On 6 November 1991 Boris Yeltsin issued a decree banning the Communist Party of the Soviet Union. On 30 November 1992, the Russian Constitutional Court upheld this decree on the grounds that the CPSU was a criminal organisation that had ruled the Soviet Union as a dictatorship in violation of the Soviet Constitution and barred the CPSU from being refounded. The Communist Party of the Russian Federation was re-established in 1993 and has since been an active participant in elections.
In part, the decree issued by Boris Yeltsin reads:
‘The events of August 19-21 made it glaringly obvious that the CPSU was never a party. It was a special mechanism for shaping and exercising political power by fusing with state structures or making them directly subordinate to the CPSU. The CPSU leadership structures exercised their own dictatorship and created, at state expense, the property basis for unlimited power. […] It is the CPSU leadership structures, which to all intents and purposes swallowed up the state and used it as their tool, that bear responsibility for the historical impasse into which the peoples of the Soviet Union have been driven and the state of disintegration we have reached. The activity of these structures was clearly anti-popular and unconstitutional in nature and was directly linked to the incitement of religious, social and nationality-based strife among the country’s peoples and to the infringement of basic human and civil rights and liberties that are recognized by the entire international community.’
Source for the translation of Yeltsin’s decree: ‘Communist Party Banned,’ Seventeen Moments in Soviet History.
On the history of the CPSU see Wikipedia.