THE LAWYER for a key witness in ASADA's anti-doping case against Essendon players will still be fighting a subpoena only days before the AFL tribunal hearing is due to start.

The barrister for compound chemist Nima Alavi, Tony Rodbard-Bean, said he was not given enough time to respond to affidavits filed in the Victorian Supreme Court as ASADA sought to subpoena his client.

The Australian Sports Anti-Doping Authority was back in court on Wednesday seeking subpoenas that would compel Shane Charter and Mr Alavi to give evidence when the anti-doping hearings begin next week.

The tribunal, which will conduct a closed hearing, will rule on anti-doping infraction notices against 34 current and past Essendon players.

Mr Rodbard-Bean said he could not answer assertions that were only sent on Tuesday night, and it was agreed he would have until Thursday morning to respond.

The subpoena hearings are expected to run until Thursday afternoon, four days before the tribunal begins hearings on Monday.

ASADA lawyer Dan Star said it was an urgent case and everything was being done on an urgent basis.

"There can be little doubt Charter and Alavi are material witnesses," Mr Star said on Wednesday.

"Players wish to cross-examine these persons."

ASADA says the court should grant the subpoena under the Commercial Arbitration Act.

Mr Star told the court the AFL was a commercial enterprise and the players were participants of that business.

They were obliged to compete in Australian football in accordance with its laws, Mr Star said.

"The integrity of the game is important for that business," Mr Star said.

He said players' obligations extend to abiding by anti-doping rules.

Mr Alavi and Mr Charter were not in court and Mr Charter was not represented.

However, Mr Charter provided the court with an affidavit stating he was adopting Mr Alavi's position.

The hearing continues.