In the legal domain, ontologies enjoy quite some reputation as a way to model normative knowledge about laws and jurisprudence. This paper describes the methodology followed when developing the ontology used by the second version of the prototype Iuriservice, a web-based intelligent FAQ for judicial use. This modeling methodology has had two important requirements: on the one hand, the ontology needed to be extracted from a repository of professional judicial knowledge (containing nearly 800 questions regarding daily practice). Thus, the construction (...) of ontologies of professional judicial knowledge demanded the description of this knowledge as it is perceived by the judge. On the other hand, due to the distributiveness of the environment, there was a need for controlled discussion and traceability of the arguments used in favor or against the introduction of a concept X as part of the domain ontology. This paper presents the Ontology of Professional Judicial Knowledge (OPJK), extracted manually from the selection of relevant terms from judicial practice questions and modeled according to the DILIGENT methodology. We will show that DILIGENT has proved to be a methodology that facilitates the ontology engineering in a distributed environment, although appropriate tool support needs to be developed. (shrink)