So here's the deal. There's a big rugby game being played at the park and instead of engaging in the now tiresome "streak" some clown decides (after about seven bottles of the sponsor's product) to drive his car from one end of the playing field to the other ... weaving like an elusive winger all the way.
So he gets thrown out of the park, but would he also get arrested for drink-driving?
He could argue that no, it's not a public road ... but the NZ Transport Agency regulations simply refer to the situation as "you must not drive if you have consumed more than the legal alcohol limit".
So the great and sober hand of the law would more than likely tap the miscreant on the shoulder and say, "you're nicked".
But then he could argue that what happens on the field should stay on the field, pointing out that three minutes earlier the prop on one side delivered a sly left hook to the head of the hooker on the other side ... and all he got was a yellow card.