The legal domain is a complex and dynamic area of knowledge, where the interpretation of legal texts requires a high level of precision and accuracy. Legal information, such as statutes, regulations, case law, and contracts, are typically written in a formal language that is difficult to understand for non-experts. Moreover, legal concepts and terms often have multiple meanings and can vary depending on the context and jurisdiction. Therefore, legal researchers, practitioners, policymakers and even citizens need efficient ways to access, organize, and analyse legal information. Knowledge Organization Systems (KOS) provide a structured way to represent legal concepts, relationships, and rules, which can facilitate access to legal information and improve legal reasoning. Of special interest is the development of specific ontologies conceived to represent fundamental legal concepts which offer a classification of legal provision types (i.e. Obligation, Permission, Right, Duty) and related properties (i.e. PermissionAddressee, PermissionAction), including logical relations between legal concepts. The aim of this approach is to improve the quality of legal texts and ensure the maintenance of legal information by monitoring the impacts of new regulations on the legal system.