This presentation introduces case frames as a way to provide a more meaningful structure to vocabulary mappings used to bridge the gap between laymen and legal descriptions of court proceedings. Case frames both reduce the ambiguity of queries, and improve the ability of users to formulate good quality queries. We extend the BestMap ontology with a formalisation of case frame based mappings in OWL 2, present a new version of BestPortal, and show how case frames impact retrieval results compared to simple contextual mappings and a direct fulltext search.

1. Case Frames as Contextual Mappings to Case Law in BestPortal Rinke HoekstraArno LodderFrank van Harmelenhttp://www.best-project.nl

2. Overview Introduction Translation Approach Contextual Mappings Case Frames Vocabularies and Fingerprints BestPortal/Justfind Evaluation & Conclusions

3. Introduction Netherlands Council of the Judiciary 150 thousand verdicts... and growing BEST Project http://www.best-project.nl Alleviate burden of the judiciary Improve access to court proceedings Focus: unlawful act (Tort) JURIX 2009

4. Problem No standard information retrieval possible, why? In general ... Communities are speech communities ... they use different vocabulary ... to talk about the same things (hopefully) ... these vocabularies may be incommensurable More specifically ... Lawyers and laymen form speech communities “contagious verbosity” (Mellinkoff, 1963) Everyday words refer to technical concepts (Dick, 1987)

5. The Layman’s Approach Monica: It doesn’t make any sense. Joey: Of course it does! It’s smart! I used the the-saurus! Chandler: On every word? Joey: Yep! Monica: Alright, what was this sentence originally? (shows the sentence to Joey) Joey: Oh, ‘They are warm, nice, people with big hearts’. Chandler: And that became ‘they are humid prepossessing Homo Sapiens with full sized aortic pumps...? Joey: Yeah, yeah and hey, I really mean it, dude.

6. Translation Approach Knowledge acquisition effort Why no machine translation approach? From laymen to legal vocabulary Reducibility problem From legal vocabulary to query on corpus Lexical manifestation in texts ‘term vectors’ or ‘fingerprints’ Improved!

7. From Layman to Legal Legal qualification of a case definition of legal concepts in layman terms knowledge intensive expensive modelling effort difficult to maintain theoretical commitment to reducibility Legal description of a case (Hoekstra, 2009) translation of layman concepts to legal terms knowledge intensive ? expensive modelling effort ? difficult to maintain ? ... but no theoretical commitment

9. A mapping is an OWL 2 class definition

10. A description is an individual with property assertions to layman concepts

11. We use a reasoner to classify case descriptions as mappings

13. 2010: Context is not enough... Problem: Unable to distinguish between very different case descriptions Solution: Identify the roles played by concepts in the case description “A horse kicked a woman at a riding school, resulting in damage” “A woman kicked a horse at a riding school, resulting in damage”

14. Case Frames “Case Frames” (Winkels & De Bruijn, 1997) Forms designed for gathering required information, specific to types of cases Guide user to use of proper term in labour law “Case Frames” (linguistics) The complex of thematic roles associated with a verb Case Frames in BestPortal Standard queries for types of cases Thematic roles related to a case description Both for layman description and legal description

15. Thematic Roles (1) Action Relates a description to the action that took place (e.g. ‘hitting’, ‘threatening’). ActorRelates a description to the agent that performed the action (e.g. ‘child’, ‘dog’). Object Relates a description to the thing on which the action was performed (e.g. ‘house’, ‘agreement’). LocationRelates a description to the location where it took place (e.g. ‘farmyard’, ‘factory’). ResultRelates a description to the result of the action (e.g. ‘financial damage’). SituationRelates a description to a special situation in which the action took place (e.g. ‘under duress’, ‘by accident’).

16. Thematic Roles (2) Ground for UnlawfulnessRelates the description to the grounds on the basis of which the act is deemed unlawful, e.g. ‘violation of right’. Applicable to almost all cases. Duty of CareRelates the description to a possible violation of duty of care, e.g. knowledge of a concrete danger. Ground for JustificationRelates the description to possible excuse or grounds for justification, e.g. the right of self-defense. Applicable only in cases of guilt. Ground for Reduced Compensation Relates the description to a possible reduction of compensation, e.g. in case of an accepted risk. Applicable only in rare cases. Ground for Exclusion of Guilt Relates the description to a possible exclusion of guilt, e.g. when the actor is a child under 14 years of age.

17. Thematic Roles (3) Ground for Attribution Relates the description to the grounds on which the act is attributed to the liable person, e.g. on the grounds of guilt, on grounds of a specific law. Criterion for Strict Liability Relates the description to criteria that may hold in the case of strict liability, e.g. the volatility of animal behavior. Liberating CircumstanceRelates the description to certain circumstances that may lift strict liability, e.g. when the damage was caused as a consequence of civil war. Liable Person The person held liable on the basis of the description.

18. Case Frames

20. And... what does it cost me? Case frames increase precision, but may increase effort Two important requirements Redesign structure of vocabularies Optimise interactions between fingerprints

21. Need to guide the question: “What concepts should I add to my mapping?” Move from rigid ontological hierarchy to informed categorisation Top categories form main aspects of a case Lower categories reflect progressively more specific distinguishing features Provide intuitive ‘latch points’ for thematic roles

22. Layman Vocabulary Old: Many concepts ‘left over’ from NLP adventure Thematic roles latent in vocabulary structure New: Straightforward correspondence to thematic roles Multiple-inheritance allows concepts to fill multiple roles

23. Legal Vocabulary Old: Collection of concepts related to unlawful acts Large variety of top level categories Several branches under developed (‘flat’) New: Categorisation based on Spier et al. (1997) Similar to factors Lower level categories need to be considered before higher level applies

24. Combination of concepts vs. Combination of fingerprints 2008: Task: single concept per search Fingerprints have a very broad coverage 2009: Task: multiple concepts per search Combinations of fingerprints guide search Broad coverage reduces ‘added value’ of more specific concepts Solution: remove overlapping fingerprints Extra: Lexical-alignment to bootstrap fingerprint pruning Co-occurrence matching Revamped

25. BestPortal/JustFind

28. 12/16/10 25 September 2010: 25 Billion triples, 395 Million links

29. Evaluation Simple search User evaluation Try to guess judgment for three cases Law students vs. AI students Rechtspraak.nl vs. BestPortal

30. (Preliminary) Evaluation Results Law students (15) “impossible to formulate legal issue” expected very high precision preferred Rechtspraak.nl AI students (5 and counting) much easier to formulate question much more inclined to take results at face value preferred BestPortal

31. Discussion Case frames add extra context to query Much more distinctive retrieval Costs are relatively low Initial high vs. continuous high Mappings are more intuitively specified Queries Easier to formulate for laymen Harder to formulate for lawyers They pose a different type of question