Erich Schweighofer University of Vienna, Austria TXT, HTML, XML, RDF, OWL, DLEC: European legal ontologies – What should be the next step to do? Erich Schweighofer  University of Vienna, Austria

Outline (1) State of the art: legal research and legal retrieval systems (TXT, HTML) + hypertext, + some meta information N-Lex: Standard for exchange of legal information Good start, but improvements necessary Legal Semantic Web, Legal Social Web XML, RDF, RDF schema, OWL Knowledge management in legal units Known applications: knowledge representation, conceptual information retrieval, advanced lexical thesauri, exchange standards (MetaLex)

Outline (2) Other uses; more support for European legal work? Status quo of legal searching insufficient Exchange of electronic legal meta data a big problem Need for a legal „Dublin Meta Core“ Future: Dynamic Electronic Commentary Support tools for European legal work Next steps Conclusions

Text archive & retrieval (1) Standard service Easy access and efficient handling of the now so many legal documents Retrieval: discrimination task more and more difficult (e.g. finding the Boolean combination that sufficiently selects only those documents I am interested in [e.g. finding 1 to 10 documents in a collection of 1 to x million documents])

Text archive & retrieval (2) Legal retrieval ≠ “To Google” Exact legal provision (or paragraph in a legal judgement); not just some information available in a redundant way No Social Web (e.g. lawyers as a community are linking sufficiently to important legal documents) Only in law firms with efficient knowledge management possible Semantic Web?

Semantic Web Tim Berners-Lee: [T]he Semantic Web is "not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation”. Standards for semantic information on the web Tagged and linked using the technologies of Resource Description Framework (RDF), XML and URIs Web Ontology Language (OWL) Next layer: may be a logical one, an inference machine Remains largely unrealised

Legal web, legal text corpora and beyond Legal web = huge text corpora Legal information systems Web sites Boolean logic + hypertext Some mark-up (text structure) Good coverage, easy handling of documents Problem: semantic meaning and searching is insufficiently developed Same situation as semantic web To do: adaptation of standards for mark-up + implementation

XML (eXtensible Markup Language) General specification for creating markup languages Subset of the Standard Generalized Markup Language (SGML) but human-legible Free standard of the W3C; versions 1.0 and 1.1 Recommendation XML 1.1 (Second Edition): http://www.w3.org/TR/2006/REC-xml11-20060816/ Structure has to be represented like a tree Document type definition (DTD) Mark-up tags are freely extensible Allows semantic mark-up Law: definition of semantic document structure, e.g.: <!ELEMENT judgement (title, summary, grounds, operational part, citations*)> Attribute values Automatic verification

XML (2) Valid documents conform with a particular DTD/schema XML schema definition (XSD) Successor of DTDs XML Style Sheet Extensible Style Sheet Language (XSL) Client-side XSLT XML-based document transformation language Extensible Linking and Pointer Languages XLink: simple and multiple links Xpointer: links to other document parts Browser: Internet Explorer from version 5.0 File format: OpenOffice, Word2007 DTD for legal documents for Electronic Data Interchange (EDI)

Why XML? Main uses in law Advantages Disadvantages Semantic meaning for syntactic data <name>schweighofer</name> Reuse + recycling of information Change of layout Improved searching of documents Unicode Open document format Disadvantages Hierarchical model for representation has its limits Redundancy of data Main uses in law Interchange of documents Interchange of knowledge

RDF (Resource Description Framework) RDF syntax Description of meta data in web documents Each data can be linked with a file that describes the type of this data. Recommendation: http://www.w3.org/TR/2004/REC-rdf-primer-20040210/ RDF statement: subject-predicate-object expression (triples in RDF terminology) Subject (described websource = URL) – predicate (attribute, e.g. author) – object (value, e.g. name) Query language for RDF graphs: SPARQL Semantic web Automated storage, exchange and use of machine-readable information on the web Applications: exchange and common use of web data, improved implementation of search engines, classification of a website (also with software agents) etc.

