Judge-made law plays an important role in contemporary criminal law system, which appears to be more and more fragmentary and puzzling with regard to its sources. Adjudication implies a space for creativity. Nevertheless the undeniable judicial creativity is tolerated only on condition that judge's productive power is limited. Legal hermeneutics shows that the question of interpretation resides in the dialectic tension between creativity and restriction, discretion and rationality. It points out the restraints against arbitrary judgments. According to the principle of legality, the peculiar functions of criminal law deal with the traits of the interpretive process that has the legal text as its object. Legal methodology is functional in need of staying connected to texts. It can provide a basis for rational control of judicial decisions.