What was the IAAF's decision?
Already banned from international competition since last November, the IAAF Council has decided to keep Russia's athletics team in exile during the period of the upcoming Olympics. That means that, as things stand, there will be no Russian athletes competing under the Russian flag in Rio. Rather surprisingly, there could yet be a select few Russian athletes allowed to compete at the Olympics under an unspecified "neutral flag". Those athletes - who are likely to number no more than three of four - must live and train outside of Russia, as well as proving they have been subject to drugs testing conducted by a suitable anti-doping body.
Why did the IAAF decide to keep Russia's ban in place?
In a nutshell, because there was overwhelming evidence that Russia had failed to clean up its act and the IAAF Taskforce ruled that it had not fulfilled the criteria required to end its ban. Contrary to recent protestations from Russian officials, every independent piece of anti-doping information to emerge from the country over the past year or so has been negative.
A devastating Wada report released this week could not have been more damning of Russia's anti-doping efforts, with details of a seemingly relentless quest by their athletes and government agencies to obstruct and deceive drug-testers. The IAAF Taskforce was equally scathing, stating that many athletes "appear unwilling to acknowledge the extent of the doping problem in Russia".
Are Russian athletes' Olympic hopes over?
Despite the team's ban, it is almost certain that some Russian athletes will be present on the Rio start line. Doping whistleblower Yuliya Stepanova is one of very few Russian athletes who appear eligible to compete under a neutral flag in Rio. However, pending the result of legal action, there could yet be more Russian-based athletes who end up competing in some guise as well. A number of them have already confirmed they will challenge the IAAF ruling and Russia's Ministry of Sport has appealed to the International Olympic Committee "to not only consider the impact that our athletes' exclusion will have on their dreams and the people of Russia, but also that the Olympics themselves will be diminished by their absence."
So can the IOC overturn the IAAF's decision?
That's a tricky question to answer. Due to the fact that the Olympics take place under the IOC umbrella, it would appear that they have ultimate say over what happens in their own competition. However, the athletics competition remains sanctioned and run by the IAAF. Should the IOC decide to overrule the IAAF, officials and lawyers would be left to examine whether the athletics governing body have final veto over Russia's participation. It appears unlikely that the IOC would attempt to overturn Friday's decision though and Seb Coe, IAAF president, maintained that it was not something he was concerned about.
Who are CAS and how will they be involved?
The most likely way that Russian-based athletes can secure their place in Rio is by route of appeal to the Court of Arbitration for Sport (CAS). Based in Lausanne, CAS exists to settle sport-related disputes and it appears almost certain that it will be inundated with appeals from Russian athletes. Double Olympic pole vault champion Yelena Isinbayeva has already confirmed she will bid to show the IAAF's ruling is in "violation of human rights". Crucially, the IAAF must accept any decision made by CAS. So if the court decides Russian athletes should compete in Rio, then that is what will happen.