ESSENDON claims ASADA's joint investigation with the AFL into the club's supplements program made a "mockery" of anti-doping laws.

The Australian Sports Anti-Doping Authority had no right to include the AFL in its doping probe of the Bombers, but did so to ensure it had the power to force players to face interviews, Essendon's barrister Neil Young QC said.

"That is why it had to be a joint investigation," Mr Young told the Federal Court in his closing address.

"Once they (AFL) are at the interview, you have crossed the line."

He said allowing the AFL to sit in on the Essendon interviews was the price ASADA paid to tap into the league's powers to compel players to face a grilling from its interviewers.

Mr Young said ASADA was only legally able to pass on information to a sporting body if it directly assisted with its investigation into doping claims.

But he said the interim report it delivered to the AFL was used by the league to punish Essendon for offences which related to "management failings" not doping.

"It's an ASADA investigation into anti-doping violations, not an investigation at large," he said.

"If any information gathered in the investigation can be disclosed by ASADA to the sporting administration body, at any time, to be used by the body for any purpose, that makes a mockery of all of the surrounding provisions."

Essendon claims the investigation into its 2012 supplements program was a joint venture between the AFL and ASADA and was therefore illegal, and conducted for improper purposes.

But ASADA says it was entitled to seek AFL assistance to probe the Bombers and did nothing unlawful.

ASADA's national operations manager Trevor Burgess told the trial the AFL wanted ASADA to be 

depicted as the "bad guys".

The AFL also told ASADA it would prepare its own report in order to punish Essendon if the interim report was not provided, Mr Burgess said.

A note taken by Mr Burgess in mid-June read "AFL keeping pressure on ASADA to be bad guys", the trial heard.

Mr Burgess said he was told this during a discussion with an employee of the then Labor government, who had been briefed by an AFL employee.

Another note read "player support staff, AFL will go them" and "coach, minimum six months or much longer".

Mr Burgess said he was also told by the AFL its own employees would write a report if ASADA did not deliver an interim report.

"(AFL) said 'If you don't give us the report we'll have to sit down one weekend and do it ourselves'," Mr Burgess' notes said.

The AFL based its decision to ban the Bombers from the 2013 finals and suspend coach James Hird on the interim report it received in August last year.