Thomson Reuters released its self-developed AI model, Thomson, claiming it outperformed GPT-5.5 in legal benchmark tests.

In July 2026, Thomson Reuters announced the launch of its self-developed AI model, Thomson, designed specifically for professional services workloads. The company claims the model outperforms GPT-5.5, Claude Sonnet 5, and Gemini 3.1 Pro in legal and general benchmark tests.

The model is integrated into CoCounsel, Westlaw's AI platform, and also integrates with Anthropic's Claude platform, allowing lawyers direct access to Westlaw's Primary Law database and Practical Law guidelines through Claude.

A Forrester-commissioned study found that law firms deploying CoCounsel Legal achieved a 400% ROI and a 25% increase in lawyers' caseload capacity without requiring additional staff.

RELX (LexisNexis's parent company) reported 10% growth in its legal division that same month. However, the share prices of Thomson Reuters, RELX, and Wolters Kluwer all came under pressure due to concerns about AI companies entering the legal field.