Dan Roan reports from the discredited Moscow anti-doping laboratory

It is seen as one of the biggest decisions sport has ever had to face. When the IAAF Council meets in Vienna on 17 June, the participation of athletes from one of the world's most powerful countries - Russia - at sport's greatest event, the Olympic Games, will be at stake.

Or will it? Even if Russia is not reinstated this month, many of its track and field stars could still appear in Rio.

Here's how:

In an unprecedented move, Russia was suspended from international competition in November after a damning report by a Wada independent commission found evidence of state-sponsored doping.

Since then, Russia has been in a race against time, with an IAAF independent task force monitoring its efforts to rebuild its anti-doping operation.

Veering from defiance to contrition, Russia has attacked, then apologised, and insisted it has done all that has been asked of it. All potential Olympians have been subjected to extra doping controls, the leadership of anti-doping agency Rusada and athletics federation Araf have been overhauled, and testing has been run by UK Anti-Doping (Ukad).

Russian Sports Minister Vitaly Mutko has told the BBC he expects the ban to be lifted for Rio

Furthermore, Russia has made the point that doping is a global problem, not a Russian one. As respected Olympic writer Alan Abrahamson recently pointed out, few suggested the whole US track and field team should be banned from the 2004 Athens Games because of the Balco scandal. No one is calling for the country's cycling team to miss Rio because of the doping programme of Lance Armstrong and his US Postal team.

Even so, the chances of Russian readmission appear to have been receding rapidly with a steady stream of negative news stories:

Scores of Russian athletes failed tests for the newly banned heart disease drug meldonium.

Shocking allegations from a former head of Russia's anti-doping laboratory, Grigory Rodchenko, that the federal security service and government officials actively helped Russian athletes hide doping activity during the 2014 Winter Olympics in Sochi. Wada is now investigating the claims.

Twenty-two Russian athletes have now tested positive in the re-analysis of samples from the Beijing 2008 and London 2012 Olympics. And Ukad has complained of a lack of co-operation when their testers have tried to do their jobs.

And it could get even worse with highly-respected German investigative-journalist Hajo Seppelt working on a new ARD documentary, due to be broadcast on 8 June.

Considering all this, it is easy to see why many observers now expect the IAAF, athletics' world governing body, to keep Russia out in the cold. The critics simply do not believe the country can be trusted so soon.

Politically, extending Russia's exile would enable the IAAF and its president Lord Coe to demonstrate they have teeth, to confound those critics who doubt they are really serious about cracking down on doping, and make a big statement of intent after the governing body's credibility crisis following its own corruption scandal.

Coe is under mounting pressure from athletes like Britain's Olympic long-jump champion Greg Rutherford, who wants Russia banned, and javelin thrower Goldie Sayers, who said she has considered boycotting Rio if Russian athletes are allowed to compete.

In fact, some believe that such is the gravity of Russia's cheating, the question should not be whether its track and field athletes are excluded from Rio, but whether Russians in any sport should be there at all.

And yet forcing Russia to miss a first Olympics since the Soviet Union boycotted the Los Angeles Games in 1984 is not a decision to take lightly.

The country hosts more championships and tournaments than any other nation. And as legendary two-time Olympic pole-vault champion Yelena Isinbayeva told me when we spoke in Moscow last week, a host of entirely innocent Russian athletes would be punished because of the wrongdoing of others, denied the chance to compete in Rio.

Yelena Isinbayeva has said the ban on Russian athletes violates her human rights

This collective form of justice can strike many not just as unfair, but may also be legally unsound. Isinbayeva suggested as much when she threatened to file a discrimination case at the European Court of Human Rights if she was barred from competing in Rio. Others could seek recourse at the Court of Arbitration for Sport, and experts believe they would have a good chance of success.

The International Olympic Committee - as it prepares for one of the most crucial executive board meetings in its history later this week - is all too aware of these moral and legal difficulties.

And BBC Sport understands that senior figures in the Olympic movement are now actively discussing the possibility of a controversial compromise agreement that would enable Russian athletes to compete in Rio - even if the IAAF refuses to lift the ban on 17 June.

Remember that the Olympics comes under the jurisdiction of the IOC, not the IAAF.

So while an IAAF ban would apply to the Russian athletics federation, the IOC could then decree that Russian athletes who prove they are clean, with additional independent tests, would still be allowed to compete. Not under the Olympic flag as has been suggested - but under the Russian flag itself. So a 'ban', but only a partial one.

Many critics would no doubt attack such a proposal as a contradiction in terms, and a fudge. They would ask how any athlete could actually prove they are clean. They would insist that this falls a long way short of the proper punishment that Russia deserves and which is needed to establish a true deterrent.

But the IOC could point to the fact that the retesting of samples from 2008 and 2012 has flushed out any remaining cheats, that the Russian athletics federation says it will not select any known dopers for Rio, and that those that remain should now be trusted.

The IOC could also receive support from the likes of UK Athletics chief Ed Warner who told the Telegraph last week external-link that he endorsed allowing 'clean' Russians to compete in Rio.

IOC president Thomas Bach has hinted at reaching a compromise

The president of the IOC, Thomas Bach, gave a major clue to such a compromise on 18 May, when in a statement external-link he said his organisation may have to consider "whether the burden of proof could be reversed. This could mean that concerned athletes would have to demonstrate that their international and independently proven test record is compliant with the rules of their international federation and the Wada code."

My understanding is that there have also been discussions over whether this approach should apply to Kenya - another Wada non-compliant country with a recent history of doping.

As they prepare for this week's executive board meeting, Bach and his IOC colleagues have much to consider: corruption allegations levelled at the Tokyo 2020 bid, a lack of drug-testing by amateur boxing's governing body, economic and political turmoil in Brazil, the delayed construction of the Rio velodrome, and of course calls to postpone the Games because of mounting fears over the Zika crisis.

But it is the Russia dilemma that is giving them most cause for concern. Two months out from the Games, if ever the Olympic movement needed some proper leadership it is now.