‘The literature produced by a profession is often the clearest guide to the state of its intellectual development’. On this basis, then, the story presented by the literature of the medieval Welsh lawyer suggests a very high state of intellectual development. The medieval manuscripts preserving a text of Cyfraith Hywel, the law of medieval Wales, comprise the largest single corpus of manuscripts of any genre surviving in middle Welsh. The manuscripts themselves are varied, evidencing considerable editing and reorganising of the abundant material available to the lawyers and compilers. As such, a study of the legal texts and their development in medieval Wales may reveal a highly developed legal profession, and sheds light on the cultural life and political development of the country at that time.

This study is a full examination of the contents of the law manuscripts, the material that was drawn into them, how the manuscripts are structured, parallel texts in the law manuscripts and their occurrence, and the reasons for including the material in the way it was incorporated. It is primarily a textual study, although consideration is given to the context of this collation and editing by the jurists, the legal scholars in medieval Wales, and in addition to looking at the working methods of the compilers of the lawtexts, the reasons for their work are examined as well. As the main focus of the work is on the law manuscripts, the discussion in the first chapter on medieval Welsh law and its background, with a survey of the manuscripts, is the starting point. The background information presented in the introduction to the manuscripts in Chapter 1 is essential for understanding the following chapters, but the descriptions of the redactions and of the manuscripts within them is designed to be a ready-reckoner, which may be returned to during the discussion in the following chapters, although every attempt is made to keep the subject clear and further information on the manuscripts is added in context. A full list of the law manuscripts by sigla is also included at the start of the work, following the abbreviations, and may serve to avoid confusion as sigla will usually be used rather than full details of each manuscript.