Thomson Reuters

Thomson Reuters is a global information services company providing news, data, and technology to legal, tax, accounting, and compliance professionals worldwide. The company serves as the primary information infrastructure for the legal and financial professions.

Thomson Reuters has invested heavily in AI across its product portfolio. Westlaw AI and CoCounsel provide AI-powered legal research, document analysis, and drafting capabilities for lawyers. The company's tax and accounting products use AI for automated compliance, audit support, and regulatory change analysis. Thomson Reuters has partnered with Microsoft to bring AI capabilities to its professional products and has acquired AI companies to accelerate its AI roadmap.

Thomson Reuters' enormous corpus of legal cases, tax codes, regulatory filings, and news content gives its AI products a unique data advantage — the AI can reference authoritative, curated professional content rather than general web data. This combination of domain expertise, proprietary data, and established distribution in law firms, accounting practices, and corporate legal departments makes Thomson Reuters the leading AI provider for professional knowledge work.

In August 2026 the company took that data advantage a step further and trained its own model, Thomson, rather than only pointing licensed frontier models at its archive. It was built on an open-source base and then mid-trained and post-trained on decades of Westlaw, Practical Law, Checkpoint and Reuters content, with hundreds of in-house lawyers, tax specialists and editors involved. Thomson Reuters put the cost at $40 million, says early evaluations place the model on par with current frontier models on legal and tax reasoning at a fraction of their cost, and notes it has drawn on under 10 percent of its archive so far. CoCounsel Legal is the first product to ship it, and a smaller version is published on Hugging Face for academic and non-commercial use. The strategic point is ownership: a professional-information business that trains on its own corpus stops renting its core capability from labs that also sell to its competitors — though the evaluations behind the parity claim are the vendor's own.