CoCounsel: Thomson Reuters Legal AI, Formerly Casetext

CoCounsel is an AI assistant for lawyers. Casetext made it, and Thomson Reuters bought Casetext in 2023. CoCounsel is not a public web search engine. A website owner cannot submit a site to it and does not need to change robots.txt for it.

Who makes CoCounsel

Casetext was a legal technology company founded in 2013. Thomson Reuters completed its purchase of Casetext on August 17, 2023, for $650 million in cash. The press release describes CoCounsel as an AI legal assistant powered by GPT-4. It lists tasks such as document review, legal research memos, deposition preparation and contract analysis.

CoCounsel Legal

Thomson Reuters launched CoCounsel Legal on August 5, 2025. The product brings together legal research, workflow automation, document search and AI legal help. Its Deep Research feature makes research reports with citations. Thomson Reuters says that Deep Research is grounded in Westlaw and Practical Law content. Westlaw and Practical Law are the legal research products of Thomson Reuters.

Casetext is no longer available

On October 22, 2026, casetext.com showed a short notice: “This service is no longer available”. The notice sends visitors to Westlaw for legal research and to CoCounsel for legal AI. We did not find a Thomson Reuters source that gives the date when the Casetext service stopped.

What this means for website owners

Thomson Reuters describes CoCounsel research as grounded in its own legal content. It does not describe CoCounsel as a search engine for the public web. We found no Thomson Reuters documentation of a web crawler, a user-agent string or a publisher program for CoCounsel. For this reason, there is nothing to allow or block for it.

If you publish legal content and want it to show in AI answers, the public AI search engines are more relevant. See the guides to ChatGPT Search and Perplexity. For other legal AI tools, see the guides to Westlaw Edge AI and Lexis+ AI.