Thomson Reuters
Thomson Reuters CoCounsel is an agentic AI assistant for legal, tax and accounting. The 2026 rebuild runs on Claude Agent SDK with Westlaw Brief Builder.
About Thomson Reuters
What is Thomson Reuters (2026 update)
Thomson Reuters is a professional information company, and its main AI product is CoCounsel, an AI assistant built for legal, tax, and accounting professionals rather than a general-purpose chatbot. The company is tagged under Coding and Development in some directories, but that is a mistagging: Thomson Reuters sells research, compliance, and workflow software to law firms, corporate legal departments, and tax and accounting firms, and CoCounsel is the AI layer sitting on top of its Westlaw and Practical Law content.
What is new in 2026
Thomson Reuters reached general availability of the next generation of CoCounsel Legal on August 20, 2026, after opening early access in June 2026. The rebuilt product is a fully agentic experience: instead of running one prompt at a time, it plans a task, chooses the right skill or workflow, retrieves authoritative content, and adapts mid-task, closer to how a senior associate would work a matter. Thomson Reuters says this generation is built on Anthropic’s Claude Agent SDK, a shift from the OpenAI-based version CoCounsel launched with in 2023.
Two features stand out in the 2026 release. Westlaw Brief Builder grounds drafted briefs in verified Westlaw and Practical Law case authority while keeping the lawyer in control of the final language. Tabular Analysis, powered by Thomson Reuters’ own AI model, can now review up to 10,000 documents in a single table, useful for due diligence and large-scale contract review. CoCounsel Legal also expanded into the UK market in January 2026, extending beyond its US base.
Key features
- Agentic workflows that plan multi-step legal tasks instead of answering single prompts
- Westlaw Brief Builder for drafting briefs grounded in cited case law
- Tabular Analysis reviewing up to 10,000 documents per table for due diligence and contract review
- Legal research tied directly to Westlaw and Practical Law authority
- Matter-centric workflows connecting research, drafting, and verification in one place
- CoCounsel for tax and accounting professionals, separate from the Legal product line
- UK market availability alongside the US, added in January 2026
Pricing in 2026
Thomson Reuters does not publish a self-serve price list for CoCounsel; enterprise pricing is quote-based and depends on firm size, modules, and existing Westlaw or Practical Law subscriptions. Third-party breakdowns from 2026 report CoCounsel plans running roughly from the low hundreds to over $600 per user per month, and note CoCounsel is currently sold bundled with a Westlaw subscription rather than as a standalone product. Treat any number below as a third-party estimate, not an official price, and confirm the real quote on the official site.
| Plan | Price | What you get |
|---|---|---|
| CoCounsel Essentials | Custom (reported around $293/user/month by third parties) | Core CoCounsel research and drafting skills bundled with Westlaw access |
| CoCounsel Legal | Custom (reported around $492/user/month by third parties) | Full agentic workflow suite including Westlaw Brief Builder and Tabular Analysis |
| CoCounsel Tax and Accounting | Custom | AI assistant tuned for tax research, accounting workflows, and compliance, sold separately from the Legal line |
| Enterprise | Custom quote | Firm-wide deployment, negotiated terms, multi-year discounts reported for 2 and 3 year commitments |
Who should use it
CoCounsel is built for law firms of any size that already rely on Westlaw or Practical Law and want an AI layer for research, drafting, and document review inside that same ecosystem. Corporate legal departments handling due diligence or contract review at volume benefit from Tabular Analysis’s document-count ceiling. CoCounsel Tax and Accounting is a separate track aimed at tax professionals and accounting firms that need AI support for research and compliance work rather than litigation or contract tasks.
Limitations and alternatives
The main limitation is cost and structure: CoCounsel is not sold as a cheap standalone tool, third-party analyses describe it as bundled with Westlaw, and first-year costs for a mid-size team have been estimated well into six figures once training and companion subscriptions are included. Firms without an existing Westlaw relationship, or wanting a lighter self-serve tool, may find the bundling and quoting process slower than expected. For cross-border legal research outside the US-centric Westlaw base, coverage may feel narrower than a tool built multi-jurisdictionally from the start.
Harvey is a common alternative for large firms wanting agentic drafting and review without a Westlaw bundle requirement. Legora, based in Stockholm, focuses on a shared human-AI workspace for law firms and is often named as Harvey’s closest direct competitor. vLex, with its Vincent AI assistant, is worth comparing if the work spans multiple jurisdictions or needs broader global primary law coverage than Westlaw provides on its own.
Frequently asked questions
What is CoCounsel by Thomson Reuters?
CoCounsel is Thomson Reuters' AI assistant for legal, tax, and accounting professionals. It handles legal research, drafting, document review, and workflow tasks, tied to Thomson Reuters' Westlaw and Practical Law content.
How much does CoCounsel cost in 2026?
Thomson Reuters does not publish a fixed public price list. Enterprise pricing is quote-based, and it is currently sold bundled with a Westlaw subscription. Check the official site for a quote specific to your firm size and modules.
What changed in CoCounsel's 2026 update?
Thomson Reuters shipped a next generation of CoCounsel Legal, reaching general availability on August 20, 2026, moving to a fully agentic model built on Anthropic's Claude Agent SDK, and adding Westlaw Brief Builder and Tabular Analysis, which reviews up to 10,000 documents per table.
What are the main alternatives to CoCounsel?
Harvey and Legora are the most commonly cited alternatives for enterprise legal AI, and vLex's Vincent AI is often compared for firms needing broader multi-jurisdiction legal research coverage.
Information last verified: September 2026.
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