Thomson Reuters Unveils New Sovereign AI for Professional Services

Thomson Reuters has officially launched “Thomson,” its own large language model (LLM) built in-house using decades of proprietary content from Westlaw, Practical Law, Checkpoint, and Reuters. The company announced this development on Monday, August 24th, emphasizing the model’s unique advantages stemming from its specialized training data.

The Thomson LLM began with an open-source foundation but has since been refined through extensive training on Thomson Reuters’ vast content libraries and domain expertise. This approach allows the company to maintain complete control over the model while avoiding the high inference costs associated with typical frontier models.

According to CEO Steve Hasker, Thomson is initially being deployed in CoCounsel Legal, with plans for broader integration across the legal and tax portfolios. Early evaluations indicate that Thomson performs comparably to leading LLMs on various tasks—demonstrating that specialized AI can achieve competitive results without requiring massive computational resources.

CTO Joel Hron highlighted this efficiency as a key differentiator: “Start with a strong foundation, specialize it deeply for the work that matters, and you can build intelligence that is highly capable, far more efficient, and entirely under your control.” This approach offers a viable alternative to simply building larger models with greater compute requirements.

Thomson Reuters’ investment in AI has been substantial—with over $8 billion allocated to expand its capabilities in this space. The company sees itself transitioning from a content provider to a “content-driven” technology leader, offering increasingly sophisticated AI solutions for professional workflows.

The launch of CoCounsel Legal in June 2024 marked an early application of Thomson’s AI expertise—allowing professionals to automate complex tasks while maintaining audit trails and data controls. Since then, over 1 million professionals across 107 countries have adopted CoCounsel as part of their daily workflows.