The subject of the article is the application of the constitutional foundations of federalism by the constitutional courts of Germany and Russia. The contribution of the highest courts of Russia and Germany to the development of the constitutional concept of the Federal system through judicial interpretation of the basic principles of Federal statehood directly enshrined in the Constitution and the discovery of unwritten principles is studied. The purpose of the article is to confirm or disprove hypothesis that German federalism reflects mostly competition model with specific elements of cooperation of federative entities, while the Russian federalism demonstrates the increasing vertical cooperative principles. The methodology of the study includes analysis, synthesis, description as well as particular academic legal methods (comparative analysis of legislation and judicial decisions, formal-legal method, interpretation of legal acts). The main results and scope of their application. Competitive and cooperati