OpenAI: Top US Law Firms Back New Legal AI Platform Astra

By Legal Cheek on Sep 18 2026 10:46am Latham, Ropes, Cooley and SullCrom back ChatGPT creator’s latest push into law OpenAI has tapped some of BigLaw’s biggest names for its latest push into legal AI, with Latham Watkins helping shape governance controls and Sullivan Cromwell , Ropes Gray and Cooley building their own AI tools with the tech giant. Dubbed Astra for Law , the new offering combines OpenAI’s latest GPT-6 Astra model with legal research tools and settings tailored to legal work. Selected firms will initially get access through ChatGPT and Codex, with the technology also set to become available through OpenAI’s API. But perhaps more interesting for aspiring lawyers is the role some of BigLaw’s biggest names have played in its development. OpenAI says it is working with Latham Watkins to design the platform’s approach to information permissions, ethical walls, client instructions and firm oversight. In other words, the safeguards needed when increasingly capable AI is used on confidential client work. The OpenAI tie-up comes just a week after Latham splashed out on its own Nvidia-powered servers to run AI models in-house, as the firm continues to ramp up its investment in legal tech and AI. Speaking as part of OpenAI’s announcement, Michael Rubin, chair of Latham’s AI strategy committee, said the collaboration “builds on Latham’s broader investments in AI development, governance, and infrastructure across the firm, which underpin our enterprise-wide strategy for responsible AI”. And Latham isn’t the only BigLaw name working with OpenAI. Sullivan Cromwell has built an agreement analysis tool using the firm’s own negotiating playbooks and precedents to flag risks, suggest redlines and help draft client advice. Co-chairs Robert Giuffra Jr. and Scott Miller said OpenAI’s engineering expertise had helped the firm refine an initial test application and prepare it for wider deployment. Ropes Gray has also developed a deal diligence system designed around how its lawyers work through data rooms and identify issues that could affect an acquisition. The firm said the collaboration is “shaping how frontier AI applies to the most demanding legal work”, with the goal of bringing lawyers’ insight into the process earlier and delivering “faster execution” for clients. Over at Cooley, the firm has built “GO Public”, a tool which brings its capital markets expertise into the IPO process. Dave Peinsipp, partner and co-chair of its global capital markets group, said the collaboration has allowed lawyers and management teams to move more quickly towards questions requiring “judgment, market experience and strategic thinking”. The launch is the latest sign of the AI arms race gathering pace across BigLaw, as firms look beyond off-the-shelf chatbots towards bespoke tools built around their own lawyers, data and ways of working. US giant ramps up in-house tech to build bespoke AI models