The tribunal chairman, Mr Justice Flood, refused applications from several media organisations, including The Irish Times, to be allowed to attend hearings in Guernsey next week when Mr Joseph Murphy snr will give evidence.
He said he was taking his decision based on the reports from Mr Murphy's medical advisers who said a hearing accompanied by "excessive publicity" could put his health under serious strain.
Mr Flood told the legal representatives of the media: "It's not a decision I took readily".
He summarised the two reasons for his decision as follows: "One, it might, in the light of the medical evidence, seriously affect the health of Mr Joseph Murphy. Two, create a situation where Mr Murphy on medical advice would decline to give evidence to the tribunal. It should be remembered that Mr Murphy is not within my jurisdiction and is not a compellable witness by subpoena or otherwise."
He delivered his judgment after hearing submissions from several media organisations, including The Irish Times, Independent Newspapers, The Examiner, RTE and TV3.
He said he was satisfied that he had jurisdiction under the Tribunals of Inquiry Act, 1921, to exclude the public and therefore the media as part of the public. Mr Justice Flood said he would, however, provide transcripts of the day's proceedings to the media.
He will take the evidence on commission, and the only people present will be his own officials and legal teams for the tribunal, Mr Murphy snr and Mr James Gogarty.
"In my view, under normal circumstances I would be quite happy to make an exception to the general practice of hearing evidence on commission in private," Mr Justice Flood said. "This is not a case in which I think I can take that liberty," he added.
He quoted medical reports from Mr Murphy's medical adviser, Mr G. Curran, which said that Mr Murphy's anxieties about a hearing were "increased by the fact that for many years he has lived in privacy and in retirement in Guernsey, which is a small island".
"I have two objectives to fulfil. The first is to ensure that his evidence is duly taken and recorded at the first opportunity. The second objective is one of very considerable importance. It is that I should affect the health and comfort of the deponent as little as possible," he said.
"Evidence has been provided to the tribunal by Mr Joseph Murphy's solicitor, on affidavit, of the views of Dr Curran," he said. "In that affidavit are recorded details of Mr Joseph Murphy's ailments. Suffice it to say they are serious and quite debilitating," he added.
Counsel for the public interest, Mr James O'Reilly SC, who appeared at the tribunal in the afternoon, said he was "unaware of any Irish authority to the effect that the public and the press as a matter of entitlement are entitled to be present at evidence taken on commission".