Because of systematic and widespread, state-sponsored doping, Russian Track And Field athletes have been barred from competing in the Rio Olympics although there is some wiggle room for potential exceptions. From the head of the task force that made the call: “Because the system in Russia has been tainted by doping from top level and down, we cannot trust that what we call and what people might call clean athletes really are clean.” (I’m pretty sure his speech-writer was on the juice.)