Since Thomson Reuters acquired legal research company Casetext last summer, it has gradually been incorporating the startup's headline-grabbing artificial intelligence legal assistant CoCounsel, the first legal tech tool to publicly confirm using OpenAI's GPT-4 large language model, into its broader workflows. Previously, CoCounsel functioned essentially as a chatbot in various Thomson Reuters legal offerings, and has also been offered as a stand-alone product called CoCounsel Core, available without a Westlaw subscription.