The author reflects on reasons why national law wasn’t taught at medieval academies. National law in Poland, derived from a customary system of law and was the dominant element of the justice system until the termination of the tenure of the State of nobility. The failure to teach the law should not have been caused by lack of staff able to teach, nor by lack of students interested in learning. Hence, one might consider whether it wasn’t in fact a feature of the law itself that constituted this obstacle. In light of research into the characteristics of oral culture societies, where the common law developed, the hypothesis may be constructed that the customary system of law that existed in preliterate times could not create a system of norms, whether general or individual – as it is assumed based on the content of the common law that was written down. Although in the absence of a written record, we do not have specific information concerning the functioning of this system, it can be assumed that it contained only the rules, indicating the measures to be taken to settle the dispute arising within the society. It was not possible to apply the norm, but using the mechanisms to preserve social peace.