Thomson Reuters shakes up the legal AI race with major CoCounsel update

Thomson Reuters has made one of its most consequential legal AI moves yet by launching CoCounsel Legal in the UK, rolling out agentic AI capabilities across its flagship Westlaw and Practical Law products.

The UK release follows the launch of CoCounsel Legal in the US last year, but with deeper integration into Thomson Reuters’ most valuable content libraries.

At the heart of the rollout is Deep Research, an AI solution that brings together legal research, workflow automation, intelligent document search and AI-powered legal assistance inside a single interface.  

The advantage

The key differentiator against third-party AI platforms is that CoCounsel is embedded directly within Thomson Reuters’ Westlaw and Practical Law content, offering citation-backed outputs grounded in its proprietary material.

Many UK firms already license Westlaw and Practical Law, and adding advanced AI capabilities is likely to be an easier sell than onboarding entirely new vendors. That positions it not only against standalone AI providers, but also against LexisNexis, which has been pursuing a similar strategy through its Protégé product.

Chief product officer David Wong said CoCounsel Legal was about more than efficiency: "It's about empowering legal professionals with AI that reasons through complex problems, integrates seamlessly into existing workflows, and scales across entire organizations."

A shifting competitive landscape

Most legal AI platforms such as Harvey or Legora sit alongside products like Westlaw and Practical Law, rather than being natively embedded within them. CoCounsel, by contrast, is designed to pull more of that work back inside Thomson Reuters’ ecosystem - a strategic move in a market where data access and workflow integration are becoming decisive differentiators.

That distinction helps explain Harvey’s partnership with LexisNexis announced last year. While the arrangement allows Harvey users to tap licensed LexisNexis content, it still operates as a separate interface, sitting alongside the core research platforms.

With drafting and assistant capabilities already live - and more advanced review tools on the way - CoCounsel is quickly looking like a serious competitor to the current generation of legal AI platform frontrunners, particularly as firms decide whether to consolidate tools or stick with specialist platforms.

What’s next

Thomson Reuters said it has also launched Tabular Analysis in the US, a high-volume document review feature capable of analysing up to 10,000 documents across multiple questions, with a global rollout expected soon.

The UK launch also underscores how aggressively Thomson Reuters is investing in AI. CoCounsel began life as Castext, which Thomson Reuters acquired in 2023 for $650 million, and the media giant has continued to build out its capabilities through further acquisitions, including legal AI startup Safe Sign Technologies - founded by former A&O Shearman trainee Alexander Kardos-Nyheim - last year.

Last year, Thomson Reuters said it had around $10 billion earmarked for potential AI acquisitions through 2027.