Trevor Bench-Capon

University of Liverpool | UoL · Department of Computer Science

We report on a study undertaken to analyse AI performance on two tasks involved in automating processing of cases from the European Court of Human Rights: classification of legal case outcomes and keyword prediction. Results show variation across Articles and Court levels, and challenge the common viewpoint that larger legal corpora combined with l...

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 disagree...

We present a novel annotated dataset of legal cases pertaining to Article 6 – the right to a fair trial – of the European Convention on Human Rights (ECHR). This dataset will serve as a useful resource to the research community, to assist in the training and evaluation of AI systems designed to embody the legal reasoning involved in determining the...

This paper explores the extension of formal accounts of precedential constraint to make use of a factor hierarchy with intermediate factors. A problem arises, however, because constraints expressed in terms of intermediate factors may give different outcomes from those expressed only using base level factors. We argue that constraints that use only...

We report a study undertaken to analyse human performance on the verdict classification task. Several approaches have addressed this task with outcomes compared against the outcomes from actual legal cases. Results vary and we investigate how classification is done by humans. A key finding is that fact descriptions alone are insufficient for accura...

In recent years a considerable amount of research has been devoted to formal theories of precedential constraint. In this note I consider a recent paper which explores the use of factor hierarchies in this connection. In that work it was shown both that cases constrained with the use of a hierarchy may be unconstrained if the hierarchy is flattened...

Current theories of precedential constraint attempt to incorporate dimensions into the reasons for decisions. We argue that this is an unnecessary complication, and precedential constraint can be handled using only factors. In our account the role of dimensions is to organise facts, and their effect operates at the factor ascription level, prior to...

This paper provides a formal description of two legal domains. In addition, we describe the generation of various artificial datasets from these domains and explain the use of these datasets in previous experiments aligning learning and reasoning. These resources are made available for the further investigation of connections between arguments, cas...

Although argumentation is often studied in AI using abstract frameworks, actual debate often shows a dynamic interaction between argument structure and attack. Often intermediates steps in the reasoning are omitted, but it may be these intermediate steps which are the vulnerable parts of the argument. Inspired by Loui and Norman’s work on the ratio...

Reasoning with legal cases has long been modelled using symbolic methods. In recent years, the increased availability of legal data together with improved machine learning techniques has led to an explosion of interest in data-driven methods being applied to the problem of predicting outcomes of legal cases. Although encouraging results have been r...

We describe a system for constructing, evaluating and visualising arguments based on a theory of a legal domain, developed using the Angelic methodology and the Carneades argumentation system. The visualisation can be used to explain particular cases and to refine and maintain the theory. A full implementation of the well known US Trade Secrets Dom...

We present argumentation schemes to model reasoning with legal cases. We provide schemes for each of the three stages that take place after the facts are established: factor ascription, issue resolution and outcome determination. The schemes are illustrated with examples from a specific legal domain, US Trade Secrets law, and the wider applicabilit...

Reasoning with legal cases by balancing factors (reasons to decide for and against the disputing parties) is a two stage process: first the factors must be ascribed and then these reasons for and against weighed to reach a decision. While the task of determining which set of reasons is stronger has received much attention, the task of factor ascrip...

The first issue of Artificial Intelligence and Law journal was published in 1992. This paper provides commentaries on landmark papers from the first decade of that journal. The topics discussed include reasoning with cases, argumentation, normative reasoning, dialogue, representing legal knowledge and neural networks.

The first issue of Artificial Intelligence and Law journal was published in 1992. This paper offers some commentaries on papers drawn from the Journal’s third decade. They indicate a major shift within Artificial Intelligence, both generally and in AI and Law: away from symbolic techniques to those based on Machine Learning approaches, especially t...

The first issue of Artificial Intelligence and Law journal was published in 1992. This paper provides commentaries on nine significant papers drawn from the Journal’s second decade. Four of the papers relate to reasoning with legal cases, introducing contextual considerations, predicting outcomes on the basis of natural language descriptions of the...

The first issue of Artificial Intelligence and Law journal was published in 1992. This special issue marks the 30th anniversary of the journal by reviewing the progress of the field through thirty commentaries on landmark papers and groups of papers from that journal.

