This article describes parallels between Roman procedural law and trends incorporating sociology in legal science. The author is persuaded that legal theoreticians at the end of the nineteenth century must have been inspired by Roman law, and in particular by praetorian law. The leader of these lawyers was a Romanist Eugen Ehrlich, so-called “the founder of legal sociology”. The author gives detailed attention to the dichotomy between the free and bounded approach in the application of law, specifically with regard to the
filling-in of gaps in the law. In the conclusion the author proposes that we be inspired by Ehrlich’s theory, especially by the fight against contra-factual norms of state law, which are of course in conflict with social law.