Full-text case law searching is inefficient due to the vagaries of, and subjective qualities of language, and the objective nature of standard search algorithms. Mining secondary materials for cases identified by scholars as leading ones, and then using them as a core filter in which to begin an online research session is one way to make full-text searching more efficient. The resulting algorithm, the "Leading Cases Filter" (also embarrassingly know as the "Leiter Filter"), is open source and freely available to all developers.