The first issue of Artificial Intelligence and Law journal was published in 1992. This paper discusses several topics that relate more naturally to groups of papers than a single paper published in the journal: ontologies, reasoning about evidence, the various contributions of Douglas Walton, and the practical application of the techniques of AI an...

Explanation and justification of legal decisions has become a highly relevant topic in light of the explosion of interest in the use of machine learning (ML) approaches to predict legal decisions. Current suggestions are to use the established factor based explanations developed in AI and Law as the basis for explaining such programs. We, however,...

The need to explain the output from Machine Learning systems designed to predict the outcomes of legal cases has led to a renewed interest in the explanations offered by traditional AI and Law systems, especially those using factor based reasoning and precedent cases. In this paper we consider what sort of explanations we should expect from such sy...

In this paper we describe the impact that Walton’s conception of argumentation schemes had on AI and Law research. We will discuss developments in argumentation in AI and Law before Walton’s schemes became known in that community, and the issues that were current in that work. We will then show how Walton’s schemes provided a means of addressing al...

Explanation has been a central feature of AI systems for legal reasoning since their inception. Recently, the topic of explanation of decisions has taken on a new urgency, throughout AI in general, with the increasing deployment of AI tools and the need for lay users to be able to place trust in the decisions that the support tools are recommending...

Doug Walton, who died in January 2020, was a prolific author whose work in informal logic and argumentation had a profound influence on Artificial Intelligence, including Artificial Intelligence and Law. He was also very interested in interdisciplinary work, and a frequent and generous collaborator. In this paper seven leading researchers in AI and...

In this paper we consider how the three main approaches to ethics – deontology, consequentialism and virtue ethics – relate to the implementation of ethical agents. We provide a description of each approach and how agents might be implemented by designers following the different approaches. Although there are numerous examples of agents implemented...

Dung’s abstract argumentation frameworks have had a very significant role in the rise in interest in argumentation throughout this century. In this paper we will explore the impact of this seminal idea on a specific application domain, AI and Law. Argumentation is central to legal reasoning and there had been a considerable amount of work on it in...

A successful dialogue requires that the participants have a shared understanding of what they are trying to achieve, individually and collectively. This coordination can be achieved if both recognise the type of dialogue in which they are engaged. We focus on two particular dialogue types, action persuasion and deliberation dialogues, which are oft...

Modelling reasoning with precedents has been a central concern of AI and Law since its inception. A recent paper has provided a discussion (in jurisprudential terms) of whether such reasoning is best seen as rule application or analogy. We review some of the prominent AI and Law approaches and find that over the years there has been a move away fro...

This paper discusses reasoning about norms using Extended Argumentation Frameworks. We argue that norms emerge from a process of value based practical reasoning. We model practical reasoning using Action Based Alternating Transition Systems with Values, with the resulting arguments evaluated in an Extended Argumentation Framework, which permits arg...

This paper considers dynamic aspects of the development of case law. The underlying approach is to see law as a "moving classification system" based on Levi's notion of a three stage life cycle for case law. Our aim is to provide foundations for computational support for consideration of these dynamic aspects. We first use a fictional example to sh...

The ANGELIC methodology was developed to encapsulate knowledge of particular legal domains. In this paper we describe its use to build a full scale practical application intended to be used internally by Weightmans, a large firm of legal practitioners with branches throughout the UK. We describe the domain, Noise Induced Hearing Loss (NIHL), the in...

Practical reasoning, reasoning about what actions should be chosen, is highly dependent both on the individual values of the agent concerned and on what others choose to do. Hitherto, computational models of value-based argumentation for practical reasoning have required assumptions to be made about the beliefs and preferences of other agents. Here...

This paper describes a computational procedure for interpreting contracts in accordance with the English common law rules of interpretation of contract as stated by Lord Hoffmann. Our approach makes extensive use of an ontology of legal terms, specialised for the context in which the contract was made. We illustrate the approach using three example...

A development environment for the Angelic Methodology.

Stories can be powerful argumentative vehicles, and they are often used to present arguments from analogy, most notably as parables, fables or allegories where the story invites the hearer to infer an important claim of the argument. Case Based Reasoning in Law has many similar features: the current case is compared to previously decided cases, and...

