The focus of this study is on three problems. The first area of concern is the substantive scope of the concept of “proceedings following a final court decision” as a type of follow-up proceedings, as well as with their underlying interpretative framework, with a view to assessing the adequacy of legislation governing aggregate sentence. The second area of concern is to reconstruct the criteria that the legislature relied on when introducing into the Polish legal system procedures derogating from the principle of incontestability of final court decisions. The third problem relates to the rationale of applying the institution of aggregate sentencing to penal litigation. The paper closes with a number of de lege ferenda postulates.