One million professionals now rely on CoCounsel AI

Thomson Reuters reports that one million professionals across 107 countries now use its CoCounsel artificial intelligence technology, as it expands the product across regulated sectors including legal, tax, audit, risk and compliance.

The milestone reflects a broader shift in how organisations in high-stakes fields deploy AI. Many are moving beyond limited trials and embedding AI tools in day-to-day work, where outputs may be scrutinised by courts, auditors and regulators.

Thomson Reuters positions CoCounsel for work that requires traceable sources and controlled handling of sensitive information, arguing that regulated professionals need outputs that stand up to review and reflect jurisdiction-specific rules.

Regulated focus

General-purpose AI systems can draft text and summarise material, but they can also produce confident errors and incomplete citations. In legal and financial services, such mistakes can bring professional and commercial consequences. As a result, buyers have put greater emphasis on source provenance, citation checking and guardrails for confidential data.

CoCounsel spans several Thomson Reuters products, including CoCounsel Legal, CoCounsel Tax and Audit, and ONESOURCE+. Thomson Reuters says it is embedded in existing research, drafting and compliance software rather than offered only as a standalone chatbot.

The system draws on licensed content built up over decades and uses validation logic developed by subject specialists. Thomson Reuters says customer data remains protected and is not repurposed to train third-party models.

Thomson Reuters also points to human oversight in the product's design. More than 4,500 subject matter experts contribute to validation and ongoing refinement of outputs across legal, tax and compliance areas.

Trust and accountability have become central themes as firms weigh where to deploy AI. "Professionals are not deciding whether to use AI anymore. They are deciding which AI they trust when their reputation and their clients' data are on the line," said Steve Hasker, President and Chief Executive Officer of Thomson Reuters.

"CoCounsel 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. That is why one million professionals rely on CoCounsel," Hasker said.

How it is built

Thomson Reuters outlined design choices it says are tailored for regulated work. CoCounsel grounds outputs in licensed, editorially enhanced legal and tax sources rather than publicly scraped data, and domain specialists shape workflow logic and quality standards in areas where errors have consequences.

CoCounsel runs within established professional platforms, keeping work inside existing systems used for research and drafting. Thomson Reuters says it does not repurpose customer inputs to train third-party models or use one customer's inputs to generate outputs for other users.

On model strategy, Thomson Reuters says it works with multiple frontier model providers and combines them with proprietary AI and structured datasets, including Anthropic's Claude, OpenAI's GPT and Google's Gemini. It also says it is developing a proprietary large language model for regulated professional use cases.

Next generation

Thomson Reuters plans a new version of CoCounsel Legal that it says will enter beta soon. The product will centre on conversational task execution, allowing users to describe an objective in natural language and receive a structured work product within a single system.

The next-generation workflow can draw authority from Westlaw and Practical Law and search relevant user documents and precedent. Thomson Reuters says it will analyse the material and verify whether citations remain in good law before producing outputs.

Further updates are planned for CoCounsel Tax and ONESOURCE+ later in 2026, according to Thomson Reuters.

David Wong, Chief Product Officer at Thomson Reuters, said the milestone shows AI adoption in regulated industries is moving from experimentation into daily operations. "When the work matters, the AI must be professional grade. Professionals need systems that can complete sophisticated work within the standards they are accountable to every day. That's the gap between CoCounsel and everything else," Wong said. "One million CoCounsel users across 100+ countries reflects a shared global consensus," he added.