This collection of papers from the Twentieth British Legal History Conference explores the relationship between substantive law and the way in which it actually worked. Instead of looking at what the courts said they were doing, it is concerned more with the reality of what was happening. To that end, the authors use a wide range of sources, from court records to merchants' diaries and lawyers' letters. The way in which the sources are used reflects the possibilities of legal historical research which are opening up in the twenty-first century, as large databases and digitised images – and even online auction sites – make it a practical possibility to do work at a level which was almost unthinkable only a short time ago.