Reuters Launches Next Generation of CoCounsel Legal, the AI Ecosystem Built for Legal Professionals Thomson Reuters, 2026-08-20
- Thomson Reuters Launches CoCounsel Legal with Agentic AI and Deep Research Capabilities, Along with A New and 'Final' Version of Westlaw LawSites, 2025-08-05
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