The opposition has said the Government's plans to ask a barrister to review a dossier of alleged wrongdoing in the Garda is "unbelievable".
With the Cabinet discussing its response to the document compiled by Garda whistleblower Maurice McCabe, Fianna Fail said it was an avoidance tactic.
The dossier given to Taoiseach Enda Kenny last week is understood to contain a sample of 10 cases including murder which were not properly handled by the Garda.
An official announcement on the appointment of a senior counsel to review the document and advise on the way forward is expected by the Government this afternoon.
Fianna Fail's justice spokesman Niall Collins said: "This latest development is quite simply u nbelievable.
"Almost one full week ago the Taoiseach was sent a dossier of some very serious incidents that point to very serious problems with the administration of justice. In the first instance, the Taoiseach acknowledged the gravity of what he had been given.
"Unfortunately, there seems to have been a process of minimisation and misdirection ever since. This has culminated this afternoon in an unbelievably weak response. What is the Government trying to hide?
"The Government's effort seems to have moved from getting to the truth, to establishing a method to avoid a thorough examination. This falls far short of what is needed and will only serve to further undermine public confidence."
The file of allegations is said to involve rogue policing and cover-ups connected to assault, abduction and even murder.
Some of the cases date back to between 2007 and 2009 and it is understood that issues of inadequate policing were first reported by Mr McCabe, a serving garda, five years ago.
Sean Guerin SC, a criminal lawyer, will head up the review of the allegations made by Sgt McCabe since 2008, the Taoiseach told the Dail.
Mr Kenny said he will be able to recommend a wider investigation if needed.
"If he recommends a Commission of Investigation should be established, this will be done," he said.
The lawyer's report is to be completed and published before Easter.
Mr Kenny said public confidence in the administration of justice, the Garda and its official watchdog needed to be rebuilt.
"In recent weeks a number of events have served to weaken and undermine that confidence," he told the Dail.
The controversies are to be discussed in the Dail tomorrow.
Fianna Fail leader Micheal Martin said a Commission of Investigation - with full High Court powers - was necessary to get to the truth of the issues and to thwart suspicions of a cover up.
Mr Shatter also needs to come before the Dail and retract remarks he made alleging Sgt McCabe did not co-operate with an internal Garda inquiry into the penalty points saga, Mr Martin said.
Sinn Fein leader Gerry Adams also demanded a full Commission of Investigation be set up.
The Louth TD said the review was another delaying tactic and typical of how business was done in Ireland through a cosy relationship between powerful elites.
"People are sick of it," he said.