I sampled three popular law dictionaries for Kindle (1) Law Dictionary, (Mass Market) 6th Ed. (Barron's Legal Guides) , (2) Merriam-Webster's Dictionary of Law, and (3) Nolo's Plain-English Law Dictionary. By far, the best I'd seen is Barron's. Among other things, instant search is enabled, and there are hotlinks to related terms. Webster's is next (it's got hotlinks, but shows only one definition per page). Nolo is the worst; it's like all they did was convert the text.
Major problem with Barron's: can't search by keywords. Searches bring up index entries only.