In multi-agent systems (MAS), abstract argumentation and argumen-tation schemes are increasingly important. To be useful for MAS, argumentation schemes require a computational approach so that agents can use the components of a scheme to present arguments and counterarguments. This paper proposes a syntactic analysis that integrates argumentation s...

In this paper we address some limitations with proposals concerning an argumentation scheme for practical reasoning grounded on action-based alternating transition systems augmented with values. In particular, we extend the machinery to enable the proper representation of, and ability to reason with, goals. This allows the more satisfactory represe...

This paper presents a methodology to design and implement programs intended to decide cases, described as sets of factors, according to a theory of a particular domain based on a set of precedent cases relating to that domain. We use Abstract Dialectical Frameworks (ADFs), a recent development in AI knowledge representation, as the central feature...

Dialetical Frameworks (ADFs) are a recent development in computational argumentation which are, it has been suggested, a fruitful way of implementing theories of case law expressed in terms of factors. In this paper we evaluate this proposal, by representing the CATO analysis using ADFs. We evaluate the ease of implementation, the efficacy of the r...

In this paper we revisit reasoning with legal cases, with a view to articulating the relationships between issues, factors, facts and values, and to identifying areas for future work on these topics. We start from the different ways in which attempts have been made to go beyond a fortori reasoning from the precedent base, so that conclusions not fu...

Tools for e-participation are becoming increasingly important. In this paper we argue that existing tools exhibit a number of limitations, and that these can be addressed by basing tools on developments in the field of computational argumentation. After discussing the limitations, we present an argumentation scheme which can be used to justify poli...

Argumentation Frameworks (AFs) provide a fruitful basis for exploring issues of defeasible reasoning. Their power largely derives from the abstract nature of the arguments within the framework, where arguments are atomic nodes in an undifferentiated relation of attack. This abstraction conceals different senses of argument, namely a single-step rea...

The emergence and maintenance of cooperation in a society of agents is an important issue and some recent research has explored the role that can be played by a functional model of emotions. For example, it has been shown that the emotions of gratitude and anger can be used to produce cooperative behaviour in a public goods game from agents acting...

In this article, I offer an interpretation of cycles in Dung-style argumentation frameworks in which even length cycles are treated as dilemmas and odd length cycles as paradoxes. The different properties of cycles with different parities arising from the use of preferred semantics are argued to be coherent with this interpretation.

In characteristic function games, an agent can potentially join many different coalitions, and so must choose which coalition to join. To compare each potential coalition, the agents need to calculate a value for each coalition. As the number of coalitions grows exponentially with the number of agents, the burden of requiring every agent to compute...

Argument schemes can provide a means of explicitly describing reasoning methods in a form that lends itself to computation. The reasoning required to distinguish cases in the manner of CATO has been previously captured as a set of argument schemes. Here we present argument schemes that encapsulate another way of reasoning with cases: using preferen...

Citizens have a variety of ways to consult with their representatives about policy proposals, seeking justifications, objecting to all or part of it, or making a counter-proposal. For the first, the representative needs only to state a justification. For the second, the representative would want to understand the objections, which may involve askin...

In this article, we present a proposal to enable agents to discuss the suitability of plans based on an argumentation scheme and associated critical questions. Agents coordinate their beliefs, intentions and preferences using a dialogue game based on this argumentation scheme and its critical questions. The detail encompassed by the argumentation s...

Open multiagent systems (MAS) typically require the participating agents to comply with system-level rules, or norms, and may punish non-compliance. An interesting challenge for designers of such systems is how to provide for dynamic, run-time allocation of norms. In this article, we present a novel, framework-independent approach enabling a norm a...

In this article we offer a formal account of reasoning with legal cases in terms of argumentation schemes. These schemes, and undercutting attacks associated with them, are formalized as defeasible rules of inference within the ASPIC+ framework. We begin by modelling the style of reasoning with cases developed by Aleven and Ashley in the CATO proje...

Several dialogue types, including inquiry, persuasion and deliberation, transfer information between agents so that their beliefs and opinions may be revised. The speech acts in different dialogue types have different pragmatic implications. For a representative sub-type of persuasion dialogues we consider how they can be conducted efficiently, in...

