Casetext, founded in 2013, was a legal-technology company whose AI legal assistant, CoCounsel, launched in early 2023 powered by OpenAI’s GPT-4. CoCounsel could perform tasks like document review, legal research memos, deposition preparation, and contract analysis in minutes - work that previously took associates hours. It was one of the first products to put a frontier language model directly into the daily workflow of practicing lawyers, and by acquisition it served more than 10,000 law firms and corporate legal departments.
On August 17, 2023, Thomson Reuters - owner of the dominant Westlaw legal-research platform - completed its acquisition of Casetext for $650 million in cash, having signed the definitive agreement that June. Thomson Reuters CEO Steve Hasker framed it as part of a “build, partner and buy” strategy to bring generative AI to its customers. The deal folded a fast-moving AI startup into one of the incumbents it might otherwise have disrupted, and CoCounsel became the brand for Thomson Reuters’s broader push into generative-AI legal tools.
The acquisition was an early signal of how quickly the legal-AI market would consolidate after ChatGPT. Within roughly a year of GPT-4’s release, the leading legal-research incumbent had spent over half a billion dollars to bring a generative-AI assistant in-house.
Why business readers should care: the Casetext deal is a textbook example of an established player buying its way to the AI frontier rather than building from scratch - and of how fast generative AI reshaped a conservative, high-margin professional-services market. It also set up a tension: the same company now selling AI legal tools, Thomson Reuters, was simultaneously litigating to protect its content from being used to train a competitor’s AI.