Casetext unveils AI legal assistant powered by OpenAI’s “most advanced” large language model

US legal research provider Casetext today (1 March) unveils a legal assistant powered by OpenAI’s “most advanced” large language model, which it has customised for the legal sector. We’re told that CoCounsel is already being deployed firm-wide by US labour and employment firm Fisher Phillips and received rave reviews from beta firms including Eversheds Sutherland and Orrick, Herrington & Sutcliffe.

CoCounsel can be used for legal research, document review and contract analysis, responding to natural language questions. It couples OpenAI’s technology with its own proprietary legal databases and legal search system, ParallelSearch.

Casetext says it’s unable to say which version of OpenAI’s generative pre-trained transformer (GPT) technology CoCounsel is based on.

The work done to date by Casetext in partnership with OpenAI and a wider number of law firms and in-house lawyers has involved putting guard rails on the way the technology works, including, Casetext’s CEO and co-founder Jake Heller told Legal IT Insider, ensuring that it does not return false positive results, often referred to as “hallucinating.”

Unlike generalized, publicly available large language models, Heller says that CoCounsel offers the reliability and security critical for legal matters, including ensuring that no data is retained by CoCounsel and that client data is not used to develop the model.

To tailor general AI technology for the demands of legal practice, Casetext established a trust and reliability program managed by a team of AI engineers and litigation and transactional attorneys. We’re told that Casetext’s Trust Team spent nearly 4,000 hours training and fine-tuning CoCounsel’s output based on over 30,000 legal questions.

All of CoCounsel applications were used extensively by a group of beta testers composed of over four hundred attorneys from elite boutique and global law firms, in-house legal departments, and legal aid organizations, before being deployed.

“CoCounsel is completely changing the equation for law firms,” said Chris Austin, director of records and information management at Bowman and Brooke. “Our firm has been part of Casetext’s rigorous beta testing program from its first few days, and the benefits have been immense. CoCounsel doesn’t just eliminate essential yet time-consuming work—it enables our attorneys to become more agile and precise—it’s changing how we practice law for the better.”

“CoCounsel is a truly revolutionary legal tech innovation,” added John Polson, chairman and managing partner of Fisher Phillips. “The power of this tool to help our attorneys perform efficient legal research, document review, drafting, and summarizing, has already resulted in immediate, sustained benefits to our clients, and we have only scratched the surface of what it has to offer.”

While OpenAI’s technology inevitably presents – really for the first time – some existential questions for lawyers, all of Casetext’s customers have been overwhelmingly positive about the new offering.

“Casetext has transformed the AI landscape with CoCounsel,” said Scott Bailey, director of research and knowledge services at Eversheds Sutherland. “The power of this technology, deployed in a product that is secure and reliable, is a huge leap forward in what legal technology can do.”

Wendy Butler Curtis, chief innovation officer at CoCounsel beta customer Orrick commented: “Like our clients, we pay attention to technology that has the potential to improve outcomes and make work better. We’ve already seen CoCounsel’s technology add value and we’re excited to explore additional ways our teams can embed it in our practice.”

Casetext’s assistant follows the adoption last month by Allen & Overy of OpenAI-based ‘co-pilot’ Harvey, however Heller said: “Our AI legal assistant is the first of its kind. It creates a momentous opportunity for attorneys to delegate tasks like legal research, document review, and contract analysis to an AI, freeing them to focus on the most impactful aspects of their practice.”

Casetext says that CoCounsel’s speed and high-quality output enable attorneys to focus on the most valuable parts of their practice and take on projects that would otherwise be impossible.

Immigration attorney and CoCounsel beta customer Greg Siskind said: “We are working on a class action case on behalf of Ukrainian refugees who were improperly charged millions of dollars in illegal fees. CoCounsel has been instrumental in supporting us. It was able to expedite the vetting process of a legal theory that is foundational to our arguments at superhuman speed.”

caroline@legaltechnology.com