Why Mack Horton and the swimming world are attacking Sun Yang - and is it fair?

Sun Yang's incredible medal haul portrays him as one of the greatest swimmers in history.

History won't look kindly on the 2m tall Chinese freestyle. Drug suspicions have sparked a level of outrage among his rivals which will never be forgotten.

Australian Mack Horton refused to share a podium with Sun at the current world championships. Brit Duncan Scott followed suit. There was a heated exchange, in a swim drama which has gripped the sports world.

But the level of outrage aimed at Sun is also open to question, given the widespread use of drugs in sport and considering a swim panel actually found in his favour after a bizarre drug test.

The 27-year-old Sun's official day in court will come at a Court of Arbitration in Sport hearing in September, around claims emanating from a chaotic doping test at his house last September.

At that test, Sun refused to supply a urine sample and had a vial of his blood smashed with a hammer by a bodyguard.

But in his defence, a FINA panel found the Chinese swimmer was correct in claiming the test was not conducted properly.

Outside of China at least, he has already been judged guilty by the sports and swimming community.

But swimmers like Horton might hit tricky waters themselves if the arbitration court hearing - which Sun wants held in public - also finds in his favour.

Britain's bronze medalist Duncan Scott, right, looks to gold medalist China's Sun Yang, left, as joint bronze medal winner Russia's Martin Malyutin looks on. Photo / AP

Sun's record, on the face of it, is amazing. He took the sport to new places, winning Olympic and world championships gold medals from 200 to 1500 metres.

But in mid-2014, it was discovered Sun was secretly banned by China's swimming authority after testing positive for the stimulant trimetazidine, which had been placed on the World Anti-Doping Agency's banned list early that year.

Trimetazidine is a heart medication. Sun claimed that he had a heart condition and did not know that the drug had become illegal in sport.

Confusing the situation slightly, trimetazidine had initially only been banned for in-competition testing. In 2015, it was reclassified as a metabolic modulator, which made it illegal for out-of-competition testing as well.

One of the big problems for Sun is his reputation in general, which in turn doesn't help any claims of innocence on the doping charges.

There have been other incidents which portray him as immature and arrogant, with no care for the sport.

In short, Sun has - quite bizarrely - been accused of bothering other swimmers in the pool.

At the 2015 world championships in Kazan, Russia, he was accused by Brazil of harassing and even assaulting one of their female swimmers Larissa Oliveira.

Brazilian coach Alberto Pinto da Silva was quoted as saying: "He was warming up and he pulled the Brazilian girl's foot.

"He ran her over. She got angry and had it out with him. He tried to elbow her and kick her.

"Chile, Argentina, everyone came to tell me what to do. If he's doing that to everyone then he's a dangerous guy, he has no place in sport."

FINA later blamed over-congestion in the pool.

Having won the 400m and 800m gold medals at that meeting, Sun mysteriously pulled out of the 1500m final citing his heart problem.

He apologised, saying: "I didn't feel well in my heart. I felt uncomfortable in the warm-up tonight so I had to give up the idea of competing."

There were also reports of him being "very upset and aggressive" in the locker room while watching that final, according to an anonymous Danish swimmer.

China's Sun Yang celebrates after winning the men's 200m freestyle final at the World Swimming Championships in Gwangju, South Korea. Photo / AP

There were also problems in China over missed training sessions and commercial activities. He spent a week in jail for driving without a licence.

The protests against Sun have been led by his Aussie rival Mack Horton, who beat the Chinese swimmer for gold in the 2016 Olympic 400m.

Horton's primary complaints are related to the doping accusations against Sun, but he also said Sun splashed water on him during a training session in Rio.

There were even complaints that Sun over-celebrated in South Korea for a victory obtained when an opponent was harshly disqualified. He can do no right, it seems.

Everything came to a head last September when international dope testers arrived at Sun's home during the appointed time frame.

Sun was absent and after being rung, arrived in a car with family members. Sun gave a blood sample, but refused to supply urine.

This chaotic scene involved claims by Sun that the testers were not qualified, and that they were secretly photographing and videoing him.

Both Sun's mother and doctor were involved in the arguments. According to official documents obtained by media, Sun used his phone as a flashlight as a bodyguard smashed one blood vial on the instructions of his mother and doctor. The doctor is said to still have a second blood vial.

The FINA panel, with members from Switzerland, Algeria and Canada, exonerated Sun of any dope testing violation.

The panel concluded the collection officer did not produce proper evidence of her qualifications, so the testing session should have been abandoned.

WADA will take over the prosecutorial baton in September. Stay tuned.