Essendon CAS verdict: ASADA boss defends agency's pursuit of players

Chief executive officer of ASADA Ben McDevitt also took a swipe at his predecessor and the former Labor government for politicising the scandal before the agency had the powers it needed to fully investigate doping claims when they first emerged in 2013.

"To not pursue the Essendon players would have been an injustice to clean athletes who do the right thing and take their anti-doping responsibilities seriously," Mr McDevitt said in Canberra on Tuesday.

The players were "not just innocent bystanders" but had chosen to enter the drug program, he said. He hoped that the case "serves as a warning to any other athletes who may be considering doping or who are offered secret substances".

"At best, the players did not ask the questions of the people that they should have," he said. "At worst they were complicit in a culture of secrecy and concealment."

Australian athletes were all told they were "responsible for what goes into their bodies".

"You simply cannot shift that personal responsibility to any support person or any other person full-stop. It remains fully and squarely with the athlete."

Mr McDevitt said there were now greater sports policies and education on anti-doping in schools.

"It has taken a long time but the result is the exposure of the worst case of team-based doping that this country has ever seen."

Many, including Opposition leader Bill Shorten, argued that players were unfairly targeted following the Court of Arbitration for Sport's decision to ban the players for the 2016 season. Mr Shorten said they were "paying a big price for other people's decisions".

Essendon chairman Lindsay Tanner also called the ban "manifestly unfair".

Sport Minister Sussan Ley said that "protracted legal appeals and the political interference of the previous Labor government drew out the length of this case and frustrated fans, players, administrators and authorities alike."

The Gillard government in 2013 released an Australian Crime Commission report on professional athletes' use of peptides and hormones at a press conference, two days after Essendon had asked the AFL to investigate the potential inappropriate use of supplements during the 2012 season.

Mr McDevitt said the way the government released the report was "ill-timed" and "ill-conceived", and that former head of ASADA, Richard Ings' comment that the report marked the "blackest day in Australian sport" was "not helpful".

"It obviously placed ASADA in an extraordinarily difficult position in being able to then do its job and determine whether or not some of the things some of the things being spoken about had a factual basis."

One of the reasons its investigation took so long was that it needed laws to be passed to give it the powers it needed for it.

Mr Shorten dismissed Ms Ley's critique as an attempt to "play politics" with Tuesday's decision, insisting his thoughts were with the players who had been caught up in the scandal.

With Michael Gordon