Graham Smith, a partner with Clayton Utz and an industrial relations and employment law specialist, contacted Fairfax Media on Monday after ASADA filed its defence document to the James Hird and Essendon camps on Friday.

ASADA strongly suggests it would reissue show-cause notices to the 34 current and former Essendon players should it lose the Federal Court case, which begins on August 11.

Smith said Essendon, Hird and the players could have grounds to lodge a complaint to the federal attorney-general.

"The actual re-issuing of actual infringement notices would not infringe the model litigant rules because they are not being issued in a court proceeding," Smith said.

"But it's the implied threat in their defence that they have filed in the court that they would re-issue them that would arguably infringe the model litigant rules.

"It's putting that implied threat in the statement of defence that arguably is not consistent with the model litigant rules. They require a Commonwealth litigant to act fairly at all times in relation to the litigation, both in terms of their conduct and the way they present the case, the way they argue the case.

It is understood the federal attorney-general could force ASADA to erase the implied threat should it be found to have breached the legal services directions 2005. ASADA, as a statute of the Commonwealth, would fall under the jurisdiction of the directions laws.

In what appeared to be a chilling warning to the players, ASADA said in its document: "Even if ASADA obtained information unlawfully in the course of the joint investigation [which is denied], the grant of relief should be refused on discretionary grounds because ASADA could lawfully obtain all the exact same information [again] by the issue of disclosure notices under division 3.4B of the NAD scheme, and then issue fresh show-cause notices to the [Essendon] players.''

ASADA had previously maintained it could reissue the notices with information secured after the joint investigation was completed in August last year, but its defence document raised the stakes by claiming it could even re-use information gleaned from interviews with Essendon players, coaches and officials.

The 34 players are alleged to have been administered the banned drug thymosin beta-4. They have opted not to be a party to the case brought by Hird and the Bombers, a move that some lawyers outside the case have questioned.

Essendon and Hird want the investigation deemed illegal, meaning the show-cause notices would be void.

But ASADA also maintains the Federal Court must find in its favour even for the benefit of the "public at large".

A hearing in the Federal Court on Monday for a "return of subpoena" was adjourned for a fortnight.

In the third directions hearing earlier this month, Hird's lawyer Nick Harrington had been granted permission by Justice John Middleton to subpoena the AFL. This may have specifically been to integrity department chief Brett Clothier, who led the league's investigation into the Bombers' 2011-12 supplements program.

Clothier had been forced to provide an affidavit in the case brought against the AFL by Essendon doctor Bruce Reid last year.

Hird, who is in France on a business study tour, is due back in Melbourne on July 28.