CoCounsel Legal (Thomson Reuters)
Thomson Reuters' legal AI for research, analysis and drafting, grounded in Westlaw and Practical Law. Sold on its own (CoCounsel Essentials) or bundled with Westlaw Advantage research and the KeyCite citator.
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AI features
- Research, analysis and drafting grounded in Westlaw content, Practical Law guidance and your own documents, with linked citations to click through and verify
- Westlaw Advantage plans include KeyCite, Deep Research, Litigation Document Analyzer and the West Key Number System
- CoCounsel Essentials lists Quick Check integration, Finalize Citations and Add KeyCite Flags
- Westlaw Quick Check verifies the citations and quotations in an uploaded brief (Word up to 20 MB, PDF up to 30 MB, about 120 pages) and can analyze an opponent's brief for negative treatment and omitted authority
- Works inside Microsoft Word, Outlook and Teams
Pricing
Thomson Reuters publishes online prices for new customers at firms with up to 10 attorneys on its plans page; 2-year terms are 12% off and 3-year terms 18% off. Reported prices for one attorney on a 1-year plan, all states and federal: CoCounsel Legal $784/month, Westlaw Advantage with CoCounsel Essentials $639.20/month, CoCounsel Essentials alone $360/month (Cases.ai, read Oct 9, 2026; Costbench, checked Oct 13, 2026). Larger firms and existing customers get a quote from sales.
Best for
Small firms already on Westlaw, or litigators who want a citator and a brief checker in the same product as the AI.
Watch out for
Thomson Reuters' plans page says law-firm subscriptions carry annual price increases (12% for 1-year, 5% for 2-year and 4% for 3-year plans), so price the renewal, not just year one. Thomson Reuters says it never uses customer data to train underlying models and lists SOC 2 and ISO 42001 certification. Legal-specific AI still gets things wrong: a peer-reviewed Stanford study of earlier versions found Westlaw's AI-Assisted Research hallucinated more often than the other legal tools tested, and courts have sanctioned lawyers who copied Westlaw AI output without checking it. Verify every authority.
Playbooks that use CoCounsel Legal (Thomson Reuters)
Sources
- Thomson Reuters: CoCounsel Legal
- Thomson Reuters: Westlaw Advantage with CoCounsel Essentials plans and pricing
- Thomson Reuters help: Use Quick Check
- Cases.ai: CoCounsel pricing for solos and small firms (reported prices)
- Costbench: CoCounsel pricing (reported prices)
- Magesh et al., Hallucination-Free? (Journal of Empirical Legal Studies, 2025)
Last verified 2026-10-19.