Definition
OpenAI’s Legal Search Index is a retrieval layer powering astra-for-law, spanning U.S. case law, statutes, regulations, court rules, and administrative decisions across 230M+ URLs with daily source additions.
Key Points
- Built on courtlistener / Free Law Project corpus (99.9%+ U.S. precedential case law)
- Complements licensed content from Thomson Reuters and specialist legal databases
- Benchmark impact: 54.0% vs 38.7% Legal Research Bench correctness vs web search alone
- Pattern: proprietary domain index + frontier model > general web search for vertical RAG