In what is believed a world first, the third umpire is able to be consulted, where television replays are available, on all decisions except leg before wicket.
The system was first used at the weekend in the Shell Super Max league tournament in Christchurch. Umpire Chris King called for assistance during the Auckland-Northern Districts match to help clarify a decision. It involved uncertainty over a caught behind appeal where there had been a sound as the ball went past the bat.
The fielders appealed and subsequent replays showed that bat had hit the ground, not the edge, and the batsman was given not out.
The move is being trialled in televised Max matches and if successful will be used in Shell Cup fixtures.
National umpiring manager Brian Aldridge, who instigated the move, said the aim was to assist umpires.
``If people in their living rooms can watch replays a few seconds later and decide whether it's right or wrong then we feel the umpire out in the middle should have the benefit of that help.''
The third umpire is used internationally already to help with run outs, stumpings, hit-wicket, and boundary-line decisions.
Aldridge said the issue was highlighted for him during the previous international season when replays showed a couple of decisions made were palpably wrong.
He also mentioned another incident in the England-South Africa test series which was crucial in the series outcome.
England opener Mike Atherton was given the benefit of the doubt when replays clearly showed he had gloved a ball off South African paceman Allan Donald and was caught behind the wicket early in an innings. Atherton went on to score a match-winning century for England to then square the series.