Although the representation of normative texts and simulation of legal acts are commonly interdisciplinary themes in the field of Artificial Intelligence and Law (AI & Law), some questions remain open or are scarcely explored. As for these incipient fields, we can mention the formalization of the legal body in the face of explicit or implicit exceptions in the juridical reasoning that occurs daily, and the treatment of readability issues, in exposing or justifying decisionmaking. In this paper, we present the prototype LEGIS and discuss a proposal to simulate legal action on two fronts. We adopt a non-monotonic semantics for knowledge representation that is appropriate to the singularities of the legal realm, the Preferential Semantics, and propose a transformation to a formal logic argumentation style, the Sequent Calculus, in order to raise the inference proofs to a level of legibility not yet conveniently attained by conventional reasoners.