Swimming superstar Sun Yang has been called a drug cheat, but do the facts stack up?

When the Swimming World Championships get underway in Gwangju, South Korea, this morning, more than 1 billion people will be taking an interest in one race above all — the men's 400 metres freestyle.

Many Australians will be following the fate of Rio Olympic Games champion Mack Horton, who failed to qualify for any event in Gwangju but was selected anyway.

Everyone will be watching the man Horton beat at the Olympics — defending world champion Sun Yang from China, a man widely considered the one of the greatest freestyle swimmers of all time.

In the West, much has been written about Sun and the hammer that was used to smash a vial of his blood, preventing drug testers taking it for analysis last September.

Swimmers are being asked what they think and, naturally, they are not impressed — they say they want their sport to crack down on "drug cheats".

One of this country's top swimmers, Cate Campbell, told The Australian "there are discussions that need to be held", while America's Lilly King says the sport's governing body can start with "not letting people who have smashed blood vials in tests compete in their meets".

Listening to the questions posed by journalists and the swimmers' answers reveals no one seems to have actually read the detailed findings of an official inquiry into Sun.

Yes, there has been one, and the doping tribunal found the Chinese swimmer not guilty. Why was he let off? Because the drug testers failed to follow their own procedures.

Here's the crucial chronology of what happened on that night:

• Of the three people who arrived to test Sun at his home at around 11:00pm on September 4, 2018, only one had proper accreditation.
• The swimmer had blood extracted and when filling in the paper work noticed anomalies, which he queried.
• When the answers weren't to his satisfaction he called his coach, the head of China's swimming delegation and his lawyer, all of whom advised against signing incorrect paperwork.

The report says:

The blood that was initially collected (and subsequently destroyed) was not collected with proper authorisation and thus was not properly a "sample" … as a result, the sample collection session initiated by IDTM on September, 4, 2018, is invalid and void.

No FINA DC rule violations can result therefrom.

One of the testing entourage was at the time taking photos and taking video of the swimmer without authority or permission to do so.

The conduct on the part of the DCA (doping control assistant) is highly improper and extremely unprofessional. This should never happen … proof of this conduct by a DCA prior to the athlete providing a chaperoned urine sample is unquestionably reason to immediately suspend the DCA's involvement in the testing mission.

With no other male DCA's to perform this role, the mission with regard to urine collection must be abandoned. Such facts, once established, are a compelling justification for the athlete to refuse to have any further personal and sensitive contact with the DCA.

Sun's entourage queried the qualifications of the nurse who collected the blood from Sun, known as a blood collection assistant or BCA.

FINA called no evidence to rebut the serious contentions made by the athlete regarding the BCA's claimed lack of qualification … Ultimately, the BCA did not testify at the hearing or answer any questions from the athlete.

The Doping Panel is left with significant doubt whether the BCA was properly qualified to draw blood from an athlete.

At around 3:00am, four hours after the drug test had begun, Sun's camp — including his mother, his doctor and a security guard from the compound where the swimmer lives — decided they had no trust in the testers and refused to let the blood vial be taken.

They phoned the chief doctor of the local hospital, who also acts as deputy director of the Zhejiang Anti-Doping Centre, asking what should be done to dispose of the blood sample.

Importantly, the person who oversees International Doping Tests and Management was called into these discussions from his base in Sweden.

As the standoff continued, and several alternatives were canvassed, the Chinese team decided to have the security guard smash the vial with a hammer.

The tribunal described this decision as "foolish" and took the opportunity to warn against such action.

As many CAS awards have stated, it is far more prudent to comply with the directions of a DCO and provide a sample in every case, even if provided "under protest". Subsequently, all manner of complaints and comments can be filed, rather than risk any chance of an asserted violation when an aspect of the doping control process becomes a concern. Staking an entire athletic career on being correct when the issue is complex and contentious is a huge and foolish gamble.

But crucially the panel concluded:

Mr Sun Yang has not committed an anti-doping rule violation.

FINA accepted the findings of the inquiry, but the World Anti Doping Agency (WADA) did not. WADA is appealing the finding to the Court of Arbitration for Sport (CAS).

WADA has not yet pushed for the case to be heard ahead of the world championships, thus clearing Sun to swim and sparking headlines of "dope cheat" and claims he is staring down a "lifetime ban".

What the headlines don't say is that he could also be exonerated.

The ABC has approached lawyers representing Sun, and WADA has been unavailable for comment.

While athletes are being asked their opinions about Sun, this case raises an important question they should all be asking themselves.

If it was you that night, confronted with a three-person doping control entourage, with only one properly accredited, while another videos you without permission, and yet another extracts your blood before you become aware of the flawed process, what would you do?

Entire careers rest on this, a lifetime of training and performance.

To be called a drug cheat is sport's worst slur. If the public is to have faith in athletes, then athletes need to be able to have faith in the system that tests them.

There is still another chapter to play out in the case of Sun — in the pool and out — but what we know right now is that an independent investigation found the swimmer hasn't failed a drug test, and that the anti-doping system has failed him.