Thomson Reuters Launches Westlaw Japan AI Research

Thomson Reuters (TSX/Nasdaq: TRI) announced the launch of a new feature, "Westlaw Japan AI Research," on "CoCounsel," an AI technology for highly specialized and regulatory compliance work. The integration of CoCounsel and Westlaw Japan enables Japanese legal professionals to conduct critical legal research while balancing speed, confidence, and accountability. This realizes verifiable and cited AI research on CoCounsel as part of Thomson Reuters' AI strategy in Japan. This feature marks a significant milestone in Thomson Reuters' AI roadmap in Japan.

This feature directly addresses the need for "verifiable AI output" required in highly specialized work. All AI output is generated based on Westlaw's reliable laws and precedents database and presented with clear citations and direct links to the original text. By combining fiduciary-grade AI, which allows questioning in natural language, with reliable legal content, Thomson Reuters will transform the nature of legal research in Japan.

Thomson Reuters has served the Japanese legal community for over 150 years and has supported more than 6,000 organizations through reliable content and technology. In October 2025, the company launched "CoCounsel Japanese Version," a fiduciary-grade AI solution optimized to handle Japanese legal thinking. This integration is the next step, unifying CoCounsel's AI-driven drafting, review, and analysis capabilities with Westlaw's reliable legal information research foundation.

Kento Miura, President and Representative Director of Thomson Reuters, stated:

"What Japanese legal professionals are looking for is AI that can explain its reasoning in court, present it to clients, and withstand audits. Thomson Reuters is proud to offer an unprecedented research experience to Japanese legal professionals by combining the advanced reasoning capabilities of our reliable fiduciary-grade AI with Westlaw's trusted content. With verifiable, citable, and actionable AI, you will be able to proceed with your work in the practical field with greater confidence than ever before."

Addressing Reliability Challenges in AI Utilization for Legal Professionals

Concerns about reliability and accuracy remain significant barriers to the use of generative AI in business. According to Thomson Reuters' report, "Generative AI in Professional Services Report 2025 (Japanese Corporate Legal Departments Edition)," 61% of respondents cited "concerns about reliability and accuracy" as the reason for not using generative AI in their daily work.

Westlaw Japan AI Research is designed to solve this challenge. When users enter questions about Japanese law in natural language, they receive structured answers based on Westlaw's carefully selected laws and precedents database. The answers provide clear citations, including direct links to the source (original text), allowing users to check and verify the content without leaving the research screen. This minimizes the risk of hallucinations, reduces the time required for verification, and improves the overall speed of legal research. This new feature enables a clear transition to the next-generation Westlaw Japan scheduled for late 2026.

Westlaw Japan AI Research is available to all CoCounsel users in Japan, including those on a free trial. New customers can sign up for a free trial and request a demonstration by a sales representative.

Customers currently using Westlaw Japan can smoothly transition to the expanded next-generation platform in the future, allowing them to continue using it without disruption to ongoing cases and existing workflows.

About Thomson Reuters

Thomson Reuters (TSX/Nasdaq: TRI) combines trusted content and technology to provide the forward-looking information needed for individuals and companies to make the right decisions. Thomson Reuters serves professionals in the legal, tax, audit, accounting, and compliance fields, as well as governments and the media. Products from Thomson Reuters, which combine highly specialized software and insights, provide information-based decision-making...