Citizens may engage with policy issues both to critique offi-cial justifications, and to make their own proposals and receive reasons why they are not favoured. Either direction of use can be supported by argumentation schemes based on formal models, which can be used to verify and generate arguments, assimilate objections etc. Previously we have e...

In this paper we demonstrate how a qualitative framework for decision making can be used to model scenarios from experimental economic studies and we show how our approach explains the results that have been reported from such studies. Our framework is an argumentation-based one in which the social values promoted or demoted by alternative action o...

An important aspect of e-democracy is consultation, in which policy proposals are presented and feedback from citizens is received and assimilated so that these proposals can be re-fined and made more acceptable to the citizens affected by them. We present an innovative web-based application that uses recent developments in multi-agent systems (MAS...

The emergence and maintenance of cooperation in a society of agents is an important issue. Hitherto it has largely been investigated in the framework of game theory, but we have previously explored the role that can be played by a functional model of emotions [11]. For example, we have shown that the emotions of gratitude and anger can be used to p...

In order to create a comprehensive dialogue game for autonomous agents to engage in rational debate over plans we present in this report a list of critical questions that match an argumentation scheme for plan proposals. Ques-tions are grouped in six categories regarding the level of detail they focus. The critical questions are formalized in terms...

Human reasoning and behaviour is undoubtedly influenced by emotions. However, the role of emotion in reasoning has, until recently, been viewed as secondary, with preference given to game theory principles in order to explain how the reasoning of an individual affects sociable interaction and the phenomenon of co-operation. Despite this, developmen...

This paper describes an approach to multi-agent classification using an argumentation from experience paradigm whereby individual agents argue for a given example to be classified with a particular label according to their local data. Arguments are expressed in the form of classification rules which are generated dynamically. As such each local dat...

Inquiry, Persuasion and Deliberation Dialogues are all designed to transfer information between agents so that their beliefs and opinions may be revised in the light of the new information, and all make use of a similar set of speech acts. These dialogues also have significant differences. We define success conditions for some different dialogue ty...

Argumentation is key to understanding and evaluating many texts. The arguments in the texts must be identified; using current tools, this requires substan-tial work from human analysts. With a rule-based tool for semi-automatic text anal-ysis support, we facilitate argument identification. The tool highlights potential ar-gumentative sections of a...

We introduce a derivative of Dung's seminal abstract argu-mentation frameworks (afs) through which distinctive features both of Dung's semantics and so-called "value-based" argumentation frame-works (vafs) may be captured. These frameworks, which we describe as uniform afs, thereby recognise that, in some circumstances, argu-ments may be deemed acc...

The abstract nature of Dung’s theory of argumentation accounts for its wide-spread application as a general framework for various species of non-monotonic reasoning, and, more generally, reasoning in the presence of conflict. In this article, we formalize reasoning about argumentation within the Dung argumentation paradigm itself. A metalevel Dung...

The Structured Online Consultation tool (SCT) is a component tool in the IMPACT Project which is used to construct and present detailed surveys that solicit feedback from the public concerning issues in public policy. The tool is underwritten by a computational model of argumentation, incorporating fine-grained, interconnected argumentation schemes...

Autonomous planning agents that share a common goal should be able to propose, justify and share information about plans. To reach an agreement on the best plan, strategies for persuasion and negotiation could be used by agents in order to share their beliefs about the world and resolve conflicts between the agents. We present an argumentation sche...

In this paper we offer an account of reasoning with legal cases in terms of argumentation schemes. These schemes, and undercutting attacks associated with them, are expressed as defeasible rules of inference that will lend themselves to formalisation within the AS-PIC+ framework. We begin by modelling the style of reasoning with cases developed by...

Semantic models have received little attention in recent years, much of their role having been taken over by developments in ontologies. Ontologies, however, are static, and so have only a limited role in reasoning about domains in which change matters. In this paper, we focus on the domain of policy deliberation, where policy decisions are designe...

An approach to multi-agent classification, using an Argumentation from Experience paradigm is describe, whereby individual agents argue for a given example to be classified with a particular label according to their local data. Arguments are expressed in the form of classification rules which are generated dynamically. The advocated argumentation p...

