Aug 05, 2025 | AI and product innovation

In 2023, we launched AI-Assisted Research in Westlaw, ushering in a new era of legal research powered by generative AI. It helped professionals start faster, explore more broadly, and surface insight with less effort.

But legal research is a multi-step process, where researchers iteratively review what’s been found and intelligently alter course based on new information. And they don’t just search. They use a wide variety of research tools to find relevant information in ways that can be far more efficient and effective when combined with search. With agentic AI, we can emulate the best practices of great researchers using the full research toolset Westlaw has to offer, tools like Key Numbers, KeyCite, Precision Research classifications, and statutes annotations.

Today we’re introducing Deep Research: an AI-native legal research system that doesn’t just summarize search results. It plans, reviews, and strategizes like a great researcher would, and it uses the full set of research tools Westlaw has to offer. Not only does Deep Research emulate the best practices of savvy researchers, but its AI agents use research tools in parallel, making research exponentially faster. What used to take hours now takes minutes and what used to be manual is now orchestrated by AI agents designed specifically for the legal domain.

What Makes Deep Research Different

While others layer generic AI on top of legal content, we’ve built something fundamentally more advanced: AI agents trained, equipped, and trusted to use Westlaw’s exclusive research toolset with the curated and up-to-date content of Westlaw and Practical Law to move through complex legal research workflows with unprecedented speed and precision.

These AI agents are:

• Instructed by the experienced attorneys from Westlaw and Practical law how to approach legal research like an expert
• Equipped with Westlaw’s exclusive research toolset, including Key Numbers, KeyCite, Precision Research classifications, statute annotations, and more
• Fueled by Westlaw and Practical Law’s up-to-date curated legal content
• Guided by orchestration logic grounded in decades of domain-specific workflow expertise

We’ve spent more than a year pushing AI frontier models to their limits in legal research workflows. We’ve tested where they succeed and fail. We’ve studied how they reason and what it takes to make them behave like thoughtful legal researchers. We’ve designed for long-document comprehension, multistep reasoning, and structured tool usage, all while working with domain-specific legal content and workflows.

And we didn’t do it alone. We reviewed and tested the designs, plans, and capabilities of Deep Research with over 1,200 customers to make sure we built it right. This isn’t just a simple connection to the off-the-shelf deep research capabilities of major LLM providers. It is a product transformation rooted in real testing, real constraints, and real customer experiences and expectations. This level of AI agent autonomy, reasoning, and transparency will define future workflows, and we’re excited to bring it to our customers for legal research.

To see it in action, watch the demo:

Seamless Integration with CoCounsel

Deep Research is featured prominently on the homepage of our new version of Westlaw, Westlaw Advantage, and it’s also fully embedded into the CoCounsel experience, so our customers can access it through the cutting-edge guided workflows in CoCounsel Legal.

Built for What’s Next

Deep Research will be available in Westlaw Advantage and CoCounsel Legal next week! I’m so excited for our customers to use it, and I’m beyond grateful for the enormously talented teams of experts at Thomson Reuters who have worked tirelessly to bring Deep Research to our customers. It’s a huge leap forward and yet, still, just the beginning. We see so much potential for developing this technology even further into legal workflows and thrilled about the breakthroughs to come. Stay tuned!