Before World War II Polish lawyers were very much interested in the changes taking place in Soviet law. They were making comparative studies, both from the theoretical and practical perspectives. Szymon Rundstein played important role in this research. He was outstanding lawyer, specialist in the international public law. He was taking part in preparing conventions in the League of Nations and also he was a judge in the international arbitration in Hague. He is recognized as a representative of Kelsen’s normativism. He was analyzing the political system and law of the totalitarian states, including Soviet Union.