When reasoning about the facts of a case, we typically use stories to link the known events into coherent wholes. One way to establish coherence is to appeal to past examples, real or fictitious. These examples can be chosen and critiqued using the case-based reasoning (CBR) techniques from the AI and Law literature. In this paper, we apply these t...

The paper addresses the extraction, formalisation, and presentation of public policy arguments. Arguments are extracted from documents that comment on public policy proposals. Formalising the information from the arguments en-ables the construction of models and systematic analysis of the arguments. In addi-tion, the arguments are represented in a...

According to argumentation theory, reasoning takes place in different types of dialogue: persuasion dialogue, negotiation, deliberation, information-seeking dialogue, inquiry, and eristic dialogue. These different dialogue types may be nested within one another. Current research in artificial intelligence is building formal models corresponding to...

The Association for the Advancement of Artificial Intelligence was pleased to present the 2009 Fall Symposium Series, held Thursday through Saturday, November 5–7, at the Westin Arlington Gateway in Arlington, Virginia. The Symposium Series was preceded on Wednesday, November 4 by a one-day AI funding seminar. The titles of the seven symposia were...

Extended Argumentation Frameworks (EAFs) are a recently proposed formalism that develop abstract argumentation frameworks (AFs) by allowing attacks between arguments to be attacked themselves: hence EAFs add a relationship D ⊆ X × A to the arguments (X) and attacks (A ⊆ X × X) in an AF's basic directed graph structure (X, A). This development provi...

This paper argues that accrual should be modelled in terms of reasoning about the application of preferences to sets of arguments, and shows how such reasoning can be formalised within metalevel argumentation frameworks. These frameworks adopt the same machinery and level of abstraction as Dung's argumentation framework. We thus provide a dialectic...

We have previously introduced the notion of arguing from experience, whereby agents debate a classification problem using arguments based on association rules mined “on the fly” from their individual datasets. In this paper we extend PISA, which allows for n agents to argue about cases which have n possible classifications. By allowing any number o...

Our focus in this paper is to explore how emotional factors can complement rationality in decision making. Our approach is to develop a model of the situation and use this model to generate arguments for and against the actions that an agent can perform. Actions are then chosen by evaluating this set of arguments according to the subjective prefere...

We describe PADUA, a protocol designed to support two agents debating a classification by offering arguments based on association rules mined from individual datasets. We motivate the style of argumentation supported by PADUA, and describe the protocol. We discuss the strategies and tactics that can be employed by agents participating in a PADUA di...

A process, based on argumentation theory, is described for classifying very noisy data. More specifically a process founded on a concept called "arguing from experience" is described where by several software agents "argue" about the classification of a new example given individual "case bases" containing previously classified examples. Two "arguin...

In this paper we discuss how recent developments in argumentation frameworks, most notably Extended Argumentation Frameworks, can inform the representation of a body of case law using abstract argumentation techniques. This builds on previous work which has first used abstract Argumentation Frameworks, and then Value based Argumentation Frameworks...

As knowledge representation tools become more sophisticated, and computer systems increase in power and ubiquity, the prospects of building practical applications based on the representation of large amounts of legislation draw closer. In this paper we reflect on our experience with developing a knowledge representation language for legal rules and...

In this paper, we present a particular role for abductive reasoning in law by applying it in the context of an argumentation scheme for practical reasoning. We present a particular scheme, based on an established scheme for practical reasoning, that can be used to reason abductively about how an agent might have acted to reach a particular scenario...

A framework, PISA, for conducting dialogues to resolve disputes concerning the correct categorisation of particular cases, is described. Unlike previous systems to conduct such dialogues, which have typically involved only two agents, PISA allows any number of agents to take part, facilitating discussion of cases which permit many possible categori...

Abstract argumentation frameworks, as described in Chapter 11 are directed towards determining whether a claim that some statement is true can be coherently maintained in the context of a set of conflicting arguments. For example, if we use preferred semantics, that an argument is a member of all preferred extensions establishes that its claim...

In this paper we report some experiments designed to clarify some issues and to test some of the assumptions in the model of reasoning with legal cases ad- vanced by Bench-Capon and Sartor. We identify the questions to be explored, briefly describe a tool developed to support these experiments and report the results of a se- ries of experiments bas...