In 2018, the centenary of the Constitution of the Russian Socialist Federative Soviet Republic (RSFSR) was celebrated. Scholarly debate over this legal and political document – Russia’s first constitution – has continued across time up to the present day. The process of drafting the Constitution of 1918 has received very contradictory coverage in the historical and legal literature. Writers’ assessments of the works on this topic have often been influenced by political circumstances. In particular, for a long time the role of the famous Soviet legal scholar and lawyer Mikhail Reisner in the preparation of the draft of the first Soviet Constitution was hushed up. This article examines Reisner’s contribution to the creation of the draft of the first Soviet Constitution and his confrontation with Joseph Stalin over the issue of federation in the Constitutional Commission. These two men proposed diametrically opposed approaches to the principles and foundation of the Soviet Federation. If Stalin believed that the Soviet Federation should be built on the national-state principle, Reisner considered this principle bourgeois and offered to abandon the national principle and build a Federation of Russia as a multi-stage Federation of Soviets. The article then analyzes the content of the draft of the Constitution prepared by Professors Reisner and Goikhbarg (the “professorial project”) and identifies its provisions, borrowed by the authors of the final text of the Constitution of the RSFSR of 1918. Additionally, the article describes a number of the provisions of the draft prepared by Reisner and Goikhbarg and distinguishes it from the final text of the Constitution of the RSFSR of 1918.