This has considerable potential. I've been looking at the study of law as a career move and and studying over the last month as preparation to acquiring some make-up credits: I've been struck by the inefficiency of cross-referencing large numbers of documents. Legal citation is highly refined, and services like Lexis/Nexis & Westlaw make research comparatively easy, but are expensive^. So I'm glad to see an effort to build something more open. I do think they need to look beyond the hierarchical model alone for exploration and presentation - a freeform relational explorer like Directed Edge could be a major asset here as the database fills out.

^ That said most of the database vendors give access to law students for free or a nominal annual cost.