The Potential of Ontologies for Courts

Erich Schweighofer University of Vienna, Austria*

At present on leave, working for the European Commission.

The expressed views are those of the author.

Outline

Concept and aim of legal ontologies Legal ontologies: state of the art Proposal of a comprehensive legal ontology Steps to take: hybrid information system, lexical

ontology, pre-ontology, dynamic electronic commentary

LOIS project Potential for courts Conclusions

Concept and aim of legal ontologies

– Explicit formulation of a legal domain– Conceptual model

• Abstract, simplified, computable– New form of abstraction and formalisation of law

• Theory of formalisation (?)– Advantages

• Computable• Links with world ontologies• Re-use of existing ontologies• Important tool for automation of law

– Problems• High efforts required for knowledge acquisition• Scaling-up (well-known problem in AI & law)

Frames-Based Ontology Frames-based ontology, van Kralingen and Visser

– Common legal ontology; re-useable, 3 classes of model primitives, for each class a frame structure has been defined with all relevant attributes:

– Norm: 8 elements (norm identifier, norm type, promulgation, scope, conditions of application, subject, legal modality, act identifier)

– Act: 14 elements (act identifier, promulgation, scope, agent, act type, modality of means, manner, temporal and spatial aspects, circumstances, cause, aim, intentionality, final state)

– Concept: 7 elements (concept, concept type, priority, promulgation, scope, conditions, instances)

• Vocabulary: notions for actions, agents, objects, relations, properties, words indicating place, source, textual constructions, arithmetical operations and legal modality

– Application: Dutch Unemployment Benefits Act Good representation model, very different for scaling-up from a small

ontology

Functional Ontology (1)

Functional ontology / Valente– Aim: organisation and linking of legal knowledge, in

particular in respect to conceptual information retrieval

– 6 basic categories of legal knowledge• Normative knowledge, meta-legal knowledge, world knowledge,

responsibility knowledge, reactive knowledge, creative knowledge

– Follow-up:• ON-LINE (architecture of legal case-solving)

• CLIME/MILE (legal information server)

• PROSA (training system for legal case-solving)

– Problems: modelling of world knowledge; scaling-up

Functional Ontology (2)

Functional Ontology / Valente

E-Court, LRI-Core (1) Project E-Court/University of Amsterdam

– Goal: semi-automated multi-lingual information management for various sources (audio, video, text); application area: penal law

– Main functions: audio, video and text synchronisation, advanced IR, database management, workflow management, security management

– LRI-Core: broad concept structure with typical legal main concepts• Basic assumptions:

– Objects and processes are basic entities in the physical world– Mental entities behave mostly like physical objects– Communication is done over physical objects (documents) and actions

(language)– Mental und physical world overlap in the concept of “agent”– Social order and processes consist of rules and functions that are implemented

by identifiable agents as individual persons– Time and place have a two-dimensional status (position, supplementary

attributes)• About 200 concepts, in development

E-Court, LRI-Core (2)

Structure LRI-Core/E-Court University of Amsterdam

E-Court, LRI-Core (3)

Anchors– Links between foundational (upper) ontology

(= world knowledge) and legal core ontology (legal concepts)

– Support legal subsumption– Select/direct from various acts or agents to the

legally relevant ones Important aspect for improving legal

commentaries

E-Power E-Power, project of the Dutch Tax and Customs

Administration– Application-oriented knowledge system; formalisation

of laws and regulations as conceptual models– Automated tasks (e.g. subsumption, calculation,

document assembly); comprehensive support from legislation to application

– Unified Modeling Language (UML)/Object Contraint Model (OCL)

– Prototype: Dutch income tax law; used by Fortis Banque, Belgium, and the Pension Administration of the Dutch Finance Ministry

Semantic links between words and meanings Automated Text Analysis / Conceptual Indexing

– Text corpora are analysed for legal meanings Many projects, e.g.

– KONTERM/LabelSOM/GHSOM (Schweighofer et al. 1993-), Vienna University/ Vienna University for Technology

– FLEXICON (Smith et al. 1990-1997), University of British Columbia

– SALOMON (Moens et al. 1997-), University of Leuven – SMILE (Brünninghaus/Ashley 1999-); University of Pittsburgh

Advantage: high knowledge in working with text corpora Problems: knowledge acquisition, scaling-up from small

applications

WordNet (1)

English lexical database– Linguist George Miller/Princetone University– http://www.cogsci.princeton.edu/~wn/

EuroWordNet EWN– Goal: mono and cross-lingual information retrieval– WordNet lexica for different European languages, linked

by an inter-lingual index (ILI) – Basis structure of the American WordNet– Extended seminatic-lexical relations (in particular

synonymy, antonymy or hyponomy)– Three top level categories ("top-ontology" with 63

semantic distinctions – 1st, 2nd, 3rd Order Entity) -

WordNet (2)

– form together the common semantic framework for all European languages http://www.illc.uva.nl/EuroWordNet/

– German variant: GermaNet http://www.sfs.nphil.uni-tuebingen.de/lsd/

Global WordNet– Based on WordNet and European World Net

http://www.globalwordnet.org

WordNet = world ontology or upper level ontology (?)

Proposal for a Comprehensive Ontology (1)

Real world (world knowledge)– Subjects = persons (agents)– Objects = things– Acts or omissions (intention, negligence), processes– Formalisation using existing world ontologies (zB

WordNet or CYC) Legal system as a order of norms : socio-economic

governance by law with the goal of risk reduction– Formalisation with a frames-based ontology– Frames for subjects (agents), objects, acts, concepts,

norms, anchors

Proposal for a Comprehensive Ontology (2)

– Extension of norm frame: including evaluation criteria of the legal order

– Purpose of legal order: risk reduction– Efficiency and reasonableness as essential criteria

– Criteria (bench-marking)– How high is the probability of compliance?– How high is the probability of acceptance?– How strong is the law enforcement?– How high is the required control (surveillance and sanctions)?– How high is the risk of non-compliance?– How easy can be norm be understood?– How easy is the norm to be applied?– How good is the contribution to stabilisation of behaviour?

(Luhmann)

Proposal for a Comprehensive Ontology (3)

Anchor frames– Subsumption between real world and legal system

Dynamic and electronic commentary replacing traditional paper commentary– Legal concepts linked with:

• Norms – Formal rules

» Application of law (procedures, execution)» Procedural charts

– Material rules» Acts and omissions with legal consequences» Frames

• Anchors• World ontology

Steps towards a Comprehensive Ontology

Start: information system (text archive)• Published, communicated and documented legal order; now in

the form of a legal information and search machine

Hybrid knowledge-based system Advanced vocabulary Pre-ontology

Hybrid knowledge-based system

Concept proposed by Schweighofer (1996) Information system should be transformed into

such a system by (semi)automatic analysis– Norms as logical sentences or process diagrams (e.g. SoftLaw)– Classification (e.g. GHSOM, LabelSOM)– Cross-references (e.g. AustLII, SiteSeer)– Concept analysis (e.g. KONTERM)– Summaries (e.g. KONTERM, FLEXICON)– (Semi)automatic text analysis

Result: semantic description of the legal order; some “primitive” anchors to legal system and world knowledge

Advanced lexical ontologies

Vocabularies and thesauri, classifications– Anchors between world and legal order

Types– Verbal, non-verbal

– Different levels of thesauri (lawyers, laymen, librarians)

Advantages• Reduction of world complexity

• Description of structure of vocabulary: synonymy, homonymy, polysemy, antinomy, generic terms, sub terms

• Linking of different linguistic levels

• Linking of different languages

• Legal input: Linking of legal concepts with facts (world knowledge)

LOIS Lexical Ontologies for legal Information Serving

– 10 European partners (universities and enterprises) – Multi-lingual access to European legal databases– Formal representation of legal concepts in all languages on the basis of

the WorldNet technology; similar concepts– 6 languages should be linked (synsets, EWN)

• Italian, Dutch, Portuguese, German, Czech, English

– Project duration: 24 months; result: 5000 synsets in each language – Further research:

• Information retrieval: improved techniques• Document standards: common XML standard for the representation of

legal documents• Commercial use of public sector information• Showcase Applications: test and demonstration purposes• Product integration: integration in commercial applications

Pre-ontology

Transformation of hybrid knowledge-based system in a frame structure for norms using advanced vocabularies

• Norm frame (e.g. van Kralingen)– Type of norm (typology of Hohfeld or better Herrestad)– Links to the advanced vocabularies (e.g. for subsumption)– Links to concept frames

• Concept frames• Extension: socio-economic description of norm (risk

reduction)

Potential for Courts (1)

Improving existing legal information systems– Hybrid knowledge based system– Advances lexical ontologies

• Improved access; better description

– Pre-ontologies• Formalisation of laws and court decisions

– Norms will be formalized in a frame-based structure– Procedures will be presented as procedural models

Potential for Courts (2)

Final goal: dynamic electronic commentary– Comprehensive description of the legal order

– Precise links from legal concepts to world knowledge • Lexical ontologies

– Dynamic and (semi)automatic description

– Efficiency criteria for each norm (risk reduction)

Advantages– Better description of world and its legal consequences

– Legal subsumption easier and quicker

Conclusions Ontologies are the key for a computer-useable

formalisation of the world and the legal system Integration of all existing ontologies required Comprehensive model necessary Intermediate steps necessary: legal information system,

hybrid knowledge system, thesauri, pre-ontologies Ontology will be a new form of a legal commentary Ontology will be comprehensive instrument of analysis

of legal order; risk reduction is central element of efficiency evaluation