In our research group working on normative systems, we develop (Normative) Agent Based Models for evaluating policies, and as a basis for building distributed (normative) control components. If and how interactions between actors (represented by agents) take place are heavily impacted by the (dis)trust between those actors. In this paper, we discuss a model of the representation of the three components of the agent’s trustworthiness: competence, benevolence, and integrity. The model presented in this paper is being illustrated by a small simulation experiment.

The paper addresses the problem of making legal decisions about regulations such that they are compliant with legal principles. While decision-making using legal rules is well-developed in the literature, few researchers address reasoning with principles. A key difference between applying rules versus principles is that rules have a binary character, they are applied or not, while principles can be applied to a certain extent and in the case of conflicting principles, they require balancing instead of defeat. This paper provides a novel approach to balancing principles and deciding amongst regulations by proportional optimisation of values associated with regulations and principles. The approach can be generalised to other areas of decision-making.

In Value-based Argumentation Frameworks (VAFs), values are ascribed to abstract arguments and ordered one to another to reflect an audience’s preferences. An attack of one argument on another is successful only if the audience does not prefer the value of the attacked argument to the value of the attacking argument. Audiences can disagree about admissible arguments relative to their value preferences. Complementary to VAFs, this paper presents a novel integration of Value-Based Reasoning Frameworks (VBFs) with instantiated argumentation, specifically we focus on the structured argumentation approach of ASPIC+. Agents associate literals with social values and weight of values; together, these are used to filter the literals compatible with their values. Such a set of literals is used to construct agent-relative ASPIC+ knowledge bases, agent-relative instantiated arguments, and argumentation frameworks (AFs). Agents can attack one another’s arguments. VAF and VBF present complementary perspectives on values on arguments. VBF contributes a new, formal, articulated view of agreement and disagreement amongst agents, which is grounded in their values. In addition, VBF helps us understand how different agents choose what to argue from out of a pool of common resources.

Argumentation is often an attempt to resolve disagreement, but it is not always possible to reach a resolution. This is illustrated in law where multi-judge trials often end with a split decision. Not only do the judges disagree as to outcome (dissenting opinions), but also as to the reasons for a given outcome (concurring opinions). These disagreements can be explained in terms of different values held by the judges concerned. But while the role of values in determining which arguments are accepted has been widely explored, values can also determine which arguments can be constructed. The paper provides an analysis of this phenomenon.

We present an approach designed to support the process of legislative drafting by helping to detect errors in a normative text. It is based on a framework allowing for representation and comparison of structure and semantic content of legal provisions. Such comparison serves as a starting point for detection of (potential) legislative errors. The approach provides in particular criteria to select provisions to be compared, related to the phenomenon of provisions overlapping. We show that specific cases of such an overlap may amount to legislative errors. The presented framework enables a precise and transparent account of these errors. We also acknowledge that textual provisions enable various interpretations, while the error methodology detection assumes that the semantic representation of provisions is a result of a specific interpretation. We introduce the notion of Constraining Interpretive Rules which are used to evaluate the acceptability of specific interpretations of legal provisions. We discuss the features of the model on a real example and we present an implementation of the approach by using semantic technologies.

Given a common pool of facts and legal rules, Judges on a panel may form different justifications for decisions, which are then voted upon. It is clear that a Judge’s personal values and purposes play in developing their opinion, which is a form of teleological reasoning. The paper introduces the Value-based Formal Reasoning (VFR) framework, which describes how a Judge’s personal values can be used in the construction of a justification for a decision.

The paper presents a formal model and an experimental verification of the system controlling the International Humanitarian Law compliance for the autonomous military device.

This paper presents a Semantic Web–based model for detecting contradictions in regulations. We introduce a conceptual model of contradictions and, on the basis of this model, a knowledge representation–based model is used, which is able to represent the semantics of provision types and related properties. The usefulness of the model is shown through an example.

The paper discusses the problem of formal modeling of the interpretation of statutory legal norms.The authors propose a comprehensive framework that allows the representation of the interpretation process.The authors' proposal is illustrated by a real-life example.

The issue of decision-making and teleological reasoning of autonomous agents constitutes the current work topic for many researchers.The author of [1] presents a framework allowing for teleological reasoning with the use of values and the possibility of autonomous goal-setting by a device.In this paper we propose to extend this framework by a new manner of representation of the level of value promotion including the required modifications of the reasoning mechanism.The proposed model may become a formal foundation for the realization of the autonomous agent.

The paper presents a general formal framework representing the role of balancing of values in interpretation of statutory rules. The model developed here is an extension of the model of teleological interpretation, where a given interpretive outcome is justified if it satisfies a given goal (or a set of goals). Herein, a richer argumentative structure is discussed: an interpretive proposition concerning the interpretation of a statutory condition is justified if it is in accordance with the proper balance of applicable legally relevant values.

The main aim of this work is to formalize the mechanism of resolving conflicts between statutory legal rules with a view to implementing them into a legal advisory system.The model is build on the basis of the ASPIC + argument modeling framework.The paper presents a discussion and a formal model of the mechanism of conflict recognition as well as models of three different mechanisms of conflict solving and a discussion of the relations between them.

This paper contributes to the formal research on legal interpretation by presenting a structure of normative agents. Each normative agent consists of a knowledge base, a set of preferences, and certain procedures related to the interpretation conducted by this agent. A part of typology of normative agents is presented. The investigations are illustrated with a model of a real-life example.

This paper evaluates the Parenting Plan Support System, a partially implemented decision support system designed to help parents to draft an agreement concerning relations with their children after the divorce, against the background of a real-life case. The focus here is on knowledge representation issues and the functioning of the inference engine.

The paper discusses the complexity problem in the interpretation of statutory legal norms. The authors propose a comprehensive framework that allows the representation of the interpretation process.

The main aim of this work is to formalize one of the mechanisms of resolving conflicts between statutory legal rules. The argument from social importance is based on the distinction between axiological contexts of conflicting norms. One of this norms may be more significant from the point of view of social importance and this norm should prevail over the less significant one.

The paper presents a model of teleological interpretation of statutory legal rules as well as an example of the genuine law case, which has been modeled with use of established methodology.

The paper presents the model of two variants of a fortriori reasoning applicable in the case of statutory law as well the example of the genuine law case, which has been modeled with use of established methodology. The model of reasoning assumes the existence of "less-more" relation between the analyzed actions, which has been expressed by means of strict partial order and some additional assumptions. The paper also contains the implementation of the analyzed example.

Statute law legislators are usually not in a position to foresee each and every situation or event which may actually occur in real life. That is why lawyers in the course of their everyday practice very often struggle with interpreting the cases which are not expressly regulated in the law. The legal theory and practice has given rise to a wide array of methods to deal with this type of problems. The aim of this study is to develop and implement an instrumental inference model, i.e. one of the non-standard inference mechanisms used to interpret the rules of statutory law.

Statute law legislators are usually not in a position to foresee each and every situation or event which may actually occur in real life. That is why lawyers in the course of their everyday practice very often struggle with interpreting the cases which are not expressly regulated in the law. The legal theory and practice has given rise to a wide array of methods to deal with this type of problems. The solutions described in this article have been implemented in the advisory system developed by the authors whose main goal is to provide automatic legal advice on the Agricultural Tax