Former minister for justice Alan Shatter has launched an extraordinary attack on the Guerin report describing it as fundamentally flawed and also likening it to "kangaroo courts".

In a detailed and hard-hitting speech in the Dáil yesterday, Mr Shatter made numerous criticisms of the report which he portrayed as “hastily and prematurely completed”.

The Government commissioned barrister Seán Guerin to review allegations of Garda misconduct by whistleblower Sgt Maurice McCabe in February last year. His report in May of this year found the Garda Mr Shatter failed in their duties to properly investigate allegations of corruption and malpractice in the force and that a statutory inquiry was required to investigate the issues that remained unresolved.

In the speech which ran to 4,000 words, and was made under Dáil privilege, Mr Shatter was also scathing about the manner and methodology of senior counsel Seán Guerin in conducting the inquiry into allegations of garda misconduct.

He compared the speed of the inquiry (conducted in 9½ weeks) unfavourably to the report into GSOC bugging allegations conducted by Judge John Cooke (which took a month longer).

He also criticised Mr Guerin for proceeding to his report in the absence of voluminous documentation from GSOC, which had delayed the handing over of information in its possession.

He also accused Mr Guerin of giving only a partial account of a key letter containing advice from the Attorney General’s office. In perhaps the most serious criticism, Mr Shatter denigrated what he said was the failure of Mr Guerin to interview him during the course of the inquiry.

‘Entitled to an explanation’

“I believe that I am entitled to an explanation for the approach adopted in the preparation and finalisation of the Guerin report and to an explanation as to why conclusions were reached and a factual finding made that, as minister for justice, I did not ‘heed’ what Sergeant McCabe had to say without my being interviewed or a single question put to me or to Justice officials,” he said.

“My accusation is that of a fundamentally flawed preliminary inquiry and report and an unprecedented rush to judgment. As a prosecuting counsel, Mr Guerin must know that the manner in which he conducted his role and some of the conclusions reached by him would not withstand court scrutiny.”

There was no official response from Government or from the main Opposition parties last night. One deputy from his party said privately that it was clear the former minister considered his resignation had been forced and it still rankled.

Mr Shatter, accused Mr Guerin of ignoring basic principles of justice and fair procedures. "To ignore them is to endorse the creation of kangaroo courts as dramatically depicted in Kafka's book The Trial," he said.

The former minister hones in on the Guerin report’s finding on the attention given by him to allegations made by Sgt McCabe. Mr Shatter contended he could have provided comprehensive information detailing the “substantial attention” he gave to the allegations.

Attempts to contact Mr Guerin last night were unsuccessful.