In his Lex Castrensis, the twelfth-century Danish writer Sven Aggesen tells the story of the creation of a law that he attributes to Knútr inn ríki (Cnut the Great) as a means of governing his substantial military following of retainers, known as the hirð. As unlikely as it is for Sven to claim that he preserves the law exactly as it was in Knútr’s own time, the text’s focus on process and punishment raises an intriguing question: can evidence be seen for shifting punitive attitudes and legal exchange in the late Viking-Age period of intense contact, interaction, and accommodation between Scandinavia and the British Isles? This chapter will offer a first step in considering the possibility for the exchange of legal practices and concepts in this context, and present a newly refined picture of England and its Scandinavian neighbours – one which points to sophisticated legal interchange happening much earlier than usually thought.