Abstract
The prohibition of reformatio in peius is an important procedural institute of the remedies procedure. The prohibition of reformatio in peius means the prohibition of changing a decision for the worse, i.e. to the detriment of the person who has been affected by the contested decision and has himself brought an appeal against that decision or in whose favour such an appeal has been brought. The legal regulation of this institute in the Slovak Republic is unsatisfactory, since there is a different legal regime in the application of the prohibition of reformatio in peius in the derivation of administrative liability for offences and other administrative offences. In the present article, the author compares the legal regulation of the institute of the prohibition of reformatio in peius in the Slovak legal system with the aim of possible inspiration of the legal regulation of this institute in the legal systems of selected states (Poland, Hungary, Czech Republic).