Mar 10, 2026 | AI and product innovation

 

When we first introduced CoCounsel, we made a promise: AI that works the way you work, built on the sources you trust. That promise resonated. Today, more than one million professionals across 107 countries and territories have chosen CoCounsel — a signal that AI has shifted from experimentation to production in the world’s most high-stakes professional workflows. 

What began as a bold idea has become enterprise infrastructure because it delivered. CoCounsel — Thomson Reuters AI Technology — is built for moments when being almost right is not good enough. It is grounded in decades of authoritative content, validated by domain experts, and backed by a clear commitment that customer data remains theirs.

And we didn’t stop there. Because the best version of that promise was still ahead of us. 

“Lawyers don’t want to just operate software, and that’s not what great AI should do. CoCounsel keeps them in the analytical mindset they were trained for: going back and forth, challenging answers, and steering the work. With sourcing directly from Westlaw and Practical Law, they’re not wasting time second-guessing the results. We’re seeing adoption from associates to partners across every practice area. When it spreads that quickly, the experience just works.”

– Andrew P. Medeiros, Managing Director of Innovation, Troutman Pepper Locke

 

From Assistance to Completion 

The first wave of AI showed us that machines can reason. They can summarize, suggest, and draft. But legal professionals need systems that can complete work — not just assist at moments within it. There’s a meaningful difference between the two. 

Professional legal work is structurally complex. It demands authoritative content, jurisdictional nuance, multi-step workflows, and outputs that can withstand scrutiny. General-purpose AI stalls at the edges of that complexity — it assists at moments within the work, but it doesn’t deliver end to end. 

For two years, CoCounsel has proven it can complete that complex work across the high-stakes legal workflows professionals trust. But directing it still required professionals to do the orchestration themselves — choosing the right skill, defining the workflow, crafting detailed prompts. The AI could finish the work; getting it started still took effort. 

That gap — between an AI that can complete the work and one that simply does — is exactly what we set out to close. 

 

Introducing the Next Generation of CoCounsel Legal 

Last week we teased the next generation of CoCounsel Legal — our most advanced version yet, out in beta soon. It’s a smarter, more powerful, and more flexible experience designed to handle more high-stakes work than ever before by eliminating the friction between asking and completion.  

Now, professionals can complete any legal task with a single query, even if no predefined skill or workflow exists. Simply describe what you need in plain language and CoCounsel Legal gets to work, using advanced reasoning to understand the full scope of work, assessing the available content and tools, building multi-step plans dynamically, adapting to the complexity of the task, and executing every step automatically. Plus, it explains its reasoning along the way. Legal research, document analysis, drafting, strategic guidance — all from a single prompt.

With native access to both customer documents and the proprietary tools and content within Westlaw and Practical Law, CoCounsel Legal automatically surfaces the most relevant research and expert guidance. Every result includes full visibility into the steps taken, the sources used, and citations to source materials. The outputs are fiduciary-grade, transparent, and verifiable — the kind you can stake your reputation on.  

Less prompting. Less orchestration. Easier verification. More completion. Greater ROI. Without compromising professional standards.

 

Built to be Different from the Ground Up  

A reimagined experience demands a reimagined foundation. CoCounsel Legal was re-architected from the ground up to incorporate Anthropic’s Claude Agent SDK at the model layer — creating the only legal agent with native access to Westlaw and Practical Law. 

“Anthropic’s Claude provides advanced reasoning capability at the foundation layer — but what customers get from Thomson Reuters is a complete, governed system built around that foundation,” said Joel Hron, Chief Technology Officer, Thomson Reuters. “Our proprietary content, our domain expertise, and our governance framework are what turn raw AI capability into trusted, fiduciary-grade outcomes. That’s a combination others simply cannot replicate.” 

Thomson Reuters operates a model-agnostic AI architecture — meaning we work closely with frontier model providers at the capability level while owning and operating the full professional system: designing the workflows, orchestrating execution, integrating authoritative content, and standing behind the outcomes. 

This is not a chatbot with legal content bolted on. It is a purpose-built agentic system engineered for high-stakes legal work, built on a foundation that others can’t replicate. 

 

Models are table stakes. The real differentiator is the system around the model. 

General‑purpose AI is built for breadth, not standards. Vertical startups bring focus, but they lack the authoritative content, trusted tools, and enterprise‑grade foundation required for high‑stakes legal work. 

Thomson Reuters brings all of it together: 

• Our authoritative content grounds every AI output in sources professionals can defend. CoCounsel Legal has native access to Westlaw and Practical Law — the same sources professionals rely on to produce outputs ready for litigation, regulatory, advisory, and transactional legal work across law firms and corporate legal departments. 

• Our thousands of attorney-editors and domain experts shape and fine-tune the AI to reflect real-world professional standards, grounding CoCounsel Legal deeply in authoritative legal content and real-world legal reasoning patterns. 

• Our native workflow integrations mean CoCounsel Legal doesn’t sit alongside your work — it sits inside it, connecting to the tools professionals already use including Deepjudge, NetDocuments, Icertis, Microsoft 365, iManage, and many more. 

• Trust is not a feature; it’s the product, as CoCounsel Legal is designed to produce explainable, traceable outputs that professionals can stand behind. Every recommendation is grounded in authoritative sources. Every step in the reasoning process can be reviewed. Every output is ready for human review and should meet the rigorous standards required for court filings, regulatory submissions, and high-stakes decisions. 
• Customer data remains secure and is not used to train general-purpose foundation models. CoCounsel Legal operates with enterprise-grade security, strict data governance controls, auditability, and clear boundaries between customer environments. 

If AI can’t complete work to fiduciary standards, it won’t deliver ROI. What we’re building, others can’t replicate.  

 

Part of a Broader AI Transformation 

The commitment to developing systems that offer “Fewer Steps. Bigger Outcomes” is transforming products across our portfolio. Deep Research on CoCounsel Legal launched in August 2025 and is an AI-native legal research system that plans, reviews, and strategizes like a great researcher would — now using Westlaw and Practical Law in parallel to make research exponentially easier.  

Ready to Review on CoCounsel Tax and Audit, launched in December 2025, is modernizing 1040 tax return preparation, taking on heavy, repetitive work so tax professionals can focus on what matters most.  

On ONESOURCE+, we launched ONESOURCE Sales and Use Tax AI in January 2026. It’s already transforming the compliance landscape, reclaiming time, reducing audit risk, and cutting internal compliance cycles from day one. And we’re not stopping there. We’re building toward the next frontier: connected and embedded intelligence that orchestrates across the ONESOURCE tax ecosystem, bringing decades of tax content and regulatory intelligence to the moment decisions get made. 

To complement this work, we are combining frontier research talent and our deep domain expertise to accelerate development of the Thomson Reuters large language model, Thomson — trained on professional-grade data and purpose-built for high-stakes work. 

Our strategy is built around what professionals need: AI workflows grounded in proprietary content, deep domain expertise, and the latest AI capabilities. We’re delivering fiduciary-grade results no one else can. 

 

Sign Up Now 

The new CoCounsel Legal is entering beta in the United States soon, with general availability planned for later this year. More regions and territories will follow. 

Sign up now to join the waitlist for early beta access to the fully reimagined CoCounsel Legal experience. 

Fewer Steps. Bigger Outcomes. A fundamentally better way to practice law.

Check out the Next Generation of CoCounsel Legal (click to enlarge):

Read more: Rebuilding for the Agent Era: The Next Generation of CoCounsel Legal