1. 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

2. 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)

3. 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

4. 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])

5. 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?

6. 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

7. 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

8. 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):
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

9. 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)

10. 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

13. 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:
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.

14. 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: :
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

15. 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
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)

16. 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

17. 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

18. 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)

19. 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.

20. 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

21. 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

22. 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

23. 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)

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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?)

32. 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

34. 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 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

35. 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

36. 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

37. 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

38. Arbeitsgruppe Rechtsinformatik
Contacts
Erich Schweighofer
Universität Wien
Arbeitsgruppe Rechtsinformatik
Wiener Zentrum für Rechtsinformatik
IRIS2009 Internationales Rechtsinformatik Symposion, Salzburg