The principle of ignorantia juris non excusat is commonly justified as a prerequisite for legal certainty and effective law enforcement. Comparatively little attention, however, has been paid to the question of what legitimizes the state's authority to presume that every person knows the law. This article argues that the principle generates not only a duty of legal compliance for citizens but also a reciprocal obligation for the state to provide conditions under which the law can reasonably be known. Employing normative legal research with conceptual and statutory approaches, while using the implementation of the Bone Legal Documentation and Information Network (JDIH) as an empirical illustration, the article develops the concept of access to know the law as a normative consequence of the principle. It proposes five minimum elements: availability, discoverability, accessibility, authenticity, and continuity. The article concludes that access to know the law functions as a minimum condition of legitimacy that strengthens the normative basis of the state's claim to legal obedience.