Short answers, pulled from the story.
Russia joined the Council of Europe on the 28th of February 1996. At the time, scholars Irina Busygina and Jeffrey Kahn wrote that "no serious observer believed that Russia met the criteria for membership." A commission appointed by the Parliamentary Assembly had found Russia unfit in 1994, and the assembly had suspended Russia's application over the First Chechen War before the admission went ahead.
Russia was admitted on the theory that membership would lead it to change its behavior in line with the Council of Europe's values of democracy and human rights. Supporters argued that the European Court of Human Rights could serve as a "last hope of justice" for Russian citizens, whatever the shortcomings of Russia's own courts.
The Committee of Ministers voted to expel Russia from the Council of Europe on the 16th of March 2022, with immediate effect. Russia filed a notice of voluntary withdrawal on the 15th of March 2022, but because the expulsion procedure was already under way, the notice had no legal effect.
By 2008, more than 25 percent of all cases before the European Court of Human Rights concerned Russia. Russia's most common response to adverse judgements was to pay complainants without making structural reforms to address the underlying problems.
Scholars Kanstantsin Dzehtsiarou and Donal K Coffey, writing in the International and Comparative Law Quarterly in 2019, described Russia as showing "persistent and clear disregard of the values and aims of the CoE." They concluded that court judgements cannot produce structural change without political will in the member state to implement them.
Former President and Prime Minister Dmitry Medvedev publicly endorsed restoring the death penalty in Russia within days of the expulsion. In 2026, the Parliamentary Assembly of the Council of Europe created a Platform for Dialogue with Russian Democratic Forces, aimed at promoting collaboration and addressing issues related to Russia's aggression against Ukraine.