In the early 20th century, J.H. Wigmore described a new method for analysing and laying out arguments in legal cases. His proposal was the first system of argument diagramming, and it is still in use in jurisprudence today. Wigmore diagrams offer a rich ontology of argumentation concepts which in some respects are close to ideas in other, more modern systems of argument analysis and argument diagramming – whilst in other areas, is much richer and more specific than alternatives. The features of Wigmore analyses might reasonably be expected to contribute to modern, computational approaches to argument, both in the legal domain and more broadly. This paper explores some of the key issues in representing Wigmore analyses and translating between them and other systems of analysis such as those founded upon Toulmin models and scheme-based models.