Legal Ontologies and How to Choose Them: the InvestigatiOnt Tool: “Ontologies are often at the basis of systems that support question answering, information extraction and knowledge modelling tasks. They are used to model the domain of knowledge for which a system is developed and the underlying concept structure. The design of ontology-based systems is usually assigned to computer scientists which need, in addition to the technical knowledge, a further knowledge about the domain for which the system is developed (e.g., economics, health care, law, agri-food sector). A particularly challenging domain is law, where concepts of increasing complexity are used and related to each other. In this context, there is the need to define tools able to support both developers and end-users towards a better understanding of the legal concepts expressed in the legal ontologies, so that an informed decision about the best ontology to select, depending on the target application, can be taken.”