CoCounsel

CoCounsel is Thomson Reuters' AI-powered legal assistant built on large language model technology and trained specifically for legal workflows. Originally launched by Casetext in 2023, CoCounsel was acquired by Thomson Reuters and has since been deeply integrated into the Westlaw Precision platform as well as offered as a standalone product called CoCounsel Core.

The platform addresses a core challenge in legal practice: attorneys spend an estimated 30-40% of their time on research and document review tasks that can be accelerated with AI assistance. CoCounsel uses retrieval-augmented generation (RAG) grounded in Thomson Reuters' proprietary legal databases, including Westlaw's collection of over 40,000 databases covering case law, statutes, regulations, and secondary sources. This grounding approach is designed to reduce hallucination risk, a critical concern when AI is applied to legal work where accuracy directly affects case outcomes and professional liability.

Key capabilities include AI-assisted legal research that can search across jurisdictions and synthesize relevant case law, statute analysis, and secondary authority into structured memoranda. The document review function can process contracts, briefs, and filings to extract key provisions, flag potential issues, and summarize content. Contract analysis features identify non-standard clauses, missing provisions, and risk areas across large document sets. The platform also supports deposition preparation by analyzing transcripts and suggesting lines of questioning based on case materials.

CoCounsel operates within Thomson Reuters' secure cloud infrastructure and maintains SOC 2 Type II compliance. The system includes audit trails showing which sources informed each AI-generated response, supporting the professional responsibility requirements attorneys face. As of early 2026, Thomson Reuters reports that CoCounsel capabilities are used by professionals at over 1,000 law firms and corporate legal departments.

The integration into Westlaw Precision, rolled out through 2025, means that CoCounsel's AI features are now accessible directly within the legal research workflow rather than requiring a separate application. This positions CoCounsel not as a standalone chatbot but as an embedded AI layer across Thomson Reuters' legal technology ecosystem, including Practical Law, Drafting Assistant, and HighQ document management.