The article regards to the problem related to the rules that constitutional proceedings based on. Firstly the author describes elements of the contradictory rule in civil law proceedings. It is mentioned that the rule consists of four components: 1) litigious of a case; 2) a plaintiff is suppose to proof their demands; 3) the rule of procedural truth predominates upon the rule of objective truth; 4) protection of individual and private interests. In this part of the analysis the investigatory rule of courts proceedings is presented as the rule that is placed in the opposition to the contradictory rule. The author describes relationship between these two basic procedural rules. In the second part of the article the author focuses on elements of the contradictory rule in Tribunal Court proceedings. He points that this procedure doesn’t have litigious character, that the rule of objective truth is the most important, and the whole procedure is concerned on protection of public interests. These elements are characteristic to court procedures based on the investigative rule. In summary the author indicates that components that are characteristic to the contradictory rule generally do not occur in Tribunal Constitutional proceedings. He finds that the investigatory rule has got basic importance in this procedure.