The article deals with selected problems that have occurred in the case law of the Supreme Administrative Court and provincial administrative courts in matters concerning the procedural position of a party’s representative in administrative proceedings. Selected issues relate in particular to the scope of the power of attorney, the obligation to submit the power of attorney to the case file, legal and actual effects of the representative’s actions and the limits in which the representative may act for a party. Case law of the administrative court regarding the above issues has an impact on the interpretation of provisions of law and their proper application and is a valuable source for creating the methodology for the work of professional representatives in administrative proceedings.