The aim of the article is to answer the question whether the mixed system of aggregate penalty adopted by the Polish legislator in its current form can be considered rational. Firstly, the basic assumptions of the model of rational law creation developed in the theory of law were presented. Secondly, the basic assumptions of the aggregate penalty in Polish criminal law were discussed, as well as the aggregate penalty system and its consequences at the level of statutory regulation regard-ing the aggregate penalty. When considering whether the system of imposing an aggregate penalty is rational, the expectations regarding rational lawmaking were confronted with the statutory limits of the imposition of an aggregate penalty, in particular with the possibility of inflicting in an aggregate sentence an aggregate penalty more severe than the sum of the penalties subject to merger.
