Taoiseach Bertie Ahern said the granting now of free legal representation to the McBrearty family was a matter for the Morris tribunal.
He was replying to Fine Gael leader Enda Kenny and Labour spokesman on justice Joe Costello, who said the family's request for free legal representation in advance of the tribunal's conclusion should be met.
Mr Ahern said he understood the current position was that Mr Frank McBrearty snr had given evidence to the tribunal, but was now no longer taking part in the process because his legal fees were not guaranteed.
"The facts of the matter are quite clear. The family concerned applied for and was granted a right of legal representation at the outset of the tribunal's business in the summer of 2002.
"Under the terms of the Tribunals of Inquiry (Evidence) Acts 1921 to 2002, the question of costs is solely a matter for the tribunal.
"This is not only the legal position, but it also has important practical implications for tribunals in the search for the truth.
"The Acts allow that where a tribunal, having regard to its findings and all other relevant matters, is of the opinion that there are sufficient reasons rendering it equitable to do so, it may order the whole or part of the costs of representation to a person appearing before it to be paid at the end of each module."
Mr Ahern said that a tribunal, when determining when and whether costs should be paid, might take into account failure to co-operate or provide assistance to, or knowingly give false or misleading information.
"In this regard, it is worth noting that in the chairman's judgment in relation to the costs associated with the first module, he regards co-operation with the tribunal and truthfulness in giving evidence as matters of paramount importance.
"In deciding the costs, he made reductions in some cases, and totally rejected other applications where he was of the opinion that persons deliberately lied or otherwise hindered him in his efforts to get to the truth."
He said the tribunal awarded costs at the end of each module so that nobody had to wait for years to be awarded costs. "It is vital for the proper operation of the tribunal that the chairman does not have his powers on costs pre-empted. The tribunal is dealing with all witnesses with scrupulous impartiality."
Mr Ahern said he would say that if one gave a guarantee before a module, one could not have circumstances in which the chairman could make a judgment on whether a person co-operated.
"It is not possible, and that is the advice I have received from the Attorney General."
Labour leader Pat Rabbitte said that, while he understood the legal advice given to the Taoiseach, the minister for justice of the day was enabled to make special arrangements in the case of the Stardust tribunal.
"There is a precedent without abrogating the rights of the chairman of the tribunal in this particular case."
Asked by Mr Rabbitte if the House would debate the first report of the Morris tribunal, Mr Ahern said he would have no personal difficulty with it.
"I do not know if there is any implication for a tribunal if one discusses part of it. I can check and let the deputy know."
