The country's highest court has dismissed an appeal by two men associated with a motorbike gang infiltrated by undercover police.
The appeal followed an 2009 police investigation into links between the Red Devils Motorcycle Club and the Hells Angels.
In the course of the investigation, two undercover police officers infiltrated the Red Devils.
When suspicion developed about one of them, known in the gang as Michael Wiremu Wilson, the police took steps to strengthen his credibility.
A fake search warrant, which on its face appeared to have been issued by a court official, was prepared and "executed".