That is the opinion of Labour’s Alan Kelly whose probing of the department prompted the review of the department’s actions.
A review concluded that certain documents were not handed over by the department to the Charleton Tribunal and that email accounts of senior officials were not searched for.
But the review stopped short of attributing blame and stated the mishandling of the emails was “ad hoc” and “unsatisfactory” but not deliberate.
Senior counsel Michael Collins, who conducted the review, found that there was no particular system in place in the department to ensure emails were filed properly.
The review was carried out in the wake of concerns about the handling of internal emails in May and July 2015 around Sgt McCabe.
“The principal issue of general concern identified in the review relates to the lack of a clear system for the filing and storage of emails,” the review noted.
Mr Kelly, though, responded he now had greater concerns and did not believe the department’s position.
“I think the report is an extraordinary report in the fact it is saying Justice is incapable of looking into its own information and delivering that to a tribunal it set up.
“It’s essentially saying that the Department of Justice is completely incompetent,” he said.
“It is not credible to say Department of Justice which set the criteria for the tribunal then accidentally refused to look at the most senior people in the department, their email traffic for the period.
“It’s not credible, it’s unbelievable.
“If I did not pursue the parliamentary questions which I did,” he said, “we would not have the information we now have at the tribunal.
“This would never have been delivered down to the tribunal, the people questioned at the tribunal would never have been questioned, we would never have know about the famous May 15 email traffic, we wouldn’t have known about the email traffic in July, and really the Department to say they just didn’t look at these emails, it’s not credible.
“And it, for me, raises deeper questions about the Department of Justice as well.”
Other responses, including reports, parliamentary questions and freedom of information requests, should also be examined now in the wake of the review, the Tipperary TD believes.
“It also raises questions about other reports, other FOIs going back a generation.
“If they were so incompetent that they couldn’t deal with requests from a tribunal they set up themselves, then what else have they missed over the years?”
Justice Minister Charlie Flanagan, meanwhile, said he has concerns that certain emails were not located by the department.