This article addresses issues arising in the context of transition to democracy in Central and Eastern Europe, namely in Germany (former East Germany), Czech Republic, Slovakia and Hungary. The contribution reflects various means of transitional justice which were applied in these countries: access to the archives of secret police, lustration and prosecution of the crimes of the past (successor trials). Central issue of this article is the criminal prosecution of communist crimes. Here authors focus their attention on two interrelated aspects: choice of applicable law and statutory limitations, which both are linked to the principle of legality. Practice and methods in prosecution of the communist crimes adopted across the analyzed countries reveal considerable heterogeneity and from comparative perspective pose a unique legal laboratory. Despite differences in applicable law, including treatment and interpretation of statutory limitations, and differences in overall outcomes of prosecution and punishment of the communist crimes, all countries were conformed to requirements of the principle of legality. The article thus confirms that states, when dealing with their past, enjoy a wide margin of appreciation.Keywords:  Communist crimes. Central and Eastern Europe. Transitional justice. Successor trials. Nullum crimen sine lege.