When Chinese swimming superstar Sun Yang faces his accusers in a doping appeal case tonight, the whole sporting world will be watching.
The World Anti Doping Agency's (WADA) appeal against a finding by swimming's governing body, the Federation Internationale de Natation (FINA), to let Sun off an anti-doping violation is a test case balancing the rights of athletes against the complicated machinery of the anti-doping system.
"The obligations on the athlete under the World Anti-Doping Code are so intense and strenuous," said University of Canberra sports law lecturer Dr Catherine Ordway.
"For an athlete to bring a case that says, 'Well, I'm under this much scrutiny, then you as a testing body should also be under the same amount of scrutiny', is either extremely courageous or extremely foolish," she said.
The case, which will be heard at the Court of Arbitration for Sport in Switzerland, has been clouded by Sun's abrasive personality, and the intense feeling about the use of drugs in world sport.
Earlier this year, a FINA anti-doping panel found Sun had not violated anti-doping rules, despite him refusing to give a urine sample and one of his security guards smashing a vial containing a blood sample.
WADA signalled it intended to appeal against that decision, but Sun was still allowed to compete at July's World Swimming Championships in South Korea.
That was controversial because Sun had priors. In 2014, he had served a three-month ban for taking a banned stimulant.
At the Rio Olympics, Australian swimmer Mack Horton described his Chinese rival as a "drug cheat".
He doubled down at this year's world titles, refusing to share a podium with Sun, while another swimmer, Britain's Duncan Scott, wouldn't shake his hand.
On the face of it, Sun's situation looks bad. A known drug cheat smashes a vial of blood, rather than give a sample.
And although Horton and Scott's protests drew widespread praise at the time, the situation is not as straightforward as it may seem.
Sun case not black and white
Sun's case rests on the inconsistent accreditation held by the three anti-doping officials who turned up at his house last September.
From the moment they arrived, Sun had taken issue with the credentials held by a male chaperone who was there to accompany him while he gave a urine sample.
And while he had initially consented to a blood-collection assistant taking a sample from him, he later raised concerns about the nursing accreditation she held.
The doping control officer who led the three-person team was properly accredited, and is adamant her colleagues were too.
Who said what that night will be debated at tonight's hearing, which will be broadcast live for the first time in 20 years.
What isn't in doubt is that at some point a security guard at Sun's compound smashed the blood sample container.
When FINA's independent panel ruled in Sun's favour in January, it found that the official documentation held by the collection team had been "deficient".
Will that finding be overturned, now it's being appealed?
Human rights lawyer and former Canadian Olympic Swimmer Nikki Dryden believes Sun can get off the violation again.
"Well I think he has a pretty good chance if you focus on this very minutiae of whether or not these doping control officials had the proper authority," Dryden said.
"If this test couldn't even happen because notification didn't happen, then everything that happens after — the smashing of the vials, all of the drama — then all of that stuff becomes just noise."
Dr Ordway believes WADA — which has engaged Richard Young, the lawyer who brought down Lance Armstrong — will argue the accreditation issue is not enough to absolve Sun's actions that night.
If its appeal is successful, Sun faces a possible life ban, given he has a previous anti-doping violation.
"So, this is very serious," Dr Ordway said.
"You can feel some empathy for Sun Yang in this case, because he can understand the implications."
Dryden said it was important to separate the issue from the athlete, even though the swimming world had largely come out against him.
"The last person on earth I really want to be supporting is Sun Yang," she said.
"But, at the same time, I want to make sure that the next athlete who comes into this system and is being held to a strict liability level, that the authorities are held to the same standard."
"And so, if Sun Yang wins his case, that will be great for all athletes," the former Olympian said.
The stakes on all sides are high. For Sun, it is the loss of a possible career, while the worldwide anti-doping machinery is facing a much higher level of accountability.