Legal ontologies over time: A systematic mapping study

•A broad systematic mapping study for legal ontologies is provided.•4315 articles from 7 databases were analyzed through a rigorous search strategy.•Formalization of legal ontologies is practically falling on semantic web standards.•Semantic shortcomings in legal corpus suggest the use of non-monotonic formalisms.•Legal ontologies are, in general, context-sensitive, impairing reusability. Over the last 30 years, AI & Law has provided breakthroughs in studies involving case-based reasoning, rule-based reasoning, information retrieval and, most recently, conceptual models for knowledge representation and reasoning, known as Legal Ontologies. Ontologies have been widely used by legal practitioners, scholars, and lay people in a variety of situations, such as simulating legal actions, semantic search and indexing, and to keep up-to-date with the continual change of laws and regulations. Given the high number of legal ontologies produced, the need to summarize this research realm through a well-defined methodological procedure is urgent need. This study presents the results of a systematic mapping of the literature, aiming at categorizing legal ontologies along certain dimensions, such as purpose, level of generality, underlying legal theories, among other aspects. The reasons to carry out a systematic mapping are twofold: in addition to explaining the maturation of the area over recent decades, it helps to avoid the old problem of reinventing the wheel. Through organizing and classifying what has already been produced, it is possible to realize that the development of legal ontologies can rise to the level of reusability where prefabricated models might be coupled with new and more complex ontologies for practical law.