Crown lawyers are today attempting to overturn a High Court ruling forcing a spy agency to reveal secret details of their surveillance of Kim Dotcom.
In December Justice Helen Winkelmann ordered "discovery" of documents related to the Dotcom operation. Her ruling also allowed the internet mogul to pursue the police and Government Communications Security Bureau for damages.
The GCSB must sit alongside the police as a defendant as the court continued to investigate illegal search warrants used in the raid on Dotcom's mansion in January 2012, she said.
At the Court of Appeal in Wellington today, the Crown is expected to argue that GCSB should not be joined to the proceedings.
It has already admitted it acted unlawfully by spying on the German-born millionaire. And the Crown is expected to say that compensation is not available in judicial review proceedings.
The case started out as a judicial review of search warrants.
Dotcom's lawyers are expected to reiterate suspicions that GCSB was spying on the alleged internet pirate and his co-accused longer than it has admitted to.
Justice Winkelmann ruled the spy agency must disclose anything it shared with other intelligence agencies in the "Five Eyes" intelligence alliance - made up of the US, Australia, UK and Canada.
Dotcom's extradition hearing has been delayed to August.
The month-long hearing was due to take place in March and now could stretch into 2014 as a series of legal twists and turns play out.