Thomson Reuters (TRI) has opened early access to a completely rebuilt version of its CoCounsel Legal product, marking the most significant overhaul since acquiring Casetext in 2023.
The company abandoned its original codebase entirely, opting to reconstruct the flagship legal AI assistant from the ground up using Anthropic’s latest models and agent technology.
Ragunath Ramanathan, Thomson Reuters’ president of the legal professionals business, confirmed the radical decision to scrap existing code and start fresh.
“We abandoned all of the old code lines, and we said this feels like a shift that we need to rebuild the product from scratch,” Ramanathan said.
“Of course, we’ve done it on the basis of Anthropic and the latest models,” he added, signalling a deep partnership with the AI firm behind the Claude family of models.
The next generation of CoCounsel Legal is built on Anthropic’s Claude Agent SDK, creating a unified agentic platform capable of planning, selecting tools, retrieving authoritative content, and adapting mid-workflow.
The original CoCounsel Legal was built around specialised skills and guided workflows, a model that worked well for clearly defined tasks but struggled to match the unpredictable nature of real legal work.
Product co-heads Colbert and Ashraf wrote that they had expected a typical beta cycle of feature requests and refinements but instead received unsolicited praise from testers almost immediately.
More than a few users reportedly told the team that they “F#@%ing loved” the product, which Colbert and Ashraf described as a direct quote from beta participants.
Testers also reported that they had begun starting nearly every project within the new experience rather than reserving it for specific tasks, a behavioural shift that suggests the rebuild has meaningfully changed day-to-day usage patterns.
Every CoCounsel Legal customer in the United States has been given a toggle allowing them to switch between the new experience and the current version at will during the early-access period.
Thomson Reuters has confirmed that full general availability is planned for August 2026 in the United States, followed by subsequent rollouts in Canada, the United Kingdom, and Australia.
The rebuilt product includes workspaces that give lawyers a dedicated environment for individual matters, allowing documents, precedents, and prior positions to inform analysis from the outset.
Context is maintained between sessions, colleagues, and matters, addressing one of the most persistent limitations of first-generation legal AI tools that required users to re-establish context repeatedly.
Brief Builder, an agentic AI drafting tool designed for complex briefs and motions, is also included, with Westlaw and Practical Law context and citation checking built directly into the workflow.