Rodney Hide has laid a complaint with the police over NZ First's failure to declare donations in 2007. The question now is whether the police will do their job and formally prosecute.
Unfortunately, I doubt it. The last time they were confronted with electoral cases - in 2005, over Labour's overspending on their pledge card and National's convenient "mistake" of not including GST in their broadcasting spending - the police dropped the ball and didn't prosecute anyone. The key problem seems to be that they just don't take electoral cases seriously; IIRC one of the detectives assigned to investigate those cases complained that they were a distraction from "real work" like burglaries and murders - the theft of our democracy apparently not being a serious crime in their book. But there's also the problem of the police's natural authoritarianism, which means that when they are confronted with apparent wrongdoing by those in power, their natural response is to sniff the arse of authority rather than kick it. And the result, in 2005, was parties getting away with egregious breaches of the law. While I'd like to think they've learned from their mistakes and changed, given their signal failure to learn anything from the police rape cases suggests that they are institutionally incapable of it. Which means that despite a clear case, once again we are likely to see corrupt lawbreaking politicians walk.