The Russian Federation, main successor state to the Soviet Union, has been officially a democracy since its founding in 1991. But there has been doubt that their elections have been open, free and fair under Russian President Vladimir Putin and his cohort.

Researchers at Cornell University, in a paper updated in late June, argue that data show "convincing evidence of election fraud" in federal Russian elections since 2004.

"We analyzed raw data from seven federal elections held in the Russian Federation during the period from 2000 to 2012 and found that in all elections since 2004 the number of polling stations reporting turnout and/or leader's result expressed by an integer percentage (as opposed to a fractional value) was much higher than expected by pure chance," researcher Dmitry Kobak and his colleagues write.

"Unlike previously proposed statistical indicators of alleged electoral falsifications, our observations can hardly be explained differently but by a widespread election fraud," they allege.

President Putin has dismissed concerns about election fairness in the past, and stood by the legitimacy of the results.

"That happens every time and will be happening in the future. The opposition always struggles and takes every opportunity to sideline the authorities, to blame them and to highlight their mistakes. It is a totally normal thing," Putin said in 2011 following elections for Russia's parliament, the Federal Assembly.

Putin has been either president or prime minister, Russia's first and second ranking positions, respectively, since 1999.

But the Cornell researchers agree with conclusions reached in a 2011 Wall Street Journal analysis, among other reports critical of Russian election.

"In the Soviet period, the Communist Party routinely reported 100 percent results for turnout and support in its elections, in which other parties weren't allowed to run. In recent years, similarly high tallies for United Russia have come from Russia's Caucasus and other ethnic regions," Gregory White and Rob Barry wrote, following the parliamentary elections that Putin vouched for.

Of course, it is possible the elections are actually largely legitimate and that Putin and his United Russia party are simply popular. Putin's approval ratings are sky-high— over 80 percent in 2015 and 2016, numbers that are corroborated by Western firms.

Michael Birnbaum of The Washington Post points out what could be a separate problem than election fairness—the lack of open media in Russia.