CoCounsel is Thomson Reuters' AI assistant for professionals. Its legal product, CoCounsel Legal, which Thomson Reuters says is engineered to work at the level of a senior associate, reasons from Westlaw content, Practical Law guidance and a firm's own documents to handle research, analysis and drafting from a single request. Thomson Reuters rebuilt CoCounsel Legal as an agentic system in August 2026: from one plain-language request it builds a plan and works through each step, with its reasoning and citations visible. CoCounsel was originally developed by Casetext, which Thomson Reuters acquired in August 2023, and the CoCounsel brand now also covers tax, audit and accounting work. The CoCounsel page says the product is trusted by 1 million users, and named legal customers include Cole, Scott & Kissane, Robinson & Cole, Troutman Pepper Locke and Albright Yee & Schmit.
Deep Research builds a plan for a legal question and works through it step by step with Westlaw and Practical Law content, explaining its reasoning and delivering a cited report. Deep Research Verify checks that the cited Westlaw and Practical Law authority supports each legal assertion. Tabular Analysis answers up to 100 questions across as many as 10,000 documents in one table that can be filtered and sorted, with every answer traced to its source, and it runs on Thomson, Thomson Reuters' own AI model built for legal work. Other features include the Litigation Document Analyzer, document summaries, review and comparison, Westlaw Brief Builder, which drafts litigation briefs while the attorney chooses the arguments and validates the citations, integrated drafting, and Workspaces that keep a matter's documents, templates and conversations together. A Forrester Total Economic Impact study commissioned by Thomson Reuters in 2026 reports a 33% average reduction in time spent on document review, research and drafting.
CoCounsel Legal connects to iManage, NetDocuments, SharePoint, HighQ, DeepJudge, Smokeball, Box and Litify, works inside Microsoft Word, Outlook and Teams, and links with Supio for personal injury case intelligence. Thomson Reuters also publishes a CoCounsel Legal MCP connector, announced with Anthropic on 12 May 2026, which brings the CoCounsel agent into Claude: Claude hands the legal task to CoCounsel and streams back the result. It requires a CoCounsel Legal subscription and works across Claude on the web, the desktop app and Cowork. Thomson Reuters offers the connector as a pilot it may modify, suspend or withdraw at any time, and its General Terms prohibit using Thomson Reuters content with another professional AI tool, including through an MCP interface. No public developer API is published.
Thomson Reuters sells CoCounsel online to law firms of up to 10 attorneys, and larger organizations buy through sales. On the law-firm pricing pages read on 1 November 2026, CoCounsel Essentials, the document analysis, review and drafting package, costs $360 per attorney per month on a one-year plan, $315 on a two-year plan and $292.50 on a three-year plan. CoCounsel Legal for all states and federal law, which bundles Westlaw Advantage, the Practical Law Dynamic Tool Set and CoCounsel Essentials, costs $784 per attorney per month on a one-year plan. Plans run for one, two or three years. Online prices apply to new customers only, and Thomson Reuters says most online buyers receive access within one business day.
The CoCounsel Legal page says the product is SOC 2 and ISO 42001 certified and that customer data is never used to train the underlying models. Thomson Reuters' trust profile for CoCounsel Legal, hosted on Whistic, lists SOC 2 Type II, ISO 27001 and ISO 42001, with the reports available under a confidentiality agreement.
CoCounsel suits firms and legal departments that already work in Westlaw and Practical Law. Firms that research in LexisNexis can look at Lexis+ with Protégé, plaintiff firms that want intake, medical chronologies and demand letters in one platform can look at Eve, teams focused on contract drafting in Word can look at Spellbook, and firms that want legal AI not tied to one research database can look at Harvey AI or Legora.
Current state Q4 2026: on October 14, 2026 Thomson Reuters launched the next generation of CoCounsel Legal globally, adding a Multinational Profile with legal content from more than 100 countries and territories, and the upgraded platform is rolling out to customers in more than 90 countries and territories through 2026. CoCounsel Legal also received the American Association of Law Libraries 2026 New Product Award. The CoCounsel Legal MCP connector for Claude remains a pilot, and its help page says it is available in Cowork but not yet fully optimized for it. G2 lists CoCounsel Legal under Thomson Reuters with 116 reviews at 4.7 out of 5.