Semantic Interoperability for Legal Information: Mapping the European Legislation Identifier (ELI) and Akoma Ntoso (AKN) Ontologies

The legislative landscape, characterized by overwhelming amounts of legal data which, on many occasions, is only accessible by legal experts, the fragmented nature of information and the ever-increasing number of disparate systems, have given more impetus to the interoperability realm of legal data. The semantic interoperability of Linked Open Legal Data (LOLD) requires rich and well-defined metadata, as well as the establishment of standards, in order to be able to connect and link these scattered legal data resources. This is usually achieved through the transformation of legal information into structured format and through the utilization of legal ontologies whose main purpose is to connect the legal basis of two or more countries by allowing for reusability and the ability to adequately represent legal information, which is understood and retrieved across borders. Within the context of this study, the European Legislation Identifier (ELI) and Akoma Ntoso (AKN) ontologies are mapped in order to make legal data compatible and reusable in as many contexts as possible and to support the Linked Open Legal Data (LOLD) concept. The mapping of these two widely used legal ontologies was evaluated by domain experts and strongly validated by tools. The usefulness of the produced mapping is proven through its real-life context application, although one thing to consider regarding possible future perspectives, could be the inclusion and mapping of more legal ontologies to expand the application domain and improve the semantic interoperability of legal information. These mappings could be either achieved using similar methodological approaches or applications of automated and AI-based ontology mapping techniques.