Minister for Transport Leo Varadkar has said the Department of Justice is not fit for purpose.
Speaking on RTÉ's The Week in Politics, Mr Varadkar said it was clear that big changes were required in the department.
It follows criticism of the department in the Guerin report into how allegations from garda whistleblowers were handled.
The minister also said that he always had the sense that the department's role was less to control the gardaí but to just accept whatever they were told and to back them up.
The minister also called for a change of culture.
"We need cultural change. You know, too much in Ireland - and it's not just a garda issue - we still have the culture of doing favours, the nod and the wink, the use of discretion and those type of things.
“We need now over the next ten or 20 years a move to a rules-based society so that this kind of stuff doesn't happen any more."
He said one of the difficulties for former Minister for Justice Alan Shatter is that he accepted that former Garda Commissioner Martin Callinan was telling him was the truth and he trusted his officials to brief him properly.
He said: "One of the criticisms that were made in the report is a fair one and one that politicians now have to have a regard to challenge advice.
“I think one of the difficulties for Alan Shatter, one of the brightest and one of the most capable people in Irish politics, is that he accepted that the former garda commissioner was telling him the truth, and he trusted his officials to brief him properly and that didn't happen."
Meanwhile, Tánaiste Eamon Gilmore has described reports of further allegations of garda misconduct as "very serious" and said it is important they are investigated as soon as possible.
Mr Gilmore was responding to details of cases in the Sunday Business Post, which it said were contained in a dossier from a campaign group that has now been handed over to the Department of Justice.
He said he was concerned about the amount of allegations now being levelled against gardaí and said it was important they are dealt with quickly and he said that is Minister for Justice Frances Fitzgerald's intention.
He said public confidence in the gardaí had to be restored.
He said the recent problems were a consequence of not dealing with complaints quickly and letting them drift. That approach was now being changed, he said.