Fianna Fail has said that it "will hold the Government to account" in relation to the appointment of Máire Whelan to the Court of Appeal.
The Government is still standing over its controversial decision to appoint former attorney general Máire Whelan to the Court of Appeal.
President Michael D Higgins will formally make the appointment at a ceremony in Áras an Uachtarain this morning.
But political debate continues over the appointment, with Fianna Fail arguing that the appointment broke the “no surprises” clause in the agreement with the Government.
Speaking on Newstalk Breakfast, Fianna Fail's Jim O'Callaghan said that the Government "circumvented the law" in relation to the appointment.
"Since 1995 we’ve a law in place to deal with how a person applies for judicial office, how they’re nominated, how they’re appointed," he said.
"There’s a specific part that deals with an attorney general who has an interest in being nominated and that wasn’t dealt with at all here.
"On a basic, simple level we know that the attorney general remained in the cabinet room while her candidacy was being discussed. That was a breach of any form of fair procedure."
Ms Whelan's nomination was pressed by Enda Kenny during his final Cabinet meeting as Taoiseach.
It did not come about as a result of a recommendation by the Judicial Appointments Advisory Board (JAAB) which is the current routine procedure.
Her name was put forward by former Justice Minister Frances Fitzgerald and Ms Whelan is understood to have stayed in the room as ministers discussed her appointment to the Court of Appeal.
Mr O'Callaghan argued that this is a "clear breach of procedure" in respect of this nomination.
"The way they’re ramming it through now underlines what an unorthodox and what an irregular appointment this is," he said.
"I'm not suggesting there's anything illegal or unconstitutional here but the Oireachtas put in place a mechanism and a statutory procedure for the nomination of the appointment of judges back in 1995 and that was circumvented.
"They didn’t go through that. No explanation has been provided. Ms Whelan didn’t apply for this position through the judicial appointment advisory board, the way virtually every person has got their nomination.
"Frances Fitzgerald ahad a responsibility to put all the relevant and eligible candidates before the cabinet and she didn’t do so. She only put one name. And it is undermining the judiciary because it presents appointment to judicial office to be be a parting gift that a Taoiseach can hand out."
Mr O'Callaghan argued that it was "grossly unfair that three people who had communicated their interest didn’t have their applications considered."
He said he believes the Government are trying to rush the appointment in order to "defuse this as a political issue by shrouding [Maire Whelan] in the cloak of judicial office in the hope that will protect her".
He said that they are "reviewing their options" in relation to the appointment.
"We will vigorously pursue this matter," said Mr O'Callaghan.
"We will fulfill our primary responsibility as an opposition party. We will hold the Government to account. We need answers from Frances Fitzgerald as to why it was she did not bring the names of the other eligible judges who’d applied for this post to cabinet.
"There are issues here that need to be answered, it was a highly unorthodox nomination and appointment and I’m not going to shy away from raising the issues."