The Garda negotiator at the Abbeylara siege was at an "unacceptable risk" of being shot by taking up a position directly in the line of fire of Mr John Carthy, the tribunal has heard.
Mr Alan Bailey, a consultant on UK police use of firearms, has told the tribunal that a UK commander would not have put a negotiator in such danger, and he personally thought the high risk of being shot was unacceptable.
At the Abbeylara siege in April 2000, the Emergency Response Unit (ERU) negotiator, Det Sgt Michael Jackson, took up a position outside the boundary wall of Mr Carthy's house, facing the window out of which Mr Carthy was firing shots.
The 27-year-old manic depressive fired several shots in the direction of Det Sgt Jackson during the 24-hour siege.
One shot blew a loudhailer from the wall, another knocked a breeze block, which partially landed on Det Sgt Jackson.
Mr Bailey was giving evidence into the appropriateness of the Garda response at the Abbeylara siege, and the likely response of UK police to a similar situation.
He said a UK commander would not have decided to deploy a negotiator to such a position.
"It is very unlikely a commander in the UK would have permitted that point to have been taken up in the first place.
"If he did it would only have been until the firearm was pointed out the window, and certainly not after shots had been fired."
Mr Bailey agreed with Mr Diarmuid McGuinness, counsel for the Garda Commissioner, that relocating the position may have made negotiations impossible. However, he said that would be considered best practice.
"In my view the risk wasn't acceptable. Clearly to the commander at Abbeylara the risk was acceptable, as he went ahead and did it."
Mr Bailey said there was also a great danger of the ERU officers and the local gardaí shooting each other because of the way they had been positioned.
The ERU formed a cordon nearest Mr Carthy's home, while the local armed members formed a separate cordon around them.
It would not be best practice internationally, Mr Bailey said, to have two separate armed cordons.
"If you put two rings of officers and the subject gets in between there is a real risk of officers facing each other shooting each other."
If the local armed gardaí had a better defined role they would not have needed to "run away" when Mr Carthy left his house, he added.
