The company that operates the Hawk-Eye score detection technology in use at Croke Park insists that it can tell when a ball has fully passed over the crossbar.
There was some doubt cast over a Kilkenny point by John Donnelly in the first half of the All-Ireland final last Sunday.
The ball was caught by Tipperary goalkeeper Brian Hogan, who says that his hand didn't go behind the crossbar.
Hogan was involved in a similar incident in the semi-final win over Wexford, when a Tipp goal was chalked off as the play had to be brought back and a point awarded to the Yellow Bellies after the keeper had caught one over the bar.
"We can confirm that the Hawk-Eye system installed at Croke Park can determine if the ball crosses the line," said a representative of the company in a statement released to RTÉ Sport.
"The system only gives a point when the ball has crossed the plane of the goal and in between the goalposts.
"This point in the trajectory of the flight is signified by the trajectory changing from red to white. This, therefore, does not occur when the ball is wide of the posts."
Hawkeye is called in again when an effort for point is caught just above the crossbar. John Donnelly benefits from the decision.— The Sunday Game (@TheSundayGame) August 18, 2019
Watch #SundayGame highlights from 9:30pm on @rte2 #KKvTipp pic.twitter.com/jg533XeKnP
Hawk-Eye is widely used in cricket and tennis, but is only available for GAA games in Croke Park and Semple Stadium due to the costs involved.
It was first introduced in 2013 and there was early controversy that year when it was stood down during the minor hurling final between Limerick and Galway.
A Limerick point was disallowed on the advice of the Hawk-Eye official and they went on to lose after extra-time. It turns out that the wrong dimensions had been fed into the system – they used the measurement of a football rather than a sliotar – and this led to the error.
It has operated largely controversy-free since then, though the incidents in the recent Tipp games have put it in the spotlight once more.
Hawk-Eye generally adjudicates on whether a ball has gone wide or is a score and has been widely hailed as a great innovation for big games at Croke Park and in Thurles.
Normally the umpire or referee calls for the technology to be put to use, though sometimes the Hawk-Eye official, in Sunday’s case it was former inter-county referee Dickie Murphy, alerts the referee.
They can only do so during a break in play and this is partly the cause of the confusion in the two recent cases involving Hogan.
"This is one of the challenges we face," said GAA Director of Communications Alan Milton, speaking to RTÉ Sport. "We don’t have a mechanism to stop the play so we can’t just stop and check."
On Sunday Murphy would have received an alert and at the next break in play he would have contacted match referee James Owens and advised him to use Hawk-Eye to check for a possible score.
There are six cameras, three on each stand, monitoring the goals at either end of the ground and between them they generate a 3D image and can then rule whether or not a ball has gone between the posts and fully over the crossbar or not.
"It has been very reliable for us so far. We carefully monitor the system and if any county has any concerns they can feed those back to us either through our Games Department or Central Council," added Milton.