ASADA went verdict shopping: senator

Ultimate responsibility lies with the 34 banned Essendon players in knowing what went into their bodies, the head of the nation's anti-doping agency says.

Australian Sports Anti-Doping Authority chief Ben McDevitt faced a grilling at a Senate estimates hearing on Thursday about the fate of the players embroiled in the AFL doping scandal.

Greens senator Richard Di Natale questioned Mr McDevitt about how young footballers could be expected to know what prohibited substance Thymosin Beta-4 was.

"They're not kids, they're not children, they're fully grown adults," Mr McDevitt told the Canberra hearing.

Mr McDevitt questioned why the players didn't go to a doctor - a proposition which Senator Di Natalie criticised as ridiculous.

"These are young players, they don't understand pharmacology," the Greens leader said.

"Senator, would you let someone come up and give you multiple injections and say `Don't worry it's all good'?" Mr McDevitt replied.

It was their job as professional athletes to make it their business to know, he said.

"You just cannot shift that personal responsibility to anybody, full stop."

Independent senator John Madigan accused ASADA of "verdict shopping" and outsourcing the appeals process to a foreign body, the Court of Arbitration for Sport.

The court has upheld WADA's appeal against the original AFL anti-doping tribunal hearing that had cleared the players.

Mr McDevitt said the agency was a model litigant and the court was not an unknown foreign entity, but an eminent body.