Passim is an immigration law research library designed to connect AI tools with authoritative legal materials. It works with Claude, ChatGPT, and other clients that support the Model Context Protocol (MCP), allowing users to ask questions in plain language and receive answers grounded in immigration law. The library includes precedents, unpublished decisions, statutes, regulations, and agency guidance, with a citator to help users trace and assess legal authorities.

Passim reports access to more than 10.9 million decisions, including full-text records, and daily updates from over 120 official sources. Its citations link to official sources, helping users verify the materials behind an answer. The service can search unpublished Board of Immigration Appeals decisions, read relevant decisions in full, and present findings with linked documents. A sample answer demonstrates research on hardship in cancellation-of-removal cases, summarizing patterns across decisions and providing links to decision PDFs in the EOIR reading room. Passim is intended to support legal research by connecting an existing AI subscription to a broad, regularly updated collection of immigration law.