There is an interesting effort underway to build a new legal search engine. The new engine — PreCYdent is up and runing, and getting some quite positive reviews — here and here for example. PreCYdent was founded by my brother-in-law Tom Smith, who blogs at the Right Coast, and Antonio Tomarchio, a mathematician from the Politecnico di Milano. The PreCYdent site is the "alpha" version, so it is still in development, and the site indicates that feedback and comment are encouraged.

According to the site, the search technology works by mining information in the legal citation network, which enables it to rank cases by "authority", with the most important cases appearing nearer to the top of the results list than in Lexis or Westlaw searches. From what I can see, the search engine outperforms both Westlaw and Lexis natural language search algorithms by a wide margin in systematic tests. I ran a few searches on some topics in criminal procedure, one of my areas of expertise, and it seemed to work quite well.

I've always wondered how long Westlaw and others will be to maintain a pay-for-search system of court opinions. Court opinions should be easily accessible to the public — for free — and maybe PreCYdent will prove to be an open source way to do it.