The article introduces JudO, an OWL2 ontology library of legal knowledge that relies on the metadata contained in judicial documents. JudO represents the interpretations performed by a judge while conducting legal reasoning towards the adjudication of a case. To the aim of this application, judicial interpretation is intended in the restricted sense of the acts of judicial subsumption performed by the judge when he considers a material instance (token in Searle’s terminology), and assigns it to an abstract category (type). The ontology library is based on a theoretical model and on some specific patterns that exploit some new features introduced by OWL2. JudO provides meaningful legal semantics, while retaining a strong connection to source documents (fragments of legal texts). The application task is to enable detection and modeling of jurisprudence-related information directly from the text, and to perform shallow reasoning on the resulting knowledge base. The ontology library is also supposed to support a defeasible rule set for legal argumentation on the groundings of judicial decisions.