Lawyers for some of the 17 people charged in nationwide police raids are expected to argue that the warrants used to intercept their communications were illegal.
The accused are due to appear in the High Court in Auckland on Tuesday despite the main case being heard in the District Court.
Some of the lawyers say the surveillance used to gather a large part of evidence against them is illegal.
The Crown says because that must be argued in the High Court, the whole case should be moved there.
But defence lawyers say that would suggest the charges, which are mainly related to firearms, are more serious than they actually are.