The Bodleian Law Library's collection focuses on the laws/legal system of Germany from 1871-1945, of West Germany and of post-Unification Germany. Works on these periods are together, in a collection with shelf marks starting German.
The Law Bod also has a smaller, distinct collection of works on the law of former East German (and some on Socialist law in general) Please click on GDR/DDR tab above.
Holders of an Oxford SSO have access BeckOnline via link below. For German primary sources there also are a couple of free websites.