CoCounsel Review 2026: Is Thomson Reuters’ Legal AI Worth It?
What Is CoCounsel?
CoCounsel is an AI legal assistant developed and distributed by Thomson Reuters. It originated as the flagship product of Casetext, a legal AI startup that Thomson Reuters acquired in 2023 for $650 million. Following the acquisition, Thomson Reuters rebranded the product under the CoCounsel name and integrated it with Westlaw, the world’s largest commercial legal research database.
The product has gone through significant development since the acquisition. What began as a research-first tool has expanded into a full-stack legal AI assistant capable of handling research, document review, contract analysis, deposition preparation, and litigation drafting. The integration with Westlaw remains its defining advantage: CoCounsel can cite and retrieve from Westlaw’s primary and secondary source database, giving it a research foundation that independent AI startups cannot replicate.
As of 2026, CoCounsel has surpassed one million users. It serves both corporate legal departments and law firms, with dedicated enterprise deployment options for large organizations that require data isolation, custom integrations, and compliance controls.
A Note on the Casetext History
Many attorneys who evaluated legal AI in 2022 and 2023 will remember Casetext as a well-regarded standalone legal research platform with an AI overlay. The current CoCounsel product is substantially different. The Thomson Reuters acquisition brought capital, Westlaw data access, and enterprise distribution that transformed it from a research tool into a comprehensive legal AI platform. If your last exposure to this product was Casetext prior to 2024, this review covers a materially different product.
Core Features
AI-Assisted Legal Research
CoCounsel’s research capability is its strongest feature. Powered by the Westlaw database, it can answer complex legal questions, retrieve relevant cases and statutes, and synthesize research findings into structured summaries. Unlike general-purpose AI tools that rely on training data of uncertain currency, CoCounsel pulls from Westlaw’s continuously updated legal database.
Research queries can be conversational. Attorneys can ask questions like “What is the standard for granting a preliminary injunction in the Ninth Circuit for trade secret claims?” and receive a synthesized answer with citations that link directly to Westlaw sources. The citations are verifiable and traceable, which matters for attorney work product.
KeyCite integration means CoCounsel research is validated against Westlaw’s citator, flagging overruled or questioned precedent automatically. This reduces the risk of citing bad law, a critical safeguard for substantive legal work.
Document Review and Analysis
CoCounsel can review uploaded documents — contracts, pleadings, discovery productions, due diligence materials — and answer specific questions about them. Attorneys can upload a document and ask targeted questions: “Does this contract contain a limitation of liability clause?”, “What are the indemnification obligations of each party?”, “Summarize the key risk provisions.”
For due diligence and contract review workflows, CoCounsel supports batch document processing, enabling analysis across large document sets rather than requiring document-by-document review. This is particularly valuable for M&A due diligence and commercial contract portfolios.
Deposition Preparation
One of CoCounsel’s more specialized features is deposition preparation assistance. Attorneys can upload case materials — prior testimony, document productions, expert reports — and CoCounsel generates suggested deposition questions, identifies inconsistencies in prior testimony, and surfaces relevant factual details. This is a genuine time-saver for litigators handling complex matters with extensive document records.
Contract Analysis and Playbook Application
For transactional practices, CoCounsel supports contract markup against firm or client playbooks. Attorneys can define standard positions on key contract provisions, and CoCounsel reviews incoming contracts against those positions, flagging deviations and suggesting markup language. This is most useful for in-house legal teams and transactional practices that handle high volumes of similar agreements.
Drafting Assistance
CoCounsel can draft legal documents from prompts and source materials. This includes demand letters, brief sections, contract provisions, and client correspondence. The drafting is research-grounded — it can incorporate Westlaw research into drafted content rather than relying solely on training data. Quality varies by practice area and document type, and attorney review and revision remain essential.
Who Is CoCounsel Best For?
Mid-size and large law firms: Firms with 50 or more attorneys handling diverse practice areas — litigation, transactional, regulatory — get the most value from CoCounsel’s breadth of features and Westlaw integration.
Corporate legal departments: In-house teams with high volumes of contracts, due diligence work, or regulatory research benefit from the enterprise deployment options and contract analysis capabilities.
Existing Westlaw subscribers: If your firm already pays for Westlaw, the CoCounsel bundle is the most cost-effective path to enterprise legal AI.
AmLaw 200 and BigLaw firms: CoCounsel’s enterprise controls, security standards, and scale make it appropriate for large practice environments with strict data governance requirements.
Less suitable for:
- Solo attorneys and very small firms (pricing and complexity)
- Litigation-only practices looking for a specialist tool (Briefpoint may be better fit)
- Budget-sensitive practices looking for entry-level AI access
Bottom Line
CoCounsel is the most complete legal AI platform available in 2026 for firms willing to pay for it. The Westlaw integration, enterprise reliability, and breadth of use cases — research, document review, drafting, deposition preparation, contract analysis — make it a genuine productivity platform rather than a single-use tool. Its weaknesses are pricing opacity and a product focus that leaves smaller firms and solo practitioners underserved.
For mid-size and large law firms, especially those with existing Thomson Reuters relationships, CoCounsel is the clear benchmark to evaluate against. The question is not whether it is capable — it clearly is — but whether the cost is justified for your firm’s specific volume and use case.
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Disclosure: LegalAIReviews.net does not have an affiliate relationship with Thomson Reuters or CoCounsel. This review is based on publicly available product information, user feedback, and independent analysis. We receive no compensation for reviews or recommendations.