Westlaw CoCounsel: AI Legal Research Tool Profile

Product Overview

Westlaw CoCounsel is Thomson Reuters' generative AI layer built directly into the Westlaw legal research platform. It is not a standalone product — it operates within the existing Westlaw environment and draws on Westlaw's primary law database, including cases, statutes, regulations, and secondary sources. The integration means attorneys using CoCounsel are working with the same source corpus they already rely on for manual research, rather than a separate AI-indexed database.

The tool is marketed specifically to practicing attorneys, law firm associates, and in-house legal teams. Thomson Reuters positions it as an AI research assistant capable of drafting research memos, answering legal questions with citations, reviewing documents against specific legal standards, and extracting information from uploaded documents. Each of these functions is tied to a specific task type within the interface.

Structured Field Summary

Deployment Model

CoCounsel is fully cloud-hosted. There is no on-premises deployment option. Attorneys access it through the standard Westlaw web interface or through the CoCounsel Core product, which can also be embedded in other workflows via API. The cloud-only architecture means firms with strict on-premises data requirements — certain government agencies, regulated financial institutions, or firms under specific client confidentiality mandates — should evaluate whether cloud processing of query content is permissible under their obligations.

Data Retention Policy

This is one of the most frequently evaluated dimensions for law firm procurement teams. Thomson Reuters' stated position, as documented in its CoCounsel terms and AI policy disclosures, is that customer query data and uploaded documents are not used to train Thomson Reuters' AI models. The company describes this as a zero-training-data commitment for customer inputs.

What that policy does not address directly is session-level processing retention — how long query data persists in the processing pipeline before deletion, and what logging occurs for security, debugging, or service improvement purposes. These distinctions matter for privilege and confidentiality analysis. Thomson Reuters' data processing agreement (DPA) governs these terms for enterprise subscribers and should be reviewed directly for specific retention window commitments.

Core Task Capabilities

CoCounsel is organized around discrete task types rather than an open-ended chat interface. This is a deliberate design choice — each task type is scoped to a specific legal workflow, which constrains the model's behavior and makes output more predictable for professional use.

• Research Memo: Generates a structured memo responding to a legal question, with citations to Westlaw-verified primary sources. Citations link directly to the source documents in Westlaw.
• Ask a Document: Accepts uploaded documents and answers questions about their content. Useful for contract review, deposition preparation, or analyzing opposing filings.
• Draft a Document: Produces first-draft legal documents based on user prompts, grounded in Westlaw content where relevant.
• Review a Document: Evaluates an uploaded document against a specified legal standard or checklist — for example, checking a contract against jurisdiction-specific enforceability requirements.
• Find Answers: A more conversational query interface that retrieves and synthesizes answers from Westlaw primary and secondary sources.

Jurisdiction Coverage

CoCounsel's research capabilities are directly tied to Westlaw's database coverage. For US practitioners, this means comprehensive federal and state coverage — all circuit courts, district courts, state appellate and supreme courts, federal and state statutory codes, and administrative regulations. Secondary sources including law review articles, treatises, and practice guides are also within scope.

International coverage is available through Westlaw International, which covers selected common law jurisdictions including the UK, Canada, Australia, and the EU. The depth of AI-assisted research in international jurisdictions is more variable than the US coverage — practitioners relying on CoCounsel for non-US research should verify source currency and completeness for their specific jurisdiction before relying on AI-generated outputs.

Documented Limitations and Risk Factors

Citation Accuracy

CoCounsel's citations link to actual Westlaw documents, which substantially reduces the hallucination risk that has affected general-purpose LLMs used for legal research. Because the model retrieves from a verified database rather than generating citations from parametric memory, fabricated citations are less likely than with tools not grounded in a live legal database.

That said, citation grounding does not eliminate mischaracterization risk. The model may accurately cite a case while misstating its holding, scope, or precedential weight. Independent verification of cited authority remains a professional obligation — the tool's citation links make that verification faster, but do not substitute for it.

Document Upload Confidentiality

The "Ask a Document" and "Review a Document" task types require uploading client materials to Thomson Reuters' cloud infrastructure. Attorneys should evaluate whether this transmission is consistent with their duties under applicable professional conduct rules — particularly Model Rule 1.6 on confidentiality and any jurisdiction-specific ethics opinions on cloud storage of client files. Several state bars have issued guidance on this question; the analysis is not uniform across jurisdictions.

Output as First Draft, Not Final Work Product

Thomson Reuters' own documentation positions CoCounsel output as a starting point for attorney review, not as final work product. This framing aligns with the professional responsibility consensus that AI-generated legal content requires attorney review and verification before use. Firms deploying CoCounsel should establish internal protocols specifying what review is required before any AI-generated output is filed, sent to clients, or relied upon in advice.

Pricing and Access Structure

CoCounsel is available in two primary configurations. For existing Westlaw subscribers, it is offered as an add-on to current plans — pricing is negotiated through Thomson Reuters account management and varies by firm size and existing contract terms. Thomson Reuters does not publish list pricing for law firm subscriptions.

CoCounsel Core is a separate, standalone product that does not require a full Westlaw subscription. It provides AI task capabilities with access to a subset of Westlaw content. Thomson Reuters has marketed CoCounsel Core to smaller firms and solo practitioners who may not carry a full Westlaw subscription. As of this profile's verification date, Thomson Reuters has also made CoCounsel Core available with API access for integration into firm-built workflows.

Competitive Positioning

The primary direct competitor in AI-assisted legal research is Lexis+ AI, which offers a comparable set of task-based AI capabilities integrated into the LexisNexis research environment. Bloomberg Law has also expanded its AI research features. Harvey operates differently — it is not a research database product but a general legal AI assistant that can be connected to firm data sources.

CoCounsel's differentiation is primarily the depth of Westlaw's underlying database — particularly for US case law, KeyCite citator integration, and secondary source coverage. For practitioners who already rely on Westlaw for manual research, the AI layer adds capability without requiring a separate platform. For firms evaluating from scratch, the choice between CoCounsel and Lexis+ AI often comes down to existing database contracts, interface preference, and specific task type requirements.

Verification Methodology

This profile was compiled from Thomson Reuters' publicly available product documentation, CoCounsel terms of service, and Thomson Reuters' AI policy disclosures as of May 2026. Pricing information reflects publicly available descriptions of product tiers; specific contract pricing was not independently verified. The editorial team has not conducted independent benchmark testing of CoCounsel output accuracy for this profile.

Data retention claims are based on Thomson Reuters' published AI policy. Readers requiring contractual commitments on data handling should request and review the current data processing agreement directly from Thomson Reuters.