Australian swimmers have been cheered on for pointing the finger at drug cheats this week … now the finger is being pointed back.

Mack Horton's podium protest against his main rival, China's Sun Yang, has been reversed with the revelation that Queensland swimmer Shayna Jack tested positive on the eve of the World Championships.

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Just as Australians have cast suspicion on others, now others are questioning every Australian performance.

This will test the resolve of Australia's swimming community — from the governing body down to its most outspoken individual athletes.

Swimming Australia chief executive Leigh Russell described the positive test as "embarrassing" and "bitterly disappointing".

She says Jack is now entitled to a "fair process".

Would that be the same "fair process" that found Sun not guilty of a doping breach earlier this year and has since been torn to shreds by those who doubt the validity of the investigation or the findings?

Russell also says Swimming Australia remains committed to a zero-tolerance approach.

Yet Thomas Fraser Holmes, who will compete for Australia on the final day of the World Championships, recently served a 12-month suspension for missing three drugs tests.

He has not drawn any attention from his teammates, who have chosen to focus on those from other nations.

Zero tolerance to positive doping charges in sport is like the electric chair for those found guilty of murder: there is no coming back.

What history shows us is that no two cases are the same and there is a sliding scale of charges.

Guilty charges can be thrown out or overturned.

Innocent people have been charged only to have those charges later overturned as further evidence comes to light, or evidence used may be found to have been tainted.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 33 seconds 33 s A silent Mack Horton is peppered with questions by reporter

There's a lot we still don't know about the Jack case — other than the substance she tested positive to is Ligandrol.

But how did it get in her system?

Could it have been contained in medication she had to take for a valid medical condition?

Under the zero-tolerance regime, a doctor's failure to obtain a medical certificate, known in anti-doping circles as a TUE (Therapeutic Use Exemption), could signal the end of a sporting career.

This is what happened to Sun Yang in 2014, when he was charged with using a prohibited substance prescribed for an ongoing heart condition.

He incurred a three-month penalty and was allowed to return.

The zero-tolerance advocates want him gone for life.

Is Jack guilty of ingesting a contaminated headache tablet which she would have had no way of knowing would result in a positive test?

If so, under a zero-tolerance regime, her career could be over.

Is she guilty of injecting performance-enhancing substances which may have contained the substance?

This, surely, should attract a much harsher penalty than a "no-fault" positive.

We don't know the answers to these questions.

Shayna Jack tested positive to a banned substance, which forced the 20-year-old to withdraw from the national squad. ( AAP: Matt Roberts )

Here's what we do know

Athletes, globally, are frustrated and believing drug cheats are evading a less-than-robust system.

What's seen as inaction from governing bodies has meant athletes are taking matters into their own hands and are turning on each other — country against country, and potentially this week we may see teammate turn against teammate.

Those from countries with robust anti-doping programs — such as Australia, the USA and Great Britain — feel others are not being held to the same standards of accountability, hence the Horton-Sun affair.

Athletes from countries like Russia and China, that have had systemic doping programs in the past, become trapped in their country's history, forever drawing sideways glances whenever victory is theirs.

As renowned German-based anti-doping campaigner Steven Selthoffer told The Ticket: "You can't help the country you're born in."

"Athletes who have integrity, if they know there is something wrong in their country, something wrong in the anti-doping system or the administration of sport … they tend to vote with their feet, they leave their country and train somewhere else, they want to train with a foreign coach.

"They are choosing a path of integrity as best they can with the resources they've got."

Former ASADA boss Richard Ings says the rules of anti-doping don't just apply to athletes but to the testers themselves: "It's a mutual obligation."

He supports the anti-doping tribunal that found Sun not guilty of a doping breach last year after his blood sample was destroyed — rather colourfully by a security guard with a hammer — because of a failure to adhere to protocols.

"In the Sun Yang case he had every right to refuse to provide a sample because of systematic failures by the testers involved."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 30 seconds 30 s Richard Ings says the result should have been announced with greater transparency to the public.

Australia's anti-doping system is held up as the global standard-bearer.

Such a system does not exist in all countries.

Queensland-based sports lawyer Tim Fuller says he's represented athletes who have been subjected to doping control teams who have breached their own rules, with the substandard procedure resulting in an athlete being banned from her sport for two years.

"I don't think anyone can criticise Sun Yang for raising concerns about protocols that we all know are not always met on occasion — and I can speak about that from experience," Mr Fuller said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 30 seconds 1 m 30 s Swimming officials defend delayed release of drug test result

Professor Jack Anderson, head of the Melbourne Law School and previously an arbitrator at the Court of Arbitration for Sport, says a lack of transparency is a critical issue.

As he points out, most anti-doping findings are not published.

"This goes right to the Court of Arbitration for Sport itself — the default position seems to be not to publish," Professor Anderson said.

"There are confidentiality issues with regard to the private data of individual athletes, but I think in these scenarios it's always better to publish because it engenders more public confidence."

Over the past 30 years three out of every five CAS decisions have not been published.

Until athletes can trust the system, their mistrust will see them continue to turn on each other.

Right now, Jack and Swimming Australia must hope other nations show a more respectful and measured response than we have shown them.