If the Treaty of Union of 1922 and the Constitutions which succeeded it provided for numerous mechanisms of integration to make it possible to safeguard the Unity of the entity resulting from the Revolution of 1917 while guaranteeing the sovereignty of the new Republics, the reality of Soviet power was indeed that of a monolithic dictatorship: the dictatorship of the proletariat embodied by the Communist Party.
The Communist Party was formally founded in 1919 by Lenin and was to play, according to Marxist ideology, the vanguard of the proletarian revolution. Thus, according to the brand new Marxism-Leninism ideology put in place, an elite of militants had to seize all the levers of power to guarantee the progress of society on a forced march towards Communism. It was immediately admitted that the population (mostly agrarian at the time) would not want to build communism voluntarily via a representative liberal democracy. Lenin therefore took the initiative to dissolve the Constituent Assembly which had just been elected (elections which had been organized by the Provisional Government but which were maintained by the Bolsheviks as long as they had some hope of winning them) and instituted the dictatorship of the proletariat.
The Communist Party, heir to the former Social Democratic Revolutionary Party of Russia, therefore had a monopoly on power. It appointed to all positions, whether civil or military, local, regional or at Union level. Thus, regardless of the formal aspect of the treaties or the Constitutions, the power did not reside in the institutions of the States but in the internal organs of the Party. Governments, whether local or at the Union level, were therefore subject to the orders of the Party. The power of nomination of the Party was so great that Stalin, simple Secretary General of the Party without official function in the Government, was able to monopolize all the powers after the death of Lenin. Few people remember it today, but during the Stalin era, Joseph Stalin almost never held official positions, whether ministerial or that of head of state.
Thus, while it can clearly be seen that the Treaty of Union, or the Constitutions, provided for mechanisms for the settlement of disputes between the Member States or even appeals against acts of the Republics which were not in conformity with the Constitution, all these mechanisms were in fact pointless because the orders came from the Kremlin and the Politburo of the CPSU.
When we compare, on the one hand, the clearly federal organization of the Union to the functioning of the Party, we are struck by this dichotomy specific to the Soviet Union: on the one hand, we have a federal Union with a whole system of integration to guarantee the sovereign rights of States, and on the other hand we have a single Party which appoints to all functions at all levels. So there was indeed in the USSR a vertical power which made it a centralized state even more absolute than what was the Russian Empire.
The Constitutions of 1936 and 1977 went so far as to “constitutionalise” the role of the CPSU, which in fact became an organ of the State in its own right. When Gorbachev finally had this article repealed in the Constitution, the Soviet institutional system was violently shaken because the free elections of 1990 brought local governments and representatives to Congress from different political backgrounds and who this time could use the Constitution and its provisions without political hindrance. Thus once the monopoly of the Party was broken, the normal game of Institutions could begin and it showed its flexibility because even in 1991 most of the Republics were still part of the Union.
Thus we can see that reflections on the democratic legitimacy of the Union are in fact meaningless. Indeed, the real power was wielded by a handful of people. The Soviet institutional edifice was therefore more a tool in the hands of the Party than an organization in itself.
But before studying the collapse of the USSR in more detail, it is still necessary to study another lever of Soviet totalitarian power: the political police.