CoCounsel

Thomson Reuters acquired Casetext back in 2023, and the technology they developed there was turned into CoCounsel, which has now been wholly subsumed into Thomson Reuters’ products and delivered via Westlaw. At its heart, what differentiates CoCounsel from broad-purpose AI platforms is citation grounding. When it attempts to answer your legal research query, it looks at your existing Westlaw (Thomson Reuters) database and then vets every citation you will surface against real cases. Hallucinating legal citations is a known issue for generic AI used in legal-specific workflows. Citation grounding is meant to head that off.) The CoCounsel AI can conduct research in cases, create draft research memos, summarize deposition transcripts, read uploaded documents, and review contracts. A particular use case is with preparing for deposition by reading all of a given deponent's past testimony and relevant cases so CoCounsel can suggest questions. For comparison, a recent Stanford study commissioned by LexisNexis stated that the Westlaw system's own earlier AI product had a 34% rate of citation errors, while Lexis+ AI only had a 17% error rate. CoCounsel, which is grounded on the Westlaw material set, has always tested well against citation benchmarks. CoCounsel costs $75 to $500 per user/month based on access tier and Thomson Reuters subscriptions already held. As an AI augmentation on existing Westlawnods, it's a rather direct plug-and-play solution for litigation-focused firms.

• Category: Legal Assistants
• Pricing: Paid
• Rating: 4.7 / 5 (0 reviews)
• Platforms: Web, iOS, Android

Key features

• Westlaw-grounded research — Every citation is validated against the Westlaw database before being surfaced preventing the fabricated case references that plague general AI tools
• Legal research memos — Generates structured research memos on legal questions with cited authority drawn from the Westlaw corpus
• Deposition preparation — Analyzes prior testimony and case documents to produce targeted deposition questions based on the specific witness and matter context
• Document summarization — Summarizes lengthy legal documents depositions contracts and filings into structured concise overviews
• Contract analysis — Reviews uploaded contracts and identifies key terms obligations risks and missing provisions relevant to your matter
• Brief drafting — Assists with drafting sections of legal briefs with cited authority from the Westlaw database integrated into the drafts
• Judicial analytics — Surfaces insights on judge behavior ruling tendencies and case outcomes to inform litigation strategy and forum selection
• Rebuilt on Claude Agent SDK — The AI reasoning layer was rebuilt in 2026 on the Claude Agent SDK improving multi-step research task performance

Pros & Cons

Pros

• Citation grounding in Westlaw eliminates the fabricated case reference problem that makes general AI tools unreliable for client-facing legal work
• Natural integration into existing Westlaw workflows for firms already licensed on Thomson Reuters research platforms
• Deposition preparation capability is a genuinely specialized feature that saves meaningful attorney time before complex depositions
• Rebuilt on Claude Agent SDK in 2026 for improved multi-step research performance while maintaining Westlaw citation grounding
• Pricing starts at $75 per user per month which is accessible for small and mid-size firms unlike enterprise-only alternatives

Cons

• Requires an existing Westlaw subscription on top of the CoCounsel access fee which significantly increases total cost for firms not already licensed
• Less useful for transactional and contract-heavy practices where the value of Westlaw case law grounding is less central to the daily workflow
• Contract analysis features are less refined than dedicated contract review tools like Spellbook or Robin AI that specialize in that specific task
• Response quality for highly specialized niche practice areas may require significant prompt refinement to produce reliably useful outputs

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