The volume of «Studia Politologiczne» presented here is devoted to the political processes taking place in the states of Eastern Europe and the tendencies in this respect as well as the problems which can be noticed. Attention is drawn both to the legal frameworks of the political systems of the countries of this region and the political practice in them, including the sphere of constitutional courts. The doctrine of constitutional law deals with the fundamental dilemmas arising in this connection. These are the dilemmas which were not paid any greater attention to and were passed over lightly not so long ago. What is now the judicial control of the acts of law in the context of the separation of powers? How does it affect the latter? Is it not true that constitutional courts have acquired the features so far connected with the parliament? In the process of the establishment of laws, have constitutional courts acquired the features of higher chambers of the parliament? The doctrine of post-Soviet states (e.g. the Russian Federation) clearly points to the normative character of the decisions of constitutional courts. They produce the effects similar to those of normative acts. Hence, they are a significant premise modifying the traditionally understood separation of powers.