Actions and Stable Models for Reasoning with Legal Norms and Cases

This paper describes a starting research on applications of Knowledge Representation tecniques to model reasoning about a case brought before a court of law. Modeling reasoning with laws and cases seems to us of interest for knowledge representation(KR) as legal arguments often appeal to commonsense: regulations of various sorts are present in practically every aspect of social life. Representing laws and legal reasoning is a subfield of KR as such, to which our research wish to contribute. However, the process by which an authority rules on a case is ---even after a great deal of abstraction--- a challenging issue for logic. Starting from a conceptual framework borrowed from Kelsen ---and from his rejection of logic for representing laws--- we discuss how logic programs with a Situation Calculus ontology can effectively model these forms of reasoning. Some of Kelsen's topics of interest for us are