The author discusses a question related to a certain aspect of justification of legal decisions, often so-called internal justification-a legal decision is internally justified if and only if it can be deduced from the norm(s) applicable to the case, and from the statement(s) describing the facts of the case. According to this notion, infinite irrelevant logical consequences are justified. To avoid this counterintuitive conclusion, the author analyzes three notions of relevance: Sperber-Wilson's notion, Anderson-Belnap's notion, and Schurz's notion. The author presents (...) a reconstruction of the notion of relevance very close to Schurz's notion, extended to make it suitable to the particular characteristics of deontic logic. Finally, this notion of relevance is used to discuss some aspects of the concept of normative system, conceived as a deductive system, that is, a system containing all its logical consequences. (shrink)