Overview
CoCounsel leverages advanced AI (originally built on OpenAI's GPT-4, now incorporating Thomson Reuters' proprietary AI and data) to perform core legal tasks. It allows users to ask complex legal research questions in natural language, review large document sets, analyze contracts, prepare deposition outlines, draft initial legal memos or correspondence, and summarize documents. Every answer cites the underlying source material within the Thomson Reuters ecosystem (Westlaw, Practical Law) — an important grounding feature given the surge of AI hallucination sanctions against attorneys in 2026. In early 2025, CoCounsel transitioned to version 2.0 with deeper Microsoft 365 integration and the Timeline tool for automated chronologies. In August 2025, CoCounsel Legal launched with Deep Research — multi-step research agents that autonomously execute complex research workflows across Westlaw's database, including jurisdictional comparison and multi-document analysis. As of 2026, CoCounsel is bundled exclusively with Westlaw; there is no standalone product.
Use cases
Primary: Accelerating legal research by asking complex questions in natural language and getting summarized answers with citations; Quickly reviewing and analyzing large document sets for discovery or due diligence.
Other use cases:
- • Preparing for depositions by extracting key testimony points
- • Drafting initial legal memos or sections of briefs
- • Analyzing contract clauses against standard terms or specific requirements
- • Creating timelines from factual documents (Timeline feature automates comprehensive chronologies from large document sets).
AI capabilities
- → Generative AI (drafting, summarization, Q&A)
- → Natural Language Processing (NLP)
- → Machine Learning (ML - trained on vast legal datasets)
- → Document analysis
- → Information extraction
- → Legal reasoning simulation
- → Citation checking/linking.
Pros & Cons
Pros
- ✓ Significant time savings on research and document review
- ✓ Leverages trusted Thomson Reuters content
- ✓ Reduces risk of AI hallucination through grounding/citations
- ✓ Handles complex natural language queries
- ✓ Covers multiple legal workflows (litigation, transactional)
- ✓ Potential for increased accuracy and thoroughness (when verified)
- ✓ Backed by a major legal information provider.
Cons
- ! Requires subscription to Thomson Reuters products (likely Westlaw Precision)
- ! Cost can be significant (enterprise pricing)
- ! AI outputs still require careful human review and validation
- ! Learning curve associated with maximizing its capabilities
- ! Performance may depend on the quality/nature of input documents.
Pricing
Model: Add-on subscription bundled exclusively with Westlaw (no standalone product as of 2026). Multiple pricing tiers and custom enterprise pricing available.
Pricing details: CoCounsel Core: ~$225/user/month as a Westlaw add-on. Total cost with a Westlaw subscription typically runs $300-$600/user/month depending on the Westlaw tier. Enterprise pricing requires contacting Thomson Reuters sales.
Integrations
- • Deeply integrated with Westlaw Precision.
- • Integration with Practical Law.
- • Potential integration with other Thomson Reuters legal software (e.g., HighQ, drafting tools).
- • API access might be available for enterprise clients for custom integrations.
What sets it apart
- ★ Deep integration with Thomson Reuters' authoritative content (Westlaw Precision, Practical Law)
- ★ Emphasis on reliability and reducing AI "hallucinations" through grounding in TR data
- ★ Developed by Casetext (a respected legal tech innovator) and now backed by TR's resources
- ★ Covers a wide range of core legal tasks beyond just contracts.
Compliance & security
Thomson Reuters maintains numerous compliance certifications (e.g., SOC 2, ISO 27001\) for its platforms. CoCounsel would fall under this umbrella. Adherence to GDPR, CCPA, etc.