This paper describes the author’s development and use of a diagramming model in preparing a legal case for which he was responsible. He combined Wigmorean analysis and object oriented techniques in order to model arguments based on generalisations taken from the real world and from legal precedent. The paper addresses the modelling issues, but in particular identifies the very real benefits that affected the way the case was conducted. Those areas in which the model came into its own were principally (...) the structuring of evidence, the preparation for the cross-examination of witnesses, and ensuring a consistent approach from picking up the case to making the closing submissions. (shrink)