This paper deals with the relationships between the legal traditions of Ireland and Wales in the middle ages and identifies two groups of borrowings from the early eighth-century Collectio canonum Hibernensis
in the lawbooks of medieval Wales. The borrowings all come from Books xxx and xxxiv (in Wasserschleben’s edition) and deal with deposits and sureties; however, the compilers of the Welsh lawbooks, whose earliest extant redactions date from the late twelfth and thirteenth centuries, were plainly ignorant of the relevant passages’ ultimate Irish source. After close textual analysis of the passages in medieval Welsh law derived from the Hibernensis
, the paper discusses how the Irish canons may have become known in Wales, and how they could have been transmitted into the surviving texts of Welsh law. Attention is drawn to the importance of the borrowings as a unique witness to the presence of the Hibernensis
in medieval Wales, as well as to their significance for an understanding of the sources, ecclesiastical connections, and Irish affinities of medieval Welsh law.