SAN FRANCISCO, September 19 — OpenAI has built a version of its GPT-6 Astra model specifically for legal work, and the company is betting that the lawyers who use it will care less about the model itself than about what it can find. Astra for Law launched on September 17, 2026. It is not a new model.
OpenAI wrapped GPT-6 Astra in a legal search index and a set of instructions for legal analysis, then offered the result to law firms and to the software companies that sell to them. The index reaches U.S. case law, statutes, regulations, court rules and administrative decisions across more than 230 million URLs, with sources added daily.
The nonprofit Free Law Project’s CourtListener database supplies the case law.
What the benchmark measured
The benchmark OpenAI chose rewards finding the right authority and the right passage inside it. Astra for Law passed the overall correctness check on 54% of 200 questions drawn from the private validation set of Vals AI’s Legal Research Bench. GPT-6 Astra with web search alone managed 38.7% on the same questions, with both systems run at their highest reasoning effort.
On case-law questions it found 24% more reference cases. On a separate audited set, it retrieved up to 54% more of the target passages from the correct opinions.
Access is limited at first. Selected firms reach it through a Trusted Access program in ChatGPT and Codex, where it shows up in the model picker as GPT-6 Astra Law. An application programming interface version, gpt-6-astra-law, is due later, with no date or pricing attached.
Legal AI companies Harvey Technologies Inc. and Legora AB are named as API customers for it. For eligible firms the offering carries zero data retention on the API, and ChatGPT Enterprise usage is excluded from human review by default.
Latham & Watkins is working with OpenAI on governance design for information permissions, ethical walls and client instructions.
Plugins and the wider legal stack
Twenty-six partner-built plugins launched alongside the model, connecting ChatGPT to tools such as Relativity, Clio, iManage and DeepJudge, while Thomson Reuters Corp. is bringing HighQ matter context into ChatGPT and previewing a connector for its CoCounsel Legal product. An additional nine plugins came from lawyers and legal engineers outside the vendor set, carrying 47 custom skills. ChatGPT for Word reached general availability the same day.
Joel Hron, chief technology officer at Thomson Reuters, said the link between ChatGPT and legal tools is only part of what firms need. “As AI becomes more open and interoperable, the value is not in connectivity alone,” he said.
“Legal professionals need more than access to information. They need trusted intelligence, relevant enterprise and matter context, purpose built legal capabilities, and the governance required for high stakes work.” OpenAI engineers embedded at individual firms have also been building firm-specific tools on ChatGPT Enterprise. Sullivan & Cromwell has an agreement analyzer that pulls its negotiating playbooks and selected precedents into the review of a new deal, and turns what it finds into proposed redlines.
At Ropes & Gray the work went into deal diligence. Cooley’s tool, GO Public, handles initial public offering preparation, drafting the filing included.
John Savva, a Sullivan & Cromwell partner who saw early builds, said the models showed “impressive research depth and sensitivity to authority.” OpenAI described the launch as the start of a long-term investment in law. GPT-6 Astra itself started rolling out two weeks earlier, on Sept. 3, 2026. What to watch next is the API.
Harvey and Legora are already named as customers, but the gpt-6-astra-law interface has no date and no price, and until it ships the reach of Astra for Law stays inside the Trusted Access firms and the plugin ecosystem around them.
