Some twenty years ago, the importance of international law, particularly for practical purposes, could be described as marginal in national legal orders in the socialist Central and Eastern European (CEE) Countries. The main reason for this was the dualist approach in regard to international law. Fundamental political and economic changes, such as the Velvet Revolution in Czechoslovakia, marked the end of the cold war and the beginning of a transition process. The changes in national legal orders have been accompanied by substantial modifications in the area of constitutional law, mostly resulting in the adoption of entirely new or radically modified constitutions. This is true also for the Czech Republic, Slovakia, Poland and the Russian Federation. One of the most remarkable common characteristics of the new constitutions of the CEE countries is the shift from a dualistic approach to a broad openness to international law. Despite this common feature the manifestation of this openness cannot be regarded as uniform – the methods used by states to deal with international law and to ensure the conformity of the domestic legal order with their international obligations vary. The common denominator of the constitutional orders under review is the fact that the rules of international law are considered to be a part of their national legal orders. General provisions concerning the relationship between national law and international law can be found in the Czech, Russian and Polish constitutions, but not in the Slovak constitution. The common feature of all four constitutional texts is that they take a clear position on the status of treaties, stipulating conditions (approval by parliament, promulgation, etc) under which a treaty or certain categories of treaties (eg as listed by Article 49 of the Czech Constitution) will be considered to be part of the national legal order, as well as the hierarchical status of treaties in the case of a conflict with national law. In all four countries under consideration, the rank of treaties lies between the level of the Constitution and that of ordinary parliamentary statutes. The situation is considerably different in regard to the role of customary international law: only the Russian Constitution includes not only treaties but also customary international law in the legal order. Nevertheless, Slovak, Czech and Polish constitutional provisions stipulate the commitment of the states to fulfil their obligations under international law, including customary international law. Even though legally binding, these provisions are not identical with general provisions incorporating certain categories of international law as stated above. The openness to international law is demonstrated also by the inclusion of provisions pursuant to which states can transfer certain powers to international organizations. (Such provisions were included in the constitutions of e.g. Slovakia, Poland and the Czech Republic in the context of their integration into the EU for the purpose of ensuring the direct application of Community law.) Thus, if considering the formal openness to international law, a high degree of willingness to open the domestic legal orders to international law can be discerned in the constitutional systems of the states under review. However, the extent of constitutional provisions on the relation of a particular state to international law does not necessarily strengthen its application in practice, as can be observed in the legal order of the Russian Federation.PER/PELJ Vol. 3 2008: pp. 1-49