I disagree about pagerank being appropriate for legal research. Pagerank-type algorithms will help you find the seminal, widely-cited cases in an area. But if you want background law, it is easier to just consult a relevant treatise or other reference book that has those pre-digisted and laid out for you. What really takes time when doing legal research is finding cases that have features in common with yours: similar procedural posture, similar factual wrinkles, etc. Usually, you're looking for a way to argue the opposite of the general rule set forth in the seminal cases. Pagerank-type algorithms won't help you find that; boolean searches on specific phrases will.