He was given not out by the on-field umpire but Australia called for a review and their appeal was upheld.
Cricket keeps an off-field umpire for boundary calls, and to ascertain whether batsmen are run out, and if catches are real.
Replays suggested Johnson had missed the ball but the rules state that the on-field umpire should be given the benefit of doubt.
They claimed he had edged the ball to wicketkeeper Matt Prior, but Harper agreed with the not-out decision of on-field umpire Tony Hill.
The off-field umpire must find 'compelling evidence' from the technology available to suggest to the on-field umpire that his decision should be reversed.
However, if an incorrect referral is made by either side, they lose one of their opportunities to challenge the decision of the on-field umpire.
The wicketkeeper, slips cordon and the bowler all appealed in unison, but on-field umpire Tony Hill remained unmoved, prompting England to refer the decision to Harper.
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It was a decision that split opinion in the commentary boxes at Kensington when Darryl Harper overruled the on-field umpire Russell Tiffin and gave Gayle out lbw for six.
The off-spinner had already turned his first delivery sharply to remove JP Duminy for seven, caught at slip, and in his second over De Villiers went for a sweep with England's appeal for a catch at leg-slip upheld by on-field umpire Tony Hill.
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As he stormed off the field, he started miming umpire calls, to the delight of the crowd.
If players do not agree with the decision made by the on-field umpires they can refer it to the third umpire.
India batsmen Virender Sehwag, Sachin Tendulkar and Rahul Dravid were initially given not out by on-field officials, who changed their decisions after consulting the TV umpire.
Two umpires officiate on the game from out on the field of play, but at international level there is also a third umpire on the sidelines and a match referee.
Two umpires officiate the game on the field of play, but at international level there's also a third umpire on the sidelines and a match referee.
However, just before he crossed the boundary, the Western Australian threw the ball back into play, regaining his composure before sprinting on to the field to complete a quite outstanding catch, a dismissal confirmed by the third umpire Rod Tucker.
Kluber got two outs in the second inning when play was halted by rain at 9:18 as plate umpire Fieldin Culbreth ordered the grounds crew to put the tarp on the field.
The decision prompted Wilson to protest to the Sri Lanka umpire and West Indies captain Darren Sammy intervened to tell the Irish batsman to leave the field.
The use of the third umpire in international matches is currently governed by the proviso that it is the on-field umpires alone who decide whether a decision needs to be passed on to the replay official.
Plate umpire Vic Carapazza called for the tarp almost immediately, and most Yankees players jogged off the field.
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