ArgPROLEG: A Normative Framework for the JUF Theory

In this paper we propose ArgPROLEG, a normative framework for legal reasoning based on PROLEG, an implementation of the Japanese “theory of presupposed ultimate facts”(JUF). This theory was mainly developed with the purpose of modelling the process of decision making by judges in the court. Not having complete and accurate information about each case, makes uncertainty an unavoidable part of decision making for judges. In the JUF theory each party that puts forward a claim, due to associated burden of proof to each claim, it needs to prove it as well. Not being able to provide such a proof for a claim, enables the judges to discard that claim although they might not be certain about the truth. The framework that we offer benefits from the use of argumentation theory as well as normative framework in multi-agent systems, to bring the reasoning closer to the user. The nature of argumentation in dealing with incomplete information on the one hand and being presentable in the form of dialogues on the other hand, has furthered the emergence and popularity of argumentation in modelling legal disputes. In addition, the use of multiple agents allows more flexibility for the behaviour of the parties involved.