RDF Schema Extensible knowledge representation language Language for description of the structure, the content and the semantic of XML documents Basic elements for the description of ontologies (RDF vocabularies) Recommendation: 10.2.2004: http://www.w3.org/TR/2004/REC-rdf-schema-20040210/ A RDF scheme does not only describe predicates of a web source (e.g. title, author, etc.), but also the kind of the described sources (e.g. books). Development of user-oriented RDF vocabularies Object-oriented description of data structures with multiple heritage Classes, predicates, constraints Ontology for exchange of data on the Web Important initiatives: Dublin Core Metadata Initiative, PICS labels, P2P

Web Ontology Language (OWL) Family of knowledge representation languages for developing ontologies Revision of the DAML+OIL web ontology language W3C standard 10 February 2004 http://www.w3.org/2004/OWL/ Two semantics based on Description Logics OWL-DL All OWL language constructs OWL-Lite Classification hierarchy and simple constraints (not widely used) RDF/XML syntax LKIF Core Ontology (Leibniz Center for Law, Amsterdam)

Semantic Web & ontologies Semantic Web: highly developed description languages exist Merger between web & ontologies envisaged Quantity of mark-up so far insufficient Legal semantic web Semantic mark-up of legal information systems should be re-used Field structures Thesauri Citations AI & law (legal logic, conceptual information retrieval etc.) Incorporation of world ontologies

Legal thesauri Legal thesauri Definition ISO 2788 standard Definition Precompiled list of important words in a given domain of knowledge (controlled vocabulary) Concepts are linked with relations Synonyms (polysems), antonyms, broader term, narrower term, homonyms Dictionary: definitions Information science + legal information systems Documentation and retrieval Nucleus of a lexical ontology

Legal ontologies Explicit formulation of a legal domain Thesauri + definitions + more relations + formalisation for IT applications 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)

Related work Earlier formalisation attempts 1990ies Hohfeld, Allen, McCarty, Stamper etc. 1990ies FOLaw (Valente), FBO (van Kralingen, Visser) Workshop on legal ontologies 1997 LOAIT Workshop on Legal Ontologies and Artificial Intelligence Techniques 2005 and 2007 ICAIL International Conference on Artificial Intelligence and Law Sessions on ontologies since 1997 LEX Legal XML Workshop Florence 2007 Major research: Leibniz Center for Law, Amsterdam; ITTIG, Florence; University of Turin, Autonomous University of Barcelona, University of Vienna etc.

Types of applications Representation of legal knowledge e.g. FBO, LRI Core, LKIF Conceptual information retrieval Juriservice, LOIS Advanced lexical ontologies Multilingual thesauri e.g. LOIS, Legal Taxonomy Syllabus Interchange of documents and knowledge e.g. MetaLex, eLaw

Knowledge representation (1) Language for Legal Discourse LLD / McCarty (1989) NORMA / Stamper (1991) Frames-based ontology (FBO), 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 Functional ontology (FOLaw), 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

Knowledge representation (2) ON-LINE (architecture of legal case-solving) PROSA (training system for legal case-solving) E-Court, LRI-Core, University of Amsterdam Goal: semi-automated multi-lingual information management for various sources (audio, video, text); application area: penal law LRI-Core: broad concept structure with typical legal main concepts About 200 concepts, in development anchors Links between foundational (upper) ontology (= world knowledge) and legal core ontology (legal concepts) Supports legal subsumption

Knowledge representation (3) Select/direct from various acts or agents to the legally relevant ones 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 LKIF Core Ontology (Legal Knowledge Interchange Format) (Estrella project), University of Amsterdam Standard OWL ontology OWL-DL (description logic) Description logic programs (DLP)

Knowledge representation (4) Obligation, permission, roles, rights, duties, privileges, liabilities etc. Top level clusters Mereological relations Location Time Changes (processes) Agents + actions + roles Propositions Legal agents + actions, rights, powers Norms LKIF rules – more expressive than OWL Application: traffic domain Impressive standard

Conceptual information retrieval CLIME/MILE (University of Amsterdam) Legal information server Classification of ships and maritime law Juriservice (Autonomous University of Barcelona) Web-based decision support for Spanish judges in their first appointment Database of FAQ Ontological description of documents Question topic ontology (QTO) Ontology of Professional Judical Knowledge (OPJK) Semantic distance calculation for improved retrieval

Multilingual thesauri (1) LOIS Lexical Ontologies for legal Information Serving 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, 5000 synsets ILI inter-lingual index + legal definitions 10 partners; leader: ITTIG, Florence Legal Taxonomy Syllabus (University of Turin) Tool to annotate and recover multi-lingua legal information (EU Directives) Legal dictionaries Taxanomies of legal concepts

