OWL ontology of basic legal concepts (LKIF-Core). Estrella: Deliverable 1.4.

This document is part of Deliverable D1.4 of the Estrella project. It reports the work performed under Task 1.5 of the Estrella Workplan: “Defining an ontology of basic legal concepts, using the Ontology Web Language (OWL).” The ontology itself is the other part of this Deliverable. In this document we describe the methodology used to develop the ontology, which we have named LKIF-Core ontology. The workplan suggests that by starting from an already existing core-ontology – LRI-Core [Breuker et al., 2004b]— this development process could be a rather simple top-down approach.1 This was not the case, as the number of legal concepts in LRI-Core was rather small; it was rather a top ontology covering abstract concepts of common-sense rather than the field of law. Moreover, it appeared that in law, and in particular in legal reasoning, complex patterns of concepts are used, which do not easily fit into an ontology. We adopted a rather restrictive view on what should be in an ontology and what kinds of knowledge are beyond the scope of an ontology proper, and should rather be separated from the ontology. This kind of knowledge structures are called: frameworks. This distinction was not so much inspired by conceptual puritanism, based upon experiences with earlier kinds of legal core ontologies [Breuker and Hoekstra, 2004a], but particularly by the fact that the expression of such structures in OWL-DL is often not, or only partially possible.