CoCounsel
by Thomson Reuters
Thomson Reuters legal AI assistant for research, drafting, and document review
Last reviewed 2026-06-20
CoCounsel is Thomson Reuters' AI assistant for legal work, originally built by Casetext and launched in March 2023 as the first AI legal assistant on GPT-4. Thomson Reuters acquired Casetext for $650M in 2023 and has since grounded CoCounsel in its authoritative Westlaw and Practical Law content. It performs legal research, document review, drafting, contract analysis, deposition preparation, and timeline creation, returning source-linked work product that lawyers review and act on. The next-generation CoCounsel Legal (in beta in early 2026, with broader rollout later in the year) adds agentic AI: a lawyer describes an objective in plain language and the system plans research or drafting steps, retrieves authoritative sources, searches documents and precedent, verifies citations, and assembles structured output, showing the steps and sources it used. Despite marketing that says it completes multi-step workflows autonomously, it produces work product for lawyer verification in a high-stakes domain, so it operates as a supervised agent. It serves solo attorneys through Am Law 100 firms, corporate legal departments, courts, and government.
What it can do
Deep Research over Westlaw and Practical Law
SupervisedGenerates a multistep research plan, finds relevant authority, and returns source-linked answers grounded in Westlaw and Practical Law content, which a lawyer reviews.
sourceBulk document review and analysis
CopilotAnalyzes thousands of documents at once, reviews litigation documents, analyzes complaints, and surfaces key components in a sortable, filterable table for lawyer review.
sourceDrafting and contract analysis
CopilotDrafts documents from precedents or templates and analyzes contracts with negotiation guidance and source-linked validation; a lawyer reviews and finalizes.
sourceAgentic multi-step legal workflows (CoCounsel Legal)
SupervisedFrom a plain-language objective, plans and executes multi-step research or drafting, retrieves authoritative sources, verifies citations, and assembles structured work product, exposing the steps and sources used for human verification (in beta in 2026, marketed as autonomous; in practice supervised).
sourceTimeline and chronology creation
CopilotAssembles chronologies from complex documents to support litigation and case preparation.
source
Strengths
- +Grounded in authoritative Westlaw and Practical Law content with source-linked, traceable outputs
- +Backed by Thomson Reuters with broad scale (reportedly 1M+ users across 107 countries as of February 2026)
- +Multi-model architecture spanning frontier models (reported: Anthropic, OpenAI, Google) plus proprietary AI for performance control
Limitations
- −Hallucination and accuracy risk is material in a high-stakes domain; lawyers must validate every output
- −Enterprise, quote-only pricing tied to multi-year terms (no transparent self-serve plan)
- −Agentic CoCounsel Legal is marketed as autonomous but is supervised in practice and was still in beta in early 2026
Overview
CoCounsel is Thomson Reuters' AI assistant for legal work. It was built by Casetext, which launched it in March 2023 as the first AI legal assistant on GPT-4; Thomson Reuters acquired Casetext for $650M in cash in 2023 and has since grounded CoCounsel in its authoritative Westlaw and Practical Law content. By February 2026 Thomson Reuters reported 1 million users across 107 countries and territories (reported figure, not audited).
What it does
CoCounsel performs legal research (including Deep Research, a multistep research plan over trusted content), bulk document review, drafting from precedents or templates, contract analysis with negotiation guidance, deposition preparation, and timeline creation. Outputs are source-linked and traceable. The next-generation CoCounsel Legal (in beta in early 2026) adds agentic AI: a lawyer describes an objective in plain language and the system plans the steps, retrieves authoritative sources, searches documents and precedent, verifies citations, and assembles structured work product, exposing the steps and sources it used. Thomson Reuters markets this as completing workflows autonomously, but because outputs require lawyer verification in a high-stakes domain, it functions as a supervised agent.
Integrations & setup
CoCounsel has native access to Westlaw and Practical Law content with no separate searches, and integrates with Microsoft Word and Microsoft 365 plus document-management partners including iManage and SharePoint. It is delivered as SaaS.
Pricing
Enterprise and quote-based, sold in multi-year terms (commonly 1-, 2-, and 3-year plans), often bundled with Westlaw. There is no transparent self-serve plan; third-party trackers list per-user costs in the hundreds of dollars per month for bundled solo configurations (reported, not official). See the Thomson Reuters plans-and-pricing page for current configurations.
Best for / not for
Best for solo attorneys through large firms, corporate legal departments, courts, and government that want legal AI grounded in Westlaw and Practical Law with citations and an audit trail. Less suited to buyers needing transparent self-serve pricing or fully autonomous automation without lawyer review.
Alternatives
Harvey is a competing legal AI platform for large firms and professional services; Spellbook focuses on contract drafting and review inside Microsoft Word; Robin AI focuses on contract review and management.
What people are saying
We aggregate real LinkedIn discussion into sentiment for the agents people search most. CoCounsel isn't tracked yet, want it added? Request tracking.
FAQ
Is CoCounsel autonomous?+
Not fully. Thomson Reuters markets the next-generation CoCounsel Legal as completing multi-step workflows autonomously, but it produces source-linked work product for lawyer verification in a high-stakes domain, so it operates as a supervised agent rather than acting end-to-end without review.
What models power CoCounsel?+
CoCounsel uses a multi-model architecture. Thomson Reuters has said it works with frontier models from Anthropic (Claude), OpenAI (GPT) and Google (Gemini) alongside proprietary AI and structured data, and it is developing a proprietary LLM for legal, tax, and compliance (reported, not a fixed published model list).
Who makes CoCounsel?+
CoCounsel was built by legal-research startup Casetext, which launched it in March 2023 as the first AI legal assistant on GPT-4. Thomson Reuters acquired Casetext for $650M in cash in 2023 and now develops CoCounsel.
Sources
- CoCounsel Legal product page (Thomson Reuters) · accessed 2026-06-20
- CoCounsel Legal reimagined: Agentic AI for legal work (Thomson Reuters blog) · accessed 2026-06-20
- One Million Professionals Turn to CoCounsel (Thomson Reuters press release) · accessed 2026-06-20
- Thomson Reuters CoCounsel Tests Custom LLM from OpenAI, Broadening its Multi-Model Product Strategy · accessed 2026-06-20
- CoCounsel reaches 1 million users (LawSites) · accessed 2026-06-20
Last reviewed 2026-06-20