Multilingual thesauri (2) DALOS (ITTIG, Florence) Ontological-linguistic resource for multilingual drafting process (EU) Basis: LOIS Ontological layer: conceptual modelling at a language-independent level Lexical layer: lexical manifestations in different languages Term extraction using NLP tools

Advanced lexical ontologies LOIS Legal Taxonomy Syllabus Juriservice DALOS Comprehensive legal ontology (University of Vienna) Real world (world knowledge) Legal system as a order of norms : socio-economic governance by law with the goal of risk reduction Frames Material rules Procedural rules Concepts Concept frames Starting point legal thesauri, e.g. LOIS thesauri Links: world knowledge, rules, top legal ontology Hard core of a legal ontology

Interchange of documents and knowledge Interchange standards for documents Many international and European applications e.g. EU, eLaw (Austria), MetaLex Interchangability of legal knowledge representation MetaLex (University of Amsterdam) Generic and extensible framework for XML-encoding of legal resources

Dynamic Electronic Legal Commentary (1) Abstract representation of law in a conceptual & logical-systematic structure; like printed commentary but in a machine-useable format Description of the world ([possible] facts) The core: links between possible facts (situations) and legal consequences Problem: world ontologies have still some way to improve sufficiently, legal formalisation has to move from small environments to the real big world It‘s time to move on

Dynamic Electronic Legal Commentary (2) For legal information systems: Not the very, very big step, but : Tools like a navigator [time and document types, layers of the legal order, consolidated texts] (e.g. PreLex) , citator or terminologist are possible and would be highly desirable … Thus good paying services In the near future The real thing … some automated support for legal subsumption, e.g. helping in the real game of applying legal provisions (could that also called legal reasoning or a legal expert system … maybe?)

European standard of legal ontologies Motivators Comparative legal research, harmonisation of EU law (e.g. Services Directive), European E-Government Ontologies are standards, thus an obvious thing to do Meta information in Dublin Core Metadata language Citations (standard, URI) Ontological structures Rules Haley Ltd. (formerly: Softlaw) Concepts E.g. lexical ontologies projects

Next steps (1) Interchange of documents and knowledge Legal documents: ongoing and improving Legislative documents: many applications, standards like MetaLex may improve formalisations due to inclusion of knowledge representation aspects Improvement and enlargement of legal thesauri Up to 10.000 concepts URI formalisation of citations on an EU level Multilingual information retrieval Conceptual information retrieval using legal thesauri Improved searching, classification and summarisation of documents Word sense disambiguation for easier coupling with legal information systems

Next steps (2) Text analysis and text categorisation Start: information system (text archive) Classification Concept analysis (e.g. DALOS, KONTERM) (Semi)automatic text analysis Summaries (e.g. SALOMON, KONTERM, FLEXICON) Result: semantic description of the legal order; some “primitive” anchors to legal system and world knowledge Inclusion of results of text analysis in an advanced lexical ontology

Next steps (3) “Raw” dynamic electronic commentary Concept frame Header, definition, relations + More relations, better definitions, links to legal rules + world knowledge “Raw” conceptual legal ontology “Raw” dynamic electronic commentary Conceptual description of legal order with links to legal rules and world knowledge Formalisation of dynamic electronic commentary in LKIF or other ontology languages Big step, resources not available More research required

Conclusions Big potential for easier better European legal work Ontologies are the key for a computer-useable formalisation of the knowledge on the world and the legal system XML: standard for mark-up of legal documents XML/ontologies: emerging standard for knowledge representation New form of a legal commentary: dynamic, electronic, computer-useable Big support for European legal work Legal search, exchange of data, exchange of knowledge Next steps Exchange standards Multilingual information retrieval Improvement of legal thesauri Some (semi)automatic text analysis and categorisation, advanced lexical ontologies Later: formalisation in LKIF Big potential for easier better European legal work

Arbeitsgruppe Rechtsinformatik Contacts Erich Schweighofer Universität Wien Arbeitsgruppe Rechtsinformatik Wiener Zentrum für Rechtsinformatik erich.schweighofer@univie.ac.at http://rechtsinformatik.www.univie.ac.at IRIS2009 Internationales Rechtsinformatik Symposion, Salzburg http://www.univie.ac.at/RI/IRIS2009