In his splendid report (which will probably be worth the 18m spent on it only if anybody in authority pays it a blind bit of notice; and we're not hopeful) Robert Barr nominated three gardai, Superintendent Joe Shelly, Superintendent Michael Byrne and Detective Sergeant Gerry Russell (to a lesser extent) as being responsible for Mr Carthy's death.

For whatever reason, he didn't add to his list the name of Aidan McCabe, the garda who shot John Carthy in the back and then shot him in the back again. The second shot was fatal.

However, to really get to grips with why John Carthy was mown down in Abbeylara that day, you have to go back a few years, to an incident of low-level, though routine and unsurprising, garda thuggery in Granard station, where the entirely innocent Mr Carthy had been brought for questioning about the destruction of a wooden goat, the mascot of the Abbeylara football team.

Garda Bruen was told, following a tip-off by a local publican (who should be holding his head in shame this weekend), that John Carthy had destroyed the goat.

"Without further detail or any investigation", Justice Barr said in his report, "Garda Bruen was satisfied that John Carthy was in fact the guilty party and he decided to arrest him and interrogate him accordingly."

Bruen obtained the assistance of Garda Frank McHugh in this noble pursuit of justice. Together they brought Mr Carthy in for questioning, during which their prisoner repeatedly protested his innocence.

The day after his release from custody, Mr Carthy visited his doctor, who discovered injuries consistent with force having been used, trauma having been suffered. Bruen and McHugh gave evidence that they didn't assault John Carthy, but Judge Barr was clear about what he thought of that. "I do not accept the evidence of Gardai Bruen and McHugh that neither of them physically abused the subject while under interrogation after an unjustifed arrest and charging with a substantial crime."

An Garda Siochana has almost always been a monolithic organisation, speaking with one voice, creaking under the strain of doing business in one tried and tested manner.

The recent spat over the garda reserve notwithstanding, there has never been much of a difference between what the commissioner might say on an issue and what one of the representative organisations might say. When they refuse to condemn wrongdoing in their ranks, they refuse to do it together. When they are embarrassed into having to criticise something, they do so in similar terms. "It's just a few bad apples. We'll weed them out. Badness, skullduggery is not in our nature."

And so it proved last week after Justice Barr's report. You cannot separate the see-no-evil approach of the GRA's PJ Stone or the hear-noevil approach of AGSI's Joe Dirwan from the speak-no-evil approach of their commissioner Noel Conroy.

The three men are all part of an organisation which has never shown, and still doesn't show, even after the detail of the Barr Report, any interest in reforming itself. (Since his performance in Granard station, for example, Turlough Bruen has been promoted to sergeant. ) And neither, when you come to the question of who killed John Carthy, can you separate the incompetence of the garda operation on the day . . . the 23 management errors, the 14 mistakes made by Michael Jackson, the negotiator turned shooter . . . from the grubby, despicable events at Granard garda station.

John Carthy was in the state he was on that day in 2000 partly because his experience of members of An Garda Siochana was that they were gougers who could not be trusted. The treatment by Bruen and McHugh of Mr Carthy, Judge Barr pointed out, was one of the principal reasons for his "deep animosity towards, and distrust of, the police."

Or, as Peter Mullan, the solicitor for the Carthy family, put it, what the report showed was a "train of events that began with the physical abuse of John in Granard garda station and ended in John's death on April 20th 2000".

Although Michael Jackson got a lot of things wrong that day, his job as negotiator had been made all the more difficult by the fact that every time John Carthy heard his voice or saw him through his window, he was transported back to Granard in September 1998 and to his treatment at the hands of Bruen and McHugh.

What happened at Abbeylara was a fiasco, a disaster, a major blunder . . . call it what you will . . . but its essential characteristic was that it was brought about by the combined efforts of officers at almost all levels.

It was perhaps the inevitable result of a dysfunctional force in action; it was an operation, a saga, marked at its various points by pure badness (in Granard station) and pure incompetence (outside John Carthy's house).

Which is what makes the garda response to the Barr Report thus far so depressing.

Noel Conroy praised the general performance of the members of the Emergency Response Unit, whose most recent achievement of note was to shoot dead an unarmed robber in Lusk. PJ Stone tried to make some weird connection between the four years Judge Barr conducted his inquiry and the "split second decision" to shoot John Carthy. Missing from his comments was any mention of the 25 hours leading up to the split second. Joe Dirwan said that no members of the garda went out to work purposely to kill or injure somebody. Thousands of victims of garda brutality over the years . . . John Carthy included . . . beg to differ.

Thus does the monolithic organisation refuse criticism, avoid scrutiny and circle the wagons once again.

Who can change it? Who can challenge it? Who can discipline it? Does anybody want to? Judge Barr may have answered a lot of questions last week, but as always with An Garda Siochana, we are left with these nagging, obstinate questions.

Will they ever go away?