Some commentary on what this means for Watson has, however, bordered on the hysterical. Despite the severity of the AFL's anti-doping rules, it is myopic to presume Watson ''guilty'' or ''a cheat'' based only on his candidness.

Like any athlete faced with allegations of doping, Watson must be presumed innocent and given the unfettered opportunity to successfully defend himself. He has a fighting chance.

Watson's admissions included that, in 2012, he signed a consent form concerning the Essendon supplement program. That consent form included information about the proposed future administration of the substance AOD-9604. He was specifically told that AOD-9604 did not offend the WADA prohibited list. He was also told that the substance administered to him was AOD-9604. Watson understands that this was the substance administered to him.

Read the previous paragraph carefully: the nuances of Watson's language raise important issues. Watson does not say he used AOD-9604. Watson's disclosed beliefs are something different. Evidence of what Watson was told is not tantamount to proof of what happened.

As to the substance in question, the status of AOD-9604 in sport is violently unclear. In the Organised Crime and Drugs in Sport report released in February 2013, the Australian Crime Commission stated categorically that AOD-9604 was not a WADA-prohibited substance and not a substance banned under section S2 of the WADA prohibited list relating to peptide hormones, growth factors and related substances.

The ACC report also reveals that it had been co-operating with the Australian Sports Anti-Doping Authority since early 2012. Surely the ACC's statements regarding AOD-9604 must have been verified by ASADA prior to publication.

What we don't know is whether Watson did make inquiries of ASADA in 2012 before submitting himself to the injections he admits he had. Likewise, who knows what information he received from ASADA if he did ask.

On April 22, 2013, WADA released a statement which is diametrically opposed to the ACC report. In that statement WADA decreed AOD-9604 as prohibited under class S0 of its prohibited list because it is a substance ''still under pre-clinical and clinical development and has not been approved for therapeutic use by any government health authority in the world''. WADA omitted to rebut the ACC's assertion about AOD-9604 not being prohibited under section S2.

It is unclear whether WADA considers it unnecessary to reverse the ACC's direct statement about S2 legality, or whether it agrees AOD-9604 is S2-legal based on what it actually is and does, and has therefore decided on silence.

As to WADA's statement, section S0 of the 2012 prohibited list prohibits use of ''pharmacological'' substances ''with no current approval by any governmental health authority for human therapeutic use''. WADA and ASADA must overcome the hurdles laid out in S0 in order for WADA's position on AOD-9604 to remain tenable.

The Concise Oxford English Dictionary defines pharmacology as the branch of medicine concerned the use, effect and action of drugs. A ''drug'' is a substance which has a marked physiological effect when ingested. A necessary limb of any prosecution of Watson must be ASADA proving that AOD-9604 actually has some real effect on the human body.

Equally so, it is less than straightforward for ASADA to prove the truth of the second limb of WADA's statement, that AOD-9604 has no current approval by any governmental regulatory health authority for use on humans. The intellectual property of AOD-9604 is owned by Calzada Limited, a company listed on the Australian Stock Exchange. On April 26, 2013, Calzada released a statement saying AOD-9604 had no authority in any jurisdiction to ''be marketed as a pharmaceutical product''. This is materially different to having no approval worldwide for human therapeutic use. Calzada goes on to say AOD-9604 can be legally prescribed by Australian-registered medical doctors and prepared and supplied by qualified compounding chemists. Moreover, AOD-9604 has been granted unconditional ''generally recognised as safe'' status by the US's Food and Drug Administration.

It might well be the case that AOD-9604 has similar approvals in other countries. The status of AOD-9604 seems exceptionally confused. Finally, even if ASADA successfully demonstrates that AOD-9604 was banned in 2012, it does not automatically follow that Watson is facing two years on the sidelines if it is proved he used it. WADA only asserts AOD-9604 as banned under S0.

The preamble to the WADA list decrees S0 substances as ''specified substances''. The AFL's anti-doping rules prescribe the minimum future sanction for the use of a specified substance is a mere reprimand if the athlete can establish both how the substance entered his body, and that it was not used to enhance performance. Watson may have a very robust chance of discharging his onus in each respect. These defences are available on top of the well-publicised options. Before we take aim it might well be sage to ask: what use is an unloaded gun?

Darren Kane is a Sydney-based sports lawyer.