1. Fabio Said recommends Five Great Books on German Legal Terminology. I particularly recommend the first two: Ulrich Daum’s Gerichts- und Behördenterminologie, and Corinna Schlüter-Ellner’s Juristendeutsch verständlich gemacht/Treffende Verben in der deutschen Rechtssprache.
The former is a book I discovered when I was doing the Bavarian state translators’ exam in Munich – there used to be a fill-in-the-gaps etc. exam on Gerichts- und Behördenterminologie at that time, since whatever your main subject, the exam qualifies you to translate for the courts. The book has been updated since then.
The latter starts with a list of heavy German legal vocabulary and explains it in simpler language. You won’t find all these terms in dictionaries. The Treffende Verben may be of more use to those translating into German.
The other three books I don’t possess because I have others they overlap with, but a good recommendation.
2. Wildy & Sons is a great legal bookshop in London. They also have an online shop. The London shop has a good selection of second-hand law books too, both students’ books and antiquarian stuff. On their website you can see a virtual tour of the shop (to find their link, scroll down at the left). This needs navigating in Google Maps. You can see the books, but also leave the corridor-like part of the shop with new books and navigate through to the office and second-hand departments.