A model of the development of distinctions in case law

In this paper we put forward a way of modelling reasoning with cases as it is described by writers such as Levi. This style of reasoning concentrates on finding and refining particular distinctions amongst cases which bear on the outcome. It thus contrasts with work such as HYPO in which such distinctions are the product of initial analysis of the domain, and so come already fixed. We provide a detailed walk through of a specific example to show how a legal distinction can develop, assuming initially the availability of a limited ontology and then show how a richer ontology can be used to capture increased subtlety of argument.