Lawyers for Cardinal George Pell are seeking access to the medical records of complainants in the case against him.
Cardinal Pell, 76, is set to face a four-week committal hearing in the Melbourne Magistrates' Court next month as he fights historical sexual offence charges involving multiple complainants.
No other details of the case against him can be reported for legal reasons.
One of Cardinal Pell's defence barristers, Ruth Shann, made what she described as a "responsible and considered" application to access the medial records of complainants in the case.
Ms Shann told the court the records would have substantial probative value, meaning they would contain important evidence to the case.
She said a complainant may not be in the best position to describe their own mental health.
"A particular complainant may, or may not know, the exact name of the therapy or treatment which they were subject to," Ms Shann told the court.
"We would not get very far at a committal just asking these people."
Ms Shann said there were also specific issues in the case which had led the defence to make the application and that it was not a "fishing expedition".
"We know that around the time of complaints first being made, that there is treatment and I won't go into the detail of that," she said.
But prosecutor Mark Gibson SC said the complainants objected to having their medical records subject to a subpoena and produced.
"They wish to have their privacy maintained," he said.
Mr Gibson argued it was too early for the magistrate to be able to judge whether there was any substantial probative value in the records being provided and that the issues would be fleshed out during the committal.
"At this stage it's premature," he said.
Magistrate Belinda Wallington will rule on the application to issue subpoenas at a hearing next Wednesday.
Another of Cardinal Pell's defence barristers, Robert Richter QC, told the hearing they had issued subpoenas in a bid to access material from a number of parties including several law firms and Justice Health which is responsible for delivering health services in Victorian prisons.
He told the court some material had been supplied, some was objected to, while other parties had asked for further time to consider the request.
Mr Richter said they also planned to issue subpoenas to the complainants in the case.
Cardinal Pell was not present at the hearing.
He strenuously denies the allegations.