A divisional or three-judge High Court will be convened to hear the action. Such courts are convened occasionally to deal with cases of particular national importance.
Mr Justice Iarfhlaith O'Neill said he had spoken to the President of the High Court about the case. He said it was decided to have the action heard by a divisional court because the issue of constitutional privilege relating to statements made in the houses of the Oireachtas had arisen.
Responding to this morning's decision, Mr Ahern said it showed the court believes there are significant legal and constitutional points to be decided.
Mr Ahern's senior counsel, Brian Murray, outlined a timetable agreed between the two sides for exchanging documents in the case.
He said the tribunal had agreed to the continuation of a stay on an order requiring Mr Ahern to produce documents relating to financial advice from banking expert Paddy Strong pending the outcome of the hearing in April.
Dáil statements
In the case, the Taoiseach is challenging three aspects of the tribunal's inquiries. He is arguing that the tribunal cannot question him about statements he made in the Dáil because such statements are constitutionally privileged.
He also claims advice given to his legal advisers by banking expert Paddy Strong is privileged. And he wants the tribunal to give him all its financial calculations and documentation relating to the tribunal's suggestion that lodgements of $45,000 and Stg£25,000 were made by Mr Ahern or on his behalf in late 1994.
The case is expected to last three days.
The Taoiseach is due to appear again as a witness at the Mahon Tribunal next Thursday and Friday.
Meanwhile, Fine Gael has claimed that Mr Ahern's High Court challenge will delay its work by up to six months.
In a statement, Senator Eugene Regan said it is very likely the result of the case would be appealed to the Supreme Court by either party. He said the Supreme Court is likely to see a hearing in late June or early July.
He said this meant the tribunal is unlikely to finish its hearings by the target date of the start of the summer and that it might not do so before the end of the year.
Mr Regan accused Mr Ahern of adopting a strategy of frustrating and delaying the work of the tribunal.
