By deciding not to ban Russia from the Rio Games, the International Olympic Committee has answered one very big question - but inspired dozens of new ones.
Here is a guide to the key questions, with hopefully a few answers.
Has Russia got away with it?
IOC president Thomas Bach feels that by "reversing the presumption of innocence" for Russian athletes and telling them they have to convince their respective international sports federations that they are clean, via a set of undefined "strict criteria", he has balanced the "desire for collective responsibility against the right for individual justice".
If you think that sounds like the type of thing a lawyer would say, you are right: Bach is a lawyer. But he feels that getting the sports to vet each individual competitor is the best way to keep out Russia's cheats without ruining the Olympic dreams of its clean competitors.
How will this work in practice?
Bach simply said it would be an "individual analysis" of each athlete's anti-doping record, which would only recognise tests done by credible international agencies, as the Russian anti-doping system has been dismantled, and it would allow the "specificality" of each sport.
It could mean you must have been tested a minimum number of times, out of competition, in the last year, for the full suite of performance-enhancing drugs, by a well-respected testing agency, and have normal blood and hormone levels in your biological passport. Or it could mean the sport does not think it has a doping problem and, if it did, you have given them no reason to think you could be it.
How have individual sports approached the issue?
Only two US-based Russians came through athletics' vetting process - although one of those, Yuliya Stepanova, has since been banned again by the IOC. Tennis, on the other hand, took all of an hour to digest the IOC's decision and declared all of Russia's would-be Olympic tennis players eligible on the basis of the extensive testing it has subjected them to over the last two-and-a-half years.
Why did the IOC ban Stepanova?
Because the 800m runner served a two-year doping ban between 2011 and 2013 and the IOC has also decided to ban any Russian who has already served a drugs ban, provoking howls of protest and disbelief from sports lawyers.
The problems are that Stepanova and her husband Vitaly were the first whistleblowers to alert the World Anti-Doping Agency and Western journalists to what was really happening in Russian sport.
They now live in hiding in the US and have belatedly been getting the kind of gratitude they deserve - but that memo has not reached the IOC, which has decided that various athletes with doping pasts from other countries can compete in Rio but Stepanova cannot. They have invited her and her husband to the Games as Bach's guests, though.
Can she appeal against that?
Yes, the Court of Arbitration for Sport will be open permanently in Rio and many lawyers think she would win as it is a case of "double jeopardy". She served her two-year ban and has been eligible to run again for three years. And Stepanova, if she decides to appeal, would not be alone - multiple world breaststroke champion Yuliya Efimova now finds herself banned again, as does Tour de France stage winner Ilnur Zakarin, to name just two.
Is there enough time for these appeals?
Is there enough time for any of this? Athletics is the only sport to have individually assessed the Russian team so far and it started to make plans six months ago, completed the process two weeks ago and defended it in court.
The first most sports heard about this was last Monday, when Canadian law professor Richard McLaren told them the Russians were not just cheating in athletics and in the home Winter Olympics in 2014 but in pretty much every Olympic and Paralympic sport.
Weightlifting had already said it would exclude the worst offenders from the re-analysis of samples from the 2008 and 2012 Games - Belarus, Kazakhstan and Russia - but for the likes of fencing, judo, swimming and wrestling the news of Russia's state-directed positive-sample vanishing act seems to have come as a shock.
How many Russians will be in Rio?
We will let you know when they march into the stadium on August 5. The Russian Olympic Committee has selected 387 athletes but that was before the IOC announced its second wave of positives from the Beijing and London re-tests and Sunday's surprise news about the ban on previously banned athletes, which will account for a few.
It is impossible to know how many sports will apply criteria as strict as athletics or weightlifting, who else the IOC will catch in the third or fourth waves of re-tests scheduled to arrive next month, or what else McLaren will find in Russia now that everybody agrees he should continue digging.
What we can say is that Russian athletes, in Russian kit, will almost certainly win a medal at some point and the Russian flag will fly, accompanied by the Russian anthem, and viewers around the globe will wonder if that result should be filed away under "provisional".