The document discusses representing legal knowledge on the semantic web. It outlines challenges in legal knowledge representation and proposes an incremental approach using a legal core ontology to represent basic legal concepts. It describes representing norms in OWL DL and addressing issues like exceptions, temporal aspects, and jurisdiction. Representing norms as institutional facts that impose qualifications on situations is discussed, along with addressing complexities like conflicting norms, lex specialis, and temporal scope.

1. Representing Legal Knowledge on the Semantic Web Rinke Hoekstra 30-03-2009 WAI Meeting @ VU

2. Overview Challenge for AI & Law Legal Knowledge Representation Incremental Approach Legal core ontology Social reality Representing norms Exceptions Temporal aspects Jurisdiction Scope Discussion 30-03-2009 WAI Meeting @ VU

3. “Lady Justice on a diet” 30-03-2009 WAI Meeting @ VU

4. Typical legal norm 30-03-2009 WAI Meeting @ VU

5. In short… Well (?) structured, man made We’re all subject to it There’s lots and lots of it … online (wetten.nl, rechtspraak.nl) A lot like the web distributed, cross-references But… complex knowledge management issues versions, semantic cross-references, exceptions, etc. 30-03-2009 WAI Meeting @ VU

6. AI&Law: Two Perspectives Formal representation of legal theory Determine status of facts as `legal’ (epistemology) …creating legal knowledge Representation of the law itself KR/Expert system perspective Annotation of sources versioning, authority, accessibility, cross-referencing Reasoning over contents assessment, planning, harmonisation, simulation Tractability & completeness important need correct answers! Open world, traceable to sources 30-03-2009 WAI Meeting @ VU

7. … sounds familiar? 30-03-2009 WAI Meeting @ VU

9. traceable, structural correspondence, scopeProblems! 30-03-2009 WAI Meeting @ VU

10. Incremental Approach Functional Ontology of Law (Valente, 1995) Epistemology of knowledge types in law Legal knowledge as abstraction of common sense Core Ontology Bridges the gap between ‘common sense’ reality and the legal system Norms Specify regulations that hold on reality Use concepts available in the core ontology 30-03-2009 WAI Meeting @ VU

11. From Ontology to Norms Combining knowledge types … combining representation formalisms? Where to draw the line? Approach (… or rather, experiment) Ontology: in OWL 2 DL Norms: in OWL 2 DL, as much as possible Legal Reasoning: DL Reasoning? 30-03-2009 WAI Meeting @ VU

12. LKIF Core Ontology (Hoekstra et al., 2009) http://www.estrellaproject.org/lkif-core Basic legal concepts ‘Basic level categories’ (a.o. Rosch, Lakoff) Shared across legal domains Grounding in common sense Roles Special legal inference Knowledge acquisition support Prevent loss in translation Semantic annotation 30-03-2009 WAI Meeting @ VU

13. From physical to social world Intentional Stance (Dennett, 1987) Intentional notions are generalizations over physical phenomena Construction of social reality (Searle, 1995) Constitutive rules (counts-as) Subjective entities Institutional facts (roles, functions) Propositional attitudes (beliefs, intentions) 30-03-2009 WAI Meeting @ VU

14. Social Reality (Hoekstra, 2009, Ch.7) X counts-as Y in context C 30-03-2009 WAI Meeting @ VU

15. Representing Norms Outcome of a case does not always follow ‘logically’ from premises Freedom of judge to decide Internal inconsistencies Built-in conflict resolution 30-03-2009 WAI Meeting @ VU

16. Representing Norms Norms ≠ Definitions Conflicting norms  inconsistent reality? A norm is an institutional fact that imposes a deontic qualification on aset of situations in reality. Three types permission, prohibition, obligation Two qualifications allowed, disallowed Situations as OWL restrictions on ‘Generic Case’ 30-03-2009 WAI Meeting @ VU

17. LexSpecialis (1) Students registered at this university are allowed to check out a book from this library. Art1a_GC ⊑ Generic_Case ⊑ ∃allowed_by.art1a ≡ Registered_Student⊓ ∃checks_out.Library_Book Art1a_Permission ⊑ Permission ⊑ ∀allows.Art1a_GC ≡ {art1a} 30-03-2009 WAI Meeting @ VU

18. LexSpecialis (2) Students who have checked out more than five books are not allowed to check out another book. Art1c_GC_F ⊑Generic_Case ⊑∃disallowed_by.{art1c} ≡ Registered_Student⊓≥ 6 checks_out.Library_Book Art1c_GC_P ⊑Generic_Case ⊑∃allowed_by.{art1c} ≡ Registered_Student⊓∃checks_out.Library_Book⊓ ≤ 5 checks_out.Library_Book Art1c_Prohibition ⊑ Prohibition ⊑ ∀disallows.Art1c_GC_F ⊓ ∀allows.Art1c_GC_P ≡ {art1c} 30-03-2009 WAI Meeting @ VU

19. LexSpecialis (3) 30-03-2009 WAI Meeting @ VU

20. Limitations Conflicts may arise between norms that have partially overlapping generic cases OWL 2 DL does not allow the definition of property chains over language constructs disallowsordf:typeordfs:subClassOfordf:type-o allows-->lex_specialis Implementation: HARNESS (OWL Judge) Protégé 4 pluginhttp://www.estrellaproject.org 30-03-2009 WAI Meeting @ VU

21. Lex Superior 30-03-2009 WAI Meeting @ VU

22. Lex Posterior: Temporal Scope Version management of norms and definitions Old version still holds for past cases Hold independently, at the same time Complex determination of validity retroactive, immediate, delayed applicability Approach Explicitly mark dynamic concepts with a temporal restriction Conjunction of ‘CurrentInterval’ with a validity and applicability interval Individuals are timestamped Versions and Applicability of Concept Definitions (Klarman, Hoekstra, Bron, 2008) 30-03-2009 WAI Meeting @ VU

23. Jurisdiction Jurisdiction as topic area (Delegation of authority) NL subClassOfAuthority and issues only (Norm and qualifies only NLJurisdiction) Jurisdiction as geospatial area NL subClassOfAuthority and issues only (Norm and qualifies only (located_inhas The_Netherlands)) Spatial planning IMRO standard vocabulary for categories of land use Problems Delegation causes exception to lex superior rule Spatial relations between regions 30-03-2009 WAI Meeting @ VU Explicit scope of allowed actions Explicit scope of normative content

24. Simplified spatial norms 30-03-2009 WAI Meeting @ VU

25. FEED Portal 30-03-2009 WAI Meeting @ VU

26. Semantic Scope Definitions by restricted to (part of) regulation Requires partitioning of representation Import of definitions “House, as defined in Article 4” Deeming provisions “For the purposes of this chapter, a house boat is considered to be a house as defined in Article 4” … include scope in definition of classes … scope as context in counts-as rule (Searle, 1995) Still thinking about it … 30-03-2009 WAI Meeting @ VU

27. Discussion True ontology based reasoning (LKIF Core) Cognitively intuitive (untested) Flexible system for describing social reality Circumvent inconsistencies Separate norm from situation Explicitly scope class definitions (time, location, …) … works! Limitations Limited expressiveness for describing situations Not all legal reasoning is DL reasoning Enormous threshold … what about verdicts? 30-03-2009 WAI Meeting @ VU

29. Rinke Hoekstra, RadboudWinkels, and Erik Hupkes. Reasoning with spatial plans on the semantic web. In Carole Hafner, editor, Proceedings of ICAIL 2009. IAAIL, ACM Press, June 2009 (to be published)

30. Rinke Hoekstra, JoostBreuker, Marcello Di Bello, and Alexander Boer. LKIF core: Principled ontology development for the legal domain. In JoostBreuker et al., editors, Law, Ontologies and the Semantic Web. IOS Press, Amsterdam, 2009.

31. Saskia van de Ven, Rinke Hoekstra, JoostBreuker, Lars Wortel, and Abdallah El-Ali. Judging Amy: Automated legal assessment using OWL 2. In Proceedings of OWL: Experiences and Directions (OWLED 2008 EU